Hello Paul-
Had a chance to run the PPort a few times today to collect some data for
tuning. Engine was in same state we left it at before -- manual
pressure gauge, catch-can in manifold line.
First, I reset the fuel pressure regulator. Tracy's instructions call
for appx 36 psi. I set the regulator to 40 psi using 1 fuel pump. I
switched pumps and confirmed 40 psi. Finally, I switched on both pumps
and measured 41 psi on the manual gauge.
I pulled the airplane out & started it up. Engine started on 3rd blade
and ran quite rough for a few moments with lots of missing before it
settled down and ran smoothly. I ran it for about 2 minutes before
shutting down. I attempted a restart and got it running after the 1st
blade - again rough for a few seconds but then smooth. I noted that the
rpm was still hunting between two values - about 75-100 rpm apart.
Next, I removed the manual fuel pressure gauge and reinstalled the
sender. I then walked through the calibration instructions until I had
the EM2 reading zero psi initially, and 40 psi when one pump was
running. With two pumps running, the EM2 reported 41 psi -- looks like
it is calibrated correctly now.
I pulled the airplane out again & started it up. Start was on 2nd
blade. Rough running initially again, until it settled down. MAP
values are clearly in need of adjusting -- pulling throttle out
resulted
in increased rpm. I was not able to get the engine to run below 3000
rpm -- at full aft throttle the engine ran between 3000 & 3200 before
finally shutting down by switch.
I next removed the catch can from the manifold lines to see what would
change. Engine started on first blade, and there was only the briefest
rough running before settling down. I ran the engine at around 4000 rpm
for the first minute before retarding to 3000 rpm. Hunting was still
occurring, but the range had narrowed to 50-75 vs 75-100. I was able to
idle the engine smoothly down at 2000 rpm for several minutes, but again
it was obvious that default MAP mixture was screwy - as I pulled out
the
last of the throttle, rpm increased. After about 5 minutes I began
review various temps, and here things started getting weird.
Wierdness # 1 -- EGT on rotor 2 (the one closest to the prop) topped out
at 179F after 5 minutes. Rotor 1 EGT was reporting 726F, and post-VAM
EGT was reporting around 500F. This of course troubles me, since the
last time I saw this imbalance I ended up having coolant spraying into
rotor 2, cooling it. I shut the engine down & checked the coolant cap.
I noted that coolant had been expelled out the overflow tube (as I was
expecting since I had filled the engine to the top cold). I loosened
the cap and coolant immediately tried to spray out -- clearly there was
pressure being held in the line. I pulled the prop through 3
revolutions by hand and had no signs of coolant in the exhaust system.
Thus - I have no evidence of a coolant leak into rotor 2 -- the prior
failure was obvious with white smoke, no residual pressure in the
coolant line, and fluid visible in the slide throttle and exhaust. None
of these signs today.
Wierdness #2 -- I monitored EGT temps throughout the cooldown. EGT on
rotor 2 stayed at 179~181 without changing for almost 10 minutes. EGT
on rotor 1 dropped 100F quickly after shutdown, and then trended
downward steadily as time elapsed. EGT post VAM increased for the first
few minutes, and then began a steady decline. After 10 minutes or so,
EGT on rotor 2 dropped below 179 and trended down somewhat steadily.
So, I am wondering about the EGT of rotor 2. I suppose it could be a
sensor issue, but I do not know why it would be. I plan on using a
heat
gun to individually heat each sender, beginning with EGT1 to see how hot
the gun can get it. I will then heat EGT2 and see if it behaves the
same way or not.
Thoughts? If not for the EGT numbers, today would have been a rousing
success & I would have started adjusting MAP values to get better
mixture values. As it was I decided to stop & ponder before
pressing on.
Mark (Rocky Mtn High)
Those EGT numbers seem to be missing a zero. I am sure you mean 1790 F
and not 179 F.
Tracy's default mixture table is based on a less powerful side port
motor.
Reducing the pressure to 40 psi from 60 psi moves the whole table
down. 40 psi could be too lean. Try going up 5 psi at a time and
run it again. The engine will run over a wide range of mixtures.
Do you have a mixture monitor of any kind? That will help
greatly as EGT's generally rise to a peak value and then
decrease. It is sometimes hard to tell which side of the curve
you are on.
Do you have an intake manifold pressure gauge?
At what RPM is it hunting? At what manifold pressure
is it hunting? Tracy system is staged at about 15 inches
of Hg. He switches from two injectors to four injectors
at that manifold pressure.
Tie the airplane down well and have somebody hold the tail down.
Run the engine again at steady speeds for at least 30 seconds to
a minute 500 RPM apart and record EGT for each rotor. Also record
the intake manifold pressure. Increment the RPM 500 and record
all numbers again. Keep doing this till the engine speed will
not increase. What we are looking for is trends.
It would be nice if you had a wide band mixture monitor.
http://www.shop4motorcycleparts.com/product-2911.html
http://www.ontronic.com/lambda_meters.php
<http://www.ontronic.com/lambda_meters.php>
http://www.jacsport.com/FJO.htm
http://www.turborx7.com/tuning.htm
http://www.mountainperformance.com/yamaha_specialty_tools.htm
I see them in Summit Racing. Edelbrock has a somewhat crude
narrow band unit for $129. Do not run 100 LL in it. Only run no lead
auto fuel.
Ed Anderson also makes a narrow band unit.
eanderson@carolina.rr.com <mailto:eanderson@carolina.rr.com>
Lacking that run the engine at a steady 4000 RPM
for a few minutes and shut it down. Pull the lower plugs
on rotors one and two. If they are black the engine is too rich.
If they are brown or tan it is probably OK. Also see if there is
any black smoke coming out of the exhaust. If so it is too rich.
Look in the exhaust pipe. If it is black it is too rich.
If it is brown or tan it is probably OK.
If none of this works and all else fails we can add a .044" deep
and .085" wide slot in the middle of the slide throttle cover next
to the engine and place a 2" short chunk of stright .062" diameter
Teflon O-ring in the slot to prevent air flow from one rotor to
the other one.
Paul Lamar ...No rotor no motor.
Is Mark using a propeller for this tuning? No-load EGT's might be
pretty weird.
Regards,
Matt-
Correct Matt. Prop. He is also well below static RPM hence full load.
Paul Lamar ...No rotor no motor.
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