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Tracy I only partially agree. One of the reasons diesels do well is direct injection with NO butterfly in the intake at all! As engine management systems get better we should be able to do the same thing with a gasoline engine. I heard a Mecury engine running in the test cell using this system. It was a 2 cycle which sounded really wierd since it didn't miss at idle (which is typical). Since the engine didn't "4 cycle" it sounded like it was running twice as fast! The new direct injection system running in Audis and others may be the best thing to ever happen to the rotary. I would love to work with you on it, in your "spare" time LOL.
Bill Jepson
-----Original Message-----
From: Tracy crook <lors01@msn.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Tue, 19 Jun 2007 8:13 am
Subject: [FlyRotary] Re: Fw: Different Rotary Port configurations
The very best (economy wise) piston engine designs today use variable overlap. The Prius engine may not have this feature because I think it operates at a very narrow rpm range so it is a different case. The BMW (straight 6s) vary both intake & exhause timing to make good power and economy(for a performance car) across the rpm range. Laura's 330i gets 32+ mpg at 65 -70 mph.
"getting the engine to pump the most air at a given RPM is "THE WAY."
There is absolutely no arguing this (correct) point but it only applys at WOT (where the 26B and most all race engines) operated. This is where the best SFC happens due to minimum pumping losses. But I think the pumping losses argument goes out the window as soon as you back off the throttle and manifold pressure goes down. Sucking air past that damn butterfly takes energy. You can operate at WOT and get good SFC but this ignores the real world factor that the aerodynamic losses on the airframe go way up at the higher airspeed. This is the dominant factor so in reality, all these BSFC arguments are sort of moot unless you are racing. But fun to discuss none the less.
Tracy
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