"Jay" wrote

My point about using an engine that can operate efficiently over a
large range of RPMs (like a modern automobile engine) is that the CS
prop is NOT as necessary although it certainly does help, no doubt
about it. Certainly you will get you peak horsepower at high revs,
but the moderm engine has a fatter torque curve due to being able to
change valve AND ignition timing in a manner optimum for the
particular revs it is at. The Lyco/Conti design takes a double hit
for operating at low revs, its off the peak HP point, and its timing
was peaked for a specific RPM.


IMHO, to take advantage of the auto engine's characteristics, you need a CS
prop, even more. Flat pitch for takeoff, then really get the course pitch
at high speed and high altitude, so the engine can loaf along at really slow
and low HP output, to keep the thrust up, while at the low engine RPM'S.

Most of the successful auto conversions tend to keep it simple, and variable
valve timeing is not in that spirit. YMMV.
--
Jim in NC


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