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Picked up a book on 2-stroke tuning to see how much more advanced they were in their exhaust tuning. Then I realized they are practically at full overlap for their whole events. D'oh. Is interesting to see how much of a change pulse tuning can make on them, though.
Buuuuut... I found out that some use a power valve that basically alters the height or shape of their ports. Since a rotary is essentially a 2-stroke except with a fairy-pushed couple of triangles rather than natural and godly pistons, I figured why don't they use something like this, too?
If they used one on either side (or top/bottom, whatever...) of their ports they could effectively change their advance and retard like cam phasers, AND have control over duration. However this looks more likely to apply to a peripheral port setup, and the Renesis is side ported (? in the end-piece separating parts, not the barrels) for emissions, I believe?
But if it was an overlap thing for emissions, and if they can control it they can go back to the more flow-friendly peripheral porting maybe? But maybe peripheral porting is worse for apex sealing?
Any reason this isn't used? Or maybe it has been used in the past? Reliability and complexity are the first strikes against it, off the top of my head...
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