Very interesting. Just the bare facts, and the truth. Some comments will never be worth the time of day. There will always be trolls out there spouting off just to get your goat . Ignore them, don't respond, and block them. You definitely know what you are talking about. Mike
I was watching a previous video you did the other day where you talked about using 1.150" compression height pistons. I'm interested in building up a performance 500 cid Cadillac engine. Stock stroke is 4.304". Deck height is 10.814". If I were to use a 1.150" CH piston, the rod I would need would be 7.512". With a 4.500" custom stroker crankshaft, I would still need a 7.414" rod. At this point, would you recommend a taller piston or could a custom rod that long be had?
Sure, but you can also say, pick the rod you want then get the piston and crank to work with them :) They are all part of a system. Piston shape, rod material, engine purpose, cost all are factors in what you go for. The "best" way for me is decide the purpose, then money you can spend, then build all of it to that.
@@TN_Country_Boythats not all of it though. The shorter the rod the more rod angle there is, and you are correct. There is a caveat to that though. The higher you push the pin toward the piston crown the less skirt there is available for stability by most manufacturers. I tend to keeping the oil ring away from the wrist pin and try to get as much skirt as I can while using the longest rod I can comfortably use without pulling the skirt past the cylinder guage point. Thats why I try to stay away from stroker kits for that reason alone.
Before I knew anything about rod ratios, I built a 2.5L 4cyl Turbo Dodge and made 380whp at 33 lbs of boost. I didn't know at the time but it was a 1.47 rod stroke ratio. I guess that was a bad ratio to alot of people. But I raced that engine for 4 years and never had to mess with the shortblock the entire time. It made incredible power and torque for an old 8 valve parallel flow head engine. It was running great when I sold it, and it's still probably running great. I just did it because it was what I had to use and didn't know anything about "good or bad" ratios. I like engines I don't have to tear down and service on a weekly basis, and it is even better to not have to tear into them even every 6 months. Once a year refresh is acceptable and now that I'm older I pull them apart annually just to check them for peace of mind and preventative upgrades......😁
Thats sweet numbers, I was a mechanic in the Dodge turbo era and loved driving them. Friend had the (bought new) Daytona black with the gold accents and gold rims with all the circles in them and would smoke most things in the day and was a great looking car. Just had to hold tight of the steering wheel. Must not have been many of the later years as I can find pics, but they are not exactly what he had.
Long rod / short rod is subjective of course to stroke. What makes power, ring seal! So for a give bore size get the ideal ring package and support/skirt sorted, then magically you end up with the best rod length for the application! Great vids 👌
The problem is long rod combos usually push the ring pack & pin up, which will impact all those things. So this test is representitive of the vast majority of those builds.
First let me preface this with a little background. I have over 32 years designing and developing engines for Chrysler where I was responsible for performance, fuel economy and emmisions. I agree with the conclusion that rod length has no material difference in performance within a reasonable range of course. However I disagree with the analysis of the data. Rocking the torque curve in this way is a clasical indication of a cam timing difference. I undertstand that all efforts were made to make the short blocks as identical as possible except for rod length and apparently based on the discussion pistons (though that was not actually discussed in the snippets of video shown). Cryslers NATCC (race) engine showed a 10 hp difference witha 7 degree (crank) shift in cam timing at 300 hp max. This suggest a slightly less than a 2 degree crank or 1 degree cam timing shift was responsible for a 1% shift in power. Set cam timing exactly is extremely difficult and tedious and given the uncertanty in finding and setting TDC and variation in sprockets and chains a 1+ crank degree difference is not unlikely. This is not a knock on the mechanics I have seen them do it and I have done it myself. This conclusion is also supported by the fact that peak torque and power both occured at higher engine speed with the shorter rod. A secondary though lesser effect is ignition timing. It was stated that there was no difference in performance with the long rod with ignition timings between 34 and 38 degrees indicating MBT was ~36 degrees and for the short rod 40 to 42 degrees therefore MBT at 41 degrees or a 5 degree difference. This is required due to the shorter piston dwell time around TDC for the short rod. As a result there is much more burned gas compressed over a longer period of time for the short rod leading to much higher temperature and pressure. This results in increased heat transfer reducing the energy available for making power. this effect is exacerbated at low engine speeds due to the longer period of time (per crank angle) for this to occurbut becomes less of an effect at higher engine speed. Thus this also hurts the short rod's low speed torque. The piston and rings quality should only be maifested only at higher engine speed and doesn't explain the low speed torque difference. This may, however, offset the heat transfer effects leading to similar torque differences at both low and high speed. I hope this makes sense and helps in understanding the data better.
@@RamPenndragon Well sir I'm glad you have an extensive background working for Chrysler. Let me just say I think you totally missed the whole point of the video. So to be clear the video is about people who are not pros who are chasing connecting rod ratios. To that category of people this is confusing and it is also very misleading. I don't know why about five people out of 2000 continually try to give me some technical lecture because trust me I can spit it right back. It's about preventing people from chasing connecting rod ratios and making a big mistake by running a ridiculously long connecting rod with a ridiculously short compression height only to have problems later. That's what the video is about, that's what the first video was about too and I made that extremely clear. Trust me I know the science I could write a book on it. But that's not what this was about. I understand the science and at a later time I will get into that as well but I have proven and will continually prove and have proved it for 30 years proving it, and it ain't worth risking a super short compression height just to get a super long rod in an engine because the benefits are not worth that. Anything a short rod can do better, I can correct with a camshaft and anything a long Rod can do better, I can also correct with a camshaft. But to be even a little more thorough I told people in the video that this thing has BEEN examined and examined and re-examined with hundreds of camshafts on different connecting rod ratios and the bottom line is and, it doesn't matter who says differently, the bottom line is you want to find a long enough rod to cut down on angularity but also a short enough rod to maintain stability. that is the end result because no matter what rod you put in, I can correct any downfalls about that rod with a different cam grind and to be a little more clear than that, not necessarily a different cam grind but different ramp speed of the cam by changing how fast my intake valve opens and closes same for the exhaust. So I'm not sure why people want to challenge me on this connecting rod ratio stuff I felt like the video was extremely clear as to the intent behind it. Any benefit you may gain from running a short rod which has a faster departing speed from TDC I can totally negate it with a Long rod and valve timing choices so the point is mute. I've done it. I do NOT AGREE with a lot of things that engine Masters has done but I thought this test was very well done and it corresponds with everything that I personally have done and it also corresponds with test that I know the top names have done. It is a fact it, is a 100% fact, and if you take any engine in the world with any connecting rod length You choose and you tune it with any camshaft, any induction system you choose and you make that thing the absolute best it can be where you can't squeeze another ounce of power out of it, and then you take the exact same engine combination but a whole different engine and install a longer rod in it than the one you did prior and this time you can tune it any way you want to and you can change the cam if you want to, I guarantee you 100% I will match the other one torque and horsepower output 100% tit for tat. And that is a fact. Not at any time did I ever say you have to run a really long rod and not at any time that I ever say you should run a really short rod. I said a properly built engine that will have a little longevity you should find the best between the two. If you don't believe that then you did not listen to my videos all the way through from front to back. Thank you for your comment.
@@SalterRacingEngines Please forgive me if I was unclear. I agree with you and the originators of the video you presented that chasing rod length is a waste of time given other more fruitful performance enhancing options available.
@@RamPenndragon I like your point about cam timing. Rocking the torque curve counterclockwise on the short rod engine with a retarded cam seems like a possibility. I wonder if Engine Masters did a sweep with different cam timings to optimize that on both engines.
@RamPenndragon I didn't pick up that you were saying he was wrong... but that he was using a test to prove a point, but the test itself was a bit dirty, which is an absolutely fair point to make. This video can be used to convince the inexperienced that the results are purely due to the rod length, but your logic 100% checks out. If anyone gets upset or offended by that they're missing your point.
@@joncot1812I'm not really sure by your comment who you're talking to but the basis of my videos is not to push a rod ratio or a rod length. So I'm not understanding why all of a sudden how they've done this test and that test and they try to throw up all these rod ratios and angles and all this math that I could recite in my sleep. My videos and I've said this many many times are about Not I repeat Not to chase rod length but that piston stability is far more important then installing a super long rod. I don't think anybody who seriously listens and watches both my videos can say anything different than that. No matter what rod length you choose the Piston is the bigger influencer. A light piston will recover faster pulling up through the RPM range and a heavy piston will have a lot more inertia at higher RPMs. Which this video clearly proves and that ring stability due to piston stability is far far more important not just for horsepower but also for longevity. That's been the whole point of my videos. That's why I'm not understanding why people are coming and giving me these long lectures about ratios and percentages when it has absolutely nothing in the world to do with that. Anybody would consider a 5.090 rod short but yet in context in a 302 it's almost at 1.8 rod ratio. So rather than write a whole book here as a comment I would much rather tell people to quit chasing rod ratios and get a good solid piston and connect it to the crank. No one can watch my videos and say that I am pushing a particular rod length because I am not. I am neither pushing a longer rod nor a short rod. I have defended neither rod. And I promised at the beginning of this RUclips endeavor that I would never say anything that I cannot 100% prove. Trust me everything I tell you I can prove. Which one of these rod lengths will have better emissions the 6-inch rod for the 5.990 rod. Because one is definitely longer than the other so there should be an impact according to some people.
Thanks for doing this video. I went from a 6.135 rod to a 6.385 and different compression height pistons because of counterweight redesign by previous owner. Its nice to know it wont make much difference. Also glad I had it all balanced.
anybody trying to argue w you is absolutely comical. like David Vizard says "I DONT HAVE AN OPINION I HAVE A DYNO". its kinda hard to argue with a dyno ya know lol. i thank you for sharing your knowledge yet again. you are def my fav engine builder and channel to watch. take care and stay safe. where im at in pa is supposed to get hit by Debbie as well. Buffalo got hit w a tornado yesterday in downtown Buffalo which NEVER happens. I cant thank you enough Brian as im learning alot from you my friend. take care
@@peterhart4301 everybody makes mistakes as were only human. i agree, if you dont make mistakes you arent trying hard enough. especially when starting out you def expect to make mistakes as its inevitable. a dyno is a tool to be used in conjunction with knowledge and experience and your goal. which in turn will help you determine your next move. the rod vid is perfect really. some may argue their opinion on rod lengths but the dyno doesnt have an opinion. it tells you cold hard facts. just because you think something is better the dyno will tell you the facts when testing your theory. your experience will tell you whats more reliable as well as what is actually critical. just like cams as well. most say lca isnt critical but it is. the dyno proves that as well. get a cam on the wrong lca and you will lose out on power. one will always make mistakes but the difference is most dont learn from them. im trying to learn myself as ive never built an engine yet. im trying to learn from proper teachers and currently researching. i usually try to find the best to learn from. you can learn from a hack though too. they def teach you how not to do something lol. take care and good luck w your builds.
The primary consideration for rod length wasn't even mentioned in this video. Not my opinion. I do have a dyno. Rod length determines piston speed. Piston speed determines the force applied to everything in the bottom end including oil. Should you stress over known combinations that people have been using for 50 years? No Like everything in a system each component has an effect on the surrounding components. There are no big gains at the thin edge of the wedge. In my dyno owning opinion understanding the fundamentals is really quite important.
@@jdoe9518exacty, bro! The slower piston speed makes less wear on many parts. Pistons, rings, wrist pins and the oil itself, will protect longer. Great comment!
I tend to design my piston first, short compression height for NA engines with ring pack high, then use whatever length rod connects them. Of course Nitrous or supercharged gets a thicker, heavier piston with a lowered ring pack and taller compression height. Then again, whatever rod connects them. I do think a longer rod creating a 1.6 to 1.7 rod ratio might be advantageous for N/A max-build efforts. Lots of different engines and ways to go about things. Thanks for sharing. It's fun to talk about different concepts.
Yunick used to have what he called his "Long rod engine" and his "Short Rod Engine". Depending on application he would install a certain engine. On short tracks he used a long rod engine. On long tracks he used a short rod engine. Period with no explanations Now I know why.. THANK YOU!
I'm so glad someone else is finally getting the word out on this. Thank you. I used to chase these 10 numbers here and there. I was one of those who was concerned with rod ratios. It took some time for me to stop doing it, and I'm talking almost 5 to 6 years worth of wasted time. Tom Nelson said it himself, "Why chase 10 numbers at the cost of Ring Stability?" He advised keeping the oil ring land out of the wrist pin location. Dont pull the skirt of the piston past the guage point of the cylinder. I started doing those two things and haven't looked back since. Reliable power is more valuable than Unreliable power. Stopped chasing the rod ratio and it allowed me more time to focus on things that matter like Port Matching, Crankshaft Balancing, and the biggest time saver, Clearancing issues.
My uncle Lu taught me that CH. He was a locomotive lead mechanic and street racer. I love FEs myself. My po boy 427 was his favorite. I got a D4TE block out of a new truck that was totaled and had it soniced and it could have gone to 4.13, but I kept it at 4.125 because I could get a 1.150 gas ported piston. The crank was a 410 crank from a 67 Mercury and it was great for lightening and balancing. The Rods were 7.015 and just a small radius on one side to match the crank fillet and it all balanced perfectly. I think they are really tractor rods, but they polished and peened great and had 7/16 bolts. I put all ARP hardware in it and a set of early tall ports heads, I cut the head bolt bosses as much as I dared and put 5/16 intakes with 2.15 heads and 11/32 exhausts at 1.6 with little porting. The chambers were a lot like Yates chambers that I radiused and softened. That engine when I built it in 1999 was after289s and Cleveland’s and I did this for the fun of it. It still runs great and pulls hard to 6800and right on to 7500. When I changed my pan from my home made one to a Canton big pan and pickup with baffles, I inspected the bores from underneath, and they were all perfect. As soon as the beehive springs came out, I matched them to my can and man it revs like a 289. 9 qts and baffles and 85 psig oil pressure and no blowby. I lost most of my sight and can no longer drive, and my son is afraid of it. My wife doesn’t like the straight 3 in X pipe and ragged idle exiting in from the rear wheels. It’s in a 65 Galaxie with all of the NASCAR spring adjustments and a 15 gal RCI cell with -08 lines and a 3310 downleg 780 like the 425 hp L78 396 Corvette . I want to drive it so bad. . But I had it wired with relays and spade fuses. After I lost most of my sight from the skull fracture at work. I went out just to start it and the wiring panel was gone, cut out. No ignition. 1999- I know it still runs and it’s a real badass. Alas. I ll keep it till I die. That car is a 3850 lb barrel of monkeys. But I have driven too fast, so God knows what is best. A po boys 427 FE, the funny thing is it’s 1.75 to 1 r/s. I wasn’t even thinking about it. Just my uncle Lu RIP , and my honorary uncle Salter. lol. 😂
Good stuff! Great way to defuse the argument with REAL data and common sense gained from experience behind it. Love the fact you aren’t selling us on anything but educating to keep us out of trouble due to buying marketing hype.
I love your knowledge and that you share it. I put a 6.535 rod and a cmp hight 1.270 with a 4" stroke crank on 454 bbc to get the top of the piston .005 out of the whole. I was following david vizard quench info. He also specd my cam and I very happy with the performance. Have great day. Can't wait to see more of your videos solo or with DV.
I always thought the primary reason some choose to go with a “long rod” engine is to reduce the stress on the rod bearings and the angle of the rod during rotation, while also getting a touch more RPM potential up top. My interpretation has always been that the long rod setup provided a marginally more optimal condition for a racing engine that will be seeing high RPM’s. Never really thought people viewed this configuration as something that can give you more/less power or a meaningfully different curve. Even at the same power level, I think there is a case for the long rod engine still having mechanical advantages for a racing engine. Less wear on the bearings, straighter rod angle throughout the combustion cycle (thus less load/wear on the piston skirts), and a happier engine at the high RPM’s. Prob not worth changing a perfectly good short rod to a long rod, but it still seems like a good option for someone doing a full build from scratch. Any extra margin of safety and/or less wear seems like something worth considering.
You're absolutely correct and I said that in the video my video purpose is to tell people not to get caught up in ratios but to use the longer rod just don't get a piston that's not stable because now you're going the wrong direction. But yes you are correct in what you said
This is a great video, but one thing perhaps not addressed, however, worth mentioning, is that short versus long rods are actually all a relative term. As to what constitutes a short rod versus what a long rod is considered, etc. Here in Australia we have a Holden 308 V8 that is essentially for all intents and purposes nearly identical to a 307 - 350 Chev. And what we consider a long rod in these engines when we stroke them to 350 cubes is a 6 inch rod. Which will at that length - for the correct pin and comp height piston, is considered a long rod - and will actually outperform the shorter version in every metric, which is either 5.7 inch or 5.85 inch. Considering these Holden engines are near identical to the Chevy, which both of the rods shown here would be bigger and bigger again, you can see where there is somewhat of a nice balance at a specific length zone, then there are diminishing returns so to speak by going even shorter again. We would consider both of these lengths shown to be long rods compared to what we use. Length is all relative, and perhaps even more prudent given that as Salter has said, it is effectively pointless as your piston choice dictates what that length will be. And that's the exact reason we are only stuck with those rod length choices, due to off the shelf piston height sizes that offer bang for buck, without spending huge money getting custom made CP's or similar. Which would then require more expensive rods too at the correct length to connect them to the crank. As long as your rods are of a high quality and a good cap and bolt, you're good to go whatever the length.
i was thinking something similar too, got my hands on a solid '54 ford that still has its original 239 inch Y-block, has a 3.1 inch stroke, a 6.3 inch rod, and a compression height of 2.8, with only 7.2-1 compression. it really stuns me that ford builds a combo with potential to rev right from the factory, just to go stroke their cranks and shorten the rods 1 year later. i wanna punch it out to 3.80 inch bore with a .2 inch lower comp height and make it rev like a 302, but on the contrary, it would just be easier to boost it with the compression it makes-along with the added benefit of stability with the stock long piston, dont got the 4 grand to dump into mummert cylinder heads in order to gain 2 points of compression max, the stock '54 head has a huge combustion chamber too, the quench is literally all of it, thing just eats timing advancement and loves it.
Everytime I see Freiburger, I can't help but chuckle just a bit. He and I both worked for Chris Jacobs (Jacobs Electronics) in Los Angeles back in the mid 80's. Many an hour were spent joking around about 'death burritos' and the mercilessly incompetent who would call in their quest for ignition information. Though he was never really a gifted auto genius, he WAS blessed with a sense of humor and gift of gab.
I agree with everything presented in the video. I guess this is more of a question, or I'm just seeking Mr. Salter's comments on this particular matter. For a little background, when I was younger, I worked in an engine machine shop, and a good customer raced a Chrysler 225 "Slant Six" in a local dirt oval class (they had a one-off class for American straight 6 cylinders), and in stock form, these had a 4.125" crank stroke with a reletively long 6.7" rod length and a funky type of piston. Of course with their small valves and ports, they had a very narrow window of RPM where the power came and went! The customer did have several big valve/ported heads to use, but our builder explained that with the long stroke, and the long rod combined, it took X amount of crank degrees for that piston / rod assembly to swing "over the nose" from one side of TDC, to the other, and thus was very "lazy" for that type of racing. He substituted the 6.7 rod length for a 6.0" length and had custom pistons made for the application. Of course with the bigger cyl. head and all the other go fast parts (cam, intake, carb, header, etc), this thing really did wake up! I just wonder if this is something you would do in the same situation? Thanks for the great vids!
Yes very similar. I only gave a couple main reasons in video I didn't go into great detail because the video is already getting long. I have built a lot of engines and some of them were weird engines that most people would never attempt to race. I have tried all kinds a rod lengths and I have come to the conclusion that I don't care what rod is in the engine I can make it run. But I am also found that that piston is so very important and there's just too much to talk about in that subject matter and just a 20 or 30 minute video. But it boils down to get the Piston you want and I say that loosely because most people don't know what piston they want. But in the end don't sacrifice stability for a particular rod ratio. And I mean the difference is only a .100 or .200 of an inch that right there you can make all the difference in the world.
1000% agree with you👍 Seems like forever I’ve tried it to tell people that ridiculous long rods are not the answer! Because it f’s ups your ring package, just like you said. Victory Library, and others just don’t get it, they’ll rather argue with math not real world testing. Ken Duttweilers SBC in Poteet&Mains streamliner uses a 5.7 rod! WTF
So you build a 375 stroker with 5.7 rods the shake on 350 sbc with crank throwing rod into side of cylinder and 1 sided wear and side of piston skirt breaking means nothing right
@@alonzahanks1182 okay can tell you that we have 2 SBCs with 5.7 rods. The 383 we have is clocking right at 200K, it’s in a C20 C6P that weighs 5100 lbs and hauls and tows a 7000lbs trailer. Never had any problems with the engine, was careful built with quality parts and very accurate balancing. It doesn’t shake at all, but the exhaust is loud! Every oil change the filter is cut open and carefully inspected for any metal. The 400 is in a bracket car that’s raced most weekends, has 5.7 rods housed in a Dart Little M block, Scat rotating assm. Dart heads, Crane SR, bowtie intake. Was professionally built in 2009, been in the car since then. 640 hp runs 9.40’s all day. Has been freshened twice new rings, light hone. Goes through traps at 7600 rpm, skirt wear 0.
The bee stinger flosser is 100% correct. Believe me I heard it all and built many competition engines from motorcycle to automotive. Four cylinder to V12’s. It’s all about bottom end stability. Long r😊d get a higher decked block. Simple. 🎉
You might have a crankshaft with lower stroke. rod is getting longer bore the seme deck the same displacement is smaller. RPM will be higher als exeleration of the pison is lower at the same RPM. At the same RPM ste soeed of the incomin Air is lower and depending on the airftlow You get e little bit more air in the Zylinder aand You get a little mor power in relation the the displacement. In the end You get schort stroke and bib bore and high APM out of the same block, but You get less displacement and an lower evarage Spee of the piston. If You want to keep the speed of the piston konstant bei higher RPM then You end up with higeher Ayileration of the Piston, because there is less time to reach maximum speed and zero agein. Forces grow rohghly with ( 1/ RPM) . Of cause the bore to stroke relation has beid effekts on the engine and this rpd ratio ist only one of the effekts....... Perhaps You remember Formular one motors from BMW, where the had 1500 ccm turbocharged. Teh block was always an old block that was used, and had already a lot of themal cycles.. the original blocks were used in street cars, and had much more displacement hand much higher Stroke! and therfore the relative lenth of the rod was much schorter!
I'm retired now, but I had a few customers wanting 396 ci sbc engines. They definitely had low friction with those 1 mm ring pacs but most did complain about oil consumption. Valid information 👌
I think all the long rod stuff came from Smoky Yunick back in the day. I plotted out the difference for our hemi and didn't see a lot in it. You get a bit more dwell near TDC and a bit less around BDC with the long rod and the opposite with the short rod. Around mid stroke the short rod piston moves slightly faster. It's something that might be useful if you are in an unusual situation.
I have been arguing this same thing for years! I have no dyno, or any other high tech stuff! Just a hot rodder with a great machine shop behind me that I used since high school!! Thank you for backing me up!!
Great video and your spot on with what you're trying to get across. I was always a big fan of Reher-Morrison Racing. Especially during the mid 70's and into the 80's even though I was a Mopar guy. I met them at the 1982 Summer National at Englishtown NJ. They were so out going Buddy Morrison, personally woke up Lee Shepherd from a nap Lol To make him sign my girl friends son pictures they used to hand out. I'll be looking forward to future videos, and you honestly answered questions I had about rod ratio. I want to build a 327 Chevrolet for my Camaro. I had one back in the day in my 68 Nova SS. Great engine and man you could buzz that thing in the higher rpm range, with the solid lifter can I was running. Thanks again and again great video...
You're correct, the weight of longer connecting rods means more parasitic drag, and therefore a slight loss of power. The world of racing is a little different than the world of the workday commuters, I'm no longer trying for 1st place, I want to get to work every day of the week.
Bobweight is Bobweight. If the rod is a little heavier because it's minimally longer, yet the piston is shorter and weighs less, the bobweight can be the same. Often times it's even lighter. The crank will never see it. Parasitic loss from a heavier rod? No. Not even with a heavier bobweight. Nor will power increase from a lighter one.
I thought that blowby would be good to know. Could indicate problem with ring seal on the long rod engine. But maybe there would be variation in ring end gap between the two engines that would make the comparison moot.
The best quote I ever read on the subject was from Reher and Morrison. They said the piston and ring design was much more important. So pick your bore and stroke, design the best possible piston and ring package (ring size, design and spacing, pin size and thickness, skirt design, etc) and the best rod length is whatever connects that piston to the crank!! With the unimaginable budget they got to play with in the NHRA Pro Stock ranks, if there was even a LITTLE extra performance to be found they would have been all over it!!! I've since heard several VERY prominent and successful engine builders say pretty much the same. "He flosses with a bee stinger"......THAT was a good line!!!
I had an engine builder tell me that he puts in a piston with 1.50" compression height, which is plenty enough to give good stability to the rings, and then finds / orders a set of rods as needed. In other words, he works around the piston height when possible. If a customer just demands a big enough stroker (such as a 347 inch small block Ford 302) or a 427 version of a 351 Cleveland or Windsor Ford), then he builds what the customer demands (the customer is always right). But whenever he has the option, the piston comes first.
Evolving in my experiences with the Fords of the 60's/70's, well, they all had the thinnest cylinder walls of anything I worked with. It's no wonder those engines didn't perform better. At the time, the Duffy's style piston was what was a favorite. They were very lightweight and that's the reason they were the favorite but hard on the walls. Eventually, I moved to a round skirt even though they were significantly heavier. I did this just due to the loading of the walls and less rock. I played with skirt tails, finding those to be a plus back then. I'd seen shops cut the bottom of the skirts off in their Drag engines but like one poster stated, I said nothing as someone's gotta loose the race. But like you've found to be true, it came down to stability and spreading the load to secure the ring and walls, giving the ring to do its job. I'm not sold on the cam shapes I've tried based on visible wear but that's another subject. Fords blocks were/are terribl from the era. A good fill, helped but the round skirt made them run their best. Fords development found the best for the round track C/D to be 1.74. It was all about piston stability and reliability. Rod length was moot. Learned the same in my experience then. Again, it was stability. Forget the rod.
Look at the evolution of the Ford 302 piston over the years from the factory. They finally got it right. Would have been better to keep the rod length of the 289 and tool up for a shorter compression distance piston. But it must have been cheaper to go the other route. I run a roller 1970 boss 302 . I switched to a 5.4 inch rod and shorter piston. There's a marked improvement in acceleration and breaking of the engine.
I like the 1" compression height in my 400sbc builds (3.75 or 3.80 stroke) to keep the reciprocating weight down for our bracket cars. I do run pan evac to attempt to help with ring seal. Last one made it 550 passes before it cracked a piston. Before he retired John @Mahle had told me to try their higher end gas ported pistons. He felt that the 1mm ring and gas porting would help with the ring seal on the short skirts. Just finished a shortblock with them in it and hoping to dyno this fall. Drop it in for next season. Fingers crossed I learn something from the experiment.
Spot on with this being a controversial topic. You have to consider the overall engine design before coming to any conclusions here. In this case, they were working with the big block Chevrolet which inherently favors shorter rod ratios in comparison to lets say Chrysler and Ford. Why? Might it be the difference in cylinder head design and flow characteristics? Now, the small block Chevrolet was a completely different animal insofar as it actually responded well to a much higher rod ratio (1.90) in Trans-Am racing. And then there's the saga of Bob Glidden making the switch from Ford to a Chevrolet Monza back in the day running a destroked BBC to keep it under 400 Cubic Inches back then. The thing wouldn't get out of it's own way and Glidden failed to qualify in Pro Stock with the car. Needless to say, he got rid of it in exchange for a deal with Mopar running a Plymouth Arrow using the 340 small block platform for power. That combination went onto be undefeated while he ran it. Back then, Glidden had been running the 351 Ford Cleveland, which responded favorably to higher rod rations up around 1.8:1 and my guess is he tried that with the Chevy Rat Motor, which didn't like it, particularly running a shorter stroke and state of the art Pro Stock heads back then. But then when he switched to the little Plymouth Arrow and small block 340, again the longer rod ratios brought favorable results with the Mopar. If you go back and make comparisons between the approaches the big three auto makers took with cylinder head design, crankshaft strokes and connecting rod ratios you'll find there's distinct differences that when taking them into consideration can make substantial differences in performance..... The lesson in all this is, what works great for one doesn't necessarily work for others. This goes to show it doesn't matter whether there's a bow tie, blue oval or ram affixed to the valve cover, they'll all run strong if you simply take into consideration what you're working with....
The problem with Glidden's Monza was not rod ratio. It was a mis-timed distributor. At least that's what I read about it in Car Craft back when it happened. Then John Lingenfelter came and bought the Monza from Bob.
@@andyharman3022 Mis-timed distributor? You read that in Car Craft? Mmmmmm. Might the author of that article been kidding or joking around. I have to admit in all honesty, my conclusion has been speculative in nature. However, it's difficult for me to comprehend the notion someone of Bob Glidden's level of success wouldn't understand how to time a distributor..... I've dealt with numerous freelance and staff writers of a number of car magazines and discovered there are those who were, lets say more technically advanced than others. Some loved to cover successful race operation with a whole lot of fluff with witty quotes and others were more into theories and the R&D side of things. Marlan Davis who wrote many technical articles for Hot Rod Magazine was one such individual. Marlan went onto advance to chief editor of that magazine.
All I ever read was the longer rod produced more torque and HP over the entire engine RPM range! Now I see there's really not enough difference to worry about rod length! I really appreciate and enjoyed this video! Keep up the good work!! Thanks
I was jamming to some White Zombie and this video popped up. Haven't seen it yet. Thank you for having some rocking tunage to inspire me to watch this video because I definitely have my opinion. My opinion is that a longer rod helps alleviate side throw imbalance. Therefore the rotating assembly is spinning smoother and is happier! Ok, now to watch the video!
The thing that gets me is that people have a tendency to want the "perfect storm" when it comes to engines. Back in the sixties when I was coming up and reading all this hot rod stuff in Hot Rod Magazine and Rod and Custom and so on and so on, it was the mantra that my engine has more horsepower than yours (of course the automobile companies propaganda kept that stirred up). As a teenager I wanted an engine that would do anything in any application, would snatch the front wheels off the ground at just the touch of the throttle and would want any new product that would guarantee instant power. Well in the real world that is not to be. I have learned one thing and that is the internal combustion engine is a programmed piece of equipment, and that programming is mechanical. Now grant you we have through the computerized technology we have today the ability to electronically tune engines to be at their maximum efficiency but when we fool with these racing engines and such it is still a matter of cost and reliability. A person is going to have a racing engine then build the engine for the track, a person wants a higher performance street engine then build an engine for the street, but there has to be a compromise. Your point at the end of this video drives home what any professional racing operation knows and that it is a matter of cost.
Your frustration is understandable and would be considered restrained for me! I often write things late at night, then my eyes pop open in the AM and I think "crap! I sounded like a real jerk and didn't communicate my point correctly, and now I see what they were trying to say!" My brain tumor makes it to where writing this takes many revisions and so far this has taken 2.5 hours and a migraine. Thanks for the info and the explanation! I know how to eat crow! I was really concerned about rod ratio when I wanted to build a blown gen 2 hemi, having background in true heavy duty gasoline engines that are pourpose designed for max durability. They haven't existed for 50 years. In that application those that weren't car engine based were way more expensive per HP, heavier and had 2.0 or higher rod ratios and long full trunk pistons with bottom rings. The were clean sheet designs and had unlimited deck height, and rpm was limited to about 2500 to 3600. Even with the same cubic inches and hp their pistons, and wrist pins would live 4 to 5x as long as an automotive type. The 454s were horrible in this application. I saw 5 that put the piston skirts in the oil pans at around 60k miles. A 413 Dodge would go 100+k, a 4.875 bore x 3.58 stroke, 7 inch rod GMC 401 V6 up to 300k. When I called about building my hemi I expressed my concerns and said I wasn't really worried about hp, just wanted to make 4 digits, and wanted reliability. I suggested a 4 inch stroke, 4.5 bore and really long rods. He kept gently suggesting that since I was using a standard cam block to put the biggest crank in it that would fit, "just build a 572, (4.5" stroke, 7.150 rods) it won't cost a penny more, and will require less boost and rpm for what you want. The Hemi has way too much piston above the pin, making it very heavy, it actually benefits from having a shorter compression height to a point, you have enough deck height" so I listened and did as he said. I had had previous misunderstandings about this for modern performance applications. I was looking at the lifespan of a 440 mopar vs a 454 in a heavy truck, or how a supercharged aircraft engine is built. My feelings and reasoning for using short stroke big bore long rod, long piston engines for reliability were completely valid, but like you said taken to an extreme in the wrong application with outdated information. In the 80s and 90s My engines had to be CHEAP, go to the track, lift the front wheels on a $300 newport, then pull 20k lb wagons to the elevator, and get my butt to a low paying job everyday for many years without failing. A low compression 440 six pack did so for 13 years on 87, 2500+ passes, 150k miles, a shelf full of trophies, wore out 2 cars. And while not spectacular by today's standards would push 4680 lb to 13.41 @ 107 in the 1/4. Back then the main thing you ran into was 5.0 mustangs (about 14.2 to 14.5) and IROC Z 305 camaros. (14.75 to 15.2) what you really watched out for were Buick Regal T types. I ticked off a magazine reporter for beating a new porche 911 he was there to write about! , I was on the news at 14 yrs old winning student drag day, built and tuned the car with dads advice and instruction at 12 yrs old. I was the crew cheif and mechanic he was the driver. Chassis, gear set up, building automatic transmissions machining parts, all before 14 years old. We won the street sleeper award at the mopar nationals, and made a perfect run. We dialed that car to .005 second sometimes! Why a rusty newport? Cheap, came with 440, low profile, and if I beat you it's really embarrassing, if you beat me what have you got to brag about? We ran a stock industrial shortblock out of a combine, dad made sure to put the "chrysler industrial engine" tag on top the manifold! One time at the track I went to wipe the soybean dust and oil off the engine. Standng there in his beat up steel toed boots, he said "don't do that son, I want them to know that it's a WORKING engine!" I still have the '68 Monaco we built in 1992. You are very successful on a whole 'nuther level! You are winning races with performance alone in a very competitive evolving field. We were focusing on consistency, and durability, speed was just for fun. Thanks again for sharing and trying to help us little guys thats rare!
Your passion is gr8, love it. Bring on more. The info you bring to the table is invaluable, and i for one am greatly appreciated. Love yu channel, lets 'bee sting some more'.. From the 'land down under'.OZ 🇦🇺.......👍
Okay, GM spent $1 Billion US dollars on developing the LS1 engine platform. One of the most powerful durable and efficient V8's ever built. Rod Ratio 6.098/3.622=1.6836. comp ht 1.340. In factory configuration the LS2 was designed to go to 6250Rpm. From my 40yrs of experience and getting insight from some of the most winning racers this LS configuration will have efficient cylinder function up to 6835 Rpm after that horsepower would drop off over a rod length proportional to desired Rpm. Ford's competition dominating Racing engines the 427 and Boss 302 both had 1.72 rod ratios. The Boss 351, 6250 Rpm limit 1.6514 rod Ratio. One of the negative issues with trying to put too much stroke into a given deck ht is you can't run a long enough rod and piston skirt protrusion at BDC leads to piston cocking and increased skirt wear. There are many considerations to be optimised when trying to achieve more of everything. Great to have everyone's input to learn from each other. 😊
Years ago I found an odd magazine in the magazine rack, of a company that was trying to get their business off the ground. They had some great tech and one of the articled was on long and short rod ratios. The engine builder in this article was working with a Chevy 327 which had a bore of 4.0” and stroke of 3.25” from the factory. They used either 5.7” or 6.0” from the factory. This builder took things a bit farther. He used 5.5” rods for a 1.692-1 rod ratio and ran them against a 6.5” rod for a 2-1 rod ratio. The builder took care of to get the rotating assemblies to weigh the same. The same block, was used for both combinations, but the heads differed. I’ll get to why in a moment.everything else was the same. The two combinations were tested with aftermarket heads which breathed well performed better, but by a slim margin. Then the builder put a set of small valve factory heads on both builds and measured the difference. With a more restrictive heads the builder measured more of an improvement in power than it did with the good heads. Back when you, the channel’s owner was first getting started or at least I was there weren’t any aftermarket heads to be had, hence the belief of old schoolers that rod length makes a difference. Today, there are so many aftermarket performance heads available that most guys aren’t seeing the huge improvements we saw, leading to the belief that rod length doesn’t matter. We also have aftermarket cranks and rods that will hold up to punishment. It wasn’t so long ago the 454’s and 383 Chevy strokers with their short rods were breaking crankshafts. The 454 came with either cast or forged cranks, but not too many forged cranks were available. To buy a reground crank meant paying a $600 core charge because the grinder was having a hard time sourcing forged cranks. For the 383 stroker there were no forged cranks. They had 1.534-1 and 1.49-1 rod ratios respectively. It’s not hard to understand why they broke cast iron crankshafts. One shop, around the corner from the warehouse I worked at had a pile of scrap 400 cranks in their recycle bin. Back east at the Marina my friend worked for and now owns they use 454 blocks to ties down piers. Boat engine get pushed hard and run lake water for cooling. so in the early days guys worked with what was available. Today guys have so many choices it’s hard to pick the one product they want.
Brother, I'm with you! Plus, engine building will be easier and maybe even cheaper! Not to mention, I'm more interested in maximizing cubic inches! Great video!
I agree with your analysis 100%. I knew a guy back in the early 90’s that came up with this when it was the hot thing to run long rods. He went against the grain. Years and years later I found that old timer was right all along.
I've been building and working on dirt track engines my entire life. I've lived through innumerable combos of rods, pistons, and cranks. Your one statement settles the debates of all of it. Get your crank, get your piston, and get a rod to connect them together. I have always leaned toward a good piston skirt over ultralight weight or compression height restraints. I like using the block more than a few races.
I found this video very informative and relevant, good job man! I also was surprised by the “steady state ” test and its results, great for marine applications as well. Thumbs 👍 😊
The arguments of science with engines can sometimes just boil down to "penny wise, dollar dumb" when it comes to fractional changes. People love to be right = factual while ignoring higher priority wisdom.
I remember guys in street stock using Olds rods because they were longer than SBC rods. We used stock rods and were still wiping the track with them. We had a milder cam, supposedly worse heads and intake, but everything worked together; and we had a great driver and suspension guy too, of course. It would be interesting to see a comparison done in a very short rod engine, like the 400 SBC or the 302 Ford, done for somewhat mild street. The other thing about rod length is the airflow requirements. As the rod length changes, so does the piston acceleration and dwell at TDC and BDC, which can affect the optimum intake, carb, cam and port requirements to optimize airflow for that combination. As any quality engine builder knows, it is all about everything in the combination working together, not the individual parts.
pistons should look like pistons not bottle caps was hard back in the day increasing rod length was about slowing down the speed across tdc to keep the standard piles of junk in the block i really liked this vid well done sir
Seems like you could use the same piston skirt length on both pistons correct? The pin height can just be moved up and down on the same exact piston and have the same piston stability... then the only difference would be R/S ratio assuming one don't get into the oil ring. One thing i would point out is this test they did should be more accurate than even doing twin engines because the entire top end is the same exact top end just different bottom end. One question I'm interested in still is if you have PLENTY of deck height like say a 340 Mopar where you can move the pin up and get an even longer rod in AND still have a very tall piston would you go for the longer rod in that situation,
Yes sir you are right onto the right thinking I can't tell everything I know but that's the right kind of thinking right there. But piston companies don't sell them to people that weigh their special order and you have to be really technical with how much skirt you want the great comment
I built a '62 327 using Smokeys short stroke / long rods (6") and other instructions per his SBC book; it is in my '32 roadster and is the best performing street engine I have ever built. The same engine (a stock 340hp solid lifter) is in my bros 1963 Vette and my '32 327 out runs it by far.
Great video. I learned something. I remember reading Smokey Yunick's power secrets about 35 years ago and he was talking about longer rods. But as you said, that's a different kind of application, mostly high RPM circle track cars that he was trying to get an extra few HP out of. Whenever I get myself some funds to build up a street/strip engine, I won't stress out too much about rod length. Thanks for this. Hope everything went okay with Tropical Storm Debbie.
HRM did an article back in June of 1997 called; The 350 Chevy Should Have Built, searching with this name with help it be found faster than the actual article name. In the article they used a sbc 400 block with a sbc 327 crank to get 350 ish CID. They used a long rod ratio as well, 1.91:1 ratio to make sure the pistons dwelled longer at TDC. The reason for this was to check their theory that a longer rod ratio is less detonation prone. They went with 11:1 static compression with a fairy mild camshaft 215°/215° of duration at .050" and ran it successfully on 87 cat pee octane without detonation on the dyno without removing timing. Right here is the advantage of a long rod ratio. The torque and HP numbers were very impressive for the parts used. It made over 400 lb ft from 2,800 RPM to 5,200 RPM, peak torque was 435 lb ft at 3,800 RPM. Also it made 412 max HP at 5,700 RPM. All this on cat pee 87 octane wirh a mild roller cam. So in certain short stroke applications there is a huge advantage to using a longer rod ratio. Unfortunately they didn't back up their claim with the same parts on a sbc 350 with the same compression ratio with the same cam. But I doubt it would of made the same power using 87 octane because the timing I would guess would of had to be turned down. Plus there is potential of valve shrouding among other things. In the scenario you presented, yes rod ratio isn't really a factor one should concern themselves with as long as the rods are at least the minimum required length for the crankshaft they plan on using.😎👍
@@itseithergonnaworkoritaint7852 thank you for your comment and I always say put the longest ride you can in there after you get the correct piston on any application.
Just my 2 cents worth here. I think the exercise with the rod ratio is to slow down the piston speeds going over TDC. That way one can Rev the engine higher and potentially safer to make more HP up top. Btw, I still have the magazine that the ' The engine Chev Should Have Built ' article was printed. It's not about the power it can make, but the longevity of the engine at higher speeds.
@@randypozdnikoff4099 Why would you think that when they made the peak HP at 5,700 RPM? Also they said what their goal was in the article, it was basically to build a street engine with a factory style cam with all the power lower in the RPM range. And they accomplished that goal and made more than 1 HP per cubic inch, 1.177:1 to be exact to boot. I'm sure with a different cam and intake with the long rod short stroke it wouldn't mind more RPM with the slower piston speeds because of the short stroke but that build wasn't anything about RPM.🤷 You might want to reread it?(No offense)
I have definitely learned something from this. The piston stability factor is much more important than rod ratio or length. Also, Dyno testing, and research means more than someone's theory or opinion. Richard Holdener has proven this many of times. The guy's at Westech know a lot about engines. Either way, it's all great info and good to know stuff.👍thank you.
I'm a fan of long rod length for durable engine, but ford 302 has the shortest rod and it works and a Mopar 318 with a long rod works, you in theory have more leverage on the crank with a short rod, but we are so afraid of how hard the piston is pushing on the cylinder walls, stay blessed, God is good
The problem with the rod length debate is the amount of literature on the subject. 30 something years ago a popular guru wrote a very long article that took a deep dive into the rod length theory. I bought into it. I’ve worked in auto machine shops since 1990. Many friends and family members wanting to build some kind of engine. Soon enough my uncle wanted to build a 302 that would run good. Back then stroker kits and aftermarket rods weren’t laying around everywhere. Stock 400 SB rods were. Everyone building a 400 SB wanted 5.7 rods in them. So away we went. Removed .023” off the rod journals. Narrowed the big ends some .080” and corrected the offset. 4.3L V6 Chevrolet rod bearings. Had the pin bores machined for bushings then found out Keith Black had a hypereutectic piston on the shelf for this purpose. The engine made 412 hp around 6200-6300 and that was all it took. There had to be something about that combo. Nothing else remotely close to it was making that kind of power. We had some very expensive 337 cid at 12:1 that were only making 375-380 hp. So this little 307 at 10.5:1 with those “long rods” had to be worth something. Time just proved otherwise. In current times we have all now seen or witnessed a NA pump gas 302 make 420-430 or more with stock rod lengths. About the only time I have seen rod length become a major issue is when someone takes it upon themselves to engineer their own rotating assembly and order their own parts to save money. People need to be very aware that some of these crankshafts are made with large radius counterweights and while you may have calculated your compression distance correctly for your particular block, the bottom of your pistons may hit the counterweights of your crankshaft. So look into that detail closely. It is generally listed right into the part number of the crankshaft. This mistake has been made one too many times. A conversation I do not enjoy having with a customer. I do subscribe to the 1.150” rule. I’ve seen way too many collapsed piston skirts on engines that were otherwise healthy just short lived for ring seal making them a maintenance problem. I’m hoping to hear some information shared about skirt coatings. I was recently forced to send a set of pistons in to Line to Line Coatings because of the big surprise we encountered after installing a torque plate on a Ford Motorsports block. I do like the idea of reduced skirt clearances. This should stabilize the piston and help with ring seal. My concern is where does this “abradable” coating end up, and at what cost. Does it end up in the cylinder walls and reduce the oil holding abilities of the cross hatch? Does it contaminate the oiling system to a detriment? So many questions. So many topics to discuss.
There is something missing here. The piston acceleration curve vs the burn rate of the fuel charge. They are not identical because the long rod spends more time at TDC and accelerates (initially) slower than the short rod. This is is reflected in the timing difference we see between the two engines. I expect the short rod engine can tolerate a (faster burning) lower octane fuel. Just another variable to consider -----
I respect the time taken to do all of it and thank you for your expertise and showing’ Just a comment on the ( I have been doing this for 30 years ) 😂 I once went to Washington 3 cities” flew from Houston Texas” And the family member to my girlfriend wanted me to do the front brakes on his tundra’ I am a mechanic ( uncertified tech ) 🤣 So I did, took the pads and rotors apart and out we go to the nearest O’Reilly which was like 4 blocks away’ ( lovely towns by the way ) so we left the rotors to get resurfaced and bought the pads, and I got used to using stop squeal on the pad, not on the metal part” so I asked the guy if he could sell me a stop squeal bottle’ Boy he looked at me weird and asked me 3 times what I was saying! Now I’m not from the states but my second language is pretty good; ( now I know he must have thought I was trying to make a sex joke ) so he calls the manager which was a few steps from him and said: the regular: yes sir how can I help you? I asked the same thing, and he said: there is no such thing; I said I am visiting and back in Texas o buy it often’ and here it is: the guy spit the sentence with pride: I have been doing this for over 15 years and there’s no such thing as what you’re talking about’🤣😆🤥 So you all will live the end; time came for us to pick up the rotors which were really bad vibrated ( when they don’t use the right tool while machining ) I told the manager and he said: oh, that’s all right you won’t have problems with that” I made sure to tell him: and you’ve been doing this for over 15 years???? 🫡
The actuap benefit for long rod ratio is sideloading thrust on the piston to the cylinder wall... If running short rod making heavy wear on down the bore and piston skirts, its a sign long rod setup needed.. Ultimately, tue real advantage of long rod ratio, is in high revving extended high rpm run usage scenario like roadcourse where the engine were kept at high rpm for long time throughout whole lap multiple time.... This doesnt matter much on short drag run or highway pulls or 1mile run
The difference between peak torque on the steady-state and power sweep tests is interesting. 1.7% and 2.0% error on the two engines tested. Seems like the inertia factor on the dynamometer test setup should be adjusted to eliminate that. I wonder if that means that every engine shop that gives a customer a dyno sheet from a power sweep is giving them inaccurate data.
I’ve built a couple thousand engines in the past 30 years, more than a typical hobbyist, less than full time engine builders for sure. I learned VERY early in my career that the pistons were the most important aspect of the combination. If you can keep the piston stable in the bore it produces more power and has a greater lifespan. The piston motion directly impacts the ring seal, so again, the piston is a critical factor in ring seal. I primarily build Fords and truly dislike the over hyped 3.400 stroke cranks for the short 8.2 deck blocks because the piston is sacrificed for the fitment. Even a 3.25 stroke in the short deck is typically a terrible piston design, I build them with a shorter rod to allow for a more stable piston. The fools on the internet who have built a handful to a few dozen engines will argue with you to the death on this topic because they went fast for them, but they don’t understand how to build an engine that will be successful in a competitive environment and have the longevity to meet the expectations of the engine combination long term.
Jere Stahl did a lot of testing on this back in the early 70s, he had a great article on his findings. 6.0 vs 5.7 there was no difference in power output but the 6 inch Rod needed more timing to make the same power. Late 90s I built two different 361 b blocks , stroked out to 400Ci (4.125 , .[005 for bore clean up] X 3.75 BBM crank) the Long rod engine used pistons with 1.43 DH, 6.76 length rods by Crower using 2.0 crank journal & .990 wrist pins , Short rod engine used 1.72 DH piston .990 wrist pins and 6.385 length rods both engines used the same modified BBM 3.75 crank, crank was knife edge and coated with a moly coating to help shed oil , heads were a set of old 2402286 max wedge heads , 2.125X8mm Intake valve and stock 1.88 ex size , with 5/16 stem intake port flowed 315 @.700 lift . Intake manifold was Mopar performance Low deck tunnel ram(with port openings welded up and port match to the EXTRA large Max wedge port window) pair of 700 mechanical secondaries. Cam was Racer Brown mushroom cam with .654 lift, 280 @ .050 , stock 1.5 ratio rockers by Harland sharp. Both engines were 1st step tested for 5mins at each RPM level, step 1= @ 3000RPMS, step 2 was 5500rpms 3rd was 7000rpms, after step test I did a sweep test 1st set from 3k-7k ten pulls each, 2nd set 4-8k Continuous rpm test , at 3k and 5500 both engines were with in 10hp&tq , at 7k the SR engine made 10hp over the LR Both engines were pulled 10X each for the sweep test 300RPM per second. LR made 707@ 7300RPMS max timing of 40* all in by 3000rpms SR made 725@ 7500RPMS max timing of 36* all in by 3200rpms. Now a traditional BBM 400(4.34X3.38) with the same cam(ground) and top end made 695HP@7500...... I think a big part that gets over looked in these test is efficiency , both in terms of combo, head flow and cam timing......don't misunderstand me, for the average person it's waste to chase rod ratio.
When GM redesigned the 3800 in the 90's, (the 3800 Series II) they reduced the deck height, and shortened the rods accordingly by almost an inch, along with some other improvements, picked up almost 40 hp, and made the engine smaller and lighter.
If running boost(roots) at low rpm id be worried about detonation. I build mine with short rods and put 10k miles on it on the street and to work everyday. Sold it still running like the day i broke it in. Minis a balloned converter lol. Im with finding a taller piston for stability but to be honest at the time of my build i was mainly worried about dwell time. Blowers give boost now. Regardless of rpm.
👍👍👍 I never thought at the power levels I dealt with that it matter, Thank you for confirming that for me. Excellent show Thanks again, keep up the good work.
You'd think by 2024, in the world of modern NASCAR, F1, drift racing, cranking out reliable mass-produced 20k-rpm crotch rockets like they're Volkswagens that people would have figured out the whole rod ratio debate went to bed a long long time ago. But here we are again, having to explain that rod ratio is a silly datum to build an engine around! I am too young for this stuff to have become lost art 😂
SIMPLY You know your shit. TO share your knowledge, your experience and R&D is a gift to all of us here as we increase our knowledge of High Performance from a Master. Thank you
I recall an article in HRM back in the 90's. Joe Sherman was asked about long rod vs short rod. His reply was the connecting rod connects the piston to the crankshaft, period.
Man! Really don't get this argument! Since the late 70s, the very first thing I considered in a modified engine build was the damn piston! That became especially true when I got into turbo, in the early 2000s! I remember that episode! That was quite a good one! It would have been interesting to see if they still had the same fuel consumption rates during the static tests. I would assume they were pretty close.
Can't argue with that, it the piston isn't stabile, and the rings aren't sealing you're losing power and plying with disaster. That said give me a tall deck height engine with a long rod to allow for a proper piston and engine longevity.
Engine Masters was the show we’ve all wanted for a very long time if you’re reading this comment and haven’t watched it on motor trend I highly recommend it !! And make sure you subscribe to this channel he knows what he’s talking about
THIS VIDEO IS NOT ABOUT RUNNING A LONG ROD OR A SHORT ROD. IT'S ABOUT MAKING SURE THAT YOU DON'T RUN SUCH A ROD THAT YOU LOSE PISTONS STABILITY
Very interesting. Just the bare facts, and the truth.
Some comments will never be worth the time of day.
There will always be trolls out there spouting off just to get your goat . Ignore them, don't respond, and block them.
You definitely know what you are talking about.
Mike
Won’t help with the dollar bills for salters page, but if you haven’t ran a chassis/engine dyno, much less built an engine; don’t comment please.
Joe Sherman did this test with a SBC 400 about 30 years ago...
Watching "my vintage iron "on you tube.episode on piston speed.
So... your watching somebody else's video ?
Perfect explanation. Get the crankshaft you want to use, get the piston you want to use and pick the connecting rod to connect the two together.
I was watching a previous video you did the other day where you talked about using 1.150" compression height pistons.
I'm interested in building up a performance 500 cid Cadillac engine. Stock stroke is 4.304". Deck height is 10.814". If I were to use a 1.150" CH piston, the rod I would need would be 7.512". With a 4.500" custom stroker crankshaft, I would still need a 7.414" rod.
At this point, would you recommend a taller piston or could a custom rod that long be had?
@@brianwolgamot7076 GO AZ!!!!
Sure, but you can also say, pick the rod you want then get the piston and crank to work with them :)
They are all part of a system. Piston shape, rod material, engine purpose, cost all are factors in what you go for.
The "best" way for me is decide the purpose, then money you can spend, then build all of it to that.
Long Rod, less stress on piston skirts Facts
@@TN_Country_Boythats not all of it though. The shorter the rod the more rod angle there is, and you are correct. There is a caveat to that though. The higher you push the pin toward the piston crown the less skirt there is available for stability by most manufacturers. I tend to keeping the oil ring away from the wrist pin and try to get as much skirt as I can while using the longest rod I can comfortably use without pulling the skirt past the cylinder guage point. Thats why I try to stay away from stroker kits for that reason alone.
Before I knew anything about rod ratios, I built a 2.5L 4cyl Turbo Dodge and made 380whp at 33 lbs of boost.
I didn't know at the time but it was a 1.47 rod stroke ratio. I guess that was a bad ratio to alot of people.
But I raced that engine for 4 years and never had to mess with the shortblock the entire time.
It made incredible power and torque for an old 8 valve parallel flow head engine.
It was running great when I sold it, and it's still probably running great.
I just did it because it was what I had to use and didn't know anything about "good or bad" ratios.
I like engines I don't have to tear down and service on a weekly basis, and it is even better to not have to tear into them even every 6 months.
Once a year refresh is acceptable and now that I'm older I pull them apart annually just to check them for peace of mind and preventative upgrades......😁
Thats sweet numbers, I was a mechanic in the Dodge turbo era and loved driving them. Friend had the (bought new) Daytona black with the gold accents and gold rims with all the circles in them and would smoke most things in the day and was a great looking car. Just had to hold tight of the steering wheel. Must not have been many of the later years as I can find pics, but they are not exactly what he had.
I'm rapidly becoming a BIG fan of this channel.
💯
Ditto
Me as well.👍
He's going to grow quick
Me 3
Don't beat up on the closed minded people out there somebody's got to lose the race
@@scottburrell3606 oh this is my favorite comment of all time!!!
@Salty 23:41 erRacingEngines yeah but arrogance & stupid just pisses me off ,I quess cause ya can't fix it
Long rod / short rod is subjective of course to stroke.
What makes power, ring seal! So for a give bore size get the ideal ring package and support/skirt sorted, then magically you end up with the best rod length for the application!
Great vids 👌
The problem is long rod combos usually push the ring pack & pin up, which will impact all those things. So this test is representitive of the vast majority of those builds.
All rods have a tendency to air condition the block when they get neglected..😂😂
😂😂
"Ventilate the block"
I just learned about compression height and what a number is for instability. Finally a number. Thank you
First let me preface this with a little background. I have over 32 years designing and developing engines for Chrysler where I was responsible for performance, fuel economy and emmisions. I agree with the conclusion that rod length has no material difference in performance within a reasonable range of course. However I disagree with the analysis of the data. Rocking the torque curve in this way is a clasical indication of a cam timing difference. I undertstand that all efforts were made to make the short blocks as identical as possible except for rod length and apparently based on the discussion pistons (though that was not actually discussed in the snippets of video shown). Cryslers NATCC (race) engine showed a 10 hp difference witha 7 degree (crank) shift in cam timing at 300 hp max. This suggest a slightly less than a 2 degree crank or 1 degree cam timing shift was responsible for a 1% shift in power. Set cam timing exactly is extremely difficult and tedious and given the uncertanty in finding and setting TDC and variation in sprockets and chains a 1+ crank degree difference is not unlikely. This is not a knock on the mechanics I have seen them do it and I have done it myself. This conclusion is also supported by the fact that peak torque and power both occured at higher engine speed with the shorter rod. A secondary though lesser effect is ignition timing. It was stated that there was no difference in performance with the long rod with ignition timings between 34 and 38 degrees indicating MBT was ~36 degrees and for the short rod 40 to 42 degrees therefore MBT at 41 degrees or a 5 degree difference. This is required due to the shorter piston dwell time around TDC for the short rod. As a result there is much more burned gas compressed over a longer period of time for the short rod leading to much higher temperature and pressure. This results in increased heat transfer reducing the energy available for making power. this effect is exacerbated at low engine speeds due to the longer period of time (per crank angle) for this to occurbut becomes less of an effect at higher engine speed. Thus this also hurts the short rod's low speed torque. The piston and rings quality should only be maifested only at higher engine speed and doesn't explain the low speed torque difference. This may, however, offset the heat transfer effects leading to similar torque differences at both low and high speed. I hope this makes sense and helps in understanding the data better.
@@RamPenndragon Well sir I'm glad you have an extensive background working for Chrysler. Let me just say I think you totally missed the whole point of the video. So to be clear the video is about people who are not pros who are chasing connecting rod ratios. To that category of people this is confusing and it is also very misleading. I don't know why about five people out of 2000 continually try to give me some technical lecture because trust me I can spit it right back. It's about preventing people from chasing connecting rod ratios and making a big mistake by running a ridiculously long connecting rod with a ridiculously short compression height only to have problems later. That's what the video is about, that's what the first video was about too and I made that extremely clear. Trust me I know the science I could write a book on it. But that's not what this was about. I understand the science and at a later time I will get into that as well but I have proven and will continually prove and have proved it for 30 years proving it, and it ain't worth risking a super short compression height just to get a super long rod in an engine because the benefits are not worth that. Anything a short rod can do better, I can correct with a camshaft and anything a long Rod can do better, I can also correct with a camshaft. But to be even a little more thorough I told people in the video that this thing has BEEN examined and examined and re-examined with hundreds of camshafts on different connecting rod ratios and the bottom line is and, it doesn't matter who says differently, the bottom line is you want to find a long enough rod to cut down on angularity but also a short enough rod to maintain stability. that is the end result because no matter what rod you put in, I can correct any downfalls about that rod with a different cam grind and to be a little more clear than that, not necessarily a different cam grind but different ramp speed of the cam by changing how fast my intake valve opens and closes same for the exhaust.
So I'm not sure why people want to challenge me on this connecting rod ratio stuff I felt like the video was extremely clear as to the intent behind it. Any benefit you may gain from running a short rod which has a faster departing speed from TDC I can totally negate it with a Long rod and valve timing choices so the point is mute.
I've done it. I do NOT AGREE with a lot of things that engine Masters has done but I thought this test was very well done and it corresponds with everything that I personally have done and it also corresponds with test that I know the top names have done. It is a fact it, is a 100% fact, and if you take any engine in the world with any connecting rod length You choose and you tune it with any camshaft, any induction system you choose and you make that thing the absolute best it can be where you can't squeeze another ounce of power out of it, and then you take the exact same engine combination but a whole different engine and install a longer rod in it than the one you did prior and this time you can tune it any way you want to and you can change the cam if you want to, I guarantee you 100% I will match the other one torque and horsepower output 100% tit for tat. And that is a fact. Not at any time did I ever say you have to run a really long rod and not at any time that I ever say you should run a really short rod. I said a properly built engine that will have a little longevity you should find the best between the two. If you don't believe that then you did not listen to my videos all the way through from front to back.
Thank you for your comment.
@@SalterRacingEngines Please forgive me if I was unclear. I agree with you and the originators of the video you presented that chasing rod length is a waste of time given other more fruitful performance enhancing options available.
@@RamPenndragon I like your point about cam timing. Rocking the torque curve counterclockwise on the short rod engine with a retarded cam seems like a possibility. I wonder if Engine Masters did a sweep with different cam timings to optimize that on both engines.
@RamPenndragon I didn't pick up that you were saying he was wrong... but that he was using a test to prove a point, but the test itself was a bit dirty, which is an absolutely fair point to make. This video can be used to convince the inexperienced that the results are purely due to the rod length, but your logic 100% checks out. If anyone gets upset or offended by that they're missing your point.
@@joncot1812I'm not really sure by your comment who you're talking to but the basis of my videos is not to push a rod ratio or a rod length. So I'm not understanding why all of a sudden how they've done this test and that test and they try to throw up all these rod ratios and angles and all this math that I could recite in my sleep. My videos and I've said this many many times are about Not I repeat Not to chase rod length but that piston stability is far more important then installing a super long rod. I don't think anybody who seriously listens and watches both my videos can say anything different than that. No matter what rod length you choose the Piston is the bigger influencer. A light piston will recover faster pulling up through the RPM range and a heavy piston will have a lot more inertia at higher RPMs. Which this video clearly proves and that ring stability due to piston stability is far far more important not just for horsepower but also for longevity. That's been the whole point of my videos. That's why I'm not understanding why people are coming and giving me these long lectures about ratios and percentages when it has absolutely nothing in the world to do with that. Anybody would consider a 5.090 rod short but yet in context in a 302 it's almost at 1.8 rod ratio. So rather than write a whole book here as a comment I would much rather tell people to quit chasing rod ratios and get a good solid piston and connect it to the crank. No one can watch my videos and say that I am pushing a particular rod length because I am not. I am neither pushing a longer rod nor a short rod. I have defended neither rod. And I promised at the beginning of this RUclips endeavor that I would never say anything that I cannot 100% prove. Trust me everything I tell you I can prove. Which one of these rod lengths will have better emissions the 6-inch rod for the 5.990 rod.
Because one is definitely longer than the other so there should be an impact according to some people.
Thanks Salter. I appreciate your passion. Keep it up.
Thanks for doing this video. I went from a 6.135 rod to a 6.385 and different compression height pistons because of counterweight redesign by previous owner. Its nice to know it wont make much difference. Also glad I had it all balanced.
anybody trying to argue w you is absolutely comical. like David Vizard says "I DONT HAVE AN OPINION I HAVE A DYNO". its kinda hard to argue with a dyno ya know lol. i thank you for sharing your knowledge yet again. you are def my fav engine builder and channel to watch. take care and stay safe. where im at in pa is supposed to get hit by Debbie as well. Buffalo got hit w a tornado yesterday in downtown Buffalo which NEVER happens. I cant thank you enough Brian as im learning alot from you my friend. take care
@@parkersgarage4216 thank you brother stay safe
@@peterhart4301 everybody makes mistakes as were only human. i agree, if you dont make mistakes you arent trying hard enough. especially when starting out you def expect to make mistakes as its inevitable. a dyno is a tool to be used in conjunction with knowledge and experience and your goal. which in turn will help you determine your next move. the rod vid is perfect really. some may argue their opinion on rod lengths but the dyno doesnt have an opinion. it tells you cold hard facts. just because you think something is better the dyno will tell you the facts when testing your theory. your experience will tell you whats more reliable as well as what is actually critical. just like cams as well. most say lca isnt critical but it is. the dyno proves that as well. get a cam on the wrong lca and you will lose out on power. one will always make mistakes but the difference is most dont learn from them. im trying to learn myself as ive never built an engine yet. im trying to learn from proper teachers and currently researching. i usually try to find the best to learn from. you can learn from a hack though too. they def teach you how not to do something lol. take care and good luck w your builds.
We have all made mistakes but I always called them Research and Development. Shit breaks during testing but I would rather break it than my customer.
The primary consideration for rod length wasn't even mentioned in this video. Not my opinion. I do have a dyno.
Rod length determines piston speed.
Piston speed determines the force applied to everything in the bottom end including oil.
Should you stress over known combinations that people have been using for 50 years? No
Like everything in a system each component has an effect on the surrounding components. There are no big gains at the thin edge of the wedge.
In my dyno owning opinion understanding the fundamentals is really quite important.
@@jdoe9518exacty, bro! The slower piston speed makes less wear on many parts. Pistons, rings, wrist pins and the oil itself, will protect longer.
Great comment!
I tend to design my piston first, short compression height for NA engines with ring pack high, then use whatever length rod connects them. Of course Nitrous or supercharged gets a thicker, heavier piston with a lowered ring pack and taller compression height. Then again, whatever rod connects them. I do think a longer rod creating a 1.6 to 1.7 rod ratio might be advantageous for N/A max-build efforts. Lots of different engines and ways to go about things. Thanks for sharing. It's fun to talk about different concepts.
Yunick used to have what he called his "Long rod engine" and his "Short Rod Engine". Depending on application he would install a certain engine. On short tracks he used a long rod engine. On long tracks he used a short rod engine. Period with no explanations Now I know why.. THANK YOU!
I'm so glad someone else is finally getting the word out on this. Thank you. I used to chase these 10 numbers here and there. I was one of those who was concerned with rod ratios. It took some time for me to stop doing it, and I'm talking almost 5 to 6 years worth of wasted time. Tom Nelson said it himself, "Why chase 10 numbers at the cost of Ring Stability?" He advised keeping the oil ring land out of the wrist pin location. Dont pull the skirt of the piston past the guage point of the cylinder. I started doing those two things and haven't looked back since. Reliable power is more valuable than Unreliable power. Stopped chasing the rod ratio and it allowed me more time to focus on things that matter like Port Matching, Crankshaft Balancing, and the biggest time saver, Clearancing issues.
My uncle Lu taught me that CH. He was a locomotive lead mechanic and street racer. I love FEs myself. My po boy 427 was his favorite. I got a D4TE block out of a new truck that was totaled and had it soniced and it could have gone to 4.13, but I kept it at 4.125 because I could get a 1.150 gas ported piston. The crank was a 410 crank from a 67 Mercury and it was great for lightening and balancing. The Rods were 7.015 and just a small radius on one side to match the crank fillet and it all balanced perfectly. I think they are really tractor rods, but they polished and peened great and had 7/16 bolts. I put all ARP hardware in it and a set of early tall ports heads, I cut the head bolt bosses as much as I dared and put 5/16 intakes with 2.15 heads and 11/32 exhausts at 1.6 with little porting. The chambers were a lot like Yates chambers that I radiused and softened. That engine when I built it in 1999 was after289s and Cleveland’s and I did this for the fun of it. It still runs great and pulls hard to 6800and right on to 7500. When I changed my pan from my home made one to a Canton big pan and pickup with baffles, I inspected the bores from underneath, and they were all perfect. As soon as the beehive springs came out, I matched them to my can and man it revs like a 289. 9 qts and baffles and 85 psig oil pressure and no blowby. I lost most of my sight and can no longer drive, and my son is afraid of it. My wife doesn’t like the straight 3 in X pipe and ragged idle exiting in from the rear wheels. It’s in a 65 Galaxie with all of the NASCAR spring adjustments and a 15 gal RCI cell with -08 lines and a 3310 downleg 780 like the 425 hp L78 396 Corvette . I want to drive it so bad. . But I had it wired with relays and spade fuses. After I lost most of my sight from the skull fracture at work. I went out just to start it and the wiring panel was gone, cut out. No ignition. 1999- I know it still runs and it’s a real badass. Alas. I ll keep it till I die. That car is a 3850 lb barrel of monkeys. But I have driven too fast, so God knows what is best. A po boys 427 FE, the funny thing is it’s 1.75 to 1 r/s. I wasn’t even thinking about it. Just my uncle Lu RIP , and my honorary uncle Salter. lol. 😂
Good stuff! Great way to defuse the argument with REAL data and common sense gained from experience behind it. Love the fact you aren’t selling us on anything but educating to keep us out of trouble due to buying marketing hype.
I love your knowledge and that you share it. I put a 6.535 rod and a cmp hight 1.270 with a 4" stroke crank on 454 bbc to get the top of the piston .005 out of the whole. I was following david vizard quench info. He also specd my cam and I very happy with the performance. Have great day. Can't wait to see more of your videos solo or with DV.
Yes sir, knock that carbon off the chamber!
I always thought the primary reason some choose to go with a “long rod” engine is to reduce the stress on the rod bearings and the angle of the rod during rotation, while also getting a touch more RPM potential up top. My interpretation has always been that the long rod setup provided a marginally more optimal condition for a racing engine that will be seeing high RPM’s. Never really thought people viewed this configuration as something that can give you more/less power or a meaningfully different curve. Even at the same power level, I think there is a case for the long rod engine still having mechanical advantages for a racing engine. Less wear on the bearings, straighter rod angle throughout the combustion cycle (thus less load/wear on the piston skirts), and a happier engine at the high RPM’s. Prob not worth changing a perfectly good short rod to a long rod, but it still seems like a good option for someone doing a full build from scratch. Any extra margin of safety and/or less wear seems like something worth considering.
Yeah, imagine the angles you'd get in a 347 stroker with a stock 5.09 rod.
You're absolutely correct and I said that in the video my video purpose is to tell people not to get caught up in ratios but to use the longer rod just don't get a piston that's not stable because now you're going the wrong direction. But yes you are correct in what you said
This is a great video, but one thing perhaps not addressed, however, worth mentioning, is that short versus long rods are actually all a relative term. As to what constitutes a short rod versus what a long rod is considered, etc. Here in Australia we have a Holden 308 V8 that is essentially for all intents and purposes nearly identical to a 307 - 350 Chev. And what we consider a long rod in these engines when we stroke them to 350 cubes is a 6 inch rod. Which will at that length - for the correct pin and comp height piston, is considered a long rod - and will actually outperform the shorter version in every metric, which is either 5.7 inch or 5.85 inch. Considering these Holden engines are near identical to the Chevy, which both of the rods shown here would be bigger and bigger again, you can see where there is somewhat of a nice balance at a specific length zone, then there are diminishing returns so to speak by going even shorter again. We would consider both of these lengths shown to be long rods compared to what we use. Length is all relative, and perhaps even more prudent given that as Salter has said, it is effectively pointless as your piston choice dictates what that length will be. And that's the exact reason we are only stuck with those rod length choices, due to off the shelf piston height sizes that offer bang for buck, without spending huge money getting custom made CP's or similar. Which would then require more expensive rods too at the correct length to connect them to the crank. As long as your rods are of a high quality and a good cap and bolt, you're good to go whatever the length.
i was thinking something similar too, got my hands on a solid '54 ford that still has its original 239 inch Y-block, has a 3.1 inch stroke, a 6.3 inch rod, and a compression height of 2.8, with only 7.2-1 compression. it really stuns me that ford builds a combo with potential to rev right from the factory, just to go stroke their cranks and shorten the rods 1 year later. i wanna punch it out to 3.80 inch bore with a .2 inch lower comp height and make it rev like a 302, but on the contrary, it would just be easier to boost it with the compression it makes-along with the added benefit of stability with the stock long piston, dont got the 4 grand to dump into mummert cylinder heads in order to gain 2 points of compression max, the stock '54 head has a huge combustion chamber too, the quench is literally all of it, thing just eats timing advancement and loves it.
Everytime I see Freiburger, I can't help but chuckle just a bit. He and I both worked for Chris Jacobs (Jacobs Electronics) in Los Angeles back in the mid 80's. Many an hour were spent joking around about 'death burritos' and the mercilessly incompetent who would call in their quest for ignition information. Though he was never really a gifted auto genius, he WAS blessed with a sense of humor and gift of gab.
@@bmepdoc9675 agreed
Easily becoming one of the best auto channels on RUclips hands down. Talk about professional 👏
I agree with everything presented in the video. I guess this is more of a question, or I'm just seeking Mr. Salter's comments on this particular matter.
For a little background, when I was younger, I worked in an engine machine shop, and a good customer raced a Chrysler 225 "Slant Six" in a local dirt oval class (they had a one-off class for American straight 6 cylinders), and in stock form, these had a 4.125" crank stroke with a reletively long 6.7" rod length and a funky type of piston. Of course with their small valves and ports, they had a very narrow window of RPM where the power came and went!
The customer did have several big valve/ported heads to use, but our builder explained that with the long stroke, and the long rod combined, it took X amount of crank degrees for that piston / rod assembly to swing "over the nose" from one side of TDC, to the other, and thus was very "lazy" for that type of racing.
He substituted the 6.7 rod length for a 6.0" length and had custom pistons made for the application.
Of course with the bigger cyl. head and all the other go fast parts (cam, intake, carb, header, etc), this thing really did wake up!
I just wonder if this is something you would do in the same situation?
Thanks for the great vids!
Yes very similar. I only gave a couple main reasons in video I didn't go into great detail because the video is already getting long. I have built a lot of engines and some of them were weird engines that most people would never attempt to race. I have tried all kinds a rod lengths and I have come to the conclusion that I don't care what rod is in the engine I can make it run. But I am also found that that piston is so very important and there's just too much to talk about in that subject matter and just a 20 or 30 minute video. But it boils down to get the Piston you want and I say that loosely because most people don't know what piston they want. But in the end don't sacrifice stability for a particular rod ratio. And I mean the difference is only a .100 or .200 of an inch that right there you can make all the difference in the world.
1000% agree with you👍 Seems like forever I’ve tried it to tell people that ridiculous long rods are not the answer! Because it f’s ups your ring package, just like you said. Victory Library, and others just don’t get it, they’ll rather argue with math not real world testing. Ken Duttweilers SBC in Poteet&Mains streamliner uses a 5.7 rod! WTF
So you build a 375 stroker with 5.7 rods the shake on 350 sbc with crank throwing rod into side of cylinder and 1 sided wear
and side of piston skirt breaking means nothing right
@@alonzahanks1182 okay can tell you that we have 2 SBCs with 5.7 rods. The 383 we have is clocking right at 200K, it’s in a C20 C6P that weighs 5100 lbs and hauls and tows a 7000lbs trailer. Never had any problems with the engine, was careful built with quality parts and very accurate balancing. It doesn’t shake at all, but the exhaust is loud! Every oil change the filter is cut open and carefully inspected for any metal. The 400 is in a bracket car that’s raced most weekends, has 5.7 rods housed in a Dart Little M block, Scat rotating assm. Dart heads, Crane SR, bowtie intake. Was professionally built in 2009, been in the car since then. 640 hp runs 9.40’s all day. Has been freshened twice new rings, light hone. Goes through traps at 7600 rpm, skirt wear 0.
The bee stinger flosser is 100% correct. Believe me I heard it all and built many competition engines from motorcycle to automotive. Four cylinder to V12’s. It’s all about bottom end stability. Long r😊d get a higher decked block. Simple. 🎉
You might have a crankshaft with lower stroke. rod is getting longer bore the seme deck the same displacement is smaller. RPM will be higher als exeleration of the pison is lower at the same RPM. At the same RPM ste soeed of the incomin Air is lower and depending on the airftlow You get e little bit more air in the Zylinder aand You get a little mor power in relation the the displacement. In the end You get schort stroke and bib bore and high APM out of the same block, but You get less displacement and an lower evarage Spee of the piston. If You want to keep the speed of the piston konstant bei higher RPM then You end up with higeher Ayileration of the Piston, because there is less time to reach maximum speed and zero agein. Forces grow rohghly with ( 1/ RPM) . Of cause the bore to stroke relation has beid effekts on the engine and this rpd ratio ist only one of the effekts....... Perhaps You remember Formular one motors from BMW, where the had 1500 ccm turbocharged. Teh block was always an old block that was used, and had already a lot of themal cycles.. the original blocks were used in street cars, and had much more displacement hand much higher Stroke! and therfore the relative lenth of the rod was much schorter!
Smokey Yunick is smiling at the state of the art.
I'm retired now, but I had a few customers wanting 396 ci sbc engines. They definitely had low friction with those 1 mm ring pacs but most did complain about oil consumption. Valid information 👌
I think all the long rod stuff came from Smoky Yunick back in the day. I plotted out the difference for our hemi and didn't see a lot in it. You get a bit more dwell near TDC and a bit less around BDC with the long rod and the opposite with the short rod. Around mid stroke the short rod piston moves slightly faster. It's something that might be useful if you are in an unusual situation.
This channel is great. Great info that applies across all engines. Thank you for your time making these videos.
I have been arguing this same thing for years! I have no dyno, or any other high tech stuff! Just a hot rodder with a great machine shop behind me that I used since high school!! Thank you for backing me up!!
Great video and your spot on with what you're trying to get across. I was always a big fan of Reher-Morrison Racing.
Especially during the mid 70's and into the 80's even though I was a Mopar guy. I met them at the 1982 Summer National at Englishtown NJ. They were so out going Buddy Morrison, personally woke up Lee Shepherd from a nap Lol To make him sign my girl friends son pictures they used to hand out.
I'll be looking forward to future videos, and you honestly answered questions I had about rod ratio. I want to build a 327 Chevrolet for my Camaro. I had one back in the day in my 68 Nova SS. Great engine and man you could buzz that thing in the higher rpm range, with the solid lifter can I was running. Thanks again and again great video...
You're correct, the weight of longer connecting rods means more parasitic drag, and therefore a slight loss of power. The world of racing is a little different than the world of the workday commuters, I'm no longer trying for 1st place, I want to get to work every day of the week.
Bobweight is Bobweight. If the rod is a little heavier because it's minimally longer, yet the piston is shorter and weighs less, the bobweight can be the same. Often times it's even lighter. The crank will never see it.
Parasitic loss from a heavier rod? No. Not even with a heavier bobweight. Nor will power increase from a lighter one.
Blow by readings would have been nice to know in that test.
And BSFC's at steady state.
I thought that blowby would be good to know. Could indicate problem with ring seal on the long rod engine. But maybe there would be variation in ring end gap between the two engines that would make the comparison moot.
The best quote I ever read on the subject was from Reher and Morrison. They said the piston and ring design was much more important. So pick your bore and stroke, design the best possible piston and ring package (ring size, design and spacing, pin size and thickness, skirt design, etc) and the best rod length is whatever connects that piston to the crank!!
With the unimaginable budget they got to play with in the NHRA Pro Stock ranks, if there was even a LITTLE extra performance to be found they would have been all over it!!!
I've since heard several VERY prominent and successful engine builders say pretty much the same.
"He flosses with a bee stinger"......THAT was a good line!!!
That’s like saying NASA knows it all until Musk blew them out of the water.
Thank you for your patience and I hope to see your channel grow, and I’m staying tuned to see it happen . Great informative content …thank you sir
Learnt some valuable bit of information, keep up the good work 👍
I had an engine builder tell me that he puts in a piston with 1.50" compression height, which is plenty enough to give good stability to the rings, and then finds / orders a set of rods as needed. In other words, he works around the piston height when possible. If a customer just demands a big enough stroker (such as a 347 inch small block Ford 302) or a 427 version of a 351 Cleveland or Windsor Ford), then he builds what the customer demands (the customer is always right). But whenever he has the option, the piston comes first.
Thank you again for another informative video. Can't beat real world results.
Evolving in my experiences with the Fords of the 60's/70's, well, they all had the thinnest cylinder walls of anything I worked with. It's no wonder those engines didn't perform better. At the time, the Duffy's style piston was what was a favorite. They were very lightweight and that's the reason they were the favorite but hard on the walls.
Eventually, I moved to a round skirt even though they were significantly heavier. I did this just due to the loading of the walls and less rock.
I played with skirt tails, finding those to be a plus back then. I'd seen shops cut the bottom of the skirts off in their Drag engines but like one poster stated, I said nothing as someone's gotta loose the race.
But like you've found to be true, it came down to stability and spreading the load to secure the ring and walls, giving the ring to do its job. I'm not sold on the cam shapes I've tried based on visible wear but that's another subject. Fords blocks were/are terribl from the era. A good fill, helped but the round skirt made them run their best.
Fords development found the best for the round track C/D to be 1.74. It was all about piston stability and reliability. Rod length was moot. Learned the same in my experience then. Again, it was stability. Forget the rod.
Secrete weapon on Fords - Sleeve the cylinders.
Look at the evolution of the Ford 302 piston over the years from the factory.
They finally got it right.
Would have been better to keep the rod length of the 289 and tool up for a shorter compression distance piston.
But it must have been cheaper to go the other route.
I run a roller 1970 boss 302 . I switched to a 5.4 inch rod and shorter piston.
There's a marked improvement in acceleration and breaking of the engine.
There's no free lunch in physics.
just incomplete factors that change the game and to as what they pertain to.
I like the 1" compression height in my 400sbc builds (3.75 or 3.80 stroke) to keep the reciprocating weight down for our bracket cars. I do run pan evac to attempt to help with ring seal. Last one made it 550 passes before it cracked a piston. Before he retired John @Mahle had told me to try their higher end gas ported pistons. He felt that the 1mm ring and gas porting would help with the ring seal on the short skirts. Just finished a shortblock with them in it and hoping to dyno this fall. Drop it in for next season. Fingers crossed I learn something from the experiment.
@@wayneskelly4297 thanks for the comment
Spot on with this being a controversial topic. You have to consider the overall engine design before coming to any conclusions here. In this case, they were working with the big block Chevrolet which inherently favors shorter rod ratios in comparison to lets say Chrysler and Ford. Why? Might it be the difference in cylinder head design and flow characteristics? Now, the small block Chevrolet was a completely different animal insofar as it actually responded well to a much higher rod ratio (1.90) in Trans-Am racing. And then there's the saga of Bob Glidden making the switch from Ford to a Chevrolet Monza back in the day running a destroked BBC to keep it under 400 Cubic Inches back then. The thing wouldn't get out of it's own way and Glidden failed to qualify in Pro Stock with the car. Needless to say, he got rid of it in exchange for a deal with Mopar running a Plymouth Arrow using the 340 small block platform for power. That combination went onto be undefeated while he ran it.
Back then, Glidden had been running the 351 Ford Cleveland, which responded favorably to higher rod rations up around 1.8:1 and my guess is he tried that with the Chevy Rat Motor, which didn't like it, particularly running a shorter stroke and state of the art Pro Stock heads back then. But then when he switched to the little Plymouth Arrow and small block 340, again the longer rod ratios brought favorable results with the Mopar. If you go back and make comparisons between the approaches the big three auto makers took with cylinder head design, crankshaft strokes and connecting rod ratios you'll find there's distinct differences that when taking them into consideration can make substantial differences in performance..... The lesson in all this is, what works great for one doesn't necessarily work for others. This goes to show it doesn't matter whether there's a bow tie, blue oval or ram affixed to the valve cover, they'll all run strong if you simply take into consideration what you're working with....
The problem with Glidden's Monza was not rod ratio. It was a mis-timed distributor. At least that's what I read about it in Car Craft back when it happened. Then John Lingenfelter came and bought the Monza from Bob.
@@andyharman3022 Mis-timed distributor? You read that in Car Craft? Mmmmmm. Might the author of that article been kidding or joking around. I have to admit in all honesty, my conclusion has been speculative in nature. However, it's difficult for me to comprehend the notion someone of Bob Glidden's level of success wouldn't understand how to time a distributor..... I've dealt with numerous freelance and staff writers of a number of car magazines and discovered there are those who were, lets say more technically advanced than others. Some loved to cover successful race operation with a whole lot of fluff with witty quotes and others were more into theories and the R&D side of things.
Marlan Davis who wrote many technical articles for Hot Rod Magazine was one such individual. Marlan went onto advance to chief editor of that magazine.
All I ever read was the longer rod produced more torque and HP over the entire engine RPM range! Now I see there's really not enough difference to worry about rod length! I really appreciate and enjoyed this video! Keep up the good work!! Thanks
I was jamming to some White Zombie and this video popped up. Haven't seen it yet. Thank you for having some rocking tunage to inspire me to watch this video because I definitely have my opinion. My opinion is that a longer rod helps alleviate side throw imbalance. Therefore the rotating assembly is spinning smoother and is happier! Ok, now to watch the video!
The thing that gets me is that people have a tendency to want the "perfect storm" when it comes to engines. Back in the sixties when I was coming up and reading all this hot rod stuff in Hot Rod Magazine and Rod and Custom and so on and so on, it was the mantra that my engine has more horsepower than yours (of course the automobile companies propaganda kept that stirred up). As a teenager I wanted an engine that would do anything in any application, would snatch the front wheels off the ground at just the touch of the throttle and would want any new product that would guarantee instant power. Well in the real world that is not to be. I have learned one thing and that is the internal combustion engine is a programmed piece of equipment, and that programming is mechanical. Now grant you we have through the computerized technology we have today the ability to electronically tune engines to be at their maximum efficiency but when we fool with these racing engines and such it is still a matter of cost and reliability. A person is going to have a racing engine then build the engine for the track, a person wants a higher performance street engine then build an engine for the street, but there has to be a compromise. Your point at the end of this video drives home what any professional racing operation knows and that it is a matter of cost.
Your frustration is understandable and would be considered restrained for me! I often write things late at night, then my eyes pop open in the AM and I think "crap! I sounded like a real jerk and didn't communicate my point correctly, and now I see what they were trying to say!" My brain tumor makes it to where writing this takes many revisions and so far this has taken 2.5 hours and a migraine. Thanks for the info and the explanation! I know how to eat crow! I was really concerned about rod ratio when I wanted to build a blown gen 2 hemi, having background in true heavy duty gasoline engines that are pourpose designed for max durability. They haven't existed for 50 years. In that application those that weren't car engine based were way more expensive per HP, heavier and had 2.0 or higher rod ratios and long full trunk pistons with bottom rings. The were clean sheet designs and had unlimited deck height, and rpm was limited to about 2500 to 3600. Even with the same cubic inches and hp their pistons, and wrist pins would live 4 to 5x as long as an automotive type. The 454s were horrible in this application. I saw 5 that put the piston skirts in the oil pans at around 60k miles. A 413 Dodge would go 100+k, a 4.875 bore x 3.58 stroke, 7 inch rod GMC 401 V6 up to 300k. When I called about building my hemi I expressed my concerns and said I wasn't really worried about hp, just wanted to make 4 digits, and wanted reliability. I suggested a 4 inch stroke, 4.5 bore and really long rods. He kept gently suggesting that since I was using a standard cam block to put the biggest crank in it that would fit, "just build a 572, (4.5" stroke, 7.150 rods) it won't cost a penny more, and will require less boost and rpm for what you want. The Hemi has way too much piston above the pin, making it very heavy, it actually benefits from having a shorter compression height to a point, you have enough deck height" so I listened and did as he said. I had had previous misunderstandings about this for modern performance applications. I was looking at the lifespan of a 440 mopar vs a 454 in a heavy truck, or how a supercharged aircraft engine is built. My feelings and reasoning for using short stroke big bore long rod, long piston engines for reliability were completely valid, but like you said taken to an extreme in the wrong application with outdated information. In the 80s and 90s My engines had to be CHEAP, go to the track, lift the front wheels on a $300 newport, then pull 20k lb wagons to the elevator, and get my butt to a low paying job everyday for many years without failing. A low compression 440 six pack did so for 13 years on 87, 2500+ passes, 150k miles, a shelf full of trophies, wore out 2 cars. And while not spectacular by today's standards would push 4680 lb to 13.41 @ 107 in the 1/4. Back then the main thing you ran into was 5.0 mustangs (about 14.2 to 14.5) and IROC Z 305 camaros. (14.75 to 15.2) what you really watched out for were Buick Regal T types. I ticked off a magazine reporter for beating a new porche 911 he was there to write about! , I was on the news at 14 yrs old winning student drag day, built and tuned the car with dads advice and instruction at 12 yrs old. I was the crew cheif and mechanic he was the driver. Chassis, gear set up, building automatic transmissions machining parts, all before 14 years old. We won the street sleeper award at the mopar nationals, and made a perfect run. We dialed that car to .005 second sometimes! Why a rusty newport? Cheap, came with 440, low profile, and if I beat you it's really embarrassing, if you beat me what have you got to brag about? We ran a stock industrial shortblock out of a combine, dad made sure to put the "chrysler industrial engine" tag on top the manifold! One time at the track I went to wipe the soybean dust and oil off the engine. Standng there in his beat up steel toed boots, he said "don't do that son, I want them to know that it's a WORKING engine!" I still have the '68 Monaco we built in 1992. You are very successful on a whole 'nuther level! You are winning races with performance alone in a very competitive evolving field. We were focusing on consistency, and durability, speed was just for fun. Thanks again for sharing and trying to help us little guys thats rare!
Your passion is gr8, love it. Bring on more. The info you bring to the table is invaluable, and i for one am greatly appreciated.
Love yu channel, lets 'bee sting some more'..
From the 'land down under'.OZ 🇦🇺.......👍
Okay, GM spent $1 Billion US dollars on developing the LS1 engine platform. One of the most powerful durable and efficient V8's ever built. Rod Ratio 6.098/3.622=1.6836. comp ht 1.340. In factory configuration the LS2 was designed to go to 6250Rpm. From my 40yrs of experience and getting insight from some of the most winning racers this LS configuration will have efficient cylinder function up to 6835 Rpm after that horsepower would drop off over a rod length proportional to desired Rpm. Ford's competition dominating Racing engines the 427 and Boss 302 both had 1.72 rod ratios. The Boss 351, 6250 Rpm limit 1.6514 rod Ratio. One of the negative issues with trying to put too much stroke into a given deck ht is you can't run a long enough rod and piston skirt protrusion at BDC leads to piston cocking and increased skirt wear. There are many considerations to be optimised when trying to achieve more of everything. Great to have everyone's input to learn from each other. 😊
Years ago I found an odd magazine in the magazine rack, of a company that was trying to get their business off the ground. They had some great tech and one of the articled was on long and short rod ratios. The engine builder in this article was working with a Chevy 327 which had a bore of 4.0” and stroke of 3.25” from the factory. They used either 5.7” or 6.0” from the factory. This builder took things a bit farther. He used 5.5” rods for a 1.692-1 rod ratio and ran them against a 6.5” rod for a 2-1 rod ratio. The builder took care of to get the rotating assemblies to weigh the same. The same block, was used for both combinations, but the heads differed. I’ll get to why in a moment.everything else was the same. The two combinations were tested with aftermarket heads which breathed well performed better, but by a slim margin. Then the builder put a set of small valve factory heads on both builds and measured the difference. With a more restrictive heads the builder measured more of an improvement in power than it did with the good heads.
Back when you, the channel’s owner was first getting started or at least I was there weren’t any aftermarket heads to be had, hence the belief of old schoolers that rod length makes a difference. Today, there are so many aftermarket performance heads available that most guys aren’t seeing the huge improvements we saw, leading to the belief that rod length doesn’t matter. We also have aftermarket cranks and rods that will hold up to punishment. It wasn’t so long ago the 454’s and 383 Chevy strokers with their short rods were breaking crankshafts. The 454 came with either cast or forged cranks, but not too many forged cranks were available. To buy a reground crank meant paying a $600 core charge because the grinder was having a hard time sourcing forged cranks. For the 383 stroker there were no forged cranks. They had 1.534-1 and 1.49-1 rod ratios respectively. It’s not hard to understand why they broke cast iron crankshafts. One shop, around the corner from the warehouse I worked at had a pile of scrap 400 cranks in their recycle bin. Back east at the Marina my friend worked for and now owns they use 454 blocks to ties down piers. Boat engine get pushed hard and run lake water for cooling. so in the early days guys worked with what was available. Today guys have so many choices it’s hard to pick the one product they want.
Brother, I'm with you! Plus, engine building will be easier and maybe even cheaper! Not to mention, I'm more interested in maximizing cubic inches! Great video!
I agree with your analysis 100%. I knew a guy back in the early 90’s that came up with this when it was the hot thing to run long rods. He went against the grain. Years and years later I found that old timer was right all along.
Great information I wish people could take in the talking point and decide what they want to do with it, without arguing.
Excellent content. I so appreciate you sharing your knowledge!!
I've been building and working on dirt track engines my entire life. I've lived through innumerable combos of rods, pistons, and cranks. Your one statement settles the debates of all of it. Get your crank, get your piston, and get a rod to connect them together. I have always leaned toward a good piston skirt over ultralight weight or compression height restraints. I like using the block more than a few races.
I found this video very informative and relevant, good job man! I also was surprised by the “steady state ” test and its results, great for marine applications as well. Thumbs 👍 😊
The arguments of science with engines can sometimes just boil down to "penny wise, dollar dumb" when it comes to fractional changes. People love to be right = factual while ignoring higher priority wisdom.
I remember guys in street stock using Olds rods because they were longer than SBC rods. We used stock rods and were still wiping the track with them. We had a milder cam, supposedly worse heads and intake, but everything worked together; and we had a great driver and suspension guy too, of course.
It would be interesting to see a comparison done in a very short rod engine, like the 400 SBC or the 302 Ford, done for somewhat mild street.
The other thing about rod length is the airflow requirements. As the rod length changes, so does the piston acceleration and dwell at TDC and BDC, which can affect the optimum intake, carb, cam and port requirements to optimize airflow for that combination.
As any quality engine builder knows, it is all about everything in the combination working together, not the individual parts.
@@lelandlewis7207 thank you for your comment what did you think about the video.
@@SalterRacingEngines It was great. It showed facts and had great explanations rather than the anecdotal stories many guys believe.
pistons should look like pistons not bottle caps was hard back in the day increasing rod length was about slowing down the speed across tdc to keep the standard piles of junk in the block i really liked this vid well done sir
Seems like you could use the same piston skirt length on both pistons correct? The pin height can just be moved up and down on the same exact piston and have the same piston stability... then the only difference would be R/S ratio assuming one don't get into the oil ring. One thing i would point out is this test they did should be more accurate than even doing twin engines because the entire top end is the same exact top end just different bottom end. One question I'm interested in still is if you have PLENTY of deck height like say a 340 Mopar where you can move the pin up and get an even longer rod in AND still have a very tall piston would you go for the longer rod in that situation,
Yes sir you are right onto the right thinking
I can't tell everything I know but that's the right kind of thinking right there.
But piston companies don't sell them to people that weigh their special order and you have to be really technical with how much skirt you want the great comment
"Use the Biggest bore shortest stroke and longest rod that you can" Smokey Yunick
I built a '62 327 using Smokeys short stroke / long rods (6") and other instructions per his SBC book; it is in my '32 roadster and is the best performing street engine I have ever built. The same engine (a stock 340hp solid lifter) is in my bros 1963 Vette and my '32 327 out runs it by far.
Thank you. I learn something every time i tune in.
Expert advice with information to back it up.
Thank you for your years of experience and success.
Good, real information is hard to come by.
Great video. I learned something. I remember reading Smokey Yunick's power secrets about 35 years ago and he was talking about longer rods. But as you said, that's a different kind of application, mostly high RPM circle track cars that he was trying to get an extra few HP out of. Whenever I get myself some funds to build up a street/strip engine, I won't stress out too much about rod length. Thanks for this. Hope everything went okay with Tropical Storm Debbie.
HRM did an article back in June of 1997 called;
The 350 Chevy Should Have Built, searching with this name with help it be found faster than the actual article name.
In the article they used a sbc 400 block with a sbc 327 crank to get 350 ish CID. They used a long rod ratio as well, 1.91:1 ratio to make sure the pistons dwelled longer at TDC. The reason for this was to check their theory that a longer rod ratio is less detonation prone.
They went with 11:1 static compression with a fairy mild camshaft 215°/215° of duration at .050" and ran it successfully on 87 cat pee octane without detonation on the dyno without removing timing. Right here is the advantage of a long rod ratio.
The torque and HP numbers were very impressive for the parts used. It made over 400 lb ft from 2,800 RPM to 5,200 RPM, peak torque was 435 lb ft at 3,800 RPM. Also it made 412 max HP at 5,700 RPM. All this on cat pee 87 octane wirh a mild roller cam.
So in certain short stroke applications there is a huge advantage to using a longer rod ratio. Unfortunately they didn't back up their claim with the same parts on a sbc 350 with the same compression ratio with the same cam. But I doubt it would of made the same power using 87 octane because the timing I would guess would of had to be turned down. Plus there is potential of valve shrouding among other things.
In the scenario you presented, yes rod ratio isn't really a factor one should concern themselves with as long as the rods are at least the minimum required length for the crankshaft they plan on using.😎👍
@@itseithergonnaworkoritaint7852 thank you for your comment and I always say put the longest ride you can in there after you get the correct piston on any application.
this is the engine I have in my blown 1964 austin healey sprite
Just my 2 cents worth here. I think the exercise with the rod ratio is to slow down the piston speeds going over TDC. That way one can Rev the engine higher and potentially safer to make more HP up top. Btw, I still have the magazine that the ' The engine Chev Should Have Built ' article was printed. It's not about the power it can make, but the longevity of the engine at higher speeds.
@@randypozdnikoff4099
Why would you think that when they made the peak HP at 5,700 RPM? Also they said what their goal was in the article, it was basically to build a street engine with a factory style cam with all the power lower in the RPM range. And they accomplished that goal and made more than 1 HP per cubic inch, 1.177:1 to be exact to boot.
I'm sure with a different cam and intake with the long rod short stroke it wouldn't mind more RPM with the slower piston speeds because of the short stroke but that build wasn't anything about RPM.🤷 You might want to reread it?(No offense)
As I'm watching this, that article was the first thing that came to mind. Glad you commented about it so I didn't have to.
Finally a short rod wins my girl doesn’t know what she’s talking I knew it 😅😂
Appreciate the info! Im glad Ive never fell into that rabbit hole of a discussion
Older Dodge have used tall deck blocks with long rods. I have found their engines to be torky and fun to drive
I have definitely learned something from this. The piston stability factor is much more important than rod ratio or length. Also, Dyno testing, and research means more than someone's theory or opinion. Richard Holdener has proven this many of times. The guy's at Westech know a lot about engines. Either way, it's all great info and good to know stuff.👍thank you.
I'm a fan of long rod length for durable engine, but ford 302 has the shortest rod and it works and a Mopar 318 with a long rod works, you in theory have more leverage on the crank with a short rod, but we are so afraid of how hard the piston is pushing on the cylinder walls, stay blessed, God is good
The problem with the rod length debate is the amount of literature on the subject.
30 something years ago a popular guru wrote a very long article that took a deep dive into the rod length theory. I bought into it.
I’ve worked in auto machine shops since 1990. Many friends and family members wanting to build some kind of engine. Soon enough my uncle wanted to build a 302 that would run good.
Back then stroker kits and aftermarket rods weren’t laying around everywhere. Stock 400 SB rods were. Everyone building a 400 SB wanted 5.7 rods in them.
So away we went. Removed .023” off the rod journals. Narrowed the big ends some .080” and corrected the offset. 4.3L V6 Chevrolet rod bearings. Had the pin bores machined for bushings then found out Keith Black had a hypereutectic piston on the shelf for this purpose.
The engine made 412 hp around 6200-6300 and that was all it took. There had to be something about that combo. Nothing else remotely close to it was making that kind of power. We had some very expensive 337 cid at 12:1 that were only making 375-380 hp. So this little 307 at 10.5:1 with those “long rods” had to be worth something.
Time just proved otherwise. In current times we have all now seen or witnessed a NA pump gas 302 make 420-430 or more with stock rod lengths.
About the only time I have seen rod length become a major issue is when someone takes it upon themselves to engineer their own rotating assembly and order their own parts to save money.
People need to be very aware that some of these crankshafts are made with large radius counterweights and while you may have calculated your compression distance correctly for your particular block, the bottom of your pistons may hit the counterweights of your crankshaft. So look into that detail closely. It is generally listed right into the part number of the crankshaft. This mistake has been made one too many times. A conversation I do not enjoy having with a customer.
I do subscribe to the 1.150” rule. I’ve seen way too many collapsed piston skirts on engines that were otherwise healthy just short lived for ring seal making them a maintenance problem.
I’m hoping to hear some information shared about skirt coatings.
I was recently forced to send a set of pistons in to Line to Line Coatings because of the big surprise we encountered after installing a torque plate on a Ford Motorsports block. I do like the idea of reduced skirt clearances. This should stabilize the piston and help with ring seal. My concern is where does this “abradable” coating end up, and at what cost. Does it end up in the cylinder walls and reduce the oil holding abilities of the cross hatch? Does it contaminate the oiling system to a detriment?
So many questions. So many topics to discuss.
Line2Line has all of your questions answered online. Or call them.
There is something missing here. The piston acceleration curve vs the burn rate of the fuel charge. They are not identical because the long rod spends more time at TDC and accelerates (initially) slower than the short rod. This is is reflected in the timing difference we see between the two engines. I expect the short rod engine can tolerate a (faster burning) lower octane fuel.
Just another variable to consider -----
I bet you had fun with all that power in whatever it was in . I had that motor in a little Dodge Omni with a four speed. Just stock it was a blast .
I respect the time taken to do all of it and thank you for your expertise and showing’
Just a comment on the ( I have been doing this for 30 years ) 😂
I once went to Washington 3 cities” flew from Houston Texas”
And the family member to my girlfriend wanted me to do the front brakes on his tundra’ I am a mechanic ( uncertified tech ) 🤣
So I did, took the pads and rotors apart and out we go to the nearest O’Reilly which was like 4 blocks away’ ( lovely towns by the way ) so we left the rotors to get resurfaced and bought the pads, and I got used to using stop squeal on the pad, not on the metal part” so I asked the guy if he could sell me a stop squeal bottle’ Boy he looked at me weird and asked me 3 times what I was saying! Now I’m not from the states but my second language is pretty good; ( now I know he must have thought I was trying to make a sex joke ) so he calls the manager which was a few steps from him and said: the regular: yes sir how can I help you? I asked the same thing, and he said: there is no such thing; I said I am visiting and back in Texas o buy it often’ and here it is: the guy spit the sentence with pride: I have been doing this for over 15 years and there’s no such thing as what you’re talking about’🤣😆🤥
So you all will live the end; time came for us to pick up the rotors which were really bad vibrated ( when they don’t use the right tool while machining ) I told the manager and he said: oh, that’s all right you won’t have problems with that” I made sure to tell him: and you’ve been doing this for over 15 years???? 🫡
The actuap benefit for long rod ratio is sideloading thrust on the piston to the cylinder wall...
If running short rod making heavy wear on down the bore and piston skirts, its a sign long rod setup needed..
Ultimately, tue real advantage of long rod ratio, is in high revving extended high rpm run usage scenario like roadcourse where the engine were kept at high rpm for long time throughout whole lap multiple time....
This doesnt matter much on short drag run or highway pulls or 1mile run
Presumably shorter rods may be cheaper than longer ones and the money saved could be used to chase power elsewhere if a budget has to be adhered to.
The difference between peak torque on the steady-state and power sweep tests is interesting. 1.7% and 2.0% error on the two engines tested. Seems like the inertia factor on the dynamometer test setup should be adjusted to eliminate that. I wonder if that means that every engine shop that gives a customer a dyno sheet from a power sweep is giving them inaccurate data.
Thank you for a good honest analysis and truthful information.
I’ve built a couple thousand engines in the past 30 years, more than a typical hobbyist, less than full time engine builders for sure. I learned VERY early in my career that the pistons were the most important aspect of the combination. If you can keep the piston stable in the bore it produces more power and has a greater lifespan. The piston motion directly impacts the ring seal, so again, the piston is a critical factor in ring seal. I primarily build Fords and truly dislike the over hyped 3.400 stroke cranks for the short 8.2 deck blocks because the piston is sacrificed for the fitment. Even a 3.25 stroke in the short deck is typically a terrible piston design, I build them with a shorter rod to allow for a more stable piston. The fools on the internet who have built a handful to a few dozen engines will argue with you to the death on this topic because they went fast for them, but they don’t understand how to build an engine that will be successful in a competitive environment and have the longevity to meet the expectations of the engine combination long term.
Jere Stahl did a lot of testing on this back in the early 70s, he had a great article on his findings. 6.0 vs 5.7 there was no difference in power output but the 6 inch Rod needed more timing to make the same power.
Late 90s I built two different 361 b blocks , stroked out to 400Ci (4.125 , .[005 for bore clean up] X 3.75 BBM crank) the Long rod engine used pistons with 1.43 DH, 6.76 length rods by Crower using 2.0 crank journal & .990 wrist pins , Short rod engine used 1.72 DH piston .990 wrist pins and 6.385 length rods both engines used the same modified BBM 3.75 crank, crank was knife edge and coated with a moly coating to help shed oil , heads were a set of old 2402286 max wedge heads , 2.125X8mm Intake valve and stock 1.88 ex size , with 5/16 stem intake port flowed 315 @.700 lift . Intake manifold was Mopar performance Low deck tunnel ram(with port openings welded up and port match to the EXTRA large Max wedge port window) pair of 700 mechanical secondaries.
Cam was Racer Brown mushroom cam with .654 lift, 280 @ .050 , stock 1.5 ratio rockers by Harland sharp.
Both engines were 1st step tested for 5mins at each RPM level, step 1= @ 3000RPMS, step 2 was 5500rpms 3rd was 7000rpms, after step test I did a sweep test 1st set from 3k-7k ten pulls each, 2nd set 4-8k
Continuous rpm test , at 3k and 5500 both engines were with in 10hp&tq , at 7k the SR engine made 10hp over the LR
Both engines were pulled 10X each for the sweep test 300RPM per second.
LR made 707@ 7300RPMS max timing of 40* all in by 3000rpms
SR made 725@ 7500RPMS max timing of 36* all in by 3200rpms.
Now a traditional BBM 400(4.34X3.38) with the same cam(ground) and top end made 695HP@7500...... I think a big part that gets over looked in these test is efficiency , both in terms of combo, head flow and cam timing......don't misunderstand me, for the average person it's waste to chase rod ratio.
When GM redesigned the 3800 in the 90's, (the 3800 Series II) they reduced the deck height, and shortened the rods accordingly by almost an inch, along with some other improvements, picked up almost 40 hp, and made the engine smaller and lighter.
So many surprises. For my towing pickup, it will be long rods. Thanks.
You’ll probably never notice the difference anyway, except in oil consumption.
Math tells us a lot but when it is based on theory it becomes nothing but a guess and real life implementation will separate the theory from fact.
EXCELLENT VIDEO!
Clarifying data and real tests
"Piston Stability" is key
Yup, this learned me somethin
Fantastic!
THANK YOU!!! We preach the same thing all the time!!! Piston stability is more important than the rod ratio!
If running boost(roots) at low rpm id be worried about detonation. I build mine with short rods and put 10k miles on it on the street and to work everyday. Sold it still running like the day i broke it in. Minis a balloned converter lol. Im with finding a taller piston for stability but to be honest at the time of my build i was mainly worried about dwell time. Blowers give boost now. Regardless of rpm.
👍👍👍 I never thought at the power levels I dealt with that it matter, Thank you for confirming that for me. Excellent show Thanks again, keep up the good work.
Great video I also love the engine masters videos alot of good imformation
You'd think by 2024, in the world of modern NASCAR, F1, drift racing, cranking out reliable mass-produced 20k-rpm crotch rockets like they're Volkswagens that people would have figured out the whole rod ratio debate went to bed a long long time ago. But here we are again, having to explain that rod ratio is a silly datum to build an engine around! I am too young for this stuff to have become lost art 😂
Love seeing dyno tests like this.
Short rod pulls the piston away from valve quicker, initiating airflow better. I think that explains the 10 hp on top. I like long rods though.
SIMPLY You know your shit. TO share your knowledge, your experience and R&D is a gift to all of us here as we increase our knowledge of High Performance from a Master. Thank you
Mr. Salter thanks again for the excellent information you have been posting
Love the intro music!
Interesting tests. I want an engine that lasts. Short pistons may be a bit lighter, but I want the correct pistons for stability.
1st!....Keep up the good work!....Learning a lot!
I recall an article in HRM back in the 90's. Joe Sherman was asked about long rod vs short rod. His reply was the connecting rod connects the piston to the crankshaft, period.
Man! Really don't get this argument!
Since the late 70s, the very first thing I considered in a modified engine build was the damn piston! That became especially true when I got into turbo, in the early 2000s!
I remember that episode! That was quite a good one! It would have been interesting to see if they still had the same fuel consumption rates during the static tests. I would assume they were pretty close.
Can't argue with that, it the piston isn't stabile, and the rings aren't sealing you're losing power and plying with disaster. That said give me a tall deck height engine with a long rod to allow for a proper piston and engine longevity.
Engine Masters was the show we’ve all wanted for a very long time if you’re reading this comment and haven’t watched it on motor trend I highly recommend it !! And make sure you subscribe to this channel he knows what he’s talking about
Great explanation of Rod Ratio and results for same