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
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| Subject: | rotary engine displacement |
--> Engines-List message posted by: "Gary Casey" <glcasey@adelphia.net>
<<A subject of much debate. Mazda rates it as 1308 cc.>>
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
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| Subject: | Re: Eggenfellner 6 cyl |
--> Engines-List message posted by: "Dennis O'Connor" <doconnor@chartermi.net>
Or they are not actually making the power they believe they are...
----- Original Message -----
From: "Tracy Crook" <lors01@msn.com>
Subject: Re: Engines-List: Eggenfellner 6 cyl
> --> Engines-List message posted by: "Tracy Crook" <lors01@msn.com>
>
>
> > --> Engines-List message posted by: kempthornes
> <kempthornes@earthlink.net>
> >
> >
> > >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
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| Subject: | Re: rotary engine displacement |
--> Engines-List message posted by: "Ed Anderson" <eanderson@carolina.rr.com>
----- Original Message -----
From: "Gary Casey" <glcasey@adelphia.net>
Subject: Engines-List: rotary engine displacement
> --> Engines-List message posted by: "Gary Casey" <glcasey@adelphia.net>
>
> <<A subject of much debate. Mazda rates it as 1308 cc.>>
>
> 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
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