I have a 383 lt1 motor currently built 8.1:1 compression I bought in a parts car. Wanting to use the shortblock and bring up the compression back to na. Currently has 65cc afr heads and was going to swap out to a set of ported stock casting around 54cc. How much of a difference would the head swap and a set of thin .026 gaskets net me for compression bump?

thanks.

 

Need to see what the pistons are. Are they flat tops, dished, set down in the hole some. Then you can determine what changing the chamber will do.

 

Assuming all things stay the same with pistons, and a .026 HG, going from 65cc to 54cc gets you almost a full point of compression. Without knowing what HG you have now, you can't get a true answer though.

Just throw a 88mm turbo on it and let her eat

 

General rule of thumb for every 10cc change is about 1 point in compression, so 8:1 at 65cc would be about 9.2:1 at 54 cc head.