---------------------------------------------------------- Engines-List Digest Archive --- Total Messages Posted Sun 10/05/03: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 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 _____________________________________ Time: 11:32:45 AM PST US From: "Tracy Crook" Subject: Re: Engines-List: Eggenfellner 6 cyl --> Engines-List message posted by: "Tracy Crook" > --> Engines-List message posted by: "CHUCK KELLY" > > 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 _____________________________________ Time: 11:39:50 AM PST US From: "Tracy Crook" Subject: Re: Engines-List: Eggenfellner 6 cyl --> Engines-List message posted by: "Tracy Crook" > --> Engines-List message posted by: "Healy, Joseph" > > 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 _____________________________________ Time: 11:45:57 AM PST US 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 >