Since this seems to be one of interest, let me do a core dump of what I
knew about aircraft from years ago.(I had a private ticket and quit
flying after nearly being hit midair by idiots twice - plus I was doing
aerobatics, and I KNEW I would eventually kill myself.)
Aircraft engines could not be much more different from automotive race
engines. They are low compression, low RPM (<2500 RPM) engines with very
low specific outputs (about 0.5 HP/cubic inch- compare that to my Alfa
at 1.6 HP/cu in) They are designed for reliability - 2000 hours between
overhauls means about one quarter million miles in a typical small
plane!
Problem is they turn propellers which are inefficient when the tips get
too fast, so they are most efficient at about 2000 RPM. One of the
racers used a Nissan V6 but had to gear it down either 3:1 or 4:1.
In use the AC engine is run at low speed and very high manifold
pressure, and the mixture is leaned manually to peak performance (with a
exhaust gas temp gage.)
Imagine running your engine at practically full throttle at low RPM!
So I suspect avgas is formulated to a different combustion cycle! It is
high octane, and has been used for many years in high performance
vehicles (boats included), but it is not an optimum blend.
--
Jim Hayes Winchester, MA, USA
hayes@mediaone.net http://www.fotec.com/jim/jim.htm
jeh@fotec.com http://www.fotec.com/
All generalizations, with the possible exception of this one, are false!
|