Diptenkrom
Newbie
You're assuming the published compression ratios are accurate. This is not true so your calculations from that number are not going to be accurate either. Never, have I ever measured a tear down that was even close to advertised numbers. Ford, Chevy, or Mopar. The only way for certain to calculate compression is to measure what you have or are building. If you want to run on the ragged edge of detonation one mis-step and you've built a detonation prone ticking time bomb.
Most published numbers come from a specially handled engine not your average run of the mill production line engine that's can be prone to tolerance stack up, built on worn tooling, core shift, etc.
Measure everything. You don't always hear detonation and when you do the damage may have already started.
I agree with what you are saying, i know where assumptions get you, which is why i started this thread. however i have decided to skip the decking and compression adding, other than a thin-ish HG at this point. I want reliable, daily driver capable, towing power, and i can do that without the decking.