I haven't delved far enough in the performance side to have an opinion, but I appreciate the information you've stated here, it'll definitely be useful in the future when I begin engine mods on my R/T. Thanks for taking the time to share it.
The JB Weld piston I ran in my lawnmower did the same thing, tore the piston pin bosses out of the piston after 3 minutes of grass cutting. I have suspected for years that pistons/rods in a 4 stroke engine usually fail when the piston is snapping over TDC between exhaust and intake stroke, as the gas loading on the piston is much less than during compression stroke. Thus the rod/piston would suffer a tension failure at this time versus during the power stroke when the expanding gases would push against the piston counteracting the inertia forces of the piston deccelerating approaching TDC. Just my 2 cents. I also wondered the same thing, as #2 cylinder follows #7 firing in a normal 1,8,4,3,6,5,7, 2 V8 firing order. Forgive me if the Hellcat uses the modified firing order where 7 and 4 are switched.
I don't own a Dodge but still love the channel for all the information that is shared. I am always baffled as to why this channel doesn't have a 100k plus subscribers. I watch tons of performance and automotive related channels and yours is one of the best by far.
I agree with the comment/ theory that all the parts and engines are "mass-produced" and that could be the issue. In "blown" engines (positive displacement and or turbo supercharged or composite supercharged & turbocharged engines) the smallest of issues can become major issues in a heartbeat. I have built and raced and maintained 2 and 4 stroke motorcycle road racing engines as well as 1, 2 (twin) and 4-row radial military aircraft engines prior to computer data logging abilities and had to rely on post-event evaluations as to why engines failed. I would personally believe if I had to point to a single item/ issue it would be the cost-saving measure of the factory not using a torque plate while boring/ honing the cylinders. The difference is tiny by any standards but "can be" significant during the extremes encountered by any engine not designed from the onset as a "blown" engine. The levels of stresses involved accelerate so quickly and suddenly that it can be almost impossible to catch.
That piston isnt "forged", or actually extruded, its a casting as it has cast in numbers inside the crown. It was simply termically/mechanically stressed beyond design parameters. Amazing that people expect them to survive racing and that they actually do in many cases.
@@whatchu_talkin_john_willis Maybe my grammatics are bad, I tried to say that the piston is cast and at the same time clarify that what's called a forged piston actually is extruded. Aluminium can not be forged, its instead heated and pressed into shape in a special process.
You are right and that is one reason...its normally heat related this can be due to detonation...but the pistons tops and the plugs were the wrong colour...they normally have a white coating from running lean....as he said in the end of the video the air intake temp spiked....I would say this was blow bye from 7 being forced into the intake through the crank breather...this is what probably melted the plugs due to cylinder temp being too high.....
Logs showed zero STKR. I showed that in the video as well. Not saying detonation didn't occur, but if it did the car didn't pick it up and the pistons didn't show signs either as you saw.
@@SpeedysGarage you said in the video the logs showed timing being pulled. Then you tear it down and there's evidence of detonation everywhere , melted plugs, broken ceramic on the plugs. And then you comment contradicting what you say in the video lol. Detonation doesn't always occur on the top of the Piston, usually when you're on the edge it starts at the ring lands.
I don't have time to type it all out here, just go back and watch the video again if it's not clear. Timing being pulled wasn't knock and I'm sure you know that 0 degrees of timing with 17psi of boost at WOT causes many problems (lots of heat). That's what we see here, but the problem was something else. Max timing in the tune was a paltry 10.5 deg. I've been running almost the same tune and pulley on the new motor for about a year with the same 93 fuel as well. Watch some of the newer content to see that we ended up with a 9.83 at 141mph.
Excellent input! I had a cylinder 2 fail on mine and found it out from the Buyer of the car as I did not want to rebuild the motor - so I sold it! Blessings for future success!
People most often think about the tremendous forces applied to a piston and connecting rod when a cylinder fires. But what's often forgotten are the tremendous forced applied to a piston and connecting rod when the piston goes up at high speed speed and then has to come to a dead stop before being pulled down again at high speed.
@@garypeatling7927 That isn't why, 2 strokes have the exact same forces, what limits 4 strokes is/was valve float, Ducati had/has a desmodromic system where valves were opened and closed by cams and often ran 11,000 to 12,000 rpm back before modern high tensile strength metals. Honda currently has a 250cc with a 19,000 rpm redline. And that's not even going into F1 where 20,000 rpm V6s are common. I know there was an rpm cap, there were engines faster than that.
All I see is too much timing or too much heat in that cylinder. The cylinder got super hot and seized up the piston. That’s why it’s all blue at the bottom. Haven’t built many Hemi’s but I’ve seen this on LS engines where one of the cylinders got too hot. Appreciable you sharing this with us.
I think it'd be hard to get too much timing when it maxed out at 11 degrees, but maybe too little? In the factory tuning timing is retarded in order to heat up the cylinder and light the cats off. Interestingly the factory Red Eye tunes have 9-10 degrees in them max timing.
Yeap a lot of non tuners don't realize you actually can drive EGTS UP with retarded timing as determined by cylinder head design and flame front ( aka 19 degrees is different on an engine that peaks torque at 30 degrees NA Vs say some at 42 on BBC)
I did the exact same thing to my 1985 S-10 2.5L Iron Duke motor by putting it in neutral and flooring it, seeing how high it would rev. It rev'd pretty high... then BAM... piston exploded. In my case the entire piston shattered, then I had just the rod and pin rattling around in the cylinder.. it was SO LOUD, but awesome at the same time. Good Times!
Wow, a floating piston during a quarter mile running 10s...probably just built for 6k rpm on a factory motor of 800hp, running 7k rpm on stock rods and pistons will give on a Hellcat...lesson learned..forged pistons and rods built for racing...great video along with data logging of the failure 👍
I'm pretty sure a stock hellcat uses forged rods and a forged crank and I thought the Pistons were forged to I mean I don't think Dodge is that dumb to warranty a 800 horsepower motor and not use a forged lower end AKA short block that's why they absolutely do not recommend pudding a supercharger or turbocharger on a non hellcat Challenger cuz the lower end of the motor is not forged parts
@@kennethjanosick5939 These engines, and also the LS Chevys, are well engineered to work and deliver an excellent power curve at a designated operating range. However, when tuning, and the installation of power adders like forced induction or nitrous come into play, these engines are delivering power beyond what the bean counters (engineers) anticipated. We got to work on some LS engines that originally came from a specialty division of GM Mortorsports, and they had Callies forged cranks & rods, with JE pistons. No hypereutectic pistons or powdered metal rods in those engines.
RPM kills engines. I have seen this on any engine a lot with floating wrist pins. Pistons with hardly any skirt and floating pins rock more and will break and leave the piston at the top of the engine. Piston ring gaps can also close tight and leave the piston at the top. Floating pistons get get larger as time goes by and when they jurk the piston back down can break the piston or rod. When you press any engine to its limits you can expect anything to break after time. Just the way the game is played. Its a money game if you can afford to play.
yup... those ring gaps are crazy and the rings are so thin, how did they even think they would work in the first place... cuz, you know, Mopar runs so cool and all. I didn't even think about how bad those wrist pins are. Like the pins on a Harbor Freight breaker bar.
Speedy you are definitely a racer. Awesome video. I agree with your gut feeling that it was a defective piston. I know you push your engines to the limits with your mods, but you do it by the book. So much to learn from here. Sadly, I don't think it's anything you did wrong, just a defective piston. Thank you.
I was thinking all along what you said at the very end of the video. I think it was that hot intake air temperature that did it. Piston and rings swelled up inside the bore and made that piston a little too hard to pull back down and it just ripped the skirt right off. That had to have been what happened. You got to realize, the temperature you’re seeing coming into the engine that’s all the way up in the intake. By the time you go to compress that gas before it is ignited it’s only going to heat up even more! When you compress gas together rapidly it heats up rapidly, even without igniting the mixture. By the time the spark plug hit that intake charge was surely a few hundred degrees more, if not over 1000 degrees. Plus, your back cylinders are always going to run a bit hotter than the front ones, they’re the last ones to see the coolant in the block before it goes through the cylinder heads and is cooled through the radiator. Was the engine sitting and allowed to cool way down between passes? We all know that metal expands when heated. That’s why they say to never flog a performance car when the engine is cold. Everything needs time to warm up to operating temps to allow the tolerances to tighten up. Hope this all helps
Just a failed piston. I think its a fluke. I believe the factory pistons are actually manufactured by Mahle. Not junk. Those guys know there stuff. My Buddy works for CP Pistons and has nothing but good things to say about Mahle. Id love to see the difference between a Demon/Redeye Piston and Rod assembly versus a Hellcat.
This is good to know. With me just now beginning to modify my hellcat. I am happy that this was just more than likely a one off. Not a factory problem.
Over 60% of the late model Hemi i have re manufactured (aprox 25 longblocks) had failed due to intake seats coming loose and breaking. If your rebuilding an engine with a seat failure make shure you pressure wash your intake manifold really good. Try to get every port from every angle possible. There have been reports of fresh rebuilds pulling pieces of broken seat debris into the cylinders under heavy vacuum scenarios. Some after market gaskets have a screen embedded in the intake gasket to prevent this from happening, but im shure they will adversely affect top end performance. Any sign of issues i remove the seats, machine and install new seat inserts. If there not getting replaced i will steak around the seats using a center punch to ensure the dont move.
Might have just been a perfect storm of stuff. Defective piston cast and cylinder just a bit out of round. Like you said these are mass produced parts. Quality control isn't as detailed oriented when it's a numbers game. Doesn't make it a bad product but it is man made. We haven't made anything that is perfect all the time. Great detective work and thanks for putting it out there.
Looks like the pistons use an offset pin which is great for making torque...but it also increases the side thrust on the skirts. Anything with offset pins to me means you really watch the RPM's and never exceed the factory redline or skirt failures will happen. Bet aftermarket pistons are symmetrical pin design which will hurt the bottom end torque production a bit but will be more reliable at higher revs.
When metal parts fail, it is almost always at a sharp corner. Threaded parts fail at the root of the thread. Parts with grooves fail at corner of the groove. That's why these type of parts are engineered with a radius at the root of threads and corners of other parts. The larger the radius, the stronger the part. A sharp corner causes a stress rise in the part. It is possible that the oil ring grooves of some pistons have a sharper corner than others, caused by tool wear during production. Also if the oil passages have a sharp corner where they meet the oil ring groove, it would cause a strees rise and potential failure spot.
piston skirts are way too short! yea they tried to reduce the mass... but!! you can only do that on engines that are race only!! trust me!! been there and done that back in the late 1970's!! also burned plugs. is bad fuel! advance issue!! I used to run 49 deg advance back in the day... got in to some wrong tagged fuel... these are the reasons they check fuel at the drag strip... high rpm, advance walking, bad fuel = broken parts!! forged pistons are the only way to go!! I always liked aires brand... custom were only were 400.00 each. that was back in 1980!! 100% perfect spec!!
The pattern of breakage on the piston looks like fatigue failure. Usually has a dull, satin type appearance from the cracks gradually progressing before it fails catastrophically. The final sudden fractures will be more shiny and metallic in appearance. That's also where you'd expect to see it. Those holes are at least drilled and not cast slots, but still they are stress risers.
Looks like you had some piston skirt damage and rocked the piston till it let go from what the crown is showing. But you didn't show the skirt pieces which is probably the most important pieces to look at. The top 2 ring groves look too good for it to be expansion seizure. Well that and the fact you sucked the crown out with a shop vac
As a Hellcat Owner, I just subscribed to your channel. Your content is much appreciated!!! I look forward to the what's to come this week. Thanks for sharing.
Absolutely agree. I’m glad I found this channel. I’ve learned so much about the hellcat thanks this speedy. I don’t know if there’s anyone else digging so deep into their hellcats on RUclips like this guy.
Leonard Rice not even hellcat owners only enthusiasts period ive got a scatty and i find this interesting especially considering im starting to get into putting more power in her
Looking at a Ram 2500 truck how I found The channel. Good video for me. Start towing a trailer up a mountain at 12000 feet you going to put stress on motor. Thank for the work. Also will tow my racecar to track. Malibu 383 10.69 best in quarters.
My stock piston broke as well. It was on the side. Looked fine when I took heads off. Ring lands broke on the party of the piston with no support. Now I run 2618 forged mahles. Super bummer. Hate to see that.
too much heat , expanded the rings untill they butted, seizing them in the bore, breaking piston tops. Guys who get carried away boosting LS engines without opening the ring gaps have this problem, too.
These a team of blokes on you tube, its a few years old that experiment/destroy engines on a dyno in various ways to see what happens....they showed what too much nitrous does...same as over boosting/lean mixture etc....and your right the rings butt up and break the piston...normally the top ring breaks the piston as this is the hottest part but it normally stays connected to the rod just eats the piston...
Yup ring gaps, seized up top and pulled the pin out. The unusual rocking wear on top of the piston was probably due to the piston developing a crack as the piston was getting to seize prior to complete failure.
I’m at about 850 hp rn and I’m keep having a problem where cylinder 3 is misfiring I took the spark plugs out and replaced them all the one that came out was bent as if the piston slapped it after replaced car ran fine did an oil change found a super small amount of metal shavings was in the oil but now having the same problem again about to start taking her apart hopefully I don’t have anything crazy going on
Similar failure found on entirely different engine. Found oil squirters for piston blocked, overheated piston momentarily locked ripping wrist pin out of bottom. Remaining lower portion disintegrated so rod and wrist pin were flopping up down in bore. Rod was long enough that didnt jam and break but still had bend poss due to hitting debris and piston top. In this case heat was the killer.
I think u will find u had ring pinch because of to high cylinder temps the melted/broken plugs tell u it was preigniting which will raise cylinder temps once the ring ends touched the piston tried to stop moving and the rod pulled the bottom of the piston off .i have seen this in several turbo motors including our own 2jz when we ran to much boost for a stock bottom end (data log told us tune was ok) the parts looked identical .piston , rod , plugs all looked as urs did
Haven't seen any of your videos before - very well done and excellent points raised! High ring pack is for emissions and power, lower is for top land strength. Were you able to check the remains of the connecting rod small end - if it failed it may have allowed the piston to rack sideways a little, stressing the pin area of the piston until it failed? I think, though, you and your buddies called it, though - poor piston quality allowed the 'pin bosses to fail.
piston rings butted, the crown of the piston is strong enough not to chip off so it sized the piston in the bore, pulled the wristpin out of the piston. rear cylinders run hotter on pretty much any engine due to the coolant inlet being at the front of the engine. couldve gotten one that was on the tight side of factory acceptable piston ring end gap clearances, and then turned the wick up on it.
As its been said great video...for a change a genuine informative video, I think your spot on with your theory, manufactures won't admit anything which is a shame a SHIT does happen and word soon spreads and they get a bad name rather than going... yes we've had a batch issue, Along with most manufacturers I know Ford with there ZETEC engine which the vales stuck open in the heads due to machining error.....it took us 8 months of diagnosis's to prove it was that before they agreed with our findings, they never recalled them but dealt with then on failure base only, Lexus first diesel the piston rings basically re-bored the engine due to the coating being wrong....again only dealt with failures and that's only two of many I've seen in my short life on this planet....may be if you approach Dodge and show your finding they may offer a goodwill payment?...if you don't ask you don't get.....please do more like this as your understanding and not bias in your view you accept things go wrong which is a great lesson for us all.
Awesome content bud, I have been wondering about my hellcat. I'm making good power and wanting more but it's a daily driven vehicle. I have almost 40k on it now but I did the pulley swap and tune with Petty's Garage. They did a great job with the setup but they left a lot on the table. The swap was done at almost 15k miles, another company said they can get me over 975 from their tune only with what Petty's did. Thanks for your information on what your vehicle did. Keep it up and can't wait to see what happens next. Good luck bro
That happened to a 10,000 mile 4.6 Ford 2v that I owned. Plug pieces scattered and welded to the piston top. I was running a Vortech with no intercooler racing on a hot summer day. The rod came a knocking on the block lol. It took out my valves as well so I needed a total rebuild
Looks like the piston failed first. Did you check the rings to see if the rings got hot ,expanded and lost ring gap. They do that and stick in the bore and rip the piston apart.
I had a 5.7 in a Durango do the same thing on startup bone stock engine daily driver didn't hurt the block at all so I put a new Mopar piston and rod in it and never had anymore problems with it and it was also number 7 done a quiet a few hemi now and always number 7 piston
Only time I've seen failures like that is due to pinging piston rocking in The bore if the piston was cracked you probably would have heard for a while before it failed. And the melted spark plugs seems like a tuning issue to me.
I've seen plenty of pistons break at the oil ring groove on different makes. It's high RPM on a part not really designed to live at those piston speed per mile speeds. Mopar built these cars so folks could race them and live with the damage and develop the engines to make power and live a little longer themselves . it's a story as old as the car.
I agree with you that a mass produced part failed as you pushed the revs beyond where the factory programing had it set. 1 thing of note, the 5.7s and 6.1s are fairly loose fitting engines, whereas the 6.2 and 6.4s are tighter, so they are not as forgiving. IMO, the 6.2s and 6.4s are better built then the 5.7s, especially the older 5.7s which had piston slap and oiling issues for the top end. What I found most interesting was what happened to #2. I've not seen that happen before, except when using nitrous and the tune was wrong. Do you think that the IAT caught it because after 7 let go, it was that far out of balance and the intakes were open when they shouldn't have been for just a split second on #2? OR do you think that the engine's mechanical timing was off enough to see that cough through the intake which spiked IAT? My curiosity is why did just #2 melt down, but no others did?
Since publishing this video I talked to a few folks that deal with these a lot, of course it's all theory, but we're thinking that with all the timing being pulled (which generates a ton of heat at WOT and 17psi of boost) things were hot enough that when 7 let go it fried 2 in the process. Just a theory though. The tune and logs showed fueling was good at .83 lambda and timing was max of 11 so not enough to melt things like that.
On my trackhawk Snapped my rod one #1 and it dropped a valve in that same cylinder. I was about 1k hp. Just got my new built engine in now doing tuning shake downs now
Exceptional video for all the reasons you stated! I have had 2 engine failures (different platform) - but all of the detail you are sharing here is great along with your and others theories!
Not a true statement. I've got a redeye which is a demon motor exactly. They are very slightly better on a harder rod and connector ring. The cam is better and that's all. Seriously I have a blown one.
I am a small engine mechanic. This was caused by a bad batch of aluminium. Once back in 1990 I had 12 hp Briggs and STratton engines that would stick intake valves open on brand new engines. Briggs and Stratton called it "Porus casting" from february to april that year, it was aluminium engine block, they warrantee short blocked the engine, and another that had done the same thing on another mower in the shop. That piston swole up, and Heat from combustion would do that. Only the faulty ones will do that, you gonna have to know the manufacture dates from your failed piston, and replace all with that manufacture date. Porus casting of the aluminium piston. You can open the ring end gap, you can bore the cylinder larger, none of it is gonna work because you can't tell how much that porus casting it gonna swell, its an unknown variable. Bad batch of aluminium... You gonna run 9's you need forged or have lots of room for expansion, can't run close tolerances, gonna have to open all that stuff up so it can swell up at high speed. Loose is fast!
Totally agree and like said in old comment... the hellpuss is not torque plate honed and I have seen two that seen 7000+ with wrist pin pulling out back of piston diamond pistons in the new set up with alot more bottom end also threw the blower in the corner added twin 88 ball bearing percisions added fuel injector bung to a sheet metal intake I built for the car.. the factory rearend let go on last dyno pull we knew it was on deck before we even started the tuning that hellpuss put 1691 down and still has more in it good luck with yours like the vidga
Awesome Speedy《☆》Definitely a Parts Lottery with stock Hemi engines. FCA needs to re-evaluate parts suppliers & quality control. The 6.2s are having piston issues and the 5.7s are having lifter/cam issues. Good luck with GoMango🤓☻🤠
Man lots of good info on this video. Agree with you that people want to sweep things under the rug when things go wrong. (Myself included). Can’t wait to see what you put in there next. Learning from this makes me want to get forged pistons and rods from Callies or some other place like that.
I think you are right, since the parts are made for mass production you will see stronger than spec parts. Parts that meet but don't vastly exceed the tolerances dodge specified for the order may fail unexpectedly.
I think you’re on the right track. I would say that when the engine was “ over revved” a few weeks beforehand that the Gudgen pin bore in the piston was possibly stretched and weakened the piston material as it did. The piston would probably have become weaker with each pass until it let go.
Take it from an old fast guy, many of these mopar - Ford motor fails are from 0-5 weight oil. Use 20-40 weight min. Water doesn't cut it in hp applications. I've used 50 w for 50 yrs.
The one time that happened to me was in my slant 6. I over heated the engine and a piston seized pulling the rod from the piston and putting a hole through the block. I suspect that pistons tolerances were a little tight and subject to heat. If you race, build your own engines. I've raced for 30+ years. MOPAR!
I have a 1954 354 Fire Power hemi and a buddy of mine has a hell cat hemi. I was blown away at the differences. Even the way the bearing caps are split. But yeah I'd say a fluke of a failure. Me old school carbs and engine, no juice so no "check tunes data". Seems to me some major piston slap tore it apart at high revs.
The rod and pin didn't fail the pistion did it probably over heated the pistion and it seizied. At the top of the stroke and ript the pin out I'm curious if there was drop in boost pressure before the it failed?
Thanks for the great info. Im thinking of the same upgrades this winter. I differently going ti looking into the pulley(tune), driveshaft, tires, & full exhaust. I just want low 10s. Thanks again bro
Well, high rpm on overrun would be my guess for this type of failure. It occurs at the end of the exhaust stroke and the beginning of the intake stroke. On the compression/power stroke on overrun engine compression keeps the piston and rod assembly in 'compression' but there's nothing to do that on the exhaust/intake stroke. This seems like a cast or hypereutectic piston type failure. The pin pier cracked and probably rubbed either side of the crack - hence no oil discoloration, then let go. As you point out the crack allowed rocking before the catastrophic bit. Not unheard of back in the day in cast pistons but fairly rare today I must say. You are racing it and this type of thing is par for the course ie what do you expect when you repeatedly rev it up like this? : ) Just an idea. Maybe they updated to ARPs because this failure is known to the factory and is a production fix LOL. All your other reasoning re the data logging seems quite accurate to me.
Great video! Thanks for sharing the knowledge gained from the failure. I certainly agree with your theory. The point you made previously stands: if you race, you best be prepared for things like this to happen. Thanks again for the way you present your format!
robert winton yup. You _can_ actually have performance _and_ reliability, but you are definitely going to pay for it. Honestly though, it's still cheaper in the long run than constantly breaking and replacing shit.
My buddy had a 318LA that had a similar problem, except part of the piston skirt broke off and wedged itself in the cylinder walls (It's on my channel) and it seized up the wrist pin on that cylinder and a few others, our guess was that it was ran low on oil at one point and when he got it (and he ran that thing hard) that it weakened it up causing it to fail. Could have been as simple as bad lubrication at that moment
Wrist pin went oval/seized in pin bore, possibly. This was common with 390/401 AMCs, 1" pin wasn't beefy enough @ 600+ HP.... Thicker tool steel pins fix that....
I wish someone would help me pay for my engine mine just blew a piston threw the bottom of the block 😒 am sick over this as my Hellcat challenger is my baby. Your videos are very informative and learn alot from you!
I wonder if it was RPM that did this? These parts are designed to take a pushing force not a pulling force. My best hypothesis is this rod/piston was pulled apart... Kinda like how cracked rods are made. Anyone else agree?
it is basically a quality control problem that was accepted in terms of a production engine so when you stretch the limits, you place these problems to the day light
Another great video. I lost the “strap” and porcelain on both plugs in #2 cylinder. Burnt hole in exhaust valve. My tuner thought it was a device I had plugged into the OBD port. (Discreet comment) I’d like to know if any of your members or contact have a theory. 2 and 7 are sisters but with the supercharger in between I’m not convinced the heat /fire jumped. I have seen jumping on older carburetor / intake manifolds. Thanks again for the informative video.
Usually burned plugs are a sign of extreme heat or a lean condition. My only other thought is a bad injector, but it would have shown problems before #7 broke I'd think. Gonna send the injectors out for testing and will post content on that to see what we find.
This happens to turbo LS motors, stock pistons let go. There's a few reasons, but usually too much RPM for the piston or flexing wrist pin (power or detonation). Excess RPM can cause microcracks, which slowly get worse and let go at random (even idle). Flexing pins bind up, which can snap the skirt off as piston twists in bore & bend rod. Skirt bits then get smashed between piston and rod & usually rod disintegrate. All happens VERY quickly.
What's amazing here concerns the piston failure. Normally then, the rod-end, with wrist pin, slaps like hell in the bore, wiping out the bore, and therefore the block itself. I've actually NEVER seen a piston failure where this didn't occur until now...(First time for everything?)
Mopar has a know issue with the wris pins and some of the sodium filled valves are breaking off the tulips and slamming into the top of the pistons. As for the plugs, its the electrodes that are failing not the porcelain. TSB’s went out to dealers in April of 2018 regarding wris pins and valves. Pistons are Hyperuetectic / cast with a ceramic mold. Small holes are cooling gas ports in the ring lands. Way too much gap in the rods. I would question if possibly these pistons or rods were original or not???
So engine noises can cause knock sensors to falsely pull timing? I had a top end tick, redid all the shims and I swear it's going heaps better,I was wondering if it perhaps thought the tick was detonation at higher rpm?
I have heard that the new hemi engine has camshaft lubrication issues. This is not related to this video but it's supposed to be because the camshaft placement is a little different than the old hemi engines. I was curious if you know anything about this because I have wanted a Hellcat but am afraid and don't trust Dodge to replace the engine if it's faulty !
You might consider on your piston failure, the ring gap being to tight. The heat expansion caused the piston to seize at the top of its stroke. I come from a slightly different perspective being a former technical training manager and field service engineer for Cummins Diesel. Incidentally, the highest stress on a connecting rod and piston is in tension (pulling apart) during valve overlap at TDC. Hoping my Red Eye stays together. Regards, Dave
coolant got in through steel gasket, hydraulic, bent the rod first before breaking. Clean spots around the right upper and lower head gasket water jacket holes
Aluminum head or block shrinks after so many hot -cold cycle where there is the most heat at the head gasket fire ring. you can check with a straight edge and flash light, not a feeler gauge. Head and block surface has to be absolute perfect ( low Ra )
At 4:42 it looks like your little shop helper (your cat) decided to come in to help you. Looks like a Tortoise Shell cat, I had one for 18 years and they are wonderful cats :-)
To me,the piston crown roll over deformation appears to be caused by one side of the piston pin bosses letting go before the other.This puts the power application off center,causing the piston to tilt in the bore,as the alignment skirts lie on the axis perpendicular to the pin bosses.The only thing keeping this cratical bore alignment is the wrist pin integrity.
I think i have to agree that it’s just a mass produced defective part. I’ve been boosting the hell out of my 5.7 Ram for almost 2 years now, 6-10 psi on stock bottom end depending on mood, and i always wondered if this would be what kills it. It gets spun to 6700-6800 at the track so i know I’m pushing my luck. Although I’ve got forged pistons and rods just waiting to go in so we can turn it up.
wouldn't exclude hydraulic locking of the piston, 2 reasons first there were issues with the spark plugs - result lots of fuel going in and not igniting, second, gudgeon pin pulled away from piston near TDC - on compression stroke. Do agree that the pistons weren't great, heavy cast with not a lot of meat at the bottom of gudgeon pin, BUT the remainder of your pistons didn't look too bad.. Do you run a lambda sensor, if so any signs of mixture running rich through the rpm range>
Wonder what day that motor was built , tore one apart built on a Friday , # 8cylinder , piston had no lands on one side for rings , or ring groove for lock ring on wristpin, cutting a deep gouge in cylinder wall, custom got new engine
I don’t know the specifics of the hellcat engines, but I recently saw that Power Auto Media shootout that features the mopar vs LS vs Coyote and both tha LS and Hemi teams had to replace the pistons because they said the stock pistons won’t handle a lot of boost, basically they come apart.
Curious to know how often you change the plugs while racing and pushing the motor. You have documented the timing change but did you pull plugs and bore scope to check after each inconsistency? Props for detailing such catastrophic failure on your motor.
What I'm seeing here isn't a Hellcat issue, it's an engineering and metallurgy issue. Floating wrist pins have an inherent strain built into them--there's a clearance between the pin and the piston. Awesome for efficiency, not so awesome for strength. Press-fit wrist pins create a single structure between the pin and the piston, distributing the load in a uniform fashion. It looks like a piston overspeed event. That crisp shear-line at the base of the skirt I usually only see in hypereutectic aluminum. I would HOPE to see forged pistons in a factory 700hp+ boosted engine, but with the clearances required, I wouldn't be at all surprised if Chrysler avoided it--especially after the old skirt-slap issues GM had on cold start back in the day. I'm curious to see the results of your friend's stress test on the two pistons you pulled!
Looks like he bent a rod. Piston failed secondary? How would the piston crown mushroom like that from slap if the wrist pin/wrist pin bore failed first? Had to of been slapping the cylinder walls for a while to mushroom like that which is why I say bent rod was primary. That also explains the timing pulls. Car was seeing the modified stroke from a bent rod in the CPS pulse width.
In my past 50 years of building and pushing engines (many times well beyond their limits), This looks like a classic piston skirt failure - then instant stress cracking the pin boss. The piston rocking marks smells exactly likes that. Skirt goes - then piston rocks - then a few strokes later - Boom! As far as the broken ceramic in the plugs - that is either bad plug mfg. or mild detonation. Did you change to a colder plug than stock? I hope.
if you're shattering plugs that's major detonation and if you keep doing it with plug after plug you're ignoring a problem and will pay for it eventually.
It looks like the wrist pin bent and allowed most of the force to go to one side of the piston. That usually only happens in diesels but you guys are hitting those type of torque numbers. I'd get the wrist pin out and check to see if its still straight.
Sorry for your problem Speedy. I'm a hellcat owner also, and in my opinion the entire car is a piece of Garbo. I continue to have tranny issues ( a 6 spd). The only impressive item in the car is the sound system!!
Mine's been a pretty decent car. Had the bearing issue on the supercharger and that was replaced under warranty. Kinda disappointed in the pistons though.
I haven't delved far enough in the performance side to have an opinion, but I appreciate the information you've stated here, it'll definitely be useful in the future when I begin engine mods on my R/T. Thanks for taking the time to share it.
LOTS of info on this channel about our R/T Orange Krush that should help.
I will go with skirt cracked, piston rocked in the bore on intake stroke, and the rod pulling it down ripped it apart.
The JB Weld piston I ran in my lawnmower did the same thing, tore the piston pin bosses out of the piston after 3 minutes of grass cutting. I have suspected for years that pistons/rods in a 4 stroke engine usually fail when the piston is snapping over TDC between exhaust and intake stroke, as the gas loading on the piston is much less than during compression stroke. Thus the rod/piston would suffer a tension failure at this time versus during the power stroke when the expanding gases would push against the piston counteracting the inertia forces of the piston deccelerating approaching TDC. Just my 2 cents. I also wondered the same thing, as #2 cylinder follows #7 firing in a normal 1,8,4,3,6,5,7, 2 V8 firing order. Forgive me if the Hellcat uses the modified firing order where 7 and 4 are switched.
I don't own a Dodge but still love the channel for all the information that is shared. I am always baffled as to why this channel doesn't have a 100k plus subscribers. I watch tons of performance and automotive related channels and yours is one of the best by far.
If your a racer then build them with better aftermarket pistons and rods, much better 1000hp+. If you stay stock then expect these kinds of problems.
I agree with the comment/ theory that all the parts and engines are "mass-produced" and that could be the issue. In "blown" engines (positive displacement and or turbo supercharged or composite supercharged & turbocharged engines) the smallest of issues can become major issues in a heartbeat. I have built and raced and maintained 2 and 4 stroke motorcycle road racing engines as well as 1, 2 (twin) and 4-row radial military aircraft engines prior to computer data logging abilities and had to rely on post-event evaluations as to why engines failed. I would personally believe if I had to point to a single item/ issue it would be the cost-saving measure of the factory not using a torque plate while boring/ honing the cylinders. The difference is tiny by any standards but "can be" significant during the extremes encountered by any engine not designed from the onset as a "blown" engine. The levels of stresses involved accelerate so quickly and suddenly that it can be almost impossible to catch.
That piston isnt "forged", or actually extruded, its a casting as it has cast in numbers inside the crown.
It was simply termically/mechanically stressed beyond design parameters.
Amazing that people expect them to survive racing and that they actually do in many cases.
extrusions are forgings, nothing like casting
Its a mopar thats the first issue
The piston that is broke is a forged piston. The old 5.7L piston he showed is a casting.
@@JamesBrown-hc2yg Not mopar, but no nopwr.
@@whatchu_talkin_john_willis
Maybe my grammatics are bad, I tried to say that the piston is cast and at the same time clarify that what's called a forged piston actually is extruded. Aluminium can not be forged, its instead heated and pressed into shape in a special process.
If you broke the ceramic on the plugs its from knock. It was the tune. The ceramic on plugs don't break unless there is detonation.
You are right and that is one reason...its normally heat related this can be due to detonation...but the pistons tops and the plugs were the wrong colour...they normally have a white coating from running lean....as he said in the end of the video the air intake temp spiked....I would say this was blow bye from 7 being forced into the intake through the crank breather...this is what probably melted the plugs due to cylinder temp being too high.....
Bingo! You win. Too much spark,too little octane. Dump a gallon of toluene in there.
Logs showed zero STKR. I showed that in the video as well. Not saying detonation didn't occur, but if it did the car didn't pick it up and the pistons didn't show signs either as you saw.
@@SpeedysGarage you said in the video the logs showed timing being pulled. Then you tear it down and there's evidence of detonation everywhere , melted plugs, broken ceramic on the plugs. And then you comment contradicting what you say in the video lol. Detonation doesn't always occur on the top of the Piston, usually when you're on the edge it starts at the ring lands.
I don't have time to type it all out here, just go back and watch the video again if it's not clear. Timing being pulled wasn't knock and I'm sure you know that 0 degrees of timing with 17psi of boost at WOT causes many problems (lots of heat). That's what we see here, but the problem was something else. Max timing in the tune was a paltry 10.5 deg. I've been running almost the same tune and pulley on the new motor for about a year with the same 93 fuel as well. Watch some of the newer content to see that we ended up with a 9.83 at 141mph.
Excellent input! I had a cylinder 2 fail on mine and found it out from the Buyer of the car as I did not want to rebuild the motor - so I sold it! Blessings for future success!
Thanks for going through the trouble to show us what exactly happened to this engine. Very interesting.
I wasn't made for these times. A man of my own heart, racer mechanic yet he speaks in upspeak.
People most often think about the tremendous forces applied to a piston and connecting rod when a cylinder fires. But what's often forgotten are the tremendous forced applied to a piston and connecting rod when the piston goes up at high speed speed and then has to come to a dead stop before being pulled down again at high speed.
That why two stokes can rev more than four
@@garypeatling7927 That isn't why, 2 strokes have the exact same forces, what limits 4 strokes is/was valve float, Ducati had/has a desmodromic system where valves were opened and closed by cams and often ran 11,000 to 12,000 rpm back before modern high tensile strength metals. Honda currently has a 250cc with a 19,000 rpm redline. And that's not even going into F1 where 20,000 rpm V6s are common. I know there was an rpm cap, there were engines faster than that.
All I see is too much timing or too much heat in that cylinder. The cylinder got super hot and seized up the piston. That’s why it’s all blue at the bottom. Haven’t built many Hemi’s but I’ve seen this on LS engines where one of the cylinders got too hot. Appreciable you sharing this with us.
I think it'd be hard to get too much timing when it maxed out at 11 degrees, but maybe too little? In the factory tuning timing is retarded in order to heat up the cylinder and light the cats off. Interestingly the factory Red Eye tunes have 9-10 degrees in them max timing.
Yeap a lot of non tuners don't realize you actually can drive EGTS UP with retarded timing as determined by cylinder head design and flame front ( aka 19 degrees is different on an engine that peaks torque at 30 degrees NA Vs say some at 42 on BBC)
I did the exact same thing to my 1985 S-10 2.5L Iron Duke motor by putting it in neutral and flooring it, seeing how high it would rev. It rev'd pretty high... then BAM... piston exploded. In my case the entire piston shattered, then I had just the rod and pin rattling around in the cylinder.. it was SO LOUD, but awesome at the same time. Good Times!
Wow, a floating piston during a quarter mile running 10s...probably just built for 6k rpm on a factory motor of 800hp, running 7k rpm on stock rods and pistons will give on a Hellcat...lesson learned..forged pistons and rods built for racing...great video along with data logging of the failure 👍
I'm pretty sure a stock hellcat uses forged rods and a forged crank and I thought the Pistons were forged to I mean I don't think Dodge is that dumb to warranty a 800 horsepower motor and not use a forged lower end AKA short block that's why they absolutely do not recommend pudding a supercharger or turbocharger on a non hellcat Challenger cuz the lower end of the motor is not forged parts
@@kennethjanosick5939 These engines, and also the LS Chevys, are well engineered to work and deliver an excellent power curve at a designated operating range. However, when tuning, and the installation of power adders like forced induction or nitrous come into play, these engines are delivering power beyond what the bean counters (engineers) anticipated. We got to work on some LS engines that originally came from a specialty division of GM Mortorsports, and they had Callies forged cranks & rods, with JE pistons. No hypereutectic pistons or powdered metal rods in those engines.
Ya have a sporting man's attitude, good on ya! Sorry to see GoManGo down but thanks for sharing your experience/investigation.
RPM kills engines. I have seen this on any engine a lot with floating wrist pins. Pistons with hardly any skirt and floating pins rock more and will break and leave the piston at the top of the engine. Piston ring gaps can also close tight and leave the piston at the top. Floating pistons get get larger as time goes by and when they jurk the piston back down can break the piston or rod. When you press any engine to its limits you can expect anything to break after time. Just the way the game is played. Its a money game if you can afford to play.
yup... those ring gaps are crazy and the rings are so thin, how did they even think they would work in the first place... cuz, you know, Mopar runs so cool and all. I didn't even think about how bad those wrist pins are. Like the pins on a Harbor Freight breaker bar.
Speedy you are definitely a racer. Awesome video. I agree with your gut feeling that it was a defective piston. I know you push your engines to the limits with your mods, but you do it by the book. So much to learn from here. Sadly, I don't think it's anything you did wrong, just a defective piston. Thank you.
I was thinking all along what you said at the very end of the video. I think it was that hot intake air temperature that did it. Piston and rings swelled up inside the bore and made that piston a little too hard to pull back down and it just ripped the skirt right off. That had to have been what happened. You got to realize, the temperature you’re seeing coming into the engine that’s all the way up in the intake. By the time you go to compress that gas before it is ignited it’s only going to heat up even more! When you compress gas together rapidly it heats up rapidly, even without igniting the mixture. By the time the spark plug hit that intake charge was surely a few hundred degrees more, if not over 1000 degrees. Plus, your back cylinders are always going to run a bit hotter than the front ones, they’re the last ones to see the coolant in the block before it goes through the cylinder heads and is cooled through the radiator.
Was the engine sitting and allowed to cool way down between passes? We all know that metal expands when heated. That’s why they say to never flog a performance car when the engine is cold. Everything needs time to warm up to operating temps to allow the tolerances to tighten up. Hope this all helps
Just a failed piston. I think its a fluke. I believe the factory pistons are actually manufactured by Mahle. Not junk. Those guys know there stuff. My Buddy works for CP Pistons and has nothing but good things to say about Mahle. Id love to see the difference between a Demon/Redeye Piston and Rod assembly versus a Hellcat.
As an engine machinist with 35 years of experience I agree. No one makes a better factory piston than Mahle. This is most likely a fluke .
This is good to know. With me just now beginning to modify my hellcat. I am happy that this was just more than likely a one off. Not a factory problem.
Over 60% of the late model Hemi i have re manufactured (aprox 25 longblocks) had failed due to intake seats coming loose and breaking.
If your rebuilding an engine with a seat failure make shure you pressure wash your intake manifold really good. Try to get every port from every angle possible. There have been reports of fresh rebuilds pulling pieces of broken seat debris into the cylinders under heavy vacuum scenarios.
Some after market gaskets have a screen embedded in the intake gasket to prevent this from happening, but im shure they will adversely affect top end performance. Any sign of issues i remove the seats, machine and install new seat inserts. If there not getting replaced i will steak around the seats using a center punch to ensure the dont move.
Might have just been a perfect storm of stuff. Defective piston cast and cylinder just a bit out of round. Like you said these are mass produced parts. Quality control isn't as detailed oriented when it's a numbers game. Doesn't make it a bad product but it is man made. We haven't made anything that is perfect all the time. Great detective work and thanks for putting it out there.
Looks like the pistons use an offset pin which is great for making torque...but it also increases the side thrust on the skirts. Anything with offset pins to me means you really watch the RPM's and never exceed the factory redline or skirt failures will happen. Bet aftermarket pistons are symmetrical pin design which will hurt the bottom end torque production a bit but will be more reliable at higher revs.
Im giving it a thumbs up speedy, but being a Hellcat owner myself it makes me sad.
When metal parts fail, it is almost always at a sharp corner. Threaded parts fail at the root of the thread.
Parts with grooves fail at corner of the groove.
That's why these type of parts are engineered with a radius at the root of threads and corners of other parts. The larger the radius, the stronger the part. A sharp corner causes a stress rise in the part.
It is possible that the oil ring grooves of some pistons have a sharper corner than others, caused by tool wear during production.
Also if the oil passages have a sharp corner where they meet the oil ring groove, it would cause a strees rise and potential failure spot.
piston skirts are way too short!
yea they tried to reduce the mass...
but!!
you can only do that on engines that are race only!!
trust me!!
been there and done that back in the late 1970's!!
also burned plugs. is bad fuel!
advance issue!!
I used to run 49 deg advance back in the day...
got in to some wrong tagged fuel...
these are the reasons they check fuel at the drag strip...
high rpm, advance walking, bad fuel = broken parts!!
forged pistons are the only way to go!!
I always liked aires brand... custom were only were 400.00 each. that was back in 1980!!
100% perfect spec!!
The pattern of breakage on the piston looks like fatigue failure. Usually has a dull, satin type appearance from the cracks gradually progressing before it fails catastrophically. The final sudden fractures will be more shiny and metallic in appearance. That's also where you'd expect to see it. Those holes are at least drilled and not cast slots, but still they are stress risers.
You hit the nail on the head,mass produced parts !
Looks like you had some piston skirt damage and rocked the piston till it let go from what the crown is showing. But you didn't show the skirt pieces which is probably the most important pieces to look at. The top 2 ring groves look too good for it to be expansion seizure. Well that and the fact you sucked the crown out with a shop vac
Does it look like detonation to you
As a Hellcat Owner, I just subscribed to your channel. Your content is much appreciated!!! I look forward to the what's to come this week. Thanks for sharing.
No need to "figure out" what people want to see, IMO.🤔 You're an FCA Hellcat testing lab. 😃 Those of us w/Hellcats, appreciate your documentation!😃
Absolutely agree. I’m glad I found this channel. I’ve learned so much about the hellcat thanks this speedy. I don’t know if there’s anyone else digging so deep into their hellcats on RUclips like this guy.
Leonard Rice not even hellcat owners only enthusiasts period ive got a scatty and i find this interesting especially considering im starting to get into putting more power in her
Looking at a Ram 2500 truck how I found The channel. Good video for me. Start towing a trailer up a mountain at 12000 feet you going to put stress on motor. Thank for the work. Also will tow my racecar to track. Malibu 383 10.69 best in quarters.
My stock piston broke as well. It was on the side. Looked fine when I took heads off. Ring lands broke on the party of the piston with no support. Now I run 2618 forged mahles. Super bummer. Hate to see that.
Ring lands broke because u got ring pinch
@@xenith0351 correct. Stock gaps and I was spraying it till she broke.
too much heat , expanded the rings untill they butted, seizing them in the bore, breaking piston tops. Guys who get carried away boosting LS engines without opening the ring gaps have this problem, too.
These a team of blokes on you tube, its a few years old that experiment/destroy engines on a dyno in various ways to see what happens....they showed what too much nitrous does...same as over boosting/lean mixture etc....and your right the rings butt up and break the piston...normally the top ring breaks the piston as this is the hottest part but it normally stays connected to the rod just eats the piston...
Yup ring gaps, seized up top and pulled the pin out. The unusual rocking wear on top of the piston was probably due to the piston developing a crack as the piston was getting to seize prior to complete failure.
I’m at about 850 hp rn and I’m keep having a problem where cylinder 3 is misfiring I took the spark plugs out and replaced them all the one that came out was bent as if the piston slapped it after replaced car ran fine did an oil change found a super small amount of metal shavings was in the oil but now having the same problem again about to start taking her apart hopefully I don’t have anything crazy going on
Similar failure found on entirely different engine. Found oil squirters for piston blocked, overheated piston momentarily locked ripping wrist pin out of bottom. Remaining lower portion disintegrated so rod and wrist pin were flopping up down in bore. Rod was long enough that didnt jam and break but still had bend poss due to hitting debris and piston top. In this case heat was the killer.
I think u will find u had ring pinch because of to high cylinder temps the melted/broken plugs tell u it was preigniting which will raise cylinder temps once the ring ends touched the piston tried to stop moving and the rod pulled the bottom of the piston off .i have seen this in several turbo motors including our own 2jz when we ran to much boost for a stock bottom end (data log told us tune was ok) the parts looked identical .piston , rod , plugs all looked as urs did
Good info.
Haven't seen any of your videos before - very well done and excellent points raised!
High ring pack is for emissions and power, lower is for top land strength.
Were you able to check the remains of the connecting rod small end - if it failed it may have allowed the piston to rack sideways a little, stressing the pin area of the piston until it failed? I think, though, you and your buddies called it, though - poor piston quality allowed the 'pin bosses to fail.
piston rings butted, the crown of the piston is strong enough not to chip off so it sized the piston in the bore, pulled the wristpin out of the piston. rear cylinders run hotter on pretty much any engine due to the coolant inlet being at the front of the engine.
couldve gotten one that was on the tight side of factory acceptable piston ring end gap clearances, and then turned the wick up on it.
As its been said great video...for a change a genuine informative video, I think your spot on with your theory, manufactures won't admit anything which is a shame a SHIT does happen and word soon spreads and they get a bad name rather than going... yes we've had a batch issue, Along with most manufacturers I know Ford with there ZETEC engine which the vales stuck open in the heads due to machining error.....it took us 8 months of diagnosis's to prove it was that before they agreed with our findings, they never recalled them but dealt with then on failure base only, Lexus first diesel the piston rings basically re-bored the engine due to the coating being wrong....again only dealt with failures and that's only two of many I've seen in my short life on this planet....may be if you approach Dodge and show your finding they may offer a goodwill payment?...if you don't ask you don't get.....please do more like this as your understanding and not bias in your view you accept things go wrong which is a great lesson for us all.
the quote on your shirt is actually something to live by
Awesome content bud, I have been wondering about my hellcat. I'm making good power and wanting more but it's a daily driven vehicle. I have almost 40k on it now but I did the pulley swap and tune with Petty's Garage. They did a great job with the setup but they left a lot on the table. The swap was done at almost 15k miles, another company said they can get me over 975 from their tune only with what Petty's did. Thanks for your information on what your vehicle did. Keep it up and can't wait to see what happens next. Good luck bro
Hey Jerry, how long did it take Petty's garage to do the job?
Don't apologize for the length of the video.... I actually prefer the longer videos!
That happened to a 10,000 mile 4.6 Ford 2v that I owned. Plug pieces scattered and welded to the piston top. I was running a Vortech with no intercooler racing on a hot summer day. The rod came a knocking on the block lol. It took out my valves as well so I needed a total rebuild
Looks like the piston failed first. Did you check the rings to see if the rings got hot ,expanded and lost ring gap. They do that and stick in the bore and rip the piston apart.
I had a 5.7 in a Durango do the same thing on startup bone stock engine daily driver didn't hurt the block at all so I put a new Mopar piston and rod in it and never had anymore problems with it and it was also number 7 done a quiet a few hemi now and always number 7 piston
Maybe a fueling issue for #7.
Only time I've seen failures like that is due to pinging piston rocking in
The bore if the piston was cracked you probably would have heard for a while before it failed. And the melted spark plugs seems like a tuning issue to me.
I've seen plenty of pistons break at the oil ring groove on different makes. It's high RPM on a part not really designed to live at those piston speed per mile speeds.
Mopar built these cars so folks could race them and live with the damage and develop the engines to make power and live a little longer themselves . it's a story as old as the car.
I agree with you that a mass produced part failed as you pushed the revs beyond where the factory programing had it set. 1 thing of note, the 5.7s and 6.1s are fairly loose fitting engines, whereas the 6.2 and 6.4s are tighter, so they are not as forgiving. IMO, the 6.2s and 6.4s are better built then the 5.7s, especially the older 5.7s which had piston slap and oiling issues for the top end. What I found most interesting was what happened to #2. I've not seen that happen before, except when using nitrous and the tune was wrong. Do you think that the IAT caught it because after 7 let go, it was that far out of balance and the intakes were open when they shouldn't have been for just a split second on #2? OR do you think that the engine's mechanical timing was off enough to see that cough through the intake which spiked IAT? My curiosity is why did just #2 melt down, but no others did?
Since publishing this video I talked to a few folks that deal with these a lot, of course it's all theory, but we're thinking that with all the timing being pulled (which generates a ton of heat at WOT and 17psi of boost) things were hot enough that when 7 let go it fried 2 in the process. Just a theory though. The tune and logs showed fueling was good at .83 lambda and timing was max of 11 so not enough to melt things like that.
On my trackhawk Snapped my rod one #1 and it dropped a valve in that same cylinder. I was about 1k hp. Just got my new built engine in now doing tuning shake downs now
Exceptional video for all the reasons you stated! I have had 2 engine failures (different platform) - but all of the detail you are sharing here is great along with your and others theories!
The demon engine got all strengthen internals. Wish hellcat had it too
J G So does the Redeye, but again if you’re pulling 800-1000hp on a stock 707hp engine, then you’re risking it 50/50 lol
Not a true statement. I've got a redeye which is a demon motor exactly. They are very slightly better on a harder rod and connector ring. The cam is better and that's all. Seriously I have a blown one.
I am a small engine mechanic. This was caused by a bad batch of aluminium. Once back in 1990 I had 12 hp Briggs and STratton engines that would stick intake valves open on brand new engines. Briggs and Stratton called it "Porus casting" from february to april that year, it was aluminium engine block, they warrantee short blocked the engine, and another that had done the same thing on another mower in the shop. That piston swole up, and Heat from combustion would do that. Only the faulty ones will do that, you gonna have to know the manufacture dates from your failed piston, and replace all with that manufacture date. Porus casting of the aluminium piston. You can open the ring end gap, you can bore the cylinder larger, none of it is gonna work because you can't tell how much that porus casting it gonna swell, its an unknown variable. Bad batch of aluminium... You gonna run 9's you need forged or have lots of room for expansion, can't run close tolerances, gonna have to open all that stuff up so it can swell up at high speed. Loose is fast!
EXTREMELY WELL DONE ANALYSIS AND I BELIEVE U CALLED IT CORRECTLY
Totally agree and like said in old comment... the hellpuss is not torque plate honed and I have seen two that seen 7000+ with wrist pin pulling out back of piston diamond pistons in the new set up with alot more bottom end also threw the blower in the corner added twin 88 ball bearing percisions added fuel injector bung to a sheet metal intake I built for the car.. the factory rearend let go on last dyno pull we knew it was on deck before we even started the tuning that hellpuss put 1691 down and still has more in it good luck with yours like the vidga
Awesome Speedy《☆》Definitely a Parts Lottery with stock Hemi engines. FCA needs to re-evaluate parts suppliers & quality control. The 6.2s are having piston issues and the 5.7s are having lifter/cam issues. Good luck with GoMango🤓☻🤠
Suppliers have to deal with FCA's low-quality specs. They get what they specify...
Man lots of good info on this video. Agree with you that people want to sweep things under the rug when things go wrong. (Myself included).
Can’t wait to see what you put in there next. Learning from this makes me want to get forged pistons and rods from Callies or some other place like that.
I think you are right, since the parts are made for mass production you will see stronger than spec parts. Parts that meet but don't vastly exceed the tolerances dodge specified for the order may fail unexpectedly.
Excellent information brotha, thank you.
I had a piston come apart at the Oil Grove rig on a 1963 Olds Cutless 50 years ago!! Noth-N new here!!!
Lol
I think you’re on the right track. I would say that when the engine was “ over revved” a few weeks beforehand that the Gudgen pin bore in the piston was possibly stretched and weakened the piston material as it did. The piston would probably have become weaker with each pass until it let go.
Take it from an old fast guy, many of these mopar - Ford motor fails are from 0-5 weight oil. Use 20-40 weight min. Water doesn't cut it in hp applications. I've used 50 w for 50 yrs.
The one time that happened to me was in my slant 6. I over heated the engine and a piston seized pulling the rod from the piston and putting a hole through the block. I suspect that pistons tolerances were a little tight and subject to heat. If you race, build your own engines.
I've raced for 30+ years. MOPAR!
Great video Speedy, very informative and educational, Goodluck with the new build and keep putting out informative content.
I have a 1954 354 Fire Power hemi and a buddy of mine has a hell cat hemi. I was blown away at the differences. Even the way the bearing caps are split. But yeah I'd say a fluke of a failure. Me old school carbs and engine, no juice so no "check tunes data". Seems to me some major piston slap tore it apart at high revs.
The rod and pin didn't fail the pistion did it probably over heated the pistion and it seizied. At the top of the stroke and ript the pin out I'm curious if there was drop in boost pressure before the it failed?
Thanks for the great info. Im thinking of the same upgrades this winter. I differently going ti looking into the pulley(tune), driveshaft, tires, & full exhaust. I just want low 10s. Thanks again bro
Well, high rpm on overrun would be my guess for this type of failure. It occurs at the end of the exhaust stroke and the beginning of the intake stroke. On the compression/power stroke on overrun engine compression keeps the piston and rod assembly in 'compression' but there's nothing to do that on the exhaust/intake stroke.
This seems like a cast or hypereutectic piston type failure. The pin pier cracked and probably rubbed either side of the crack - hence no oil discoloration, then let go. As you point out the crack allowed rocking before the catastrophic bit. Not unheard of back in the day in cast pistons but fairly rare today I must say. You are racing it and this type of thing is par for the course ie what do you expect when you repeatedly rev it up like this? : )
Just an idea. Maybe they updated to ARPs because this failure is known to the factory and is a production fix LOL.
All your other reasoning re the data logging seems quite accurate to me.
How other run 6800 rpm on same engine
Possibly thermal expansion issues with the wrist pin material and piston housing; causing cracks and eventually failure.
The pin boss let go because it was too thin , I saw that on an early NASCAR 429 piston .
@Chris J I seen it on a briggs and straton motor that ran talladega
@@jamesavery6671
I saw it on the 16v 71 Detroit 2 stroke that powered the first Apollo mission.
Great video! Thanks for sharing the knowledge gained from the failure. I certainly agree with your theory. The point you made previously stands: if you race, you best be prepared for things like this to happen. Thanks again for the way you present your format!
Tuning a stock engine way over what it was build for and then it´s the manufacturer´s fault ?
robert winton yup. You _can_ actually have performance _and_ reliability, but you are definitely going to pay for it. Honestly though, it's still cheaper in the long run than constantly breaking and replacing shit.
My buddy had a 318LA that had a similar problem, except part of the piston skirt broke off and wedged itself in the cylinder walls (It's on my channel) and it seized up the wrist pin on that cylinder and a few others, our guess was that it was ran low on oil at one point and when he got it (and he ran that thing hard) that it weakened it up causing it to fail. Could have been as simple as bad lubrication at that moment
Wrist pin went oval/seized in pin bore, possibly. This was common with 390/401 AMCs, 1" pin wasn't beefy enough @ 600+ HP.... Thicker tool steel pins fix that....
I wish someone would help me pay for my engine mine just blew a piston threw the bottom of the block 😒 am sick over this as my Hellcat challenger is my baby. Your videos are very informative and learn alot from you!
Sorry to hear that. Which cylinder(s) broke? #7?
I wonder if it was RPM that did this? These parts are designed to take a pushing force not a pulling force. My best hypothesis is this rod/piston was pulled apart... Kinda like how cracked rods are made. Anyone else agree?
it is basically a quality control problem that was accepted in terms of a production engine so when you stretch the limits, you place these problems to the day light
Another great video.
I lost the “strap” and porcelain on both plugs in #2 cylinder. Burnt hole in exhaust valve.
My tuner thought it was a device I had plugged into the OBD port. (Discreet comment)
I’d like to know if any of your members or contact have a theory.
2 and 7 are sisters but with the supercharger in between I’m not convinced the heat /fire jumped. I have seen jumping on older carburetor / intake manifolds.
Thanks again for the informative video.
Usually burned plugs are a sign of extreme heat or a lean condition. My only other thought is a bad injector, but it would have shown problems before #7 broke I'd think. Gonna send the injectors out for testing and will post content on that to see what we find.
This happens to turbo LS motors, stock pistons let go. There's a few reasons, but usually too much RPM for the piston or flexing wrist pin (power or detonation). Excess RPM can cause microcracks, which slowly get worse and let go at random (even idle). Flexing pins bind up, which can snap the skirt off as piston twists in bore & bend rod. Skirt bits then get smashed between piston and rod & usually rod disintegrate. All happens VERY quickly.
What's amazing here concerns the piston failure. Normally then, the rod-end, with wrist pin, slaps like hell in the bore, wiping out the bore, and therefore the block itself. I've actually NEVER seen a piston failure where this didn't occur until now...(First time for everything?)
Great video.....knowledge is everything with these motors
Good stuff man!! Crazy that it would rip it apart like that. That is some seriously high torque to do something like that.
I'm impressed, great analogy you breezed right through it. Don't forget to stop at "Go" and pick up your 200$ 💰
Mopar has a know issue with the wris pins and some of the sodium filled valves are breaking off the tulips and slamming into the top of the pistons. As for the plugs, its the electrodes that are failing not the porcelain. TSB’s went out to dealers in April of 2018 regarding wris pins and valves. Pistons are Hyperuetectic / cast with a ceramic mold. Small holes are cooling gas ports in the ring lands. Way too much gap in the rods. I would question if possibly these pistons or rods were original or not???
So engine noises can cause knock sensors to falsely pull timing? I had a top end tick, redid all the shims and I swear it's going heaps better,I was wondering if it perhaps thought the tick was detonation at higher rpm?
At the right frequencies, yes.
I have heard that the new hemi engine has camshaft lubrication issues. This is not related to this video but it's supposed to be because the camshaft placement is a little different than the old hemi engines. I was curious if you know anything about this because I have wanted a Hellcat but am afraid and don't trust Dodge to replace the engine if it's faulty !
You might consider on your piston failure, the ring gap being to tight. The heat expansion caused the piston to seize at the top of its stroke. I come from a slightly different perspective being a former technical training manager and field service engineer for Cummins Diesel. Incidentally, the highest stress on a connecting rod and piston is in tension (pulling apart) during valve overlap at TDC. Hoping my Red Eye stays together. Regards, Dave
coolant got in through steel gasket, hydraulic, bent the rod first before breaking. Clean spots around the right upper and lower head gasket water jacket holes
That's in interesting theory!
Aluminum head or block shrinks after so many hot -cold cycle where there is the most heat at the head gasket fire ring. you can check with a straight edge and flash light, not a feeler gauge. Head and block surface has to be absolute perfect ( low Ra )
Like that idea did he show us rod ?
At 4:42 it looks like your little shop helper (your cat) decided to come in to help you. Looks like a Tortoise Shell cat, I had one for 18 years and they are wonderful cats :-)
That was at my buddy's shop. I'm not really a cat fan but his run around with the dog LOL.
To me,the piston crown roll over deformation appears to be caused by one side of the piston pin bosses letting go before the other.This puts the power application off center,causing the piston to tilt in the bore,as the alignment skirts lie on the axis perpendicular to the pin bosses.The only thing keeping this cratical bore alignment is the wrist pin integrity.
I think i have to agree that it’s just a mass produced defective part. I’ve been boosting the hell out of my 5.7 Ram for almost 2 years now, 6-10 psi on stock bottom end depending on mood, and i always wondered if this would be what kills it. It gets spun to 6700-6800 at the track so i know I’m pushing my luck. Although I’ve got forged pistons and rods just waiting to go in so we can turn it up.
Is it possible the gudgeon pin lock on one side failed and the gudgeon moved to one side and twisted the piston
wouldn't exclude hydraulic locking of the piston, 2 reasons first there were issues with the spark plugs - result lots of fuel going in and not igniting, second, gudgeon pin pulled away from piston near TDC - on compression stroke. Do agree that the pistons weren't great, heavy cast with not a lot of meat at the bottom of gudgeon pin, BUT the remainder of your pistons didn't look too bad.. Do you run a lambda sensor, if so any signs of mixture running rich through the rpm range>
Wonder what day that motor was built , tore one apart built on a Friday , # 8cylinder , piston had no lands on one side for rings , or ring groove for lock ring on wristpin, cutting a deep gouge in cylinder wall, custom got new engine
Buddy has a new Hellcat, a rear wheel bearing failed at 3000 miles. He says the warranty specifically excludes wheel bearings.
I don’t know the specifics of the hellcat engines, but I recently saw that Power Auto Media shootout that features the mopar vs LS vs Coyote and both tha LS and Hemi teams had to replace the pistons because they said the stock pistons won’t handle a lot of boost, basically they come apart.
Curious to know how often you change the plugs while racing and pushing the motor. You have documented the timing change but did you pull plugs and bore scope to check after each inconsistency? Props for detailing such catastrophic failure on your motor.
Not often on these cars and plugs. The engine had about 7500 miles on it.
What I'm seeing here isn't a Hellcat issue, it's an engineering and metallurgy issue. Floating wrist pins have an inherent strain built into them--there's a clearance between the pin and the piston. Awesome for efficiency, not so awesome for strength. Press-fit wrist pins create a single structure between the pin and the piston, distributing the load in a uniform fashion.
It looks like a piston overspeed event. That crisp shear-line at the base of the skirt I usually only see in hypereutectic aluminum. I would HOPE to see forged pistons in a factory 700hp+ boosted engine, but with the clearances required, I wouldn't be at all surprised if Chrysler avoided it--especially after the old skirt-slap issues GM had on cold start back in the day.
I'm curious to see the results of your friend's stress test on the two pistons you pulled!
Looks like he bent a rod. Piston failed secondary? How would the piston crown mushroom like that from slap if the wrist pin/wrist pin bore failed first? Had to of been slapping the cylinder walls for a while to mushroom like that which is why I say bent rod was primary. That also explains the timing pulls. Car was seeing the modified stroke from a bent rod in the CPS pulse width.
*8:54** Does this engine have 2 spark plugs for each cylinder? I see 2 holes in each combustion chamber.*
Indeed it does. Emissions deal I think.
@@SpeedysGarage 10-4, Thanks for reply.
@@SpeedysGarage Exactly! Two sparks are better than one for more complete combustion.
In my past 50 years of building and pushing engines (many times well beyond their limits), This looks like a classic piston skirt failure - then instant stress cracking the pin boss. The piston rocking marks smells exactly likes that. Skirt goes - then piston rocks - then a few strokes later - Boom! As far as the broken ceramic in the plugs - that is either bad plug mfg. or mild detonation. Did you change to a colder plug than stock? I hope.
if you're shattering plugs that's major detonation and if you keep doing it with plug after plug you're ignoring a problem and will pay for it eventually.
It looks like the wrist pin bent and allowed most of the force to go to one side of the piston.
That usually only happens in diesels but you guys are hitting those type of torque numbers.
I'd get the wrist pin out and check to see if its still straight.
Never seen that good idea
Sorry for your problem Speedy. I'm a hellcat owner also, and in my opinion the entire car is a piece of Garbo. I continue to have tranny issues ( a 6 spd). The only impressive item in the car is the sound system!!
Mine's been a pretty decent car. Had the bearing issue on the supercharger and that was replaced under warranty. Kinda disappointed in the pistons though.