The NSU RO 80 also had the throttles in the p-port housing.
            It too idled
            well and pulled from low RPM as I drove one in Germany. It
            had intake
            pipes about 30 inches long or more.

            Paul Lamar


        Paul,
        A quick rough calculation on volume of the runner would indicate
        30" is
        correct ( 29.6" by my calculations). That's if volume represents
        anything at
        all, I only assume it does.
        George (down under)

        How did you calculate that? Do you mind posting the formula?

        Tuned frequency is both a function of length and diameter (volume).
        There is a third factor that affects max HP that many over look
        and that is
        the skin friction drag inside the tube. Air velocity can be 200
        MPH or more inside
        the tube.  A smaller tube tends to have higher air velocities
        and skin
        friction drag is proportional to velocity squared. Intake
        manifolds are
        primarily aerodynamic devices.

        Consequently two tubes are better than four tubes given the same
        total tube cross
        sectional area. Six tubes are not called for an AC engine that
        spends its entire
        life between 5000 RPM and 7500 RPM :)

        Small tubes work better at lower RPMs to generate torque for
        simple cars.
        Low RPM torque is what you need for simple cars if your
        transmission is
        limited in the number of different gear ratios and/or is slow to
        shift.
        A Formula One engine is a good example. It does not need low RPM
        torque.
        The transmission does the job of getting the required torque at low
        speeds and high. It spends its entire life between 17,000 and
        19,000 RPM
        with seven or more gear ratios and power shifts in a fraction of
        a second.

        Paul Lamar ...No rotor no motor.



    Paul,
    I just did a calculation of the volume of your 24" long tubes ( Pi R
    squared
    x 24"), then divided by the sq area of the smaller diameter.

    Your larger ID - Pi x .9375x .9375 x 24 =66.2679
    Smaller runner Pi x .84375 x .84375 = 2.2365
    .: 66.2679/ 2.2365 = 29.63"
    OK!?
    George (down under)

    The volume by itself has no significance. What matters is the
    combination of length
    and diameter.

    Paul Lamar ...No rotor no motor.


The NSU RO80 engine does not have a throttle in the p-port housing,Its
in the inlet manifold approx 7cms from the rotor, have just been in the
workshop to make sure of my facts. The C111 Daimler-Benz has the butterfly
in the p-port housing.
bob pay..old rotary,


7 cm is 2.5 inches. Pretty close. Good enough for government work :)

Here is a dwg of the one rotor NSU.