wasn't sure where to put this, but my dad has a 2004 lq9 pullout of an escalade. It has the stock crank and rods with flat top pistons (no reliefs), and he installed 243 heads (62cc chambers I believe) and the standard 2004 c5 z06 cam.

I plan to buy the motor off him, but he is worried about where the compression is sitting at. Can anyone give me the formula for both static and dynamic compression or calculate the compression to figure out if I will be able to buy it, install it and drive it. I have 93 octane available in my area.

Thanks in advance!

 

I have an LQ9 with 243 heads/chambers but I am sure my intake closes much later than yours. 200 psi seems to be the max pressure you want with 93 octane. Compression ratio's are just mathematical formulas while cylinder pressure (psi) is a real world number which is why I prefer to take that as gospel.
This is a good article... http://www.chevyhiperformance.com/te...ion/index.html
Static compression... http://www.csgnetwork.com/compcalc.html
Dynamic (cranking) compression... http://www.wallaceracing.com/dynamic-cr.php

 

that is exactly what I am looking for, thank you

 

Glad I could help.