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so... i was thinking about how to reply to this in a way that isn't too convoluted. i don't want to lose the original poster, but then again, i can't boil this down too far either... here goes:
motor A @ 10/10... that's 10:1 compression and 10psi boost. well (here's where i don't want to lose anyone) atmospheric pressure at sea level is around 14psi. a naturally aspirated(non-forced induction) "sees" 14 psi of air pressure. 10 psi of boost is the equivalent of 24 psi (from the perspective of the inside of the cylinder.) so, if you take the ambient air pressure (14 psi) and add the 10 psi of boost, you get 24 psi. multiply that by the compression ratio, and you get 10*24, or 240 "psi". now one more thing- there are too many variables here to count. the higher the boost, the higher the air temperature, unless there's intercooling going on. like i said, a lot of variables. remember the "240"...
motor B @ 8.5/13... 8.5:1 and 13 psi. add the 14 atmospheric psi to make 27 and 229.5 is the result. apparently this combo will make less power... but not in the real world. you have to take totally different approaches from the ground up in your engine design depending on what you want the outcome to be.
of course, if you aren't trying to squeeze every drop of performance from an engine, things don't have to be that optimized, but why not spend the extra time?
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