Ok, I understand now Bill. I think
Al answered your question on how far from 14.7:1 to 9:1 on his controller of
his 3 rotor – That’s the only information I am aware of about how
much twisting of the manual mixture control it may take. I can simply
state that with the mixture Knob at 3:00 its too much fuel for my N/A turbo
block – so I would say Al’s information sounds reasonable to me.
Unless Tracy has really changed things
with the EC3, there are NO manifold pressure values in any bins (columns of the
table) – the manifold pressure (when used) is converted into a “bin”
pointer which points to the appropriate bin (numbered from 0 – 128)
for that corresponding manifold pressure). That “bin” selected
by the manifold pressure value of the engine then contains a fuel factor value
represented by the value (height) of the bar in that bin. I believe Tracy’s default
value is 128 which theoretically would give a 14.7:1 air/fuel ratio.
Going above that value enriches the mixture and below leans it.
IF there are zeros for the values of
any of the bins then that says there is no Map correction Table (MCT)
correction factor used for that bin. . So if the values of zero are
valid, I would assume that for those regions the fuel needed must be
derived solely from some other parameter – like RPM with the manifold
pressure value only acting as a switch (above below 13Hg for example)
But, if that is indeed the case then I’m
still a bit surprised there are no MCT values for rpm.
There is the possibility that somehow the
MCT values for those bins were set to zero accidentally, but as you so rightly
surmised, only Tracy
can answer the question you have.
Ed
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Bill Bradburry
Sent: Friday, October 16, 2009
3:48 PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: Stoich
A/F Ratio?? : [FlyRotary] Re: where's the missing power?
Ed,
I don’t know if I asked the question properly. The MAP
table determines what the injectors will do with the manual mixture control set
at the 12:00 oclock position. If you move the manual mixture control
counterclockwise, it will lean the mixture from that setting. If you move
it clockwise, it will richen it from that setting. My question was:
if the MAP table gives 14.7 A/F ratio with the manual knob in the 12:00 oclock
position, what would be the most likely A/F ratio with the knob all the way
clockwise? Does it have the capability of richening it to 12.65??
Now I have more questions. I went over and copied down the
information in my MAP table today. I was surprised to learn that the
manifold pressures for all addresses from 0 to 63 were set to Zero. I
expected to find actual manifold pressures in there. Starting with
addresses 64 through 127 the manifold pressures increase from 10.0 at address
64 in 0.5 inch increments all the way to 41.8 inches at address 127. My
engine is naturally aspirated, so the addresses above about 30 or 31 will never
be used. I understand that the 0 to 31 addresses are used when the RPM is
below 2500 and the manifold pressure is below 13 inches, and that the addresses
from 32 to 63 are used when the RPM is between 2500 and 3800 and the manifold
pressure is above 13 inches. But I still don’t understand how the
controller would know which address to use with no manifold pressures entered
in the table. Does anyone know if this is OK? I assume that Tracy is still in Colorado,
so I don’t expect that he will be covering this.
I also discovered that staging was not set. At least, there is
never an astrick showing up above the V in Volt. I assume I can not
change the staging unless the engine is running??? All this was
done with the engine not running if that matters for any of the data.
My Renesis engine has not been torn down, so it still has the factory
nominal timing setting. Does anyone know what this setting is?? The
timing adjustment setting on the EC-2 is set to Zero. Due to some of the
recent discussions on timing, I am thinking that may have been a factor in not
making as much power as others when static running. I have been only able
to get 53-5400 rpm, while others could get over 6000.
Bill B
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Ed Anderson
Sent: Friday, October 16, 2009
10:06 AM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: Stoich
A/F Ratio?? : [FlyRotary] Re: where's the missing power?
Hi Bill,
I could be wrong, but, I’m fairly
certain that the position of the Ec2 manual mixture control does not necessarily
have any deterministic relationship to air/fuel ratio of the EC2. The resulting
air/fuel ratio is a combination of (among other things) the MCT bin (pointed to
by manifold pressure) in which the engine is operating plus the effect of
the manual mixture control knob.
The narrow band O2 sensor response curve
is pretty crappy for any sort of linear interpolation – but, most have a
range of from a few 10 millivolts to approx 1.1 volt. With the higher
voltage 1.0 representing higher air/fuel ratios – somewhere in the
vicinity of 12 – 10 :1 air/fuel ratio. Stioch (14.7:1)
voltage is normally around 0.45 volts (or 450 millvolts) and that is generally
the only value that is really rather accurate on a narrow band O2 sensor.
So with my EFISM if the air/fuel ratio
indictor is in the middle of its range on the display, it should be yellow in
color. I also have a feature that when looking at the air/fuel indicator
screen (the one with fuel flow and fuel used values displayed), if you press
button b3 and b4 together you will get displayed in the air/fuel ratio window
of the actual voltage being read from the O2 sensor. So if the EFISM
indicator is yellow and in the middle the voltage should read somewhere close
to 450 mv. IF it is green and near the right hand limit the voltage
will probably be reading around 900 mv indicating an higher air/fuel
ratio. If red and to the left side then it will be reading less than 450
mv.
However, remember that the curve for the
narrow band O2 sensor is not very suitable for interpolation. The wide
band O2 sensor is much better and therefore you can get more accurate
indication of air/fuel ratio.
So almost all narrow band O2 air/fuel
ratio indictors are only useful in giving you a relative indication of leaner
or richer.
In fact, I am considering a future
modification/option/user selectable Narrow band or wide band O2 sensor for the
EFISM. Initially the wide band O2 sensors were in the $250 -$300 range,
but now have dropped down to around $80 for the borsch model which makes them
more cost feasible.
I probably did not answer your question,
but that is as close as I could come.
Ed
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Bill Bradburry
Sent: Friday, October 16, 2009
8:57 AM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: Stoich
A/F Ratio?? : [FlyRotary] Re: where's the missing power?
Good point, Ed.
How much change does the mixture knob on the EC-2/3 allow? Say
for instance, if Mike was at 14.7 at full throttle with the mixture knob at the
center position, how far would he have to turn the knob to the right to achieve
12.65 AFR? I ask this because the A/F gage will not read that
mixture. It will be topped out well before that mixture ratio
occurs. How do you determine best power mixture?
Bill B
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Ed Anderson
Sent: Friday, October 16, 2009
8:35 AM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Stoich A/F
Ratio?? : [FlyRotary] Re: where's the missing power?
Hi Mike,
I guess I’m missing something - If
your mixture monitor shows stoich at full throttle, then it’s not solely
an airflow problem – it appears to me that it’s the lack of
sufficient fuel. IF you are at stoich 14.7:1 A/F ratio then that means you have
more oxygen available in your system to support burning more fuel = more
power. You should be able to enrich the mixture particularly at
full throttle (assuming you are wanting full power at full throttle) to around
12.65:1 air/fuel ratio for best power. I know you know all of this - that
is why I am puzzled by your statement that you feel it’s an airflow problem
when on the surface with the Stoich ratio it would appear it’s a lack of
sufficient fuel.
Ed.
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of Mike Wills
Sent: Thursday, October 15, 2009
11:22 PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: where's
the missing power?
Sorry for my absence on a topic I started. My nephew
had a skateboarding accident last weekend and is in the hospital in a
chemically induced coma until his brain swelling is under control. And I
thought car powered airplanes were dangerous. Stay away from skateboards.
Tracy - My
mixture monitor shows stoich at full throttle. I suspect an airflow issue
rather than fuel.
Al - my vacuum gauge is located in the plenum directly
behind the throttle plates.
Lynn - I agree
that the TB inlet is horrible and needs a bell mouth. The inlet is also pretty
obstructed by the cowl which isnt visible in the pics I sent. I think I'll make
an attempt to clean this up some and see if it gets me anywhere. If not I'll
live with it for a while.
Kelly - always tough to determine if the problem is an
engine issue or if the load is simply too much for the engine to overcome. I'm
going to experiment with the shallow dive several have suggested and see what
happens.
----- Original Message -----
Sent: Tuesday, October
13, 2009 4:21 PM
Subject: [FlyRotary] Re:
where's the missing power?
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of Al Gietzen
Sent: Tuesday, October 13, 2009
7:22 PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: where's
the missing power?
I dont have a regular manifold
pressure gauge, just an industrial type vacuum gauge ( I really gotta get an MP
gauge). Anyway, the vacuum gauge was indicating 4" of vacuum.
Where are you measuring the 4”
vacuum? If it is near the ports it is no unusual; if it is out before the
runners; something is wrong.
Al
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