This is a 250 cc. snowmobile engine that gave 22 HP, and was installed on the Hill Hummer. It is a 2-stroke engine.

The main Chaparral engine used in aviation is the 2-cylinder,  2-stroke, 460 cc, (28.8 cu. in.) It gave 36 hp at 6,500 rpm and was liquid cooled. The total weight was 36 kg (79 pounds).