My heads have been milled .025 . I will be running the Lunati 382 rotating ***. with pistons that are -8cc. The Lunati kit is supposed to give a CR of about 10.7 to 1 with stock heads. How can I figure out what my CR will be with my heads milled .025?

 

A .025 mill should raise your compression ration about 4 tenths of a point. If you want to know exactly, have your combustion chambers CC'd.

This is going to be true whether you have a stroker motor or a stock displacement motor. Milling the head raises the compression ratio because the combustion chambers are smaller.

 

I would guestime your compression to be about 10.4:1 based on the following assumptions:

3.9" bore
4.0" stroke
0.054" gasket
67.3 LS1 chambers
milling 0.025" drops 3cc in chamber volume

 

That doesn't make sense. If the CR is 10.7-1 with the Lunati kit and stock cc chambers, then it would be higher with heads milled .025.

 

did you have your heads flat or angle milled?

 

Flat

 

if the 3.9 bore & 4.0 stroke & .054gasket is corect then you should have a 11.21:1 ratio