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Re: Re: Re: BMEP of Wankel Rotary Engine?

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Posted by Sander (145.53.11.214) on February 26, 2003 at 05:20:38:

In Reply to: Re: Re: BMEP of Wankel Rotary Engine? posted by sarvesh on December 01, 2002 at 00:49:24:

: : How to plot/ calculate the pressure - crankangle diagram for engine ?

Well, I'm not an engineer too, but do know somethings about rotary engines...
Here's a formula how to caculate the volume of such engine...
It follows : Excentricity X Radius X Width X 5.196.
Excentricity about how much the excentricity is on the central shaft.. Lets say 15mm...
Radius is the distance from the centre of the rotor. lets that one is 105mm . Width is the width of a rotor.That's let say 80mm.. (actual these are from the mazda 787B engine ) Calculate all measurements in cm!
1.5cm X 10.5cm X 8cm X 5.196 = 654.7ccm...
Per Rotor chamber that is..
Since the displacement formula equals to the formula how to calculate the power of that engine, that is how it follow for calculating the power of an rotary engine... Although, it might only be an estimate of how much it produces. You still have to concider the compression-ratio and intake/exhaust size (and timing for creating the prevered power-curve..)..
Displacement X presure per square cm. X central shaft Rotation per Second! The out come must be devided by ten, or alse you have an ten time more powerfull engine out come in theory.
This a formula I picked up in a book from my school...
Lets say : 8.7kg/cm (for a compr.rat. of about 9 to one)X 654,7 X116.6rotations per second / 10 = 66343Watts!!! Is about 66,3kW@7000revs/minute(90HP).
Note : per Rotor... If you have a two-rotor engine you have, obviosly, multiply by the number of rotors the engine has..

Only thing that puzzles me is that the 787B engine has presure calculated at a 11.8kg/cm.. with a compression of 10 to 1!!!
I geuss it's deu to the peripheral port (ports directly mounded in the trochoids..) Ans second of all : It's a racing engine... That figures...

Hope you you vcan use these formula's, but you only have to recalculate it into inches of needed...

Greetig from Holland

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Subject: Re: Re: Re: Re: BMEP of Wankel Rotary Engine?

Comments:
: : : How to plot/ calculate the pressure - crankangle diagram for engine ? : : Well, I'm not an engineer too, but do know somethings about rotary engines... : Here's a formula how to caculate the volume of such engine... : It follows : Excentricity X Radius X Width X 5.196. : Excentricity about how much the excentricity is on the central shaft.. Lets say 15mm... : Radius is the distance from the centre of the rotor. lets that one is 105mm . Width is the width of a rotor.That's let say 80mm.. (actual these are from the mazda 787B engine ) Calculate all measurements in cm! : 1.5cm X 10.5cm X 8cm X 5.196 = 654.7ccm... : Per Rotor chamber that is.. : Since the displacement formula equals to the formula how to calculate the power of that engine, that is how it follow for calculating the power of an rotary engine... Although, it might only be an estimate of how much it produces. You still have to concider the compression-ratio and intake/exhaust size (and timing for creating the prevered power-curve..).. : Displacement X presure per square cm. X central shaft Rotation per Second! The out come must be devided by ten, or alse you have an ten time more powerfull engine out come in theory. : This a formula I picked up in a book from my school... : Lets say : 8.7kg/cm (for a compr.rat. of about 9 to one)X 654,7 X116.6rotations per second / 10 = 66343Watts!!! Is about 66,3kW@7000revs/minute(90HP). : Note : per Rotor... If you have a two-rotor engine you have, obviosly, multiply by the number of rotors the engine has.. : Only thing that puzzles me is that the 787B engine has presure calculated at a 11.8kg/cm.. with a compression of 10 to 1!!! : I geuss it's deu to the peripheral port (ports directly mounded in the trochoids..) Ans second of all : It's a racing engine... That figures... : Hope you you vcan use these formula's, but you only have to recalculate it into inches of needed... : Greetig from Holland

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