a.) the lower compression ratios obtainable due to the exhaust port

   b.) the lack of control over overlap while maintaining sufficient port size (I'm really thinking of piston ported engines

here - some of the other methods allow some flexibility but have other problems).  It is interesting to note that a 2-stroke
optimized for max power at 7000 RPM will suffer from dismal BSFC at low RPM due to the mixture being pushed out the open
exhaust port before the rising piston enters the compression phase.

There is some fun stuff going on here. First two strokes don't really
suffer low compression. The interesting relationship here is that two
strokes are a two chamber engine. The bottom end pumps the top end.
The rotary doesn't supercharge itself, but does have two "active"
chambers per rotor. (Don't hurt me Paul!)  The efficiency of the rotary
lies in the motion. The long thin combustion chamber has problems.
The stratified charge efforts relate closely to the difficulty encountered
in direct injecting a two stroke. Merc outboard people in Austrailia have
some of the best work done there. Seeing a two cycle direct injected
idling perfectly WITHOUT missing at all sounds really weird. It seems
like it's running twice as fast. This is a digression though, I would really
like to see the results of proper direct injection in a wankel. Sorry for all
the blather but I believe the point is the rotary is completly unique in
both form and function. I like the fact that it works as a four cycle.
Bill Jepson

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