Originally posted by ckolsen:
More important points:
(1) Doubling RPMs = Doubling displacement.
By doubling your RPMs, you are causing the same increase in combustion as doubling the cylinder displacement (or number of cylinders). (in reality, there are losses but in theory this holds true)
(2) The more cylinders you have, the higher your friction losses, and the greater the surface area for heat transfer(loss), so smaller engines are more efficient by nature.
(3) Doubling air density = Doubling displacement.
This is why turbos and SCs increase power, by increasing the air density (and thereby the air flow) in the combustion process. (Doubling air density requires 14.7 psi of boost, which is pretty high.)