I don't know what you are talking about... I run race gas alot and have cast pistons. I think when people are really using race gas alot they are ussually pushing the limits of tunning (in a good or bad way) and can tune to a piont where they either detonate(crack a piston), overheat (melt a piston) or over power (usually brake) the pistons. Forged pistons take more abuse, but alo of cast piston are really strong too.

Extra heat is not from the feul. It is from the tune. Too much timming and/or not enough feul can cause excessive heat.