Pratt & Whitney R-1340 Wasp
Pratt & Whitney R-1340 Wasp on a Boeing P-26 Peashooter.
The Boeing P-26 Peashooter, was the first American all-metal production fighter aircraft and the first pursuit monoplane used by the United States Army Air Corps. The prototype first flew in 1932, and were used by the Air Corps as late as 1941 in the Philippines.
Canadian Aviation Blog