What is the ideal clearence for "piston to cylinder wall" with forged pistons. How about with a small shot of N2O (150hp)?

 

The best source for this info is the piston manufacturer.

Rich

 

I called Mahle and they said .0025 and .003 with the juice. Thats what I'll be running, I was just curious if that was about the average for all forged pistons.

 

You need to follow the exact method for measuring defined by the manufacturer. Pistons are not perfectly round, so where you measure is crucial. Unless you were measuring the same way, comparing the measurements would not be useful.

Rich

 

One reason being, different material compositions expand different amounts for a given temp exposure.