And did you catch that those 20 hp were put out by a 265 lb engine?The surplus info says it's a Teledyne engine. Teledyne owns Continental, not Lycoming. What's with that? And it's an 84 cubic inch engine; the Cont A-65 is about 170 cubes, twice the size, and produces 65 hp at 2350 RPM. You have to run the surplus engine at very high RPM to get much power out of it.
I'm wondering about that 20 hp "USG" rating. Is that a different scale than the hp scale we use? (33,000 ft-lb/minute). 20 hp sounds rather anemic for that many cubes, at 3600 RPM.