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Listers,
One electronic ignition gives about 90% of the fuel
savings of having both.
The savings (and power increase) happen because
more of the fuel charge is burned in the cylinder and less in the exhaust
stream. (I can't imagine it being a good idea to disconnect the MAP sensor
hose.)
Try doing a mag check at any cruise power setting
and watch CHT and EGT. When one system is off, the CHT drops and the EGT
rises. This shows that more fuel is being wasted and is burning in the
exhaust pipe. When you shut down the system that is doing the most work,
you will see the biggest changes.
I have used ignitions from three makers and all
have had some issues.
So have the original mags of course.
The Electroair system was sensitive to
interference. Once I had the engine falter when I used the mike
button. I rerouted some wires.
My early Lightspeed system is pretty good but it
gets lazy at high altitude cruise LOP.
New plugs and expensive wires don't help
completely. The coils check good. Klaus last said to check the
timing.....
If anyone can help me with this I'd appreciate
it.
My P-Mag is working well now but early on there
were some issues with the sensor magnet coming unglued. Those folks have
been good to work with although they wouldn't put me on their payroll for
helping out with destructive testing.
Mark Ravinski
360 1496 hrs
----- Original Message -----
Sent: Thursday, November 11, 2010 1:24
PM
Subject: [LML] Re: Upgrade your ignition
and help LOBO
I haven't
been following this thread in detail, but I have a few questions and a
comment:
I certainly
agree that the ability to increase spark advance at low manifold pressures
gives a substantial improvement in efficiency. But how much improvement
does a single electronic ignition give compared to a dual system? The
only answer I've been given is "about half." That makes sense, I
suppose, but is there any data out there to support that? Most of my
long flights are at about 12,000 feet, so I expect some improvement over dual
mags.
Second
question: I have disconnected the MAP sensor from the intake manifold
port, leaving it to read atmospheric pressure. I can't see any real
difference in operation, since almost all cruising is done at full throttle
with manifold pressure about the same as atmospheric. The advantage is
noticed during the runup - the rpm drops are about the same, whereas with the
MAP sensor connected the rpm drop when shutting off the mag was very small,
making it a little less of an obvious test. Are other people running
electronic ignitions with the MAP sensor disconnected? The only
disadvantage I can see is if you fly a lot of the time at low altitudes and
part throttle you will lose some of the
advantage.
Finally the
comment (with a question buried in it): Several, including Bill (message
below) mention the advantage as being fuel flow reduction. But at full
throttle cruise I can't see how fuel flow could be reduced, only power
increased. Do people fly at a fixed airspeed, throttling back or
reducing rpm to save fuel? Another advantage is that LOP operation could
be smoother on account of the extra spark advance, but I've never done a
back-to-back comparison to verify
that.
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