In a message dated 97-09-24 01:16:16 EDT, mgbob@juno.com (ROBERT G. HOWARD)
writes:
<<
Granted, all MG engines were overweight. How is it that small airplane
engines can come in at about 1 hp per pound, and turn at 2500 doing it?
Granted, they are air cooled and require oil changes at 25-30 hours, but
25 hrs at 60 mph on the road would be 1500 miles. Time between overhauls
is 2000+ hours for most, again equivalent to 120,000 miles, so that's not
a bad wear rate. How do they get that amount of power per pound at such
low revs and normally aspirated?
>>
Light aircraft engines are designed to be VERY understressed because
reliability is the main thing that the manufacturer is after. Bear in mind
that at full throttle a light a/c engine at max rpm/ max manifold pressure is
spinning a prop. This is much like being hooked to a dyno or a jet boat.
Horsepower per cubic inch is usually low. A light plane with a 540 inch
engine is making about 260 horses- not much by car standards.
BUT----you want it to keep on making that power!
Regards,
Ray
(The prop is just a fan to keep the pilot cool......just watch him sweat when
it stops!)
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