Paul,

   I have noticed that on the variable intake trumpets on the 4 rotor that
   they were limited to the longest length runners which made the low end
   suffer. I would assume they did this since they would never run that low
   in the rpm range at LeMans and also their transverse space limitation
   since they mounted the engine longitudinal.  Do you think that if they
   continued to lengthen the runners that there would be addition area
   under the curve to make up and if so how low before the benefits would
   become negligible or mass airflow got to low render good charge
   velocity?

   Rob


   Hard to say without running it on a dyno. Why would you want a lower
   RPM?
   6000 RPM is a sweet spot in a rotary. Bearing loads are the lowest
   at that RPM.

   Paul Lamar ...No rotor no motor.

Paul,
Ive had a few specific questions arise from your data, which has
been based on one and four rotor test engines as near as I can tell.

1.  Is the test data directly scalable to a 13B based engine?  I'm
looking to build an intake manifold for an OEM 4-port Renesis for a
RV-9A soon and need to finalize my design criteria.

2.  Is there any reason to pick metal materials over composites for the
intake?  Guessing the easiest material to obtain and weld will
be thin-wall mandrel-bent steel; best corrosion
resistance/weight- composite, then aluminum.

3.  Where are the intake runner distances measured from (ie, rotor face
or header flange, to runner bell face, outer surface of intake plenum,
throttle body/carb, or air filter housing) in a real world system?

4.  In your opinion, what is the best diameter tubing to use assuming a
long, optimized runner length- (some have suggested small diameter 1"
tubes for velocity/torque enhancement, others 2"+ to minimize friction).

5.  Should the primary and secondary intake runners have the same tube
length and diameter?  Can they be merged?  Is there any difference
between primary and secondary ports in a Renesis without its complicated
OEM intake?

6.  What is the best intake runner length range assuming a 6000 rpm
target with normal operating envelope between 5000 economy cruise and
7500 high-power rpm.

7.  From your observations and discussions, I've gathered that we should
target a leaned 6000 rpm speed for the best cruise setting (assuming
2.85 redrive and adjustable propeller).  True?
Mike Parker


?1. I have no real idea what works best on a four port.
?2. There may be some heat transfer issues with aluminum. Steel is OK.
   Composites would be best from a heat transfer point of view.
?3. The rotor face.
?4. For a four port I have no idea.
?5. I would guess so. If you make the centers smaller in diameter
   the optimum length in theory should change.
?6. Again I have no dyno data on this.
?7. That is about right for cruising. Really depends on where the
   drag bucket is on the aircraft. Slower may be better from
   a MPG point of view.


Custom RX8 intake manifolds are a real gray area. Length also depends
on diameter. Hard for me to say what is optimum for side ports as we had
a lot of data on P-ports that we copied for our p-port engines tested on a dyno.