What do you guys think about machining a taper above top ring land?

[Jetmugg]

Some of you may be aware that I recently burned up my 1.5L "Franken" engine during competition at The Ohio Mile.  One cylinder went to zero compression after the top of the piston partially melted and got into the cylinder wall.  Another cylinder was close behind.

EGT's were 1600F or so at the time, running 40+ psi boost along with a lot of fuel, and water injection.

In any event, for the "next" incarnation of this engine, I'm considering having a slight taper machined into the area of the pistons above the top ring groove, to allow for additional expansion in this area.  I understand that this is somewhat common in sled pulling tractors and the like.

Has anyone here employed this technique, and if so, any words of wisdom?

Steve.

[golfmk1tdr]

Head and chambers made it through this alive? Any pictures?
We are talking about the famous 2l class beating engine? Sad to hear it's gone, still, was great while it lasted, wasn't it? 

Don't know about tapers, as it's extra weight on the pistons and untested trick on these engines... To me it just sounds like a thing to go wrong really, but what do I know, I can't even make engine frankenengine run, let alone run like yours did...
I think ceramic coating could help a bit but I believe you already did that so I can't help you much 

Whatever you end up doing, I just want to wish you luck...

[libbydiesel]

My guess is you either had a valve leak (float?) in the affected cylinders or you had imbalance in the intake manifold flow.