BOOSTAT4500

iTrader: (17)

Took my head off today because I thought I blew a gasket (coolent in the oil ) and found about a 1 inch piece of piston #5 broken off. The rings are fine and there is no signs of detonation such as burnt spots. Even the gasket didn't look bad. The cylinder also still holds compression. Also, the head doesn't show any signs of damage. I'm running about 9lbs. with a D1sc. Any Ideas on what might have happened? The car has about 8k miles on it with the blower.

gonbad

The short pistons on the LS1 have thin ring lands. The piston's biggest weakness is the ring land. The stock pistons don't like much boost.

LSs1Power

iTrader: (5)

Sorry to hear that. Did u get any knock? What was the Temp when u tuned ur car and what was the temp when this problem happend? Did u check the valve springs on #5? Are the valves fine?

cablebandit

iTrader: (37)

when i broke 2 ringlands, i lost some compression but had no water/oil mix. Actually, i drove it home 2 hours that way. Where did the piece come from on the piston? Your symptoms don't sound exactly like a ringland unless you split the block.

S_J_H

Your broken piston is your sign! The motor detonated, that is what happened.
A stock brittle hyper piston will not tolerate much detonation before they crack apart like an eggshell.
Been there done that. Make sure there are no cracks in the cyl.

BOOSTAT4500

iTrader: (17)

The valves look ok. I havn't pulled the motor apart yet to inspect the block, I sure hope it's ok. The piece of piston came off the top edge, the rest of the piston looks fine. The temp when tuned was within about 10-15 degrees of when it happened. It has been run in much hotter and colder weather than now with no problems. As far as I know there isn't any knock. It only has about 12-14 degrees of timing in it right now due to some false knock issues. Nothing has changed tune wise for about 5k miles so I wouldn't think that was the problem, but who knows.

NA$TY-TA

iTrader: (21)

Been there done that also...... heres some pic's of my old short block on 11 psi..... car was running lean also... plugs were green... took a piece of the head with it also.... damn 98 heads. Is it this bad??????????


Pass Side


#3 Piston

#3 piston side shot

#5 piston

#5 cracked on both sides

#7 piston


Kyle

BOOSTAT4500

iTrader: (17)

That chunk on top is about the same as mine, but my rings look ok. I don't have it out yet so I dont know what it looks like on the other side of the top ring.

taqwache

of you didnt blow a head gasket, i bet you cracked the block. i have seen it before usually with nitrous though but boost will cause the same thing.

BOOSTAT4500

iTrader: (17)

Yup, the sleeve is cracked. Not where the piston broke however. Time to start building an iron 408.

Shinobi'sZ

Nice pics Nasty TA.....
I have went through 2 motors, this one has lasted with 16lbs of boost so far.
The ring lans busted as pictured by Nasty TA...actually his look a lot worse than mine did. I noticed when my dip stick was popping up out of the holder and spraying the inside of the engine compartment with oil like a sprinkler head, oh and the white smoke that would come out of the tail pipes...it was a mess. I did a compression test just for ***** and giggles and came up with 3 cylinders at 70lbs...only about 100lbs off from the the good cylinders..it was a pretty good indication..people actually thought I needed a PCV Catch Can system and it would eliminate the oil being blown out...oh and one guy said to attach a spring to the dip stick to keep it locked down.

Bottom line is the stock Hyperuetectic Pistons are very brittle, the clearance from the factory is between .001-.003" on a Piston that will not expand....so it just breaks at the weakest point which is the ring lans. If you look at Ross or Diamonds Piston cards you will see for Forced Induction Street around .006" setup. I set mine up at .003" because I didn't want as much piston slap at cold start up and I wanted minimal blow by...I would rather have it seize than blow all the oil I have seen from blow by at hi boost...no seizures yet...good oil and a good tune should prevent that. Anyway you had detonation...that is all there is to it. Just for reference I could drive my car with 3 busted ringlans and the blower off and no oil would be present anywhere.

cablebandit

iTrader: (37)

lol...i set my ross at .006 and it sounds like a frikkin diesel. When it gets warm tho.....it sounds like a frikkin diesel Next time I'll do like .003-4