xgg2356@dcmdc.dla.mil (James Fuerstenberg) writes:
>I know several racers who run exhaust temp guages and use them to set
>their mixtures. I believe you want your exhaust temp around 1400deg F.
>hotter is too lean, cooler is too rich.
I have no idea whether this would work for cars, but it might be
worth a try. In small airplanes, the mixture is under direct control of the
pilot. Usually, he varies it according to altitude, and whether or not he
is interested in best power or best economy. Best power occurs about 50-100
degrees rich of *peak* EGT ( which is the stoichiometric mixture pt) and
best economy, which is 50-100 degrees lean of peak. Interestingly, the best
power is NOT at stoichiometric ratio; it turns out that leaving some
unburnt gasses that do some expansion work with the heat of combustion from the
rest of the gasses burning makes for optimum power. Works in my airplane!
I guess the prcedure would be to drive at a constant speed down a long
straight road, and slowly adjust for peak EGT, then richen it up a bit.
If you wanted to be really anal, you could do like the fancier airplanes,
and have a switchable probe at each cylinder- this can diagnose burnt valves
uneven fuel distribution and other unpleasantness.
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