The Lycoming R-680 is a nine-cylinder air-cooled radial engine, the first aero engine produced by Lycoming. The engine was produced in two types the E and B series both are essentially the same, the B4E was available in a trainer version with a front exhaust collector for use without cylinder air baffles.

Variants
R-680-B4E
Rated at 225 hp at 2100 rpm.
R-680-E3A
Rated at 285 hp at 2200 rpm.
R-680-13
Rated at 300 hp at 2200 rpm.