AFR225's Milled 70cc to 66cc
 

just wondering how much compression i gained going from 70cc to 66cc on my AFR 225. And what type of power would be gained
Mods in sig
Also i know it's not much but would going from a 041 head gasket to a cometic .040 do anything at all. With the .041 gasket Quench was .040

Roughly you gain about .1 SCR for each cc your heads are milled, so you'd be increasing SCR by .6 . Of course to be exact we'd need to know whether your pistons are dished/domed. Nothing substantial at all would change if you changed the gasket from .041 to .040.

Pistons are wiseco flat tops w/ 2 1/2 cc valve reliefs

Your SCR right now with the .041 head gaskets and 70cc heads should be around 11.1:1. With the 66cc heads it would change to 11.6:1.

How much power would he gain from rasing his compression to 11.6? My friend has a 402 with DCR of about 7.8:1. The car still makes pretty good power but he knows that he's leaving some power on the table. We want to raise the compression to move the DCR up to about 8.2-8.3:1. Anybody have any estimates of what he would gain off of that?

Anybody?

I would address DCR with the cam because that is what ultimately affects DCR, not use SCR to raise it. Nonetheless, I would only say the gain would be about 5-10hp, depending how good the tune is.