The PPorted engine breathed a little fire this afternoon. Here's the
details:
OAT: 73F
Alt: 6873
Timing was set using per Tracy's instructions in the EC2 manual – based
on the 0-degree reference mark on the eshaft pulley, I interpolated to
35-degrees BTDC and marked the pulley, Aligning the timing pointer with
this mark resulted in the CAS pointing exactly at the sensor, as
expected.
The engine started on the 3^rd blade, and ran quite rough at idle
power. It smoothed out mostly (but never perfectly) when the rpm got up
to the 2100 range. Note: I am obviously woefully underpropped right
now. I have a 72D 72P on there right now & the engine turns it
effortlessly. In fact, if I pushed the throttle more than about 3/8" –
½" beyond idle, RPMs shot northward heading toward 3000 rpm territory.
I quickly put a stop to that & stayed way down at idle. I believe I
must get a much more aggressive prop to consume HP before I can get the
engine into it's powerband & really start adjusting it. Until then, it
just spins too darn freely. (I am not implying a compression problem
here. If anything it seems to be compressing better on the stock Mazda
apex seals that I just put in than it was on the aftermarket seals that
were in there before.
I got in one good 10 minute run & did manage to get the engine behaving
even at the just-barely-above-idle throttle setting. The engine tended
to surge between 2 power levels. It also tended to creep upward in RPM
– meaning at a given setting of throttle & mixture, it would slowly
increase in RPM.
Here's the stats I recorded at the end of my 10 minute run:
RPM: 2100
MP: 12.6 – 13.1
EGT: 900
GPH: 1.9
H20: 178 degrees & climbing
Oil Temp: 144 degrees & climbing
Oil Pressure: 94 psi
So... if it is only consuming 1.9 gallons per hour, it obviously is not
in the power band. And since that 1.9 gallons per hour was pushing the
prop at 2100 rpm, I need to put a much bigger load on there.
After the run there were also a variety of leaks that will need to be
addressed. Mostly fittings that need a bit more tightening. Any other
comments / suggestions from anyone? Paul has asked for compression
readings, which I will try to get tomorrow (assuming I can find a
compression tester to borrow from someone). On the sound side, the
engine was in no way quiet. Of course it was echoing between hangars,
so I don't know what it was in real life – I'll get a sound meter out
there once I have it running reliably.
Mark Supinski
Good going Mark!!! Great news!!!! I am so relieved. The idle will
settle down somewhat when you get the mixture map right. We got
it to idle under 1000 RPM with the Weber carb.
Anchor that airplane down and run it up to static RPM for me.
You will be MIGHTILY impressed.
BTW don't forget folks this is a 2.85:1 gear box so the
prop is turning at 736 RPM when the engine is turning 2100 RPM.
Paul Lamar ...No rotor no motor.
So I got my math backward, huh? I was convinced that the RPM readout
was prop RPM - so I was paranoid about keeping it below 3000 (since
that would have been an engine rpm of close to 9000 rpm). After getting
your reply, I reread the EM2 manual & sure enough it explicitly says
engine RPM -- thus the shaking & whatnot was perfectly predictable & I
was nowhere near overspeeding the engine or prop. Heck, my old C-150
shook like a bashee at prop speeds below 750 rpm.
Ok, that all makes me feel better about the engine 'getting away from
me' once or twice & going above 3100rpm briefly. Assuming I can get it
good & tied down I will try to take it up to 4300 rpm (1500 prop) & see
how it does. After that, I'll try your static rpm test, as long as it
stays below 7200 rpm (2500 prop).
Everyone - ignore my prior comments about underpropped, etc. Now that I
have my math right, we'll try that experiment again...
Mark Supinski
BTW Mark if you want to cut some noise from that muffler
while you are fixing it use two smaller rectangular tubes for
that one large retangular down pipe. Say two one by twos.
By all means do the db test first to make sure it works.
Paul Lamar ...No rotor no motor.
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
Copyright 1998-2006 All world wide rights reserved.