Charles Joseph

Here are the pictures of the piston. I only had my Treo with me so the pictures are slightly grainy. The ringland broke in two seperate places. The broken sections are 1.5" and 2". No damage to the block. I am going to have them pull the other 7 pistons and check them to be sure.

They feel that this was a fluke. The engine did not go lean. No oil problems. Everything else looks fine. It was caused by a faulty piston, or possibly over-boost. My guess was that the piston had a weak spot and the boost did it in.

speedybenz

I would love to see a higher quality pic of the piston top and cylinder head chamber. I would be looking for signs of detonation. Also pics of the spark plugs. The insulater at the tip, a very, clear close up of the ceramic and ground strap.

Good luck.

dpc004

Are those pieces of the rings in the side of the piston? Can't really make it out.

Charles Joseph

I think what you are seeing are the pieces that broke off the piston. I placed them on the piston to show how big they are and that they broke off in solid chunks. If this is not what you are referring to then it is the groove that the rings sit in.

Mad TKD

wow that is pretty big chunks there. I am not sure about the 55 NA engines but is the number 6 prone to heat?

That is definately detonation there. I wish i had pics of my supra #4 piston to show you. Pretty simular to yours but the ringland was not cracked as bad as that.

Just remember that more boost causes more heat so if you plan on running it hard put a mix of higher octane with your 93 fuel for insurance.

Charles Joseph

I am going to start adding 110 octane. With the headers and the extra octane I think I will be OK. If any of the other pistons are bad I am going to have JE Pistons make me a new set.

They really do not feel that detonation was the problem.

Mad TKD

thats good that you are going to add some high octane but I still feel it is detonation. The signs you said earlier reminded me of my experience. Driving the car hard more boost than what I should have run and really and truely timing was not right for that octane and boost.

Maybe take some better pics and pics of the top of the piston.

Sure on the slight chance it could have been a bad piston but that is very slim. You are the first that i know of to have had this problem from a kleeman SC 55.

You know it could have been some bad gas too.

Jim Brady

A fractured ring land is a dead givaway in a forced induction engine to detonation. What may have happened is the spark plug insulator or electrode
seperated due to heat and detonation which became the foreign object that caused the piston damage. Very common is high boost Porsche turbo motors. I'm sure a good tech will check out the rods for straightness. You might want to do a gas sample to see what octane rating was in your beast when it blew. Just one more element of the puzzle to elimate. Good luck with your rebuild. FWIW,I don't think the JE pistons are the way to go in an AMG motor.