What caused this ?!?

[TDHAA]

I took out the pistons and this is what they look like.
I bought them new and drove them for about 600 miles.

When i tested my new big reds,hard breaking/clutch down
the engine gave up on me,and when i let the clutch go to get it going again i heard the familiar crank/conrodbearingproblem

1 piston has the bad upper ring.

Fitted them brandnew and havent got a clue what caused this.

Is the pistonring causing the crank/conrodbearing failure?

[AndyP]

Looks like the chrome has come off the ring and that knife edge on the valve pocket should have been removed at manufacturing as it's a known problem that it can melt.
What sort of pistons & rings are they?

[Jamo]

Are they custom pistons? If they are then the valve pocket need to be machined down as those cause hotspots causing the piston to melt.

See http://www.s2forum.com/forum/showthread.php?t=5523

I had mine machined down by JE just like that thread so it would not occur

[TDHAA]

They are the Mahle IMSA pistons.

[TDHAA]

Are they custom pistons? If they are then the valve pocket need to be machined down as those cause hotspots causing the piston to melt.

See http://www.s2forum.com/forum/showthread.php?t=5523

I had mine machined down by JE just like that thread so it would not occur

Thanks man,the thread figured it out for me.
I will send them back hoping they can be saved.

Still questionmarks with the ringproblem/bearingfailure though..


I hope you'll get your S2 running again soon

[GT500]

Sounds like you got oil surge under braking!

More oil and baffles needed!

[caterpillar]

you may have the ignition /coil problem... then you have some detonations/ then you get bearingsproblem, then pistonsproblem... then you have the gone engine...
if you arent sure/ change the ignitionsparts, all of them

[repo]

Looks like detonation to me. It can cause all these issues, melting, chrome chipping, bearing problem.

[90/90qs]

did that piston in shot 4 hit the oil squirter?

[SteveH]

If you use the wrong rings on a forced motor I've heard of issues with the chrome surface detatching. Detonation would most certainly assist this process.

[TDHAA]

Thanks for the help guys!!

I didnt trust the dta/haltech style ecu anyway. It doesnt have knockcontrol so
it has to go,i wil use the stock adu motronic again.

[90/90qs]

have you considered one of these?
http://www.mswanson.com/~jgreen/APC/APC.html

[A80Avant]

my stock adu motronic did not hear knock very well either.