Today's Message Index:
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1. 11:32 AM - Re: Eggenfellner 6 cyl (Tracy Crook)
2. 11:39 AM - Re: Eggenfellner 6 cyl (Tracy Crook)
3. 11:45 AM - Re: Eggenfellner 6 cyl (Tracy Crook)
Message 1
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| Subject: | Re: Eggenfellner 6 cyl |
--> Engines-List message posted by: "Tracy Crook" <lors01@msn.com>
> --> Engines-List message posted by: "CHUCK KELLY" <heavy707@comcast.net>
>
> How many cubic inches are in the 13B Rotary Mazda Engine?
> Thanks
> Chuck
>
A subject of much debate. Mazda rates it as 1308 cc. This is 80 CI. BUT,
the rotary pumps ALL of its displacement in one rev instead of two like a 4
stroke piston engine. To compare it to a piston engine, think of it as a
2.6L engine (160 ci) that safely revs to 6500 rpm. I limit it to 6400 for
prop tip speed reasons.
Tracy Crook
Message 2
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| Subject: | Re: Eggenfellner 6 cyl |
--> Engines-List message posted by: "Tracy Crook" <lors01@msn.com>
> --> Engines-List message posted by: "Healy, Joseph" <WJH@BRPLUSA.COM>
>
> I notice that your calculation does not consider compression ratio. And
> I assume these are sea level numbers. Is there a correction factor for
> compression ratio?
>
> Joe Healy,
In the range of 8 - 10 : to 1, the difference is not great. Combustion
chamber design has as much or more effect than CR, not to mention Volumetric
efficiency. Still, we are only talking about a range of 5-10%.
Intermittent combustion gasoline engines have very close to the same BSFC,
in a range of .43 - .47 when run at economy mixturte settings. There is no
magic engine technology out there.
Tracy Crook
> > --> Engines-List message posted by: Don.Alexander@AstenJohnson.com
> >
> >
> > Listers,
> > Do any of you have any idea what the anticipated output of the 6 cyl
> > normally aspirated Subaru conversion is supposed to be? Looking at
> > this engine as an option for the RV-8. Do Not Archive
> > Don Alexander
>
> Here's my favorite method of "sanity checking" HP claims and estimating
> HP
> on prospective engines. 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.
>
> For instance, an O - 360 at 2750 rpm calculates out to 286 cfm.
> (remember to divide piston engine CI by 2 because it takes two revs to
> pump all of its
> cubes) Divide this by 1.59 and you get 180 HP. If the answer comes out
> much different than what the maker says their engine makes, be very
> suspicious.
>
> This method applies only to normally aspirated engines of course.
>
> Tracy Crook
Message 3
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| Subject: | Re: 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
>
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