not enough ring gap .... or to much NOS ???here are the results after a 350 shot oh well the motor was in the car when i bought it . the new motor WILL handle it it broke #2,4,8 cylinders

mike

 

#2 and 4 closer

 

I voted not enough ring gap because with those domes detonation signs would be all over them and it isnt. the little bit of "silvery" near the bottom of the pics is where peices of the pistons went into every cylinder and went into the "low" spot and tumbled around. Your example is classic in every sense of the definitive picture. Im betting ring gaps in these will measure in the teens.

 

actually the guy that built the motor said they were .023" on the top ring. the little silver chunks are all over the motor, in every cyld. in the intake , and even in the lifter valley . i launched , leaned on the bottle in first grabed for second at 6800 and there was nothing there. the dart heads have less than 50 miles on them but they look ok

mike

 

yes be careful to get them all out of your heads intake and carb

 

350shot:rockon: :hail:

 

I voted ring gap. I'll give you a 99.99% confidence level on that. That looks EXACTLY like the picture of the bloken piston that Keith Black publishes with their pistons. VERY distinctive destruction characteristics.

HOWEVER.... remember that if you run in detonation you are AGAIN throwing an EXCESSIVE amount of heat at the top ring. Even if the detonation doesn't blow a hole through the piston it will eventually overheat the top ring, butt the ring ends together and destroy the piston in the same way.

Keith Black says that an engine run in detonation can overheat the top ring enough that even a gap of .065" (!!!!!) will eventually close, butt, lock and rip the ring lands off the top of the piston.

Regardless, .023" is a heluva small top ring gap fur just about any blown or nitroused motor with just about anybody's piston in it.

 

the new motor will be built to take lots of nitrous , after all my system is good to 600 horse and it came with the 450 horse jets . i'm thinking i'll order JE nitrous pistons . i've got good stuff every where else already (and a spare 400 laying around)so i think it will be fun next year

mike

 

automec: A little off topic but... Have you torn down the motor yet? I was wondering because you say you have C&A h-beams. Do they have "CHILD & ALBERT" stamped across the beam? I have a set of rods that are supposedly C&A but they have no identifying marks on them aside from some weird symbol and the date they were made.

Thanks,
Chris

 

after a major engine mishap always have the rods and crank (especially the rods) checked for straightness and length regardless of manufacture. also off topic but its my $0.04

 

no i have not torn the motor down yet . i know they are steel h-beam rods (i happened to see the motor going togeather at the machine shop ) and the guy i bought the car from said they are C&A but other than that i know nothing (he said a lot of other things too ) yes i plan on ck.ing EVERYTHING!

mike

 

I'm curious on how far down the first ring land is? For nos and
boosted apps it should be at least .250.

 

In a perfect world maybe, but thats not where we live...

 

well, all everyone talks about these days is ring gap,.. i guess it's the new hot thing. but,... too me that looks like a tell tale sign of detonation,... i could be wrong, but those little spots that look like your motor mashed on a pebble, are from detoation, and it is exactly on the side of the cylinder that it happens,... Also,... with that much juice,.. are you sure you didn't run it lean? you know, b4c tom,...i thought detonation was just on that side of the cylinder,...not all over the piston,... correct me if i'm wrong. thanks

 

i was worried about that . thats why i pulled it apart but there are no signs of detonation , the specs are from beating the piston pieces. the machine shop guy said ring gap (he only built the motor for 250) and also said no sign of detonation. yes its on the intake side of 2 and 4 but on the exhaust side of #8. i dont plan on pulling the rest of the motor untill winter (or when work slows enough to fit my car into my shop) when i do i'll post more pics of the pistons

mike
ps
my friend at the machine shop has built and run a doorslamer on a 500 shot into the 8's

 

oh, that looked like detonation.... good luck

 

The closer to the top the more heat the ring will see. If it is to
close, the piston is weak and it wouldn't take much to break
off the top. with detonation. I have a 4.600 bore engine that i run the top ring
.026. .300 down I run the second ring .031. The second ring being cast
grows much more than the top.
I would take the engine apart and look at the rings to see if the
end gaps are shiny and smooth from butting. the alloy of the
trw piston is also a factor here. I have read here that 'keith
black' says to open the gaps up to .031. That is for a hypertuetic,
I do not believe that much is needed for a good alloy forged piston.
If the engine is apart look real good and you will find out why.
My $.02