I've got a GM 6.5 diesel engine which I am rebuilding and I am considering installing a thicker head gasket to loose some compression in order to give it more boost. I would go with cometic gaskets but I'm wondering if diesel engines have the same concern with quench as does gas?

What I'm asking is, I wonder if I could go with .200 thickness head gaskets and what would my new compression be. Stock gaskets are .050 and I have 21.3 to 1 compression and I would like 18 to 1.

The bore size is 4.055.

I used to have a compression calculator but I couldn't find one on line. Thanks for the help.