Rorin67

Is it possible to calculate a motor's compression ratio with only the following:

Compression testing results in roughly 170 average for each cylinder (range 165 to 176).
Engine is 351W, stock stroke, bored .030 over.

Do I need more info than that?

Many thanks in advance.

r.barn

Compression you are talking about is just a leak test to test cylinder seal.

To calculate compression ratio you need to know:

cylinder bore
stroke length
head gasket bore diameter
head gasket compressed thickness
Cylinder head combustion chamber size
Piston dish or dome volume
Piston deck clearance.

Whats your engine combo, and I can type info into calculator and give you
relatively close number.
Piston deck clearance we'll have to take an educated guess since you have to tear down engine to get that.