Paul and Dale, I know this has been a source of disagreement in the
    past but I feel compelled to respond to the displacement narrative.

    Displacement is defined as "c: the volume displaced by a piston (as
    in a pump or engine) in a single stroke. All manufactures of rotary
    engines use the same method as Mazda in determining displacement.

    The only people that define the rotary displacement differently are
    sanctioning bodies to help competitors that must compete against it!
    This is also done to handicap the two stroke engine.

    A second idea for consideration. If we physically take the 3.15" wide
    X 7.5" long rotor (23.625 sq in) working against a very short 5/8"
    stroke we get our 653 cc. When we add the 1500 psi to the above
    volume we get torque.

    If we could some how magically double this displacement we would
    double torque and HP.

    Let me concede that there is a clue that might indicate that it's
    displacement is larger... and that is the way it drives a turbine
    wheel causing turbo selection to be  skewed larger than 4 strokes.

    But in the end it is a very small and intriguing simple engine with
    a very high heat load unencumbered by parasitic valve mechanisms.

    My Take, Barry Bordes


    The rotary is not a two stroke. It is a four stroke.

    Lets turn it around. How much air would a 2.6 liter two cylinder TWO
    STROKE engine pump in one revolution?

    As far as HP is concerned the ONLY thing that matters is how much air
    a four stroke engine pumps in ONE REVOLUTION at 100% VE. Not the
    physical displacement of x number of chambers.

    The definition of displacement, as far as engines are concerned, is
    only valid in context with the type of stroke.

    Here is what Ansdale has to say about that.

    13B rotaries are raced in the 2.6 liter class world wide for a good
    reason. The only reason they generate more power than a 2.6 liter
    four cylinder engine is they turn faster and breath better. Lately
    that is less true as the piston engine RPM has been raised by detail
    development and the use of high strength to weight ratio materials
    like titanium. Also four valves per cylinder has improved the
    breathing. It is very rare for any 2 valve cylinder to have a VE over
    one. The RX8 engine is just over one and P-ports are typically 1.2.

    Formula One (2.5 liter as I recall) V8 engines were turning 19,000
    RPM. At least four valves per cylinder with a very short stroke so
    larger valves can be used for a given physical cylinder displacement.
    You will not find the details of a competitive Formula One engine
    anywhere. Its a well kept secret. However I would not be surprised if
    the VE's were well over one. Applying the RPM difference to a 2.6L
    p-port rotary making 340 HP at 10,000 RPM would make the Formula One
    engine about 19,000/10,000 times 300 HP or 655 HP which is about
    right for a Formula One engine in that period.

    Paul Lamar


    Paul,

    It probably would be more correct to call a rotary a two sweep
    engine with 4 phases: intake, compression, power, and exhaust. As you
    know there is no reciprocating type stroke involved.

    The only comparison to the 2 stroke that I used was that it is also
    handicapped by sanctioning bodies because of its performance over a
    4 stroke.

    Did outlawing the peripheral port change its displacement?... no
    only its competitiveness.  That after the rotary was penalized by
    giving the 4 strokes a double displacement advantage. This does make
    sense to keep other manufactures competitive, profitable and happy.
    But it doesn't change the definition of displacement.

    The cutaway picture of the rotary that you showed in Blue is exactly
    the depiction of its displacement.  Displacement is not denoted by
    Ansdale's opinion... it is a dimensionally exact measurement.

    Our little engines are indeed more powerful than most can envision.
    Barry Bordes


    The Ansdale definition of Wankel displacement is accepted by all the
    world's engine engineers.. It is not an opinion. It is based on
    facts. That's it period :-) You need to get his book and read it.

    Paul Lamar

    Barry, I have a question. Why do you state rotor dimensions in
    imperial units and then state displacement in metric? All Mazda and I
    would suspect almost all manufacturers use the metric system.
    Ingersoll Rand may have used Imperial due to American design and the
    dimensions involved.

    Dale Davies


    Paul and Dale, Here is a list of Rotary engines produced.

https://web.archive.org/web/20050219094802/http://www.monito.com/wankel/engines.html <https://web.archive.org/web/20050219094802/http://www.monito.com/wankel/engines.html>

     The displacement figures stated represent what?  Are we to guess
    that they are 1/2 or doubled or actual? This is the problem with not
    using a standard for displacement.  You guys want to use a different
    standard... this introduces confusion. I would ask that you show one
    manufacturer that uses Ansdale's method as its standard.

    As for metric vs imperial units I tend to use either depending on the
    majority audience. Respectfully, Barry Bordes


    People have no trouble understanding that 2 cycle engines are twice
    as powerful as a 4 stroke. However the Wankel is not a 2 stroke.
    There in lies the problem.

    Just call them rotor dimensions. Or Wankel displacements so people
    that are not familiar with Wankel engines can form an equivalent to a
    4 stroke piston engine in their minds.

    BTW if you have Windows with Office please load HTML's in Word and
    save them as a pdf's and send that to me. HTML files do not forward
    well to all operating systems.

    Paul Lamar



   I have to add, just how many things done for power. Rotary doesn't do a dry fire for exhaust evac. I have to agree with the two stroke analysis. It's piston draws in combustion fires and spits it out on the same crank revolution like a two stroke. But the intake and exhaust evac are complete volume like a four stroke. Now add that it does that three times per crank revolution and it should be more effective than a two stroke if you can get the combustion efficiency worked out.

   Kurt Emerson


Kurt,
You are going to see a lot of returns on this. The rotor turns at 1/3 E-shaft speed.
Bill Jepson


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