its my understanding that the suzuki powervalves were "quasi-powervalves" in that they didnt operate by using a slide to open up teh exhaust port, but rather in some manner or fashion changed the harmonics of the exhaust pipe

 

When I say Rotary engines I dont mean a rotar/wankle engine. It used pistons but unlike most 2 strokes that have reed valves that supply the air/fuel charge to the engine the rotary engine has a rotor that spins past to holes and meter the air flow so there is no reed valves. Very slick for a 2 stroke.

RAVE is a powervalve that works on exhaust pressure to open and close the exhaust ports to deliver low end torque and top end power. Skidoo introdused power valves back in the early 80s on there race sleds and in 1989 the 583 got them. It changed the way 2 strokes could perform.

 

I have heard of different custom engine builders that have sucessfully engineerd rotary valves into a 4 stroke motor. It has been a long time since I heard this so I dont remember who or what it was on. I have also heard of a few trying to develope a power valve type system for four strokes. I think it is possible and that the technology we see now is trully just the beginning. There is a guy that is here in SLC that has even devoped a motor based on a chev 350 that runs on a mix of 75% water and 25% unleaded with no power loss and only 5% of the polutants compared to that of the current FI models. The thing is he found the research papers and continued the research because the last guy that was working on it disapeard. Hmmm wonder if the oil company's had anything to do with that? Along with several other people that have developed simular things and been found dead or disapeared. It's all about $!!!