I understand that, but you are referring to "combination" as pertaining to the entire car. We're talking here about crankshaft power output. Once you begin to consider including sub-systems beyond the engine "poor combinations" gets really vague as to the cause(s). It's arguable that most poor performances when considering the entire race car and driver are the result of parts mismatches not involving the engine, less than quality tuning, total miss on suspension setup and tuning, driver issues, and/or all of the above. I'd say based on my 30 years of doing it that engine design/spec is the culprit less than 1/4 of the time when a car is not performing as intended.
Engine output is fairly easy to figure out and calculate based on very accurate inputs. It takes "X" amount of intake charge to make "Y" amount of power in a given cylinder displacement. So if you know how much is going in, and it's not generating the expected level, you know there's a problem. Naturally aspirated internal combustion engines are their own power inducers too. As rpm increases the internal physics begin to help the power production right up until the point where parasitic and pumping losses take more than it makes and we see the power drop off. If you push the mix in with a positive displacement supercharger that 360 makes the same power at low rpm as if that 360 was revving at 6500 with a good set of heads and cam. Regardless of the method of getting that mixture in, you still need "x" for the intended "Y". That was my point.
