Boingers

Al Sites al at b137a5.hacc.edu
Thu May 7 14:08:18 GMT 1998


With the Mazda rotary for each turn of the eccentric shaft the rotor only
turns 1/3 of a rev.

Al Sites
83 RX-7 GSL

-----Original Message-----
From: Gary Derian <gderian at cyberdrive.net>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Thursday, May 07, 1998 9:26 AM
Subject: Re: Boingers


>All this talk about balance and efficiency has little meaning.
>Reciprocating motion is not necessarily wastful.  When one piston slows
>down, another is speeding up.  The net result is a flywheel.  A rotating
>radial engine would be impractical and offer no benefits.  Piston inertia
is
>useful in counteracting gas pressure forces and actually reducing bearing
>loads.
>
>A Wankle engine's displacement, say the Mazda 1.3 liter, is really mis
>measured.  For every crankshaft revolution, a 4 stroke piston engine pumps
>1/2 its measured displacement.  A Wankle pumps all of it.  To compare the
>two directly, the Wankle engine's displacement must be doubled.  But even
>that doesn't matter.  The important parameters of an engine are Specific
>Fuel Consumption, Specific Weight, Cost, Emissions and Longevity.
>Displacement is only an artificial measure used by racing organizations to
>equalize classes (doesn't work very well) and governments (not USA) to
>assess taxes.
>
>Wankles are great for high power per size, no valves to get in the way of
>flow, lots of rpm (don't forget the rotor rpm is geared up 3x) but as
>Raymond pointed out, by the time a whole car is built, there is not much
>advantage.
>
>Gary Derian <gderian at cybergate.net>
>
>From: Robert Humphris <r.humphris at indigo-avs.com>
>
>
>>The point with the Wankel is that it is a 1.3, where as a Camaro is
>>what, 3 times that displacement? Yet they have similar performance.  Add
>>that to the weight of the engine, which does add to the performance of
>>the car ( less weight = better power to weight ratio, and better
>>handling as the car ceases to be engine heavy, so you start getting
>>easier moments of force on the car ).
>>Lets compare like for like, I guarentee that if you added sufficent
>>number of rotors to take the displacement to that of the Camaro, fuel
>>injected it, you would be unable to out drag it.  Then if you take the
>>same displacement as the Saturn ( What is one of these we don't have
>>that model over here in the UK ) and put it in a similar weight car,
>>that the engine would be just as lively, and the performance would be as
>>good if not better as the weight would be less.
>>
>>Two stroke direct injection engines?  We will see what they are like
>>when they are mass produced.
>>
>>Rob Humphris
>>>
>>>I'm not talking about specialized racing applications, or even how many
>>>people it takes to pick it up.  I understand that the power/weight ratio
>>>is better than a four-stroke piston engine.  I'm talking about what sells
>>>cars.  Go down to your favorite Mazda dealer and drive one.  Yah, it's
>>>pretty fast and gets decent mileage.  Now, go to a Chevy dealer and hop
>>>into a Camaro Z28.  It'll blow the doors of the RX7, and the mileage
>>>still isn't that bad.  Now, go hop into a Saturn twin cam.  Much better
>>>mileage and not too shabby on the performance.
>>>
>>>My point is that the mileage/performance balance isn't significently (if
>>>at all) better than the other cars you can buy off the lot.  If I have to
>>>swap an engine, I might appreciate that it is lighter.  When I'm driving,
>>>I appreciate the performance of the car as a whole.
>>>
>>>There are some directly injected two-stroke engines on the drawing
>>>boards.  I don't have the exact figures, but I would be willing to bet
>>>(if I were a betting man) that the power/weight ratio of these
>>>two-strokers will be similar to the Wankyl.  They won't, however, suffer
>>>from the wierd-shaped combustion chamber and longevity of the Wankyl.
>>>
>>>




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