All,      testing the motor to find that it is running smoothest at
   an A/F ration of almost 13 at 2200 rpm. This is on a PLX meter and
   appears a little lean.  What say the experts??    Neil.

   That's about right for p-port idle. What is the manifold pressure. I
   assume engine RPM. All engines like to run a bit rich at idle.

   The p-port is no great shakes at idle. What is it for WOT with the
   airplane well tied down? Mixture, manifold  pressure, EGT, and RPM?
   That is the real proof of the pudding.

   Paul Lamar

   For a car at idle of 800-900 RPM that is about right. Slightly rich warmed
 up. Then as the revs come up they should lean a bit. Light throttle cruise may
 let it go lean to 15-16:1. Note: that is light throttle in a car!. For the AC
 engine at idle (2000 or so RPM)I would think that is OK. Now with the prop
 spinning it is not going to be light load as in a car so will not go lean the
 same until you lean it. Us the info Paul asked for above to determine where it
 should be. Idle is not a big concern as long as it is fairly smooth. During
 takeoff, I would expect 11.5-12:1 for power. Then when you get to economy
 cruise you can lean like the car engine or even more as long as it stays
 running smooth.

 Dale Davies

 Dale, the prop gear ratio is 2.85:1

 The prop RPM is only 770.

 Paul Lamar

The 2200 RPM I gather is the output shaft RPM, the rotor is at 1100 . My
interest is a 13b single rotor and I want up to 140?HP out of it.
The P port is basically an enhanced air intake duct. Those ducts seems
to be very bulky, like V8 high rise manifolds, hot roders have to cut a
hole in the hood for them.If I do not mind the extra mechanical
complexity, can I get the enhanced air flow by turbo or a supercharger.

I only want the extra power when I select it, so a manual waste gate is
what I will have, just for those heavily loaded hot and high situations.
The turbo will also act as a muffler, for I want a very quiet engine,
even with some power losses.

The supercharger may use something like a magnetic clutch, use on
demand. It will have to have some sort of spring one way air damper to
make sure the engine will get air if the charger is not working. The
engine would idle better without the P port. Not that it is that
important, as this is aircraft application, as Paul already taught me. I
also save the cost of the P port mods and the bulk. I am aware the force
feeding will cost  more. Weight wise, I think P port and turbo would be
similar.

The ideal would be to have a regular ported 13b at 95 HP, then add the
force feeding later. I wanted fuel injection from the start. Indirect or
direct?? Leave the carbs on those model T Fords. I just want to know all
the alternate ways are.

A quiet engine, with more gear reduction, using a bigger prop with more
blades, at 2200 rpm or less, it might even be quiet enough for European
standard. Comments anyone??
Tony

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