Are my pistons screwed?

Open the top piston ring gap and that will not happen.
Too much heat, not enough ring gap, equalls top ring land breaking off because the ring ends butt together and literally hold the piston in place a TDC while the crank tries to pull it down, and off come the ring land.
Knock alone does not cause that. It is the sudden rise in cumbustion tempereature, and not enough heat transfer to the cyl. walls due to the thin, low drag rings used.

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Originally Posted by QUICKSILVER462

Open the top piston ring gap and that will not happen.
Too much heat, not enough ring gap, equalls top ring land breaking off because the ring ends butt together and literally hold the piston in place a TDC while the crank tries to pull it down, and off come the ring land.
Knock alone does not cause that. It is the sudden rise in cumbustion tempereature, and not enough heat transfer to the cyl. walls due to the thin, low drag rings used.

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truth.

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Originally Posted by QUICKSILVER462

Open the top piston ring gap and that will not happen.
Too much heat, not enough ring gap, equalls top ring land breaking off because the ring ends butt together and literally hold the piston in place a TDC while the crank tries to pull it down, and off come the ring land.
Knock alone does not cause that. It is the sudden rise in cumbustion tempereature, and not enough heat transfer to the cyl. walls due to the thin, low drag rings used.

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And correct me if I am wrong, but the L32s are more prone to this.

The l32 with the higher compression will be more likely to knock/pre-detonate. Remember, it is the heat that causes the ring end to close up to the point they touch and lock the piston in the bore, causing the ring land to break on the down stroke. Higher compression equalls more heat, which inturn will need a larger top ring end gap, espacially when boosted with a s/c, or turbo charger.

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Originally Posted by QUICKSILVER462

The l32 with the higher compression will be more likely to knock/pre-detonate. Remember, it is the heat that causes the ring end to close up to the point they touch and lock the piston in the bore, causing the ring land to break on the down stroke. Higher compression equalls more heat, which inturn will need a larger top ring end gap, espacially when boosted with a s/c, or turbo charger.

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the L32 has the same compression ratio as the L67. the L26 and L36 are the high compression n/a blocks.

Did they run a tighter ring gap on the L32 motors? Or are the rings that much thinner then previous years? if filing and setting the ring end gap is all it takes,I won't have a problem running stock pistons. The car is staying stock I just don't want it to chip out more pistons.

Damn this is scary... What caused your car to start backfiring? Bad tank of gaS?

mine or OP?

This isn't from backfiring.

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Originally Posted by Thinkmoto

mine or OP?

This isn't from backfiring.

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the OP.. He stated on his post that he thinks this happened when his car started backfiring and he took one of his spark plugs out and it was damaged.............

if a spark plug is blow out and its not firing, yea that is gonna create a miss chiped pistion or not

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Originally Posted by QUICKSILVER462

Open the top piston ring gap and that will not happen.
Too much heat, not enough ring gap, equalls top ring land breaking off because the ring ends butt together and literally hold the piston in place a TDC while the crank tries to pull it down, and off come the ring land.
Knock alone does not cause that. It is the sudden rise in cumbustion tempereature, and not enough heat transfer to the cyl. walls due to the thin, low drag rings used.

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intresting

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Originally Posted by blowfishRus6

if a spark plug is blow out and its not firing, yea that is gonna create a miss chiped pistion or not

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Wait, how can your spark plug blow out?

The issue is that excessive heat and knock combine to chip the top of the piston. Those chips coming off are what smash the spark plug and cause the miss. A spark plug doesn't get "blown out."

ha well yea there you go. i was getting at a spark plug not firing is gonna cause a miss, chiped piston or not....

Yeah but i wonder what caused the car to start getting knock... Well im just wanting to know cause im interesting in buying one and i dont want to buy one that has a chipped piston As the OP stated that he didnt even know that the motor was hurt nor was the car acting up after that....... yet again, a smashed up spark plug is a real good indication of something real bad......

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Originally Posted by up in boost

Yeah but i wonder what caused the car to start getting knock... Well im just wanting to know cause im interesting in buying one and i dont want to buy one that has a chipped piston As the OP stated that he didnt even know that the motor was hurt nor was the car acting up after that....... yet again, a smashed up spark plug is a real good indication of something real bad......

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The best explanation i've heard here is about the ring gaps being too tight from the factory. If that's the case then I'd be worried about every GTP out there. Personally if pistons chip out when running premium fuel then there is a problem with the design from the factory. Do these cars have knock sensors? I'm curious to what kind of protection is built into them/programmed in the ecu?

yes, they have knock sensors. we avoid KR, which is the car pulling timing when knock is sensed. its our measurement to know when our car is running prime or not.

you really dont have problems with chipping pistons if youre not knocking excessively and you dont do long WOT runs. highway runs are a good reason why people destroy these cars.

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Originally Posted by Bio248

yes, they have knock sensors. we avoid KR, which is the car pulling timing when knock is sensed. its our measurement to know when our car is running prime or not.

you really dont have problems with chipping pistons if youre not knocking excessively and you dont do long WOT runs. highway runs are a good reason why people destroy these cars.

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So if your DD is a GTP and you drive it like grandma(my ex) and you still run into this problem? Not trying to be a dick but there has to be a reason outside of detonation.

l32,l36, I new it was one of t hose l's.

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Originally Posted by Thinkmoto

So if your DD is a GTP and you drive it like grandma(my ex) and you still run into this problem? Not trying to be a dick but there has to be a reason outside of detonation.

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there are a lot of reasons you COULD blow up a motor. what did she do to it? run it short of oil or coolant? start the car up and immediately start driving even if its sub zero outside? there is a cause behind it, but what is it?

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Originally Posted by Thinkmoto

So if your DD is a GTP and you drive it like grandma(my ex) and you still run into this problem? Not trying to be a dick but there has to be a reason outside of detonation.

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There could be many, many reasons for this or none at all. Hell you could even have just had a fluke bad motor...who knows. How many miles were on this when it happened just out of curiosity? How long have you owned the car. It could have been from a previous owners driving habits if you didnt buy it new.