Paul,

 Thought you would enjoy viewing a video of my P-Port 20B taken last
 weekend
 (11/28/10).  I was preparing for takeoff.  The video of my departure
 didn't
 turn out too well.

 http://www.youtube.com/watch?v=1Zsy-cgWvj4

 Mark S.

 What idle speed was that Mark?

 Paul Lamar


 What a very happy looking airplane  :)
 I gave it a thumb up.

 John

 Paul,

 Idle was up and down between 1600 & 2100 rpm.  It will idle slower, but
 there is no reason for it.  It needs a bit more tuning, but it is running
 much better than before the recent EC-2 upgrade.  I'm curious if it would
 idle smoother if the primary injector was downstream of the slide
 throttle.
 What do you think?

 By the way, I recently removed the tangential muffler and replaced it
 with
 my original 3-into-1 exhaust with DNA muffler and picked up gobs of
 hidden
 power.  This one is louder, but the power gain was unbelievable!  Now I
 have
 to really have to press hard on the right rudder to keep it on the
 centerline during the takeoff roll.  Ya gotta love it!!!

 Mark S.

 I don't think the idle will improve by moving the injector
 but I could be wrong. Getting a P-port to idle at 1600 engine RPM is a
 major improvement in P-ports. Prop RPM is 560 which is far lower than my
 C182 will idle. That is due to the slide throttle
 being close to the rotor housing. A P-port side exhaust RX8
 engine idles even better. NSU and the old Power Sport guys
 put the butterfly near or in the rotor housing. The NSU RO80 idle
 was great. The Spider had 2 p-ports. One small one for idle and
 a larger one for full power. I drove an RO80 in Germany back about 2000.

 It is hard to judge the sound on the video. I have a standard
 position and that is 30 feet off the wing tip. Noise should
 be in the range of 100 db to 106 DB. 100 being relatively quiet
 and 106 rather loud. The SCCA have a 103 DB limit. Noise
 pressure double every 3 DB. 60 DB is near silence.

 Here is a video of Al Gietzen's side port 3 rotor with probably
 100 HP less than yours. No db reading
 http://www.rotaryeng.net/Velocity_Vignette.wmv

 This one is of Ian's RX8 side port engine of unknown HP in WA.
 It is very quiet indeed. Again no db reading
 as I forgot to pack the Radio Shack sound level
 meter. http://www.youtube.com/watch?v=XgLw3a8DZgM

 Sometimes you get more wind noise in the mike.

 It is also hard to separate prop noise from engine
 noise.

 Here is Dave Leonard's turbo 13B. No db reading on that
 either.
 http://www.youtube.com/watch?v=o6iz7mgO4UQ
 http://www.youtube.com/watch?v=kjXEM2D_4-Q

 Paul Lamar


 Paul,

 I remember viewing those YouTube videos a while ago.  While difficult to
 tell for sure, to me they all sound quieter than my engine.  I have a db
 meter and will take some readings so we have a hard number.  My motor has
 the stock 20b exhaust inserts.  In my video the wind was blowing pretty
 good, so yes, some of the sound was wind noise.

 Mark



 Mark-great to hear that confirmation regarding exhaust.

 Regarding your question regarding idle speed and factors related....we
 found
 a lot of different variables, but generally if mixture and other factors
 are
 squared away, throttle location and not injector location was primary
 factor
 regarding idle speed--the closer to the port the lower the idle speed and
 responsiveness to throttle settings, rather than placement of injectors.
 That is why we put the throttle plates in the wall of the rotor housing.

 But with injectors we found placing them closer to the ports increased
 throttle responsiveness as opposed to them being way upstream.  For years
 we
 used direct injection right in the rotor housing, spraying against the
 rotor.  But we found the most tractable configuration was having
 injectors
 just at the end of the induction tube.  Moving the injectors further
 upstream on the induction tubes increased power by lowering charge temp
 and
 increasing density.  But even that relationship is affected by
 configuration...such as running a wet induction charge around an
 induction
 tube bend vs. straight with no bends, etc.  But that was not generally
 practical s to package everything in a compact manner in aircraft .

 Steve Beckham

 Steve,

 Thanks for the information on p-port intakes.  I located my injectors at
 the
 bottom end of the 180.  This allows them to look straight into the port,
 but
 only at WOT.  If I run at less than WOT, which I do quite often, there is
 a
 wall part way across the intake.  I was curious if it would it be better
 to
 locate the injectors downstream of the throttle plate?   Or, maybe I
 should
 leave well enough alone.

 Mark


 That puts a different light on it. I did not think of about it
 despite the fact I knew about it.

 We put the injectors up high on Mark Suspinski p-port engine
 and it idled OK. The fuel and air had plenty of time to mix
 or evaporate. I did that because Racing Beat said it gave
 slightly better BSFC. Mazda found the same results in the
 P-port Le Mans 4 rotor but they moved them closer to the
 port for throttle response reasons which is everything
 in a road racing engine.

 http://www.rotaryeng.net/Mazda_R26B_US.pdf

 Since you are staging the injectors it might be worth a try to
 put the primaries on the other side of the throttle
 plate. It would be an interesting experiment as so far as we have
 tried them in two different positions.

 I would not worry about raw fuel on the bend wall. It is not going
 anywhere other than in the engine. It probably evaporates
 anyway due to heat rising from the exhaust.

 Paul Lamar

 It would be a tight fit, but I think I can squeeze them in between the
 housing and the slide throttle assy.  Nothing that I have to do right
away,
 but I may start working on the pieces needed... new fuel rail, etc.

 Mark

 I forgot to mention that I didn't  locate them up on top due to
insufficient
 cowl clearance.

 MS

 There are a couple of ways of dealing with that which may or may not
 work with your installation. The easiest is slope the tubes back or
 forward to lower the height. Stock injector blocks will work with
 a straight fuel rail. The other way is put the blocks on the bottom.
 A third way is shoot the injectors into the mouth of the bell which
 is widely used in F1 and other race cars.

 Paul Lamar


Paul,


I should mention there is another variable that has changed in the past
eight years.  That is the atomizing efficiency of the injectors.  The new
pencil, albeit high pressure - 75 psi. Bosch injectors have an atomizing
spray that is much finer than the RX 7 or even RX-8 injectors.  The downside
is the higher pressure needed to make them perform and perhaps the need to
be more vigilant about changing the fuel filter.

Doug in Japan

Paul,

Since reinstalling the old exhaust system I have only done one WOT run and
the EM-2 showed a 12 mph increase (214 mph) @ 5000 msl.  This was at 6200
rpm, so there is more on tap, but the EGT probes weren't hooked up yet, and
tuning had changed from the tangential muffler, so I didn't want to push
things too hard.  I'll post numbers at a later date, once I've had time to
take care of these issues.

Mark