---------------------------------------------------------- Engines-List Digest Archive --- Total Messages Posted Mon 10/06/03: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:02 AM - rotary engine displacement (Gary Casey) 2. 08:55 AM - Re: Eggenfellner 6 cyl (Dennis O'Connor) 3. 05:25 PM - Re: rotary engine displacement (Ed Anderson) ________________________________ Message 1 _____________________________________ Time: 06:02:56 AM PST US From: "Gary Casey" Subject: Engines-List: rotary engine displacement --> Engines-List message posted by: "Gary Casey" <> Just to add more confusion, each rotor chamber displaces 1/4 of that, or something like 327 cc. There are a total of 6 chambers in a 2-rotor engine for a "true" calculated displacement of 1,962 cc. It is also a true 4-"stroke" engine, having separate intake, compression, expansion and exhaust events, except that each chamber will experience all 4 events in one complete revolution (not orbit) of the rotor. Each rotor is geared so that besides orbiting it rotates at 1/3 output shaft (E-shaft) speed. So it take 3 revolutions of the shaft to complete one complete cycle for the total swept volume, compared to 2 revolutions for a piston engine. Mathematically it is a 1,962 cc engine, but somewhere along the line someone decided to rate the displacement to be sort of equivalent to a piston engine and said "let's just use 2/3 of the displacement" and so it was. It displaces 2/3 of its total displacement in 2 revs, a 4-stroke piston engine displaces 100% and a 2-stroke 200%. I think that partly explains why it is a naturally high-rpm engine as the rotors are only turning at 1/3 shaft speed even though they orbit at shaft speed. Gary Casey ________________________________ Message 2 _____________________________________ Time: 08:55:04 AM PST US From: "Dennis O'Connor" Subject: Re: Engines-List: Eggenfellner 6 cyl --> Engines-List message posted by: "Dennis O'Connor" Or they are not actually making the power they believe they are... ----- Original Message ----- From: "Tracy Crook" Subject: Re: Engines-List: Eggenfellner 6 cyl > --> Engines-List message posted by: "Tracy Crook" > > > > --> Engines-List message posted by: kempthornes > > > > > > > >Tracy wrote: > > > > > >Calculate the theoretical CFM of the engine at max > > >HP rpm. It takes about 1.59 cfm of fuel air mixture to make 1 HP. > > > > I suppose this assumes stochiometric fuel air ratio. Another quick > > estimator I've heard of involves fuel burn, like 0.4 pounds per HP per > > hour. So a 180 HP engine would burn 72 pounds per hour. I think this > > would also apply to boosted engines. > > > > > > K. H. (Hal) Kempthorne > > RV6-a N7HK - Three trips to OSH now. > > PRB (El Paso de Robles, CA) > > Very true, although .4 is optomistic. Real World numbers are closer to > .45 - .47. In other words, if someone says their 165 HP engine burns 6 GPH > at 75% power, they are "streaching the truth to the breaking point". > > Tracy Crook > > > > ________________________________ Message 3 _____________________________________ Time: 05:25:54 PM PST US From: "Ed Anderson" Subject: Re: Engines-List: rotary engine displacement --> Engines-List message posted by: "Ed Anderson" ----- Original Message ----- From: "Gary Casey" Subject: Engines-List: rotary engine displacement > --> Engines-List message posted by: "Gary Casey" > > <> > > Just to add more confusion, each rotor chamber displaces 1/4 of that, or > something like 327 cc. There are a total of 6 chambers in a 2-rotor engine > for a "true" calculated displacement of 1,962 cc. It is also a true > 4-"stroke" engine, having separate intake, compression, expansion and > exhaust events, except that each chamber will experience all 4 events in one > complete revolution (not orbit) of the rotor. Each rotor is geared so that > besides orbiting it rotates at 1/3 output shaft (E-shaft) speed. So it take > 3 revolutions of the shaft to complete one complete cycle for the total > swept volume, compared to 2 revolutions for a piston engine. Mathematically > it is a 1,962 cc engine, but somewhere along the line someone decided to > rate the displacement to be sort of equivalent to a piston engine and said > "let's just use 2/3 of the displacement" and so it was. It displaces 2/3 of > its total displacement in 2 revs, a 4-stroke piston engine displaces 100% > and a 2-stroke 200%. I think that partly explains why it is a naturally > high-rpm engine as the rotors are only turning at 1/3 shaft speed even > though they orbit at shaft speed. > > Gary Casey > Excellent clarification, Gary. I think the key is (as you point out) was to give folks a basis for comparison with something they understood, they chose the 720 deg four stroke automobile standard. Since the rotary has only completed 2/3 activation of its total displacement in the 720 deg of the crankshaft, then 2/3 of the 1962 cc = 1308 cc. But for this reason, there are those who are adamantly convinced that the 13B is a 1300 or 80 CID engine. I guess for comparison purposes that is not necessarily a bad thing. Actually, I don't really care, I just like the way it likes to rev high rpms and produce power. Ed Anderson RV-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com