Quote: For example, if 165 psi is the limit for 91 pump gas at sea level, then that is the target that should be hit @ 6000'.
yes if 165 is the limit for 91 inside the cyl(s) it doesn't make any difference if the cyl(s) are located in New Mexico or death valley but since the air outside the cyls is "thinner" at NM you need more CR to squeeze this thin air inside the cyl(s) to get that 165
Correct, and that's why we generally add 2 points (maybe more depending on the other usual factors) of static CR to a "sea level" type build and then fine tune the cylinder pressures with the cam shaft. All of the various on line calculators make this a pretty simple task nowadays.
