TonyG

I've seen it. Get a aluminum deck plate, made out of an an aluminum with similar expansion rates to the factory block, machined into the new block and you won't have that problem.

Sleeves are strong, but they have their own issues.

Sucks... BTW, I've been spending a lot of time in Prescott. How far are you from Prescott?

TonyG

Thom

Not on the piston top, according to the pictures.

George, can you post a pic of the head?

944hal

Had something similar happen to a friend. What we thought was a blown head gasket was, when we pulled the head, #4 cylinder wall cracked from the top to about the lowest point in the piston travel. Stock engine in a PCA E class race car.

odurandina

thanks, Josh.

good to see she'll be in capable hands.

refresh951

Those pistons are from MM951 not George

George D

Tony, Tucson and Greer are both about 2.5 hours away driving.

George D

8.5 CR. Same as the new motor.

Thom

Sorry I read too quiclky!

MM951, can you post some pics of the head used with these pistons?

George D

I'd love to hear anyone using the MID sleeves to share their experience with their motors with at least 10K on them.

George D

Sent you a PM.

George D

No detonation visible once the head was off. No detonation was recorded from the knock sensor, nor human ear. Not one knock recorded during the tuning runs. This motor was showing great promise till the "poof" of black smoke from the tail. Glad the tuning was done on the dyno. Immediate shutdown then teardown to find the culprit as posted in color.

Rogue_Ant

George - what fuel? And what was your timing advance (if you don't mind)?

refresh951

I figured you were doing the knock monitoring. I appreciate all the pioneering work you have done with your car.

My next thought would be a fatigue fracture. Impurity inclusions in the aluminum can lead to fatigue initiation sites which result in high stress concentrations. A crack is formed and then propagates. With the power you are running, hidden weaknesses would be exposed. Be interesting to have a Metallurgist look at the fracture surface.

George D

Did have it checked. Looks like the OE casting was the issue. We all mess up. Could have been a late day when the quality control folks were , "almost off the clock".

It did some time with a NA 968 for many miles. When we stress the bores, you find lackluster supervision towards quality control.

The builder is making this right. I'm thankful this happened during the builders tuning, and not my time in the car. We both loose, but I'm not shipping the car back to him. Happened in his shop.

azbanks

Prescott to Greer in 2.5 hours???? D@mn, your car IS fast.




Payson to Greer in 2.5 hours I would agree with.



Tony, if you have room to bring my part to Prescott, I'll come pick it up from you there.