Paul, The impossible has happened, I actually left the ground
yesterday. Flew for 3 hours. Seems my prop is too big as cannot
get over 6500 revs. Currently discussing this with Lonnie Prince.
The EGT went to over 1800 and then I assume burnt away for I now
have a balmy 4-500 degrees. Is there a probe that will stand this
temp?? The alternative is to strap them to the outside of the
pipe. Not ideal, but may be an alternative. Ran most of the time
at 5000 revs, and wondered why I could only get 100 Kts, and then
realised that the prop was only turning at 1700. 5000 rpm and 21.5
MAP. Temps were a little too cold. Water 135 and oil 145. What
is the thinking on a thermostat?? Oils pressure was 80 psi, never
moved. Had over 80 litres of fuel added for the second flight of 2
hours and there is a lot remaining, so fuel consumption was low, as
is indicated by the speed. As you can see all very scientific, but
when you consider that I was just waiting for that moment of dead
silence to suddenly appear as it did twice with my Eggenfellner
monstrosity, I was not in the mood to do many calculations.

Neil.

Congratulations.

Better to use cowl flaps as it cuts the cooling drag when they are
closed. Well worth the trouble. It is worth 3 MPH on my 182.

Here are some pictures for the new guys.

What is the diameter of that prop? It could be too big as the prop
tips are running into the transonic wall.

Is 21.5" MAP the highest you have seen? Sounds like the air
filters are clogged.

Paul Lamar


Neil,

Way to go! Three hours on your first flight is fantastic.

I too saw 1800 EGT's when running a tangential muffler on my 3-rotor.
It was reasonably quiet, but didn't perform very well. I switched to
a low-tech 3-into-1 runner manifold and my EGT's dropped into the
1500-1600 range, and I picked up 20 mph on the top end. If I were
you, I would explore that possibility. Relocating the EGT probes
won't fix the root problem. High EGT's may damage your o-rings,
and/or rotor housings.

Mark S.

Neal try this low back pressure muffler.

Paul Lamar

Mark and Paul,
                         Seems unbelievable that you can drop that much
temp by just putting on a straight pipe.  In my ignorance I would have
thought that the temp will be what it is regardless of what happens after.
Can anyone explain this??  However I cannot ignore your experience and will
have to explore the "simpler' option.  What muffler did you use without the
tangential?
  Paul I have looked at your muffler and am very impressed with the
simplicity therein.  If I go with the straight exit pipes then it is little
more to alter the rest while I go.  More mods!   ARGGGG.

Neil.

Mark S has done a lot of R&D. We all owe him. He is right out there on the bleeding edge with
a 3 rotor P-port. Take off is fine with four people in a Lancair ES with half power :)

Brian Trubee is testing the new muffler on his 2 rotor side port RV4.

Neil, Try moving the EGT sensors down stream first. That is the cheapest mod. My guess is about
a foot.

Paul Lamar