does any one know why the ring landing between the top ring and the second ring out break?
on 4 pistions (1,3,5 and 7) this pistions are broken in this area

i was out playing around when this happened about 6000 rpm
its a 1991 L98 (its not stock but the bottom end was)

All on one side?

Did the batch fire stop firing all the injectors on that side or something?

no i think all the injectors were firing.
i think it might have been detonation.
i never did like that chip fastchips burnt for me
and when i did some data logs it showed it was trying to retard the spark.
the computer also wanted to put in like 40 deg+ of advance.
i am thinking its det. i was just hoping some one would say it is.

What is not stock about it? How many miles?

take them to court and lower the boom. we seem to have another freelancer getting away with murder.

i'm damn sorry about your situation

If it were detonation, I would expect to see problems in more than one bank.

its just a **** off right now. i am going to build a 383 out of it.
i just want to know what caused it so i can stop it.


the reason i am thinking that side (1,3,5, and 7) got it, is because the knock sensor is on the other side.

My experience that is a classic detonation symptom, the fact that it was all on one bank is interesting.. Remember, all the left side injectors are tied together electrically.

ya same here, but i am reading on the net one of the things det does is break the ring lands.

ya it is insteresting zr1fred.
but i am sorta thinking that the knock sensor was not picking it up
as u pro know the knock sensor is on the 2,4,6, and 8 bank

I don't disagree with detonation causing ring land failure at all. Every engine that I have seen with detonation problems usually does more damge to the top of the piston before the ring lands are broken.
Another possible problem could be a high mileage engine that was runn had higher engine speeds. The piston can rock enopugh to break ring lands and/or skirts.

det can do a few different things.
burn holes/pit the top of the pistons
can burn up valves, and from what i have read on the net also can break ring lands.

the reason i want to know the cause of this, is so when i do it up to a 383 i will not face the same problem

i think i will get pcmforless to do my next chip for the 383

when i data logged a few times the computer (had a chip burnt from fastchip) was trying to put in over 40 deg of added advance. the computer was fighting with its self. put more in and then take it out, back and forth.

i am just hoping its not a problem with the block thats all.

I have seen deck heights vary alot on different banks. If one side of the motor had a .010 taller deck, it could have had more detonation on one bank than the other.

Well I don't know how to be politically correct so I won't. If you knew that the car was running with excessive ignition timing, the engine failure could have been avoided. It appears that the controller was at least trying to control the detonation with the ESC, hence the data log file that shows the drastic change in spark timing.

jeffyc, Shouldn't be any doubt if it was caused by detonation.
Any det. severe enough to break pistons would leave the combustion chamber in the head looking like the one in attached picture.
Should be burned aluminum deposits all over the place.
This was mine after one short run with a lean mixture.