In a message dated 97-09-24 01:16:16 EDT, email@example.com (ROBERT G. HOWARD)
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!
(The prop is just a fan to keep the pilot cool......just watch him sweat when