2011 piston failure diagnosis discussion w/pics

[VET-KLR]

I finally got all the pistons pulled from my factory shortblock and took pics. Just wondering if anyone can for sure say why they failed. This motor was ran 5K miles stock, 2K miles with Edelbrock E-force base kit w/ their canned tune, and 4-500 miles with 3" pulley(10psi?), Edelbrock CAI, UPR X-Pipe, Vortech BAP.

Can we get some technical information going on what kind of failure this might be. What kind of diagnosis can be made from these pics? Or would it take a hands on look and testing to determine failure? One thing to note is the damage was all on the outside facing side of the pistons. All other pistons show no damage I can see.

The #3 piston I think just took a piece of debris and broke the skirt. Also notice the crack on the side of first ring land. It showed 150PSI on cranking compression test.

This is #5 which read 90 PSI on cranking compression test. Cracked ring lands. It's about 1" wide section of ring land broke on each side.

This is #7 which read 95 PSI on cranking compression test. Cracked ring lands. It's about 1" wide section of ring land broke on each side.

Last but not least here are some different angles on #8 which rolled in at 0 PSI for good reason, and at least alerted me to there being an issue. Rough idle and smoking bad out the exhaust. Further checking under the hood and I found oil pushing past the air filter.

 

[RI_2011_GT]

Send to a good machine shop/ Engine builder to have them Analyzed.

 

[VTXFrank]

Too lean a fuel condition resulting in detonation.

After you switched over to the 3" pulley, CAI and BAP, did you have it tuned? Or did you keep running the stock Edlebrock tune? What was the injector duty cycle? Fuel pressure?

No matter how the other pistons look, you need to replace all of them if the block cylinder walls are still good. Every bearing on the rods, crank and cams should be replaced as a precautionary measure. All oil passages need to be pressure cleaned and checked for debris. The oil pump is likely jacked as well.

Just looking at the amount of material missing from those pistons, the impact damage via debris to the #3 skirt and loss of metal mass there, I'm thinking the block is fucked.

 

[malmgrdc]

Please tell me this car had a tune for the pulley and o/r x...

 

[VET-KLR]

Yes absolutely the car had a tune on it for the specific parts and was working on dialing it in. I've had it back together with an upgraded shortblock for a while.

As for the old block and crank there's no major physical damage you can see. The #8 cylinder has some very light marring but nothing you can feel with a fingernail. It would need everything checked, but likely could throw new pistons/rings in it and go. Bearings were all perfect on the rods at least. I'd replace them just as insurance that all is well.

The #8 didn't lose all that material through the motor. It was cracked up and fell out when I removed what was left of the rings. If you look close at the pics the really clean areas came out in chunks after the piston was pulled. Most of the debris was trapped in the baffle in the oil pan.

 

[UnleashedBeast]

If the tune was close to the edge of tolerance with 93 octane, then one bad tank of fuel will do that. First WOT run and BOOM! Detonation

 

[VTXFrank]

Sorry....didn't know your background on this. Very glad to hear you've been back on the road for some time now.

I'm surprised the block isn't more damaged than it is. It sounds like a good candidate for a forged build spare as long as it checks out OK.

Without a datalog being recorded at the time of the damage, it's hard to say anything for sure. But detonation is the obvious pick on this one. That #8 is just shattered below the piston top, a classic indication of detonation.

When it comes to FI, you're really making the engine safer through the tune settings. More fuel and less chance for detonation. Unless someone gets all happy with the timing and the AFR shoots up. But typically, I would assume the damage was likely started with aftermarket tuning before the addition of the S/C. Then one bad ping while dialing it in and the pictures speak for themselves.

Were you running a CAI and tune prior to getting the Edlebrock?

 

[DILYSI Dave]

Was it tuned on the dyno or was this a generic tune?

 

[VET-KLR]

The car was 100% stock prior to Edelbrock tune. I added all the extra parts to the Edelbrock kit at once and had it tuned then. It was not tuned on a dyno. Email tunes. I was also thinking about a bad tank of gas causing it.

 

[stkjock]

any pics of the top of the pistons? #8 most importantly.

 

[Shane361]

The car was 100% stock prior to Edelbrock tune. I added all the extra parts to the Edelbrock kit at once and had it tuned then. It was not tuned on a dyno. Email tunes. I was also thinking about a bad tank of gas causing it.

Did you data log or dyno the car after the email tune?

 

[VET-KLR]

I can get pics of the tops but all the tops look great. I did several datalogson the car with the tune. I was datalogging when it happened.

 

[KenB]

I'd say you had a lean/heat issue.

 

[stkjock]

I can get pics of the tops but all the tops look great. I did several datalogson the car with the tune. I was datalogging when it happened.

so what did the logs show?


the tops should show some signs of detonation based on those pistons. how about the plugs - any pics?

 

[KenB]

the tops should show some signs of detonation based on those pistons. how about the plugs - any pics?

No necessarily. You can create a lot of heat with getting detonation.

 

[stang8psi]

to me I wouldn't go and say oh #8 #8 #8... it looks like a lean condition and just plain ol detonation, If you were logging than your answers are there as to why it blew.. Was there alot of knock,was the timing high, what was your afr, how about the fuel was there enough,there is alot that could and obviously did go wrong for you to have lost half the pistons in a motor.. So please don't be the guy spreading the number 8 frenzy again... in conclusion you took a gamble with supercharging your car and lost the gamble by than throwing more boost and not taking it to a shop to have a proper dyno tune done instead of canned tunes from a certain shop..

 

[KenB]

in conclusion you took a gamble with supercharging your car and lost the gamble by than throwing more boost and not taking it to a shop to have a proper dyno tune done instead of canned tunes from a certain shop..

I don't think PROPER email/remote tuning is a gamble. Lund Racing does a tremendous amount of remote tuning for people that aren't near a dyno tuner or are not happy with their local options with very good success.

 

[stkjock]

No necessarily. You can create a lot of heat with getting detonation.

no dispute there, however, if one had detonation, it's my understanding there would be evidence of such on the top of the pistons and the plugs.

 

[KenB]

no dispute there, however, if one had detonation, it's my understanding there would be evidence of such on the top of the pistons and the plugs.

Yes, you can see it in the plugs, tops and also bearings.

 

[VET-KLR]

The datalogs were not recording all information for some reason when it failed. I'm a little new to datalogging and it was the first few times doing it. I plan to learn more about that and make sure I'm datalogging what's needed in the future.

The plugs looked fine to me other than some oil fouling on #8, #7, and #5 for obvious reasons. The tops of the pistons I'll get some pics of, but they look just fine to me as well. As did the bearings. I don't have pics of the plugs. Now I'm no expert or I wouldn't be asking for opinions here, but I have been around motors and racing for a long time. Maybe there's something to see on the piston tops or plugs that I didn't notice. This is my first boosted motor as I've usually ran nitrous on SBFs.

to me I wouldn't go and say oh #8 #8 #8... it looks like a lean condition and just plain ol detonation, If you were logging than your answers are there as to why it blew.. Was there alot of knock,was the timing high, what was your afr, how about the fuel was there enough,there is alot that could and obviously did go wrong for you to have lost half the pistons in a motor.. So please don't be the guy spreading the number 8 frenzy again... in conclusion you took a gamble with supercharging your car and lost the gamble by than throwing more boost and not taking it to a shop to have a proper dyno tune done instead of canned tunes from a certain shop..

Thanks for all the helpful information pal!