Paul,

I made a major breakthrough today. In preparation for hooking up the
Hytek data logger, I decided that it would be good to install check
valves on each vacuum line leading from each rotor housing. (For those
who are unaware, I am running a peripheral port 3-rotor with a PL
slide
throttle.) My system measures MAP from the unused oil injection ports
in each rotor housing.) Not sure what possessed me to do a ground run
right then, but I ran the engine right after installing the check
valves. Now keep in mind that typical MAP readings at idle up to this
point was approx. 17" Hg. Well, today MAP readings were in the 14.4" -
15.0" Hg range.

Then it dawned on me that the way the vacuum lines were
plumbed the RWS EC-2 would see an average of all three rotors. Since
each rotor is 120* (crank degrees) apart in their 4-stroke cycle, the
MAP would be quite a bit different for each rotor. By installing check
valves in the vacuum lines, I have isolated each rotor from the other
two and I am measuring the lowest vacuum. Idle is now down around 1500
rpm, but the mixture is way lean, so it appears that a re-tune is in
order. I'll probably re-set the RWS EC-2 to the factory defaults and

start the process over from the very beginning.

We need to stress to anyone that is measuring MAP in the rotor
housings
to install check valves in each of the lines.

Mark

Good work Mark. Here is the latest voltage to pressure chart.

Paul Lamar


Hey Mark,

I assume you placed a check valve at each rotor that only allows air to
flow into the rotor thus presenting the lowest pressure reading in the
manifold connecting all the check valves together.  How are you allowing
pressure to flow back into the system when you open the throttle and
increase the MAP?  Seems to me that you will read the lowest MAP at idle
but you will have no idea what happens to the MAP after that because
there is no way for the increased MAP to get past the check valves, no?

Mark LaPierre



Mark,

Yes, that could be a problem... if the check valves seal too tight.
 I'm counting on a certain amount of leakage.  I haven't done
enough ground runs yet to determine if there is a problem here, but
if it is, I'll be looking for another solution to the problem of
poor idle.

Mark S.

Mark S are you having any problems landing due to the poor idle?
Are you using a 2.85:1 PSRU ratio. I forgot if I ever knew :)
I am building a 3.12:1 box for the extra power at 8500 RPM (800 prop
RPM) so 2500 engine RPM idle should be no problem in this regard.

If you blow compressed air into the rotor housing between the
exhaust port and intake port it will idle better as it will keep the
contaminated exhaust gases out of the intake. The path for these
gases is the depression in the rotor flank.

Paul Lamar


Paul,

I'll send $60 for three pressure taps.  I may also need to use the PVC
pipe trick.  I'm heading out to the airport shortly to check the vacuum
system for leaks per Tracy's suggestion.

Mark