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Brian,
Two injectors producing 295 CCs (28
pounds) at a duty cycle of 90% are only good for about 90 HP. The backfiring
may be caused by going too lean as you run too high a manifold pressure before
you stage.
With different sized injectors and that
small for primary, you may be better off with the stage set at 15-16 inches
instead of 19. I would stay away from an area where the EC-2 changes from
one area to another. (2500 rpm, 13 inches, 3800 rpm)
Bill B
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of bktrub@aol.com
Sent: Thursday, November 11, 2010
12:13 PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: Improved
performance of my new (2009) intake manifold
What I am doing is pushing button 3 and
the aknowledge button, getting the map table and then reading it as it goes
through it's paces. I'm starting out at around 1800 rpm and bin 8-28 or so,
then it goes up to round bin 70 for the high rpm, high MP table. Advancing up
through bin 90, it stages smoothly. But, I think my staging point is about 2-4
inches of MP too high.
In asking what the manifold sensor offset
and scale factor is, I'm asking what everyone else gets when they push button 3
and then 1, getting the calibration page. Then push button 2 twice to get to
the manifold pressure calibrations and let me know what your factory defaults
are. I screwed them up early and need to know what the factory settings are.
I'm pretty sure I'm staging too high, at
about 20-22 inches of MP right now. It should be lower, but I need to ba
absolutely sure I have the right MP settings.
-----Original
Message-----
From: Bill Bradburry <bbradburry@bellsouth.net>
To: Rotary motors in aircraft
<flyrotary@lancaironline.net>
Sent: Thu, Nov 11, 2010 8:45 am
Subject: [FlyRotary] Re: Improved performance of my new (2009) intake manifold
I didn’t have to calibrate my
manifold pressure readout. It was correct from the start. Sitting
in the hangar, it reads the same as my altimeters and barometric pressure info
from the tower. Are you sure yours is not correct?
On staging, did you set your staging
mixture by using mode 6 or by changing the map table? If you set it by
using the map table and are getting a different result while flying, you may be
at a point where the EC-2 changes to a different area on the MAP table. I
suggest you adjust it using mode 6 if you didn’t already do that.
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On Behalf Of bktrub@aol.com
Sent: Thursday, November 11, 2010
11:02 AM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: Improved
performance of my new (2009) intake manifold
Staging takes place at bin 90- it was
stumbling and surging on the ground when I would run it up through this bin-
until I richened it up in bins 90-92. Then it would transition without a hiccup
through these bins. I had all the injectors cleaned and flowed prior to
installation, they all checked out fine. I have 28 lb primaries and 40 lb
secondaries.
When I was flying, I was flying around at
bins 70-80, doing around 90-110 mph, and would advance the throttle through bin
90 and start the backfiring. While it was backfiring, I would lean and richen
the mixture with the mixture knob, but the engine would not settle down and the
mixture graph would be bouncing around due to erratic firing. The answer is
there somewhere, I jsut have to get some more altittude to fiddle with it in a
more leisurely fashion.
Again, Anyone remember what values they
use to set the mainifold scale factor and sensor offset?
Yep! any time the drone of the engine
changes - it immediately gets your attention (or should) {:>). I too
have turned on the cold start when meaning to change controllers -
but fortunately have always immediately recognized the problem.
There are several possibilities about
your staging problem.
1. You may not have the cross
over adjustment (mode 6) tuned properly and when it stages its either too rich
or too lean when running on all four. However, adjustment of you manual
mixture control should indicate which direction (lean or rich) helps the
situation.
2. Always possible that a secondary
injectors is not functioning properly - you should be able to check this
possibility easily (if you have the injector disable switches that Tracy shows in his
installation). While on the ground - switch off the primary
injectors (you may get a momentary hiccup if you secondaries are not adjusted
properly, but a quick tweak of the mixture control should keep it running), If
it idles/runs fine on the secondaries then they are likely to be OK.
3. You Fuel Map bin values right
after the staging point could have inappropriate values - Tracy's default
is 128 or I guess it shows up as zero on the EM2 and your adjustments are +- to
that zero reference (128).
You mention the results of
enrichen/leaning was inconclusive - what exactly do you mean? Do you mean
you could not tell if the engine was running rich or lean? The
Air/fuel Ratio indicator of the EM2 is not giving you consistent
readings?
Its pretty important as you know to
be able to discern what effect any adjustments are having and mixture is one of
the more important ones.
You'll get it sorted out - some
installations simply take a bit more sorting out than others
Sent: Wednesday, November
10, 2010 9:51 PM
Subject:
[FlyRotary] Re: Improved performance of my new (2009) intake manifold
Interesting manifold. Are you still using
the VDO fuel pressure sender? I had heard that it might not be suitable for use
with fuel, I am still using mine at present however.
I went up today for a few laps at 3000
over Paine Field. The engine ran well below the staging point, but started
stumbling when above the staging point. It ran smoothly through the staging
transition on the ground, but when in the air I could not tell by the mixture
monitor if it was lean or rich. I tried leaning it out and richening it up, but
results were inconclusive so I stayed below the staging point for the remainder
of the flight. Temps were down around 130 degrees at 4800 RPM and 110 mph, MP
was not noted.
I accidently hit the cold start switch
while on downwind with two other planes ahead of me, the tower told me to go
around on final, but the plane ahead turned off onto the taxiway just in time so
I told the tower that I would really like to land, so they cleared me. The
engine died as I turned off onto the taxiway and then I noticed the cold start
switch. The first order of business was making and installing a switch guard
for the cold start switch. I'm also going to pre-load the switch with a rubber
band so it stays in the off position unless I'm pushing it on, and can just
pull the rubber band off of it if I need to shut down a set of injectors and
run the remaining injectors on cold start.(limp home mode for failed injector.)
The fuel self transfering issue was
resolved by installing manual valve on the transfer line between the tanks.
As some of you know I started flying my
RV-7A with a cut - off Renesis intake manifold. In 2009 I installed an
new intake designed to route pressure waves from the closing of rotor
#1's intake into rotor #2 just before rotor #2's intake closed.
After using the new intake for over a year I am still very happy with it's
performance.
I gained about 15 mph TAS at the same
altitude and manifold pressure
My static engine rpm increased 300 to 350
rpm.
My takeoffs are faster and shorter with
noticeable increase in acceleration
My oil and water cooling is more critical
now because I make more HP.
But - I must confess I don't believe the
manifold can be reproduced economically. It's just too complicated.
I also believe it should have slightly
shorter intake runners to increase the performance at higher RPM.
Decreasing the intake runner length probably would require complete new
geometry of the system.
I have another concept for designing a
Renesis intake that using a reflected wave from Rotor #1 returning to
Rotor #1 .
I believe it would be much easier to
build and small enough to fit into the James rotorary cowl but because my
intake works well I am not moving ahead with completing the design and building
it.
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