compression ratio can't be mesured by any instrument or tool
you have to know :
piston to engine deck clearance
+ cylinder head combustion champer size
+ gasket volume ( when compressed )
+ crank stroke
+ bore diameter
+ piston dish or dome volume
+ the number of cylinders

then you can calculate it mathmatically on paper or by using a software

and that is what we can call it static compression ratio




لا اله الا الله