I've read in a few other threads that having JDM itr pistons or the JDM balance Spoon pistons yield an approx. compression ratio of 11.4:1 in a Gs-R motor due to the fact that the Gs-R has smaller combustion chambers. A few of u have confimed this, but what if the Gs-R head was full ported and polished? What would the compression ratio be then? I hoping to get these pistons sometime shortly and was curious as to what compression ratio i might be running since my head is fully p/p and is also milled 40thou. Figuring out how much added compression i get from my milled head is not too difficult, but getting an idea of what compression i will be running from the JDM itr OEM or Spoon pistons with my p/p head has me wondering.

 

porting and polishing the head will not effect the c/r... porting and polishing means the runners going into the combustion chamber are opened up... it has nothing to do with the actual combustion chamber... also take into account what valves u are using... as any "flat head" valve will also yield u a higher compression, as will milling the head