Paul,
If you are using a manifold absolute pressure (MAP) gauge and RPM to measure
power, and are keeping these constant while you measure speed at different
altitudes, you will actually be experiencing an increase in engine power
with altitude because the reduction in exhaust back pressure increases the
efficiency of the combustion cycle. This affects both normally-aspirated
and turbo-charged engines, but of course the turbo will increase the power
available because of the boost it can provide.
I am sure any thermodynamicist could quantify the effect, but I'm not
attempting this!
Mike
Europa Club Safety Officer
<paul.mcallister@qia.net>
Hi all,
I was wondering if some that was a little more versed in aerodynamics could
quantify my observations. I am finding that with my 914 Turbo that for a
constant power setting I pick up some where between 1.5 ~ 2.0 knots per
1000'. Is this valid or just wishful thinking.
Paul
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