On 20 Sep 2003 17:48:25 -0700, (Daniel)
wrote:

David Hill wrote ...
I'm working on a replica of a 1924 airplane originally powered by an
Indian Chief motorcycle engine. I've spent a year or two trying to find
a modern engine that somewhat resembles the Indian, and the best I have
come up with is a Harley-Davidson.

Why not a current production Indian? Can't say that I know anything
about motorsickles, but I noticed one of the new ones a couple weeks
ago & wondered.

... I can get ~40 hp at ~3400 rpm
(direct drive) or ~60 hp at ~4500 rpm (PSRU setup).

Better check your math (PSRU = more torque @ lower rpm, but the HP
stays the same).

Daniel
No, David was right. Engine torque output being the same, horsepower
increases proportional to speed. Since torque droops with RPM, the
difference is not truly linear - but running a PSRU ALLOWS the engine
to produce more horsepower with the same prop RPM.If it did not, there
would be no reason for the complexity of a PSRU.