Rotary firings

[Clare Snyder]

Greg Hermann wrote:
> 
> >On a Wankel engine you get one power pulse per rotation of the eccentric
> >shaft per rotor.
> >On a Mazda 12a or 13b that has two rotors you would get roughly 2 power
> >pulses per each eccentric shat revaluation.
> >If you had a one rotor engine:
> >
> >3-360 deg turns of eccentric shaft = 1 360 deg turn of the rotor = 3
> >faces of the rotor coming into power pulses.
> >                       or
> >1-360 deg turn of the eccentric shaft = 1 rotor face coming into a power
> >pulse.
> >
> >Being you are talking about a Mazda 12a/13b engine you have two rotors
> >the send rotor is set off of the first one. so you figure you would get
> >2 power pulses per revaluation of the eccentric shaft.
> >
> >I can go out to my garage and double check, I have an engine torn apart
> >right now waiting to be rebuilt.
> >
> >Dave S
> 
> Hi Guys---
> 
> Enough of this. There are two revolutions of the rotor for every three
> revolutions of the eccentric shaft in a (three lobe rotor, two lobe
> chamber) Wankel engine. The epitroichoidal chamber geometry will work for
> any number of rotor lobes, so long as the chamber has one less lobe than
> the rotor--and the ratio of shaft speed to rotor speed must always be the
> same as the ratio of the number of rotor lobes to the number of chamber
> lobes. ----OR THE FOOL THING WILL NOT TURN AT ALL!!!!----A 3:2
> epitroichoidal geometry is what lends itself to use as a four stroke
> engine, for reasons which I hope are obvious to all. There are plenty of
> epitroichoidal design oil pumps out there which use a higher number of
> rotor lobes (the oil pumps in old Jag twin cams, for instance).
> 
> If anyone doubts this statement--GO READ THE GODDAMN FELIX WANKEL PATENT!!
> (Or count the teeth on the shaft and rotor gears on that disassembled
> engine, and post the tooth count!) (I trust we all know how to divide, or
> at least how to push calculator buttons.)
> 
> A two rotor Wankel motor makes 4 power strokes per output shaft revolution,
> same as a 4 stroke, 8 cylinder piston engine { (3 lobes/rotor) x (2 rotor
> revs/3 shaft revs) x (2 rotors) =4} .  PERIOD!!! (And a three rotor's power
> stroke frequency is like a twelve cyl,, 4 stroke, etc., etc.)
> 
> Once upon a time (almost 30 years age) I actually got paid to figure out
> the swept displacement of a Wankel--had a curious boss who was trying to
> evaluate a similar idea. It was a fascinating exercise in calculus, and
> turned out to have a rather simple looking numerical solution (which of
> course I don't remember now) when all the integration was completed. The
> swept displacement of a Wankel relates to rotor radius, eccentricity, rotor
> width, and number of rotors, with (I think)  pi and some simple, integral
> number fraction as multipliers.
> 
> Most of the other answers which are floating around out there as to Wankel
> displacement are pure SNAKE OIL, and, I think,  the result of certain
> individuals (and/or firms) having a vested interest in fooling the
> mathematically and mechanically inept (such as members of race sanctioning
> bodies and employees of the EPA and/or (foreign) vehicle taxing
> authorities) (and apparently some members of this list, too) as to what the
> real swept displacement of a Wankel is. Getting a handle on the real swept
> displacement number for any given Wankel engine readily explains why they
> perform so strongly (despite poor VE) and (together with poor VE) why they
> get such lousy mileage.
> 
> I don't remember perfectly at this point, but I believe that it was an RX-3
> motor that I measured, and calculated the actual swept displacement for
> once upon a time, using my derived formula. Didn't Mazda claim that the
> RX-3 was the equivalent of an 1800 cc piston engine???? The hard
> calculation showed that it has more like the equivalent of 4.2 liters of
> swept displacement, if memory serves!!!! Even if the number is off, the
> difference between what Mazda claimed and what it really had was utterly
> astounding!!!!
> 
> Regards, Greg

>From what I remember working at an AMC / Mazda dealership back when the
RX3 was brand new, it had the same displacement as a 258cu in AMC
engine, and used about 20% more fuel to deliver about 10% more power.

When peoplecomplained it burned a lot of gas I asked compared to what? A
304 Gremi was about the same.
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                           Clare Snyder
                         Waterloo, Ontario