Pratt & Whitney R-1340 Wasp Engine was built to a US Navy (USN) specification for a 400 hp engine weighing less than 650 lb. It had a conventional layout but introduced a significant innovation in the form of a forged aluminum crankcase. The R-1340 Wasp first ran in late 1925 and immediately developed 380 hp, rising to 425 hp by the third run. The USN ordered 200. By the beginning of World War II, the R-1340 was rated at 600 hp take-off power at 2250 rpm for a weight of 684 lb. This version was widely used in the T6 Texan training aircraft, which was capable of 205 mph and a ceiling of 21,500 ft. One of the most successful aircraft engines ever designed, 34,966 R-1340 Wasp's were built between 1925 and 1960.

Specifications for R1340-AN1
Manufactured by: Pratt and Whitney
Power: 600 h.p. @ 2250 r.p.m.
Cylinders: 9; radial; aircooled
Displacement: 1340 cu. in.
Weight: 650 pounds
First manufactured: 1925