Compression....
 

How do I calcualte the compression of my engine?
I have ran compression tests on my engine but it only tells me the PSI of each cyl. Also, how can I bump up my compression say from 9:1 to 10:1?

Your compression is the total cylinder volume (including combustion chamber) at BDC divided by the total cylinder volume at TDC. To calculate it, you need to know your bore and stroke, the size of your combustion chamber, the thickness of your head gasket(s), and the amount of volume displaced (domed) or added (dished) by your pistons.

Compression is increased by reducing the size of the combustion chamber (changing heads, milling the head surface, installing a thinner head gasket), reducing the combustion chamber volume at TDC (installing domed pistons), or increasing the bore.

An easier estimate might be made based on what you have, and what's been done. What do you have, and what's been done to it?