StevieZ

iTrader: (3)

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?

HITMANSS

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.

ls1290

iTrader: (20)

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

StevieZ

iTrader: (3)

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.

wolfman jack

did you have your heads flat or angle milled?

StevieZ

iTrader: (3)

Flat

wolfman jack

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