First, it's good that you are looking into more than simple math to forecast performance. Second, hope I fit in the wise man category, at least close enough for this discussion LOL
Using measured pressure is very difficult, even using DCR is difficult if you rely on it as a true measurement. I am a DCR fan, so don't get me wrong, I use it to tweak cam timing a little, know when combos are extreme, etc. However, measured pressures can be all over the place
For instance, you could get 30 psi difference based on starter speed, change the valve lift or port size significantly, it changes again, so I would be leery of trying to get to a cranking compression number to determine detonation
As for variables that affect it, its far more than heat and pressure, and you eluded to that with your bore size and mixture discussion
- Mixture
- Temp
- Chamber shape
- Bore size
- Piston design
- Compression
- Cam profile
- Load
- Timing
- Atmospheric pressure
- Air temp
- Fuel (both octane and chemical make up)
I am on my first cup of coffee so there are likely more to talk about. However, FWIW, my EFI 10.7:1 489 inch wedge FE has a cranking compression of 195 psi and will run on almost anything, and if it gets fussy I can pull a little timing or fatten it up. My carbed 9.98:1 445 wedge FE has a cranking compression of 185 and it's fussier on fuel. However, by all counts, the truck 445 should be at least as octane tolerant if not more (tighter quench, smaller bore, better cooling, lower compression), however it's iron head in a 4300 lb vehicle and not EFI
As far as setting boost to zero, if you are saying in a calculator, yes, as long as you do the same thing all the time to allow comparison. In theory, you could adjust for pressure above or below 29.92 (standard atmospheric pressure) we have to do that when calculating jet engine performance for a given day based on weather, but adjusting boost by that small amount is likely insignificant unless you were comparing Cocoa Beach performance to Denver.