Thread: compression ratio

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can you use thicker compressed thickness head gaskets to help lower compression ratio a wee bit to use with a blower? obviously not just doing that alone

A thicker head gasket won't lower c.r. by much, but it'll sure screw up the squish on a motor like a small block Chevy. To put any kind of boost in the motor, you need to be at around 8.5:1 or less.

Here's a good summary of atmospheric pressure as it affects CR.

Compression Ratio and Compression

You can see that the ranges overlap greatly, and probably not a good estimation tool for CR when considering boost.

According to the chart 125 psi could indicate some CR between 6.9 and 8.0 to 1.

sweet as. cheers guys