----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]----
PROPER OPERATION OF EXHAUST GAS TEMPERATURE
This not to say my writing is the only way to operate your EGT, just to
say
I use to teach it in a
part 147 school, and did many hours of research before using it as my
curriculum for teaching.
I am going to try to answer the three e-mails on the list at the present
time, item by item at the
end of this procedure.
Then you decide if you want to change you thoughts or procedure of
operation. There is one
word I want to submit and give the meaning of. Some of you may already
know
it, but there are
some who do not. So for their enlightenment and knowledge the word is;
Stoichemetric:
A chemical relationship in which all of the constituents are used up in
the
reaction.
In the case of a stoichemetric mixture, all of the oxygen and all of the
hydrocarbon
fuel are used. There is no oxygen or free carbon left.
What this boils down to is, stoichemetric combustion, is perfect chemical
combustion.
While it is perfect combustion, it is also too hot of a temperature for
the
combustion
chamber of any engine, not just aircraft engines, but any engine. With
this
combustion
there is no excess fuel in the cylinder for cooling, the way the
carburetor
or injectors
or calibrated to do. This is why we have different size metering jets in
the
same
Model carburetors for different Model engines.
EGT OPERATION
Before installing the EGT probe, attempt to find the hottest running
cylinder, this is the
cylinder the probe should be installed in. Installing in a cooler running
cylinder could
make the hottest running cylinder run on too little fuel in the fuel air
mixture. Causing
burnt valves in some cases, on the leaner running cylinder (s).
On take-off I never try to set EGT unless I am 5,000 feet MSL or higher,
on
small aircraft.
I wait until I am in climb out to adjust the EGT. I have not checked each
system, but earlier
systems had no FAA approval for adjustment in take-off or climb, just
cruise
mode was
given FAA approval.
Lean to peak indication (stoichemetric) and enrich 100 degrees for cooling
fuel in the area
of combustion. This gives enough fuel to cool the cylinder. In cruise you
can drop the
enrichment side to 50 to 75 degrees, depending on outside air temperature,
and farther
lower the fuel consumption per hour.
Be sure to remember to enrichen the mixture as you start descend or
landing.
NOTES
1. The peak temperature will differ from day to day, because of outside
air
temperature.
2. The K&S system Ed mentions would be best for small engines
since the increments
are in the 25 degree range. Alcor would have to be interpolated.
3. If you buy a system from a salvage yard, be sure the indicator, wire
lead
between the
indicator and probe, are a matched set. All probes will not operate
with all indicators.
The wire lead has a certain number of ohms in it, coil the excess, do
not
cut to length.
There is a so called universal probe now, but it does not work on all
systems.
4. It is best to change the mixture control to a vernier type, it gives a
more accurate con-
trol of the EGT and will hold it, after you have set it to the position
you
want.
5. Running on the lean side of peak should be a no no. Sure the EGT is
showing a lesser
temp than peak, this is because there is not enough fuel to give you the
proper temp.
Remember stoichemetric is perfect combustion, lean of that does not take
care of
the valves. Four gallons per hour on a 0-200 is great the fuel stop, but
hard on the
wallet at TBO.
5. If you are running a Stromberg carburetor, it has built in leaning up
to
5,000 MSL
and should leaned only above 5,000 MSL. Unless of course if you have EGT.
Even though it has a mixture control, it does not have idle cut-off. The
pulling it
out and rapid advance of the throttle will sometimes kill it due the fact
there is no
accelerator pump, and rapid advance of the throttle will some times pull
in
too
much air for the amount of fuel, especially with the mixture in the lean
position.
Jim Lloyd has the best procedure for shut down
==^================================================================
This email was sent to: [EMAIL PROTECTED]
EASY UNSUBSCRIBE click here: http://topica.com/u/?aVxiLm.aVzvvT
Or send an email to: [EMAIL PROTECTED]
T O P I C A -- Register now to manage your mail!
http://www.topica.com/partner/tag02/register
==^================================================================
<<attachment: winmail.dat>>
