I have a question regarding the expansion chamber for a 3 cylinder engine – three into one - common chamber design. Obviously in this type of engine the cylinders are offset by 120 deg. and, as in any 2 stroke engine, the exhaust port of each cylinder is open typically for about 180 deg. This arrangement creates an overlap in the exhaust time of the adjacent cylinders. And here is my problem. The well known theory of the negative and positive pressure waves created by the chamber cones is explained and always applied to one cylinder only. In my case, with 3 into 1 exhaust manifold, the situation is not as simple as in the one cylinder engine. Exhaust ports are connected in the manifold and the overlap of timing causes pressure waves to interact with each other. Exactly when in a tuned single cylinder exhaust one would expect the returning wave to near the exhaust port just before it closes, in the 3 into 1 manifold the new pressure wave appears from the just open adjacent cylinder. And it looks to me that this new wave, because it is much stronger than the bounced one, will play the main role here. If what I think is right, what is the point of bothering with the “tuned length” of the chamber and having the baffle cone if the returning wave is overpowered by another one? Yet, we know that expansion chambers for 3 cyl. engines do exist and they seem to work.
Can anyone explain me what is wrong with my thinking here?