R-1340-AN-1 Wasp radial engine, 600 hp (450 kW), Pratt & Whitney

This one on a North American T-6 Texan. 

Pratt & Whitney R-1340 Wasp was a reciprocating engine widely used in American aircraft from the 1920s onward. It was the company's first engine, and the first of the famed Wasp family.It was a single-row, nine-cylinder air-cooled radial design, and displaced 1,344 in³ (22 L); bore and stroke were both 5.75 in (146.05 mm). A total of 34,966 engines were produced.