Originally posted by armstrkw:
Right, I am sorry it came out kinda wrong each of mazda's chambers is 654cc making it a 1308cc when having two chambers. However this is only counting two stroke's when all regular engines are calculated using a 4-stroke method. All I am saying is that this Renesis engine is breathing just as much as your 2.5 L. When you say its a 1.3 then you are saying it breaths like a prius engine which is clearly not the case. If thats the way you want to think about it the go right ahead!!! Just doesn't seem locical to me!!!



I'm not sure where or why you are including the number of cycles or 'how it breathes' in your determination of displacement. Displacement is just that - combustion chamber volume (L^3, in dimensional analysis speak). Not volume per cycle or volume per crankshaft revolution. It is not a function of crank theta or omega. It is the swept volume of each combustion chamber multiplied by the number of combustion chambers.

Indeed, 2-cycle piston engines have their displacements calculated the same way as 4-cycle versions: (pi/4)(bore^2)(stroke)(N), where N is the number of cylinders. However, their breathing (and power output) characteristics are quite different. But these characteristics are not captured by engine displacement.

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