David, since the mid eighties I have been experimenting with quench. I am a Volvo VISTA tech and have built race engines for Volvo Subaru Suzuki Audi ect. My interest in quench started in the late seventies when Volvo had a severe problem with detonation on the old pushrod B20E engines. The factory fix was a 0.020" thicker head gasket. This was a dismal failure. I found that a thinner gasket actually improved the situation. As we were doing several gasket changes a day i started to experiment with improvements. Swirl was the new thing at the time so I started to cut a shallow 8 mm trench in the quench pad on the head to promote swirl. I thought that concentrating the flow towards the plug would improve detonation control. And it did. I gradually realized that it was actually cooling the exhaust valve area. As time has gone on I have refined the situation on my Honda races engines to the point that no one can touch the output of my engines and they can't figure out why. I've been called an old school mechanic but all of my race cars hold records at our local race track. That includes a 1972 Volvo 142 that has never been bested.
@@hotrodray6802 '62? Gosh, While it must be 20-25 years since I came across it the Singh grooving, that would be 60+ years for your builder - or was it the promotion of swirl and turbulence for good combustion you meant? Can't recall if I mentioned it, but there have been high swirl truck piston designs for some years, with grooves in the piston crown designed to spin the air pushed out of the closing "quench" area. These engines tend to run flat heads and bowl in piston designs, similar to the "Heron"/ concept and similar to the Ford Kent series engines' design.
I attended Automotive High school in Brooklyn, New York from 1982 to 1986. My fellow students and I were taught about quench in engine shop class several times and it amazes me that over the years later I've read many publications about engines and engine building but only your publications and videos have gone into great detail about quench! You are truly a master!!
In reality this is such a specific subject that unless you've done many experiments on each chamber design, and had a few disasters, you'll never get to understand what does and what doesn't work. Anyone with a reasonable understanding can talk about this subject for 5-10 mins without fear of contradiction, it takes a lot more specific knowledge to talk for over half an hour and put out nothing but solid very specific facts
@@V8Lenny .................and have done since at least 1970's. You can destroy pistons real quick when things go wrong. Until about 1990 I had only ever know it as 'the squish band'
Mr Vizard, I held your first book in my hands in about 1991. I was given it to read for a couple of days as a sign of great trust. It was basically the Holy Grail of power. It was all about duct porting, valve shapes and gas processes. This attitude to a book in the US or UK would be strange - you just have to go to a bookshop and buy it. But this was in the Soviet Union. And my English at that time was not good enough to read and understand everything. Nevertheless, our engine builders made some of the best racing engines in the country, including a dozen champion engines in rally and track racing, and this is your merit among others. Thank you so much!
............................i'm 73,,,,,,,got your books like many of my friends have,,,,,,,,,,,,I rework all my heads by your instructions,,,,,,made my own flow balls to unshroud the valves,,,,,,,,learned the scavenge plateau from you months ago....................others on the tube just open up every area in the chamber,,,,,,,,,,,,,,,i.'ve seen others on the tube dessimate the pinch point with a carbide burr,,,,,,,,,,,,,,,,,thinkin more is better.....................................knowledge takes many decades of work ,,,,
Wow. I had no idea David Vizard was on here. Wish I would've known this guy 25 years ago when I was digging deep into building high horse power engines. I had so many questions I needed to know about volumetric efficiency and I heard you were the man to see. Dude, youre a legend, up there with the best of them like Shelby and other true original greats. I just cannot believe that youre on here and somehow got suggested to me. Well, cheers to you, sir!
I would agree that Darrin's page is under very underated and subscribed. I have listened to Darrin in his interviews with DragBoss and the detail he goes into about ports and chamber science is outstanding. I especially loved the stories about him working with my hero Bob Glidden. But I have just discovered Davids videos recently and it is a whole new level of knowledge for me. Thank you David for spending time to allow us into the science of engines and your mind !
I too have a channel that does some cool engineering stuff and my subscribers are less than 1000 subs , it seems that great engineering isn't high on the RUclips algorithm, DV I love watching your videos and it shows me where I've been right and shows me areas to work on 🤗 thankyou
@@johncollins5552 I'm not worried about getting the brainless followers and yes you are definitely right 😂😂😂 what a world we live in when real engineering minds aren't followed by the masses
Actually the algorithm steers videos to what you are watching and things similar. This kind of information is not what most normal people watch so it gets overlooked
We've experienced exhaust valve pre-ignition on our early nitrous motors at a certain nitrous level, no tuning would eliminate it, just improving the exhaust flow with port work and valve size.
Ben Alameda spoke of this crevice gap in one of his videos but he warned going too small especially in a boosted application can actually crack a piston easily. This is great stuff.
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,he and charley serverdo are highly educated in the engine science......................few are.......
Crevice volume is also a massive contributor to hydrocarbon emissions (more so on port injection IMO). Many manufacturers have moved up the ring pack to reduce crevice volume, only to find that the decreased ring land strength leads to more failures (Subaru EJ25, cough). The use of abradable coatings could not only help power, but also help OEMs meet tighter emissions specs.
Hi David. Thank you for some amazing info! Could you please make a video about the best way to go on quench for a 4 valve per cylinder engine? Usually in such cases there is quite a bit less room for quench action.
Thanks for doing this talk David..Iam working on a sidevalve harley which has lots of quench . It gets me thinking and that's a good thing as people with these motor are stuck back in the 40ty and 50tys with there thinking and there has been no change, and I think there is room for change and that is what I am working towards. Thanks again David keep up the good work it does help.
Dick Obrien was supposedly getting 60 horse out of the kr750 roadracers in the 60s. I believe they were pulling 150mph at daytona once they got rid of the oil roping problem
While in high school I took Automotives 12, 22 ,32. The one instructor was an old navy veteran who at home was working on H2 fuel engines. This was 1968 to 1971. The other instructor had a friend that raced a stock car in a class that required a 6 cylinder engine. I mostly was involved under his tutelage, to bore and build the engine, a 261 from a truck. He had the head milled 0.090" and the block 0.060" to raise compression. Milling the head that much took all the combustion chamber out of the head on the intake side. The exhaust is recessed deeply with the spark plug. The throat in the port bowl was cut out using a seat cutter. Larger intake valves were installed with the seats recessed so the intake head was just below the head surface. This provided pretty good quench. The racer provided a new cam that appeared to have a fair bit of lift and definitely duration. The only car faster in the first race was basically identical except it had headers. Unfortunately the engine blew in the second heat. Learned a bunch on that project.
,,,,,,,,thanks David ,,,,,,,,,,,,,,,,,,,,,after the prior weeks of doubters ; you are working stronger than ever ; putting out high tech topics ,,,,,,,,,,,,,,,,we all need to know.............
I just built a propane fueled SBC engine in 2023 . It is a 12.1 CR with a set of Vortec heads with as tight a quench area as possible . With propane not needing to be vaporized , vortec head swirl mixing and tight quench I'm expecting good performance . It is unfortunate that I could not get sodium cooled exhaust valves for this build . Good thing propane has good detonation resistance but some better valves would have been nice . Your episode has verified that I am the right track . Thank You Sir !
did you check out the ls and dodge flathead sodium exhausts. We used them in the AMC sequential twin turbo Indy engine with 60 lps boost WE built a lot of propane industrial and fleet engines, you are on the right track keep the exhaust valve on the seat (short duration)
@@jmflournoy386 The GM LS6 And LS7 use sodium cooled exhaust but to modify them for for gen 2 Vortec heads seemed a valve too far . Is it possible from your perspective ?
@@KristoffKuche you would have to do guides due to valve stem size difference, most likely conversion guides or k line conversion guides are available and if head size requires seats but then you will need hard seats if you run iron heads hard. see how your valves hold up. The Chrysler valves are 1.5 or 1.530 with 7/16 HARD CHROME stems they were used in the Sherman tank multibank engine and really work they used to be inexpensive surplus...
LOVED every single detail in this comprehensive video, and no it wasn't too long 😅 this info is 'gold' to me, and I am not even an engine builder, i am a sheetmetal worker. Anything to do with flow i want to know, cheers David. Only just started watching your videos and will be watching all of them. Good job and thanks 😀😀 and sorry for your loss.
I have been following you for over a decade. Despite what everyone has told me I'm building a 350 sbc with your advice in mind. It's ment to just be a cruiser with 9:1 compression, 60cc trickflow 175 dhc heads, isky adv 258/258 .050 208/208 with .464 lift and a 107 lsa. I will have it on the dyno next week and hope it's a low rpm torque monster.
@@TheAngryForest Sounds great, you could thin that gasket some but you go it right. For those watching Isky cams are "longer" at the same catalog duration than most other vendors more like a 264 comp or 270 Crane do you remember whose pistons? good choice in any case much better than increasing the Clerance
@@jmflournoy386 They are Keith Black's +22cc. I know isky tends to have a "lazy" advertised duration but I really didn't want alot of valvetrain noise and wanted this engine to last me as long as possible. Had a melling cam in my previous block and I got a 100,000 miles/ 11 years out of it
It was very interesting and explained very well. Keep them coming. When are You and Eric putting the gloves on again? Only kidding; don't waste your time. Your brain is like a mega computer!!! God Bless!!! Mike
Thanks David! Wonderful video... In a restricted class with flat top pistons, no touch spec heads and 10.5 to 1 compression rule with a 355 SBC, 1) are these combustion chamber mods with more than the marginal loss of compression they would create. 2) with a no touch spec head rule, could we do the exhaust"soft chamber" modification to the piston valve pocket area instead to gain the same effect? 3) typically how much coating do you add above the top ring piston wall to make a difference there.... Thanks you for all you do with all you videos to educate all us privateer engine builders ass well as a lot of pro's. We all appreciate you and what you do to help us!
Another great one, can't wait to see the one covering combustion chamber and piston crown shapes. Back in the dark days, playing with small block Chevys, I was always amazed at how much better the approx 1970 and older cylinder heads ran on otherwise the same basic combination. No better flow, just a better combustion cavity / quench situation.
Your advice about crevice volume is interesting to me as a Subaru owner. Subaru's are well known to have a weak top Ring Land and it was apparently due to the Subaru Engineers attempting to reduce HC emissions by reducing the crevice volume. By contrast, the Top Ring Land in the Mitsubishi 4G63 piston is about twice the depth of the one in the Subaru EJ Engine.
Appreciate the videos . Many years ago when i was in my teens, there was a fellow who had a 67 Camaro that had a 302 engine that he turned to i think 9500 or so . He told me when he added the extra ring to to top of the piston . I dont remember all the details. He said the engine really responded to that change
I have built @355sbc with 12.5:1 cr. Using 492 heads milled to 18 degrees, resulting in 51.5cc combustion chambers with .016 head gaskets ,I'm using the Summit 1204 hydraulic flat tappit cam with 1.6 roller rockers
At one time an outfit called M&W made L shaped piston rings that filled the crevice volume and put it between the ring and the piston instead of the cylinder wall. I installed a few sets but never got to do any testing to see how their performance was other than they ran fine.
I can see that direct injection is a massive improvement in regards to crevice volume being full of fuel. I can see that by injecting directly into the combustion chamber there is much less chance of fuel ending up on the cylinder wall. That must be fantastic for BSFC
@@hotrodray6802because people wont pay to get the valves walnut blasted or pay for new heads to be installed when they do the timing belt/chain. You can even prolong the life greatly with a good catch can and filter between the crankcase evac and intake ducting.
During my engineering studies, I recall the study material from Chrysler about combustion duration. Eleven to seventeen maximum degrees of rotation drop on the various engine bores, strokes was that determination. These were flat or decompressed pistons. The workup was one of comparatives of decks, timing and temperatures etc. The fuels used were taken into account for control etc. The studies are now old, however showed production capabilites without the fine tuning good engine builders would provide. The surprising part of the study was the time verses completed combustion. -- Your video was a good partner to that. Thank you David.
I have those papers in my files containing all the years I was a member of SAE. -- I review those now and then but my age doesn't allow me to work with all I learned through the years. Kinda funny, though, when you really get smarter or good at what you do, then you die.@jmflournoy386
U find most 2 strokes have a tapered quench to direct the fuel charge to the plug in the center of the chamber and altering chamber shape can effect the power curve quite a lot.. some things are self explanatory when looking for every last ounce of power.. the average joe has no idear how all this relates to making any engine reach maximum potential.. then you find the simple things added up make the best improvements..👍
Hi David, thank you so much for the information you’re giving us wish. I knew this a long time ago the video that you did on the quench I’m interested to know just you don’t have to make a big deal out of it. Just answer the question if you could did Pont Pontiac have a better grasp on the combustion chamber shape because it was milled verses cast chambers and if so, why don’t any of the new aluminum head guys machine, the valve pockets and combustion chamber like Pontiac did and using the 30° angles on the seat just something fellow engine builders were talking about the other day in the shop. We tend to meet once twice a week and discuss these horsepower gains that have been lost overtime or maybe just not shared with the public. We very much enjoy your show and look forward to more videos on educating us on the foundation stones that we all need to have to build the best engine possible and then look for more. It’s a way of life at least for me and my buddies. Thank you for your time and I hope that your throat surgery ends up healing faster than it’s been going, thank you from the gang at the machine shop/Dyno/oh and we have one of the older super flows benches. Thanks Dave again best wishes, Joe.
Thanks, would really like to see the BMC A head mods. Always guessed that the inertia of the fuel causes the drop out when compressed and that is what piles up carbon in the crevice.
Hello David I would like to purchase the IOP The pay button does not work I am building a 383ci I have a goal of 1.42 lb-ft per 1 ci or better. I have been following you for many many years. Now is the time to put together all of the knowledge.
It's big it's been around specialty,,, one of the can type junkers,,, you got to look at that throat,,, working on quench,,,,thank you for all the videos,,,
On a slightly different subject but related, I would love to see the science of why a good 4bbl single plane makes just about the same power as a Ir setup efi or carb. There clearly is lots to the reversion/pulsing into the plenum going on that it takes advantage of. Could you get the same power with a pair of side draft carbs and a clever design inlet? ( hood clearance stuff) Would you place the carbs fore aft or sideways?
Love your segments im a cummins turbo diesel fan i just started working with the old 12valve 5.9s and ive built a whole lot of different big blocks and small blocks . my first big block was an oldsmobile cause i was a joe mondello student
What about a spiral pattern quench pad. So as the intake flow comes into the cylinder it spirals one way. Then as the piston travels back upto tdc it forces the charge to spiral in the opposite direction causing enhanced mixture motion. Also on the exhaust stroke it forces the exhaust gasses out the exhaust valve.
At the 33:00, you mentioned increased diameter piston ring band above the top piston ring. You're talking about the distance between the top of the ring and the top of the piston, correct?
DV, These videos on quench are becoming my favorite in your library. I'm curious, if one was looking to maximize an SBC in the 9.8:1 range, is it worth the slight loss of compression to include a scavenge plateau to increase flow. I know you were an advocate of "squeezing the hell out" of what you can get in the chamber. My bottom end is set but I can still work on my heads. I like the sound of being able to rev a little higher for a given cam. In general, how does adding a scavenge plateau effect the low end for that cam? Is it like stepping up to the next one in the catalog or just extend the top end? How does this smoother transition not increase possibility of reversion? Thank you for sharing this great information.
David, you need to re-investigate (for your own satisfaction) the inverted dome in the center of the piston, this where you will reduce the engines dendancy to detonate, not at the exhaust valve. What you will find is the exhaust valve will run cooler and you can run higher compression ratios with leaner fuel mixtures. The leaner mixtures will give you more power and lower B.S.F.C than raising valve lift, Once you start to cut valve reliefs into the piston crown, your power output per pound of fuel will decrease. (But if you are cutting valve reliefs in the very center of the piston crown, that is okay.) It is the piston center that becomes the hot spot, that is why a detonating engine generally melts a hole in the centre of the piston.
Hello Mr. Vizard I hope you're doing well. I find your knowledge very facinating. It is interesting to learn about the quench area. Is it correct to say that during the compression stroke at top dead center it is called a quench area and during the exhaust stroke it is called the scavenging plateau? The goal is to get the exhaust to blow under the exhaust valve not over correct? and a scavenging plateau can be ground at the quench area to make that happen. Most factory iron heads have the exhaust valve close enough to the quench area and can easily be ground a scavenging plateau however some brand of GM engines have the exhaust and intake valves sunk deep into the combustion chamber and about .250" would have to be ground to get to the exhaust valve. I guess those heads cannot have a scavenge plateau and have their limits. Too bad I don't have a nice Chevrolet engine instead I have a Pontiac and Pontiac heads kinda suck on exhaust. Great on intake but exhaust is terrible. It can have new modern fast burn combustion chambers with new aluminum aftermarket heads but it would be an LS in disguise 😂 not a true Pontiac. I just wonder how much HP can be had with factory iron fully ported heads. 500 max ? I don't know. I haven't done business with Butler they are Pontiac specialists and I don't think they will tell me any of their secrets on factory heads. They charge $1900.00 to CNC port iron heads but I don't trust UPS
Da vid, Ive appreciated your knowledge for years, thank you. Isn't the typical 45° cut above the top ring land on GM factory pistons, to remove the crevis volume, to lower edge temps (like top fuel engines customarily do)? Also I've instinctively ground plateau slopes into the exhaust area for flow aid, not realizing the induced scavenging benefit. Thank you. It does work. I pray you stay a viable resourse for us for many more years. Home built 350 cfm @28hg flow bench.
RUclips dumped a ridiculous number of ads into this video. Good luck with your channel. I only run NA. Torque and efficiency for the sum of the parts. Started out with air cooled 2 strokes 40+ years ago, melted pistons were always from insufficient squish clearance and lean mixture at full throttle. Before the days of rev limiters, mapping and unleaded. Often see porting being done with the intention of directing the mixture towards the spark plug so not sure where it all went wrong. Buddy, that valve has been closed for best part of a stroke before the spark. Swirl with maximum micro turbulence will get the best economy. Too rich will reduce the header temperature but it's better than aluminium paste in the crankcase. Happy days.
you would spend several days formulating quench positive delta negative delta . most do not realize it but nitromethane will not light on its own very easy much like diesel and once it is quenched inside a top fuel motor the quench is so tight the nitromethane is actually converted from a liquid to a solid fuel ! the nitromethane is about the same rockwell hardness as a piece of charcoal
DV, a thought, do you have merch? I was thinking you, Andy, Brian, and Darin could benefit a bit financially by offering ball caps, t shirts, sweat shirts, and coffee cups, with your Powertec 10 logo on them. Put web addresses on the back.
I was wondering David if you have done much work on Fords Cleveland heads, here in Australia 2v+4v heads are still extremely popular. The Ford Australia heads from standard were much better than their American counterparts , i think if you have time to do a video on them it would be greatly appreciated by all. Cheers Australia.
My pistons have huge valve cut outs in flattop pistons and I suspect that my cam will be holding my exhaust valve open into the piston valve relief so at the time the gases are traveling on top of quench area of the scavenge plateau the fast gas will be directed directly at the tulip of the back of the exhaust valve and directed into the roof of the port. Is that right Mr Vizard?
Crevice volume reduction between the piston crown and cylinder wall was touched on. Although I would like to know the minimum clearance to ensure once the piston is at operational temperature, clearance is still achieved without danger of scoring the piston and bore. Obviously this clearance would varie with forced induction and or nitrous.
David, since the mid eighties I have been experimenting with quench. I am a Volvo VISTA tech and have built race engines for Volvo Subaru Suzuki Audi ect. My interest in quench started in the late seventies when Volvo had a severe problem with detonation on the old pushrod B20E engines. The factory fix was a 0.020" thicker head gasket. This was a dismal failure. I found that a thinner gasket actually improved the situation. As we were doing several gasket changes a day i started to experiment with improvements. Swirl was the new thing at the time so I started to cut a shallow 8 mm trench in the quench pad on the head to promote swirl. I thought that concentrating the flow towards the plug would improve detonation control. And it did. I gradually realized that it was actually cooling the exhaust valve area. As time has gone on I have refined the situation on my Honda races engines to the point that no one can touch the output of my engines and they can't figure out why. I've been called an old school mechanic but all of my race cars hold records at our local race track.
That includes a 1972 Volvo 142 that has never been bested.
8MM is there that much material in the quench pad to allow that much, it's like .320 thou???
@@marcumexe
I expect he meant in width, from the wording?
👍👍😎 similar to the Singh grooves.
BTW an engine builder I knew was doing this in 1962.
@@marcumexe
He said shallow and implied width of 8mm.
@@hotrodray6802
'62? Gosh, While it must be 20-25 years since I came across it the Singh grooving, that would be 60+ years for your builder - or was it the promotion of swirl and turbulence for good combustion you meant?
Can't recall if I mentioned it, but there have been high swirl truck piston designs for some years, with grooves in the piston crown designed to spin the air pushed out of the closing "quench" area. These engines tend to run flat heads and bowl in piston designs, similar to the "Heron"/ concept and similar to the Ford Kent series engines' design.
I attended Automotive High school in Brooklyn, New York from 1982 to 1986. My fellow students and I were taught about quench in engine shop class several times and it amazes me that over the years later I've read many publications about engines and engine building but only your publications and videos have gone into great detail about quench! You are truly a master!!
In reality this is such a specific subject that unless you've done many experiments on each chamber design, and had a few disasters, you'll never get to understand what does and what doesn't work.
Anyone with a reasonable understanding can talk about this subject for 5-10 mins without fear of contradiction, it takes a lot more specific knowledge to talk for over half an hour and put out nothing but solid very specific facts
2-stroke tuners talk about quench all the time.
I went to Automotive H S also...I graduated in 81 . Was a Great school !!
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,grady,,,,,,,maybe...................
@@V8Lenny .................and have done since at least 1970's.
You can destroy pistons real quick when things go wrong.
Until about 1990 I had only ever know it as 'the squish band'
Mr Vizard, I held your first book in my hands in about 1991. I was given it to read for a couple of days as a sign of great trust. It was basically the Holy Grail of power. It was all about duct porting, valve shapes and gas processes. This attitude to a book in the US or UK would be strange - you just have to go to a bookshop and buy it. But this was in the Soviet Union. And my English at that time was not good enough to read and understand everything. Nevertheless, our engine builders made some of the best racing engines in the country, including a dozen champion engines in rally and track racing, and this is your merit among others. Thank you so much!
This might be one of the most valuable tech talks yet.
43 minutes was too short, David!
Never worry about length if you're filling it with this level of tech!
Your scavenge plato is a stroke of genius.
It’s like Dennis Hopper
Apocalypse Now
“Look man - you don’t talk to the Colonel!”
“You listen to him man.”
“The man has enlarged my mind.”
@@ElvinLeadfoot absolutely
............................i'm 73,,,,,,,got your books like many of my friends have,,,,,,,,,,,,I rework all my heads by your instructions,,,,,,made my own flow balls to unshroud the valves,,,,,,,,learned the scavenge plateau from you months ago....................others on the tube just open up every area in the chamber,,,,,,,,,,,,,,,i.'ve seen others on the tube dessimate the pinch point with a carbide burr,,,,,,,,,,,,,,,,,thinkin more is better.....................................knowledge takes many decades of work ,,,,
Wow. I had no idea David Vizard was on here. Wish I would've known this guy 25 years ago when I was digging deep into building high horse power engines. I had so many questions I needed to know about volumetric efficiency and I heard you were the man to see.
Dude, youre a legend, up there with the best of them like Shelby and other true original greats.
I just cannot believe that youre on here and somehow got suggested to me.
Well, cheers to you, sir!
I would agree that Darrin's page is under very underated and subscribed. I have listened to Darrin in his interviews with DragBoss and the detail he goes into about ports and chamber science is outstanding. I especially loved the stories about him working with my hero Bob Glidden. But I have just discovered Davids videos recently and it is a whole new level of knowledge for me. Thank you David for spending time to allow us into the science of engines and your mind !
Only Masters talk about quench. Well done. 👍
Darrin Morgan, is fantastic and great at explaining.
You kno what his page is called? Darrin Morgan?
@darinmorgan3520
I too have a channel that does some cool engineering stuff and my subscribers are less than 1000 subs , it seems that great engineering isn't high on the RUclips algorithm, DV I love watching your videos and it shows me where I've been right and shows me areas to work on 🤗 thankyou
Put a cute kitten on the thumbnail or a scantily clad lady and a controversial title, people ❤ that .
@@johncollins5552 I'm not worried about getting the brainless followers and yes you are definitely right 😂😂😂 what a world we live in when real engineering minds aren't followed by the masses
@@johncollins5552 yep, shows just how simple minded most people are 😁
Actually the algorithm steers videos to what you are watching and things similar. This kind of information is not what most normal people watch so it gets overlooked
DV fine details removes our misakes . WE WANT MORE !!
Thankyou mr vizard allways leaves one wanting more.peace
We've experienced exhaust valve pre-ignition on our early nitrous motors at a certain nitrous level, no tuning would eliminate it, just improving the exhaust flow with port work and valve size.
Another great vid DV
The deeper the dive the more interesting for me.
Nice grinder work DV
You still have a steady hand a groove to the wrist.
Another generous lesson. Thanks Dr. Vizard!
You've been on a roll. Great stuff. Can't wait for more. Much thanks.
Thank you, David. This information is much appreciated!
Ben Alameda spoke of this crevice gap in one of his videos but he warned going too small especially in a boosted application can actually crack a piston easily. This is great stuff.
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,he and charley serverdo are highly educated in the engine science......................few are.......
Ben is a sharp cookie and anyone here should be subscribed to him also! He shares very good technology also!
This is very great info DV. Thank you for all the videos.
Crevice volume is also a massive contributor to hydrocarbon emissions (more so on port injection IMO). Many manufacturers have moved up the ring pack to reduce crevice volume, only to find that the decreased ring land strength leads to more failures (Subaru EJ25, cough). The use of abradable coatings could not only help power, but also help OEMs meet tighter emissions specs.
Hi David. Thank you for some amazing info!
Could you please make a video about the best way to go on quench for a 4 valve per cylinder engine? Usually in such cases there is quite a bit less room for quench action.
Thanks for doing this talk David..Iam working on a sidevalve harley which has lots of quench . It gets me thinking and that's a good thing as people with these motor are stuck back in the 40ty and 50tys with there thinking and there has been no change, and I think there is room for change and that is what I am working towards. Thanks again David keep up the good work it does help.
Dick Obrien was supposedly getting 60 horse out of the kr750 roadracers in the 60s. I believe they were pulling 150mph at daytona once they got rid of the oil roping problem
Been subbed to Darrin for a while now. Super informative.
Thank you for sharing this! I can't get enough!
While in high school I took Automotives 12, 22 ,32. The one instructor was an old navy veteran who at home was working on H2 fuel engines. This was 1968 to 1971. The other instructor had a friend that raced a stock car in a class that required a 6 cylinder engine. I mostly was involved under his tutelage, to bore and build the engine, a 261 from a truck. He had the head milled 0.090" and the block 0.060" to raise compression. Milling the head that much took all the combustion chamber out of the head on the intake side. The exhaust is recessed deeply with the spark plug. The throat in the port bowl was cut out using a seat cutter. Larger intake valves were installed with the seats recessed so the intake head was just below the head surface. This provided pretty good quench. The racer provided a new cam that appeared to have a fair bit of lift and definitely duration. The only car faster in the first race was basically identical except it had headers. Unfortunately the engine blew in the second heat. Learned a bunch on that project.
,,,,,,,,thanks David ,,,,,,,,,,,,,,,,,,,,,after the prior weeks of doubters ; you are working stronger than ever ; putting out high tech topics ,,,,,,,,,,,,,,,,we all need to know.............
I just built a propane fueled SBC engine in 2023 . It is a 12.1 CR with a set of Vortec heads with as tight a quench area as possible . With propane not needing to be vaporized , vortec head swirl mixing and tight quench I'm expecting good performance . It is unfortunate that I could not get sodium cooled exhaust valves for this build . Good thing propane has good detonation resistance but some better valves would have been nice . Your episode has verified that I am the right track . Thank You Sir !
did you check out the ls and dodge flathead sodium exhausts. We used them in the AMC sequential twin turbo Indy engine with 60 lps boost WE built a lot of propane industrial and fleet engines, you are on the right track keep the exhaust valve on the seat (short duration)
@@jmflournoy386 The GM LS6 And LS7 use sodium cooled exhaust but to modify them for for gen 2 Vortec heads seemed a valve too far . Is it possible from your perspective ?
@@KristoffKuche you would have to do guides due to valve stem size difference, most likely conversion guides or k line conversion guides are available and if head size requires seats but then you will need hard seats if you run iron heads hard. see how your valves hold up. The Chrysler valves are 1.5 or 1.530 with 7/16 HARD CHROME stems they were used in the Sherman tank multibank engine and really work they used to be inexpensive surplus...
Knowing this information 30 year's ago would have helped 😂, interesting information, thanks for sharing, all the best to you and your loved ones
awesome stuff again DV, these are the details that separate building a race engine and building a great race engine. Keep up the good work!
LOVED every single detail in this comprehensive video, and no it wasn't too long 😅 this info is 'gold' to me, and I am not even an engine builder, i am a sheetmetal worker. Anything to do with flow i want to know, cheers David. Only just started watching your videos and will be watching all of them. Good job and thanks 😀😀 and sorry for your loss.
I have been following you for over a decade. Despite what everyone has told me I'm building a 350 sbc with your advice in mind. It's ment to just be a cruiser with 9:1 compression, 60cc trickflow 175 dhc heads, isky adv 258/258 .050 208/208 with .464 lift and a 107 lsa. I will have it on the dyno next week and hope it's a low rpm torque monster.
are you using a "d" dish piston like the old TRW "turbo" piston to get quench and 9:1
@@jmflournoy386 yes it's a D dish, can't remember what CC off the top of my head but whatever worked out with the .005 deck height and .038 gasket
@@TheAngryForest Sounds great, you could thin that gasket some but you go it right. For those watching Isky cams are "longer" at the same catalog duration than most other vendors more like a 264 comp or 270 Crane do you remember whose pistons? good choice in any case much better than increasing the Clerance
@@jmflournoy386 They are Keith Black's +22cc. I know isky tends to have a "lazy" advertised duration but I really didn't want alot of valvetrain noise and wanted this engine to last me as long as possible. Had a melling cam in my previous block and I got a 100,000 miles/ 11 years out of it
It made 360 hp @5100 and 400 ft/lb @4200
Thanks!
It was very interesting and explained very well.
Keep them coming.
When are You and Eric putting the gloves on again?
Only kidding; don't waste your time.
Your brain is like a mega computer!!!
God Bless!!!
Mike
This is a great video on the charge. Do to the work and shaping of the chamber. Thanks again.
Darren’s videos are amazing. Still learning from them each time I re listen.
Thanks David! Wonderful video... In a restricted class with flat top pistons, no touch spec heads and 10.5 to 1 compression rule with a 355 SBC, 1) are these combustion chamber mods with more than the marginal loss of compression they would create. 2) with a no touch spec head rule, could we do the exhaust"soft chamber" modification to the piston valve pocket area instead to gain the same effect? 3) typically how much coating do you add above the top ring piston wall to make a difference there.... Thanks you for all you do with all you videos to educate all us privateer engine builders ass well as a lot of pro's. We all appreciate you and what you do to help us!
Another great one, can't wait to see the one covering combustion chamber and piston crown shapes. Back in the dark days, playing with small block Chevys, I was always amazed at how much better the approx 1970 and older cylinder heads ran on otherwise the same basic combination. No better flow, just a better combustion cavity / quench situation.
Your advice about crevice volume is interesting to me as a Subaru owner.
Subaru's are well known to have a weak top Ring Land and it was apparently due to the Subaru Engineers attempting to reduce HC emissions by reducing the crevice volume.
By contrast, the Top Ring Land in the Mitsubishi 4G63 piston is about twice the depth of the one in the Subaru EJ Engine.
Thank you Mr D.V.
Thank you so much for all your videos!
Appreciate the videos . Many years ago when i was in my teens, there was a fellow who had a 67 Camaro that had a 302 engine that he turned to i think 9500 or so . He told me when he added the extra ring to to top of the piston . I dont remember all the details. He said the engine really responded to that change
DAVID Thanks man and as always God Bless you
Really great info. Thanks, and 45 minutes wasn't too long at all. Even with my ADHDD!
I have built @355sbc with 12.5:1 cr. Using 492 heads milled to 18 degrees, resulting in 51.5cc combustion chambers with .016 head gaskets ,I'm using the Summit 1204 hydraulic flat tappit cam with 1.6 roller rockers
Well. This would make somenders grooves obsolete, lol.. Good stuff.
I found that the head gasket had to match the bore exactly,the thinnest possible. This helped detonation problems
Another excellent episode. Thanks DV
At one time an outfit called M&W made L shaped piston rings that filled the crevice volume and put it between the ring and the piston instead of the cylinder wall. I installed a few sets but never got to do any testing to see how their performance was other than they ran fine.
I found newer versions listed on facebook under power seal piston rings they refer to them as headland rings. It is like a dykes ring on steroids.
Mr Vizard ,I remember an article you wrote in PopularHot rodding in 1979 on 385 type ford heads .
I can see that direct injection is a massive improvement in regards to crevice volume being full of fuel. I can see that by injecting directly into the combustion chamber there is much less chance of fuel ending up on the cylinder wall. That must be fantastic for BSFC
But the GDI engines are failing catastrophically at 100-140k miles.
@@hotrodray6802 that is fair.
Actually they are worse, pre ignition is a very big problem.
@@hotrodray6802because people wont pay to get the valves walnut blasted or pay for new heads to be installed when they do the timing belt/chain. You can even prolong the life greatly with a good catch can and filter between the crankcase evac and intake ducting.
@@V8Lennybecause they use the incorrect oil.
Thank you for referencing 50 as a youngster.
I have been thinking it sucks. 😂
During my engineering studies, I recall the study material from Chrysler about combustion duration.
Eleven to seventeen maximum degrees of rotation drop on the various engine bores, strokes was that determination. These were flat or decompressed pistons. The workup was one of comparatives of decks, timing and temperatures etc.
The fuels used were taken into account for control etc.
The studies are now old, however showed production capabilites without the fine tuning good engine builders would provide.
The surprising part of the study was the time verses completed combustion. -- Your video was a good partner to that. Thank you David.
I may of helped write those, have not seen them in years, are they online?
I have those papers in my files containing all the years I was a member of SAE. -- I review those now and then but my age doesn't allow me to work with all I learned through the years. Kinda funny, though, when you really get smarter or good at what you do, then you die.@jmflournoy386
You can use well over 1h in your videos. All of them are info gems.
Good job as usual, thanks a million! :)
U find most 2 strokes have a tapered quench to direct the fuel charge to the plug in the center of the chamber and altering chamber shape can effect the power curve quite a lot.. some things are self explanatory when looking for every last ounce of power.. the average joe has no idear how all this relates to making any engine reach maximum potential.. then you find the simple things added up make the best improvements..👍
Thanks you for sharing knowledge 👍👍
That was outstanding, keep it coming!!!
Awsome content love the tech and how it is exsplained thank you
Hi David, thank you so much for the information you’re giving us wish. I knew this a long time ago the video that you did on the quench I’m interested to know just you don’t have to make a big deal out of it. Just answer the question if you could did Pont Pontiac have a better grasp on the combustion chamber shape because it was milled verses cast chambers and if so, why don’t any of the new aluminum head guys machine, the valve pockets and combustion chamber like Pontiac did and using the 30° angles on the seat just something fellow engine builders were talking about the other day in the shop. We tend to meet once twice a week and discuss these horsepower gains that have been lost overtime or maybe just not shared with the public. We very much enjoy your show and look forward to more videos on educating us on the foundation stones that we all need to have to build the best engine possible and then look for more. It’s a way of life at least for me and my buddies. Thank you for your time and I hope that your throat surgery ends up healing faster than it’s been going, thank you from the gang at the machine shop/Dyno/oh and we have one of the older super flows benches. Thanks Dave again best wishes, Joe.
Thanks, would really like to see the BMC A head mods. Always guessed that the inertia of the fuel causes the drop out when compressed and that is what piles up carbon in the crevice.
Would be nice to see where water injection possibilities lie as well for an optimized tuning window 17:1+ Cr? Thank you!!!
Why stop at water...hydrogen and oxygen inj for MPG and octane boost.
Congrats on the 60 thou , and here's to many more ,,, !,,, Cal DeBruin with Speed Pro division of Sealed Power ,,, .
Hello David
I would like to purchase the IOP
The pay button does not work
I am building a 383ci
I have a goal of 1.42 lb-ft per 1 ci or better. I have been following you for many many years. Now is the time to put together all of the knowledge.
It's big it's been around specialty,,, one of the can type junkers,,, you got to look at that throat,,, working on quench,,,,thank you for all the videos,,,
On a slightly different subject but related, I would love to see the science of why a good 4bbl single plane makes just about the same power as a Ir setup efi or carb.
There clearly is lots to the reversion/pulsing into the plenum going on that it takes advantage of.
Could you get the same power with a pair of side draft carbs and a clever design inlet? ( hood clearance stuff)
Would you place the carbs fore aft or sideways?
Love your segments im a cummins turbo diesel fan i just started working with the old 12valve 5.9s and ive built a whole lot of different big blocks and small blocks . my first big block was an oldsmobile cause i was a joe mondello student
What about a spiral pattern quench pad. So as the intake flow comes into the cylinder it spirals one way. Then as the piston travels back upto tdc it forces the charge to spiral in the opposite direction causing enhanced mixture motion. Also on the exhaust stroke it forces the exhaust gasses out the exhaust valve.
Wonderfully informative and revealing video. BTW "crevice", not "crevis" spell checker would deal with that.
Fascinating.
Would really like to cover important tips like this. Racing or not.
At the 33:00, you mentioned increased diameter piston ring band above the top piston ring.
You're talking about the distance between the top of the ring and the top of the piston, correct?
DV, These videos on quench are becoming my favorite in your library. I'm curious, if one was looking to maximize an SBC in the 9.8:1 range, is it worth the slight loss of compression to include a scavenge plateau to increase flow. I know you were an advocate of "squeezing the hell out" of what you can get in the chamber. My bottom end is set but I can still work on my heads. I like the sound of being able to rev a little higher for a given cam. In general, how does adding a scavenge plateau effect the low end for that cam? Is it like stepping up to the next one in the catalog or just extend the top end? How does this smoother transition not increase possibility of reversion? Thank you for sharing this great information.
There are a few engine master engine builders on utube that use that piston coating. Most master head porters soften the quench.
David, you need to re-investigate (for your own satisfaction) the inverted dome in the center of the piston, this where you will reduce the engines dendancy to detonate, not at the exhaust valve. What you will find is the exhaust valve will run cooler and you can run higher compression ratios with leaner fuel mixtures. The leaner mixtures will give you more power and lower B.S.F.C than raising valve lift, Once you start to cut valve reliefs into the piston crown, your power output per pound of fuel will decrease. (But if you are cutting valve reliefs in the very center of the piston crown, that is okay.) It is the piston center that becomes the hot spot, that is why a detonating engine generally melts a hole in the centre of the piston.
Is this the same as the 'super squish' pistons?
@@GTE_Channel If you are referring to my comment, my answer has nothing to do with squish, only a hot spot in the centre of the piston.
Darin Morgan is the traditional Pontiac king he has a customer making north of 1300 Horsepower N/A!
Thank you again DV
Hello Mr. Vizard I hope you're doing well. I find your knowledge very facinating. It is interesting to learn about the quench area. Is it correct to say that during the compression stroke at top dead center it is called a quench area and during the exhaust stroke it is called the scavenging plateau? The goal is to get the exhaust to blow under the exhaust valve not over correct? and a scavenging plateau can be ground at the quench area to make that happen. Most factory iron heads have the exhaust valve close enough to the quench area and can easily be ground a scavenging plateau however some brand of GM engines have the exhaust and intake valves sunk deep into the combustion chamber and about .250" would have to be ground to get to the exhaust valve. I guess those heads cannot have a scavenge plateau and have their limits. Too bad I don't have a nice Chevrolet engine instead I have a Pontiac and Pontiac heads kinda suck on exhaust. Great on intake but exhaust is terrible. It can have new modern fast burn combustion chambers with new aluminum aftermarket heads but it would be an LS in disguise 😂 not a true Pontiac. I just wonder how much HP can be had with factory iron fully ported heads. 500 max ? I don't know. I haven't done business with Butler they are Pontiac specialists and I don't think they will tell me any of their secrets on factory heads. They charge $1900.00 to CNC port iron heads but I don't trust UPS
Da vid,
Ive appreciated your knowledge for years, thank you.
Isn't the typical 45° cut above the top ring land on GM factory pistons, to remove the crevis volume, to lower edge temps (like top fuel engines customarily do)?
Also I've instinctively ground plateau slopes into the exhaust area for flow aid, not realizing the induced scavenging benefit. Thank you. It does work.
I pray you stay a viable resourse for us for many more years.
Home built 350 cfm @28hg flow bench.
Beautifully done thank you david
Great video. Thank you.
Id love to get your take and advice on how to work the combustion chamber on a volvo 8v 530 head
RUclips dumped a ridiculous number of ads into this video. Good luck with your channel.
I only run NA. Torque and efficiency for the sum of the parts.
Started out with air cooled 2 strokes 40+ years ago, melted pistons were always from insufficient squish clearance and lean mixture at full throttle.
Before the days of rev limiters, mapping and unleaded.
Often see porting being done with the intention of directing the mixture towards the spark plug so not sure where it all went wrong.
Buddy, that valve has been closed for best part of a stroke before the spark.
Swirl with maximum micro turbulence will get the best economy.
Too rich will reduce the header temperature but it's better than aluminium paste in the crankcase.
Happy days.
We want the details!!
Thx DV
you would spend several days formulating quench positive delta negative delta . most do not realize it but nitromethane will not light on its own very easy much like diesel and once it is quenched inside a top fuel motor the quench is so tight the nitromethane is actually converted from a liquid to a solid fuel ! the nitromethane is about the same rockwell hardness as a piece of charcoal
DV, a thought, do you have merch? I was thinking you, Andy, Brian, and Darin could benefit a bit financially by offering ball caps, t shirts, sweat shirts, and coffee cups, with your Powertec 10 logo on them. Put web addresses on the back.
Dv on a turbo engine do you recommend widening the ex seat to about .0.60 to pull more heat from the ex valve?
I was wondering David if you have done much work on Fords Cleveland heads, here in Australia 2v+4v heads are still extremely popular. The Ford Australia heads from standard were much better than their American counterparts , i think if you have time to do a video on them it would be greatly appreciated by all. Cheers Australia.
Wow Great video always good inf
David, the Chevy BB 820 chamber - its a "semi closed" design- did you help develop it ?
Should I keep the taper of the scavenge platoue as tight as possible so I don’t lose recovery?
How would this tapered quench work, or would it work, on a 4 valve head? Thanks.
How does compression loss effect power cutting away the exhaust pad?
My pistons have huge valve cut outs in flattop pistons and I suspect that my cam will be holding my exhaust valve open into the piston valve relief so at the time the gases are traveling on top of quench area of the scavenge plateau the fast gas will be directed directly at the tulip of the back of the exhaust valve and directed into the roof of the port. Is that right Mr Vizard?
Would a quench system work with water injection? If so, how would that change things?
Beyond great advice
The pontiac combustion chamber has that two step chamer.
Crevice volume reduction between the piston crown and cylinder wall was touched on. Although I would like to know the minimum clearance to ensure once the piston is at operational temperature, clearance is still achieved without danger of scoring the piston and bore. Obviously this clearance would varie with forced induction and or nitrous.
Would this line coating effect gas ported pistons🤔?