[petek]

From a strictly resonance standpoint things like the volume and shape of the intake and exhaust ports (as well as cam overlap) will have a large bearing on how the engine sounds. (Imagine a pipe organ.)

There is a LOT that goes into the mix to produce the sound you hear. Listen to a 5 liter Ferrari, Porsche, Chevy, and Ford. All are the same size, but each develops the engine size a different way and producing a different sound.