Melted piston... Cause/Fix?

[ctkao2112]

Took my car to a track and 20 minutes in the engine started misfiring and blowing out exhaust smoke. Also, all of my oil was ejected. Took the engine apart to discover the piston is melted and the cylinder wall is damaged (see attached). I'm planning on buying a short block and swapping that in, but I want to make sure this won't happen again.

Can anyone identify likely causes/solutions? I'm thinking running lean/detonation, but not exactly sure what's causing it. Faulty O2 sensor? Fuel injectors? Tune? Haven't done too much in terms of diagnostics due to time constraints, so I was hoping ya'll could give me suggestions.

Engine mods:
- Cobb Stage 3 Tune
- Autotech High pressure fuel pump (HPFP)
- Corksport short ram intake
- CPE top mount intercooler
- Synapse synchronic DV diverter valve

[Vansquish]

Do you have any datalogs from while you were on track, or at least some very recent ones?

The OTS maps are garbage, so it wouldn't be surprising if that was part of the problem. However, it's pretty common to have substantial air/exhaust flow volume variation from cylinder to cylinder. Cylinder 3 is the one that, historically, most frequently craps out from lean-burn conditions for this reason.

[Tomas]

The single most important variable you need to monitor on the track is knock. If the engine is knocking all the time for whatever reason no amount of timing pull back is going to save it.

Take piston out and inspect piston ring landings. I'll suspect they are cracked which led to that blow by you see.

[Jeff23spl]

i agree with the above, stock ring gap is a bit tight for higher temperature regardless of everything else. When you see knock under boost, it is time to stop and check what is going on.
Melting is from knock but was it because of being lean, too much boost or very high BAT...or all of the above...without a log you won't realy know....

Tmic works ok at high speed but if it was a short track after idling in start lane...it could be part of the problem to run higher air temperature. There is fmic options/meth corn to help it....
The uneven flow of the intake doesn't help but you could have your injector cleaned for piece of mind.

I would check if the valves are ok and if the seats still seal perfectly before assembling it on a new engine bloc...you may get surprises looking at the intake path cleanliness too.

[MSMS3]

Almost certainly detonation from a lean-out condition. What is striking is that it is limited to one cylinder (hopefully). Wise to replace the whole short block. Check the head carefully. Maybe an injector failed or got clogged on that cylinder?