Pic of Burned Piston - Why??
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Pic of Burned Piston - Why?? The picture says it all and it's cylinder #7. Why is it always #7?
http://www.photohost.org/gallery/dat...urnOut-med.JPG
This is the first time this has happened to me and I have lots of unanswered questions. No Nitrous and an NA motor. Pulling about 550HP and 505TQ at the flywheel, stock displacement and stock bottom end.
This happened at the track and detonation is suspect although the PCM has never detected detonation that we know of.
Can you guys start asking the right questions and talk to me about preventing a future occurance?
I had an engine that did that, I was spraying 100 dry shot w/ comp 224 cam and that exact same thing happen to me #7 cracked down to the top ring land. I wish someone would speak up as to why this happens.
Most believe #7 is the biggest problem because the path the air takes and it gets the most air out the intake manifold.
What some do as a trick (as ive done) is lets say you got your injector flow tested, I always take the one that came back highest and put that one in #7 because that helps to avoid the #7 piston detonating or burning up.
Dixit
What some do as a trick (as ive done) is lets say you got your injector flow tested, I always take the one that came back highest and put that one in #7 because that helps to avoid the #7 piston detonating or burning up.
Dixit
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It sounds like you guys are running more power than I am. I like the idea of putting the strongest injector over #7. I am running a FAST LSX intake that was ported by Tony Mamo, I wonder what effect that would have on #7 if any.
Does anyone know exactly what happened to Tony's 346? I have pretty much duplicated his efforts.
Keep it coming guys this is what I need.
Does anyone know exactly what happened to Tony's 346? I have pretty much duplicated his efforts.
Keep it coming guys this is what I need.
Mine did it on #5, and yes my sleeve cracked and my rod is bent.
I've got 2 questions. I'm assuming you've had it tuned. Is it possible the tuner set it up not to pull timing out with the knock sensors? Also, did you have any type of scan tool plugged in when this happened?
The reason I ask those 2 ?'s is because when my car did it, it was on my dyno with my Tech 2 plugged in and it showed 0 degree of knock. I'm assuming the previous tuner set my car up not to pull timing upon detonation. Just wondering if yours is the same way.
I've got 2 questions. I'm assuming you've had it tuned. Is it possible the tuner set it up not to pull timing out with the knock sensors? Also, did you have any type of scan tool plugged in when this happened?
The reason I ask those 2 ?'s is because when my car did it, it was on my dyno with my Tech 2 plugged in and it showed 0 degree of knock. I'm assuming the previous tuner set my car up not to pull timing upon detonation. Just wondering if yours is the same way.
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Originally Posted by 777
Typically the #7 has problems with a lean condition due to the intake manifold's design. That's why the big FI guys go with the carb style intake manifold.
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Originally Posted by Dixit
Most believe #7 is the biggest problem because the path the air takes and it gets the most air out the intake manifold.
What some do as a trick (as ive done) is lets say you got your injector flow tested, I always take the one that came back highest and put that one in #7 because that helps to avoid the #7 piston detonating or burning up.
Dixit
What some do as a trick (as ive done) is lets say you got your injector flow tested, I always take the one that came back highest and put that one in #7 because that helps to avoid the #7 piston detonating or burning up.
Dixit
At least that is the general school of thought if you were to poll most LS1 engine builders and tuners (and I feel has good merit). Flowing the injectors is a wise move and I recently did the same (especially after my mishap) and placed the "fattest" injector in the #7 hole when I recently tested the 383 I featured results on a few weeks ago. Keep in mind that the stock GM piston was never intended for 7k blasts and dynamic cylinder pressures 40% or so higher than stock. Also...lets face it....guys were having problems with "lucky #7" long before AFR released the 205 cylinder heads, buts its my hunch that the additional stress and power output takes an on going problem and somewhat amplifies it.
Hey....Its a good time to think about a 383 stroker while you have the engine out and are doing the repair. You're halfway there with new pistons anyway!
Something to certainly consider....that's for sure...
Good luck with the rebuild either way.
Tony M.
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Thanks for your thoughts Tony. You are always helpful.
Speaking of a rebuild, and this is not necessaraly directed at Tony, what about forged rods. I might do a shot of NO2 in the future. What forged steel rods would be a good value for this motor?
Speaking of a rebuild, and this is not necessaraly directed at Tony, what about forged rods. I might do a shot of NO2 in the future. What forged steel rods would be a good value for this motor?
Originally Posted by 777
I wouldn't go as far as to say half way...The crank itself is going to be twice as much as forged pistons. 
Lets face it...we all want to go faster just as soon as our latest mods start to feel not quite enough. Weve all been there. Perfect opportunity to step up the program....especially if your considering pistons and rods. Do some homework...there are 383 rotating assemblies that come balanced without breaking the bank. You will LOVE the extra TQ and power, and the fact the engine comes on hard that much sooner with the extra displacement.
Go for it
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Originally Posted by 1BDWS6
Mine did it on #5, and yes my sleeve cracked and my rod is bent.
I've got 2 questions. I'm assuming you've had it tuned. Is it possible the tuner set it up not to pull timing out with the knock sensors? Also, did you have any type of scan tool plugged in when this happened?
The reason I ask those 2 ?'s is because when my car did it, it was on my dyno with my Tech 2 plugged in and it showed 0 degree of knock. I'm assuming the previous tuner set my car up not to pull timing upon detonation. Just wondering if yours is the same way.
I've got 2 questions. I'm assuming you've had it tuned. Is it possible the tuner set it up not to pull timing out with the knock sensors? Also, did you have any type of scan tool plugged in when this happened?
The reason I ask those 2 ?'s is because when my car did it, it was on my dyno with my Tech 2 plugged in and it showed 0 degree of knock. I'm assuming the previous tuner set my car up not to pull timing upon detonation. Just wondering if yours is the same way.
No scanner was plugged in when it happened. The tuner had me set for a 13.6 AFR. My compression ratio was 11.2-to-1
The AFR heads run leaner than the LS6 heads but I am wondering if it was setup too lean? Tuner says I told him to set it at 13.6 which is BS. When he did the work I gave him the range of values AFR had told me it would be likely to fall into. I would never tell my tuner to put the car at a specific value and if he thought it was too high I would expect him to tell me so.
I may be having a talk with the shop owner about this.
Originally Posted by 1ScrudeDude
If (when) my **** blows up, a completely stroked 383 is going in.
No brainer.
No brainer.
Perry
13.6 AFR is way to lean. With a 11.2:1 CR, 12.6 to 12.8 should be the target AFR @ WOT. The PCM should have pulled out alot of timing and detacted KR. It seems that the PCM was not pulling timing as it should have.
I agree 13.6-1 is on the fine line. Some extra power is sometimes had by leaning the car out some to that area but I would not go past 13.0-1 in my personal ride. My setup is 12.9-1 from 2500-6800 at WOT.
with that high of compression if your injectors got a little dirty or clogged it could happen. My first motor did that. #7 got clogged and BOOM. but i was on a 150 dry shot and a completely stock motor. So check your injectors and maybe even your fuel filter.
ALSO i don't know how you could check this now but i blew up another motor (stock internal N/A) because my timing was jumping from 26 degrees to 34 degrees halfway down the track. Add this to i accidentally ran it with 87 octane and there was another BOOM on #7.
ALSO i don't know how you could check this now but i blew up another motor (stock internal N/A) because my timing was jumping from 26 degrees to 34 degrees halfway down the track. Add this to i accidentally ran it with 87 octane and there was another BOOM on #7.