I recently tried to order a set of NISMO 87mm flattops and bought the euro ones by mistake. I want to know how much volume the slighty raised area occupies? I have heard that they tend to raise the CR about 0.5, but I would really like to calculate it.

I am also thinking about shaving 0.040" off my P79 head and I am curious about how many cc's that will reduce the chamber volume. I guess they are 53.6cc's to begin with I am hoping for 4 - 5 cc's.

I am shooting for about 10:1

Thanks,
-Bob