The deal here is that they bored out the case to accpet the 140 piston and sleeve on the 120 engine....This combined with the extra power of the high nitro is what is causing the failures.

I have run 40-50% in 120SC and they will handle it really well. But changing the wall thickness on the case would make it weaker at the same time you are making mucho power with the higher nitro turning really high rpms...all it takes is an air bubble, or a little lean or run it out of fuel...the detonation can just eject parts and pieces. Especially if they are running 10, 000 rpm

Troy Newman
Team YS