the compression ratio - - not the compression in psi.
The ratios you see are calculations on total swept area.
Really of little value .
Why?
the porting/ and internal flow of the engine can really skew the density of the compressed charge.
for example - IF the exhaust port is raised from say----150 to 175-- the compression calculated (from top of exhaust port to top of stroke - is REDUCED.
However the density of the charge -with a tuned pipe - can increase- on the raised timing setup.
Then-- the pressure in the cylinder INCREASES.
Confusing?
Don't let the adv compression ratio influence how you about engine performance
some low compression setups run very hard.
Simply because they breath very well.