Today I compression tested my 89 Civic Si with mini-me swap. It checked as follows:

#1: 220 psi
#2: 220 psi
#3: 210 psi
#4: 210 psi

This is quite surprising. The manual says for the stock motor which is 9.1:1 that the compression should be 160 psi. The mini-me swap upped the compression a good bit. Does anyone know how to convert psi readings to compression ratio?

 

what head are you using the z6=10.4 comp and the y8=11.1comp those are not 100% accurate but close enough to within like .2.

 

I'm using the Z6 head. How did you find the 10.4:1 ratio for the Z6 head?

 

http://www.prestage.com/carmath/calc_compression.asp