During the 1940s, Wright Aeronautical Corporation was constantly in competition with Pratt & Whitney for new engine designs required for civil and military aircraft.
[1] The air-cooled R-4090 was rated to deliver 3,000 hp (2,200 kW) at 2,800 rpm for take-off, from a total displacement of 4,092 cu in (67.06 L), with a compression ratio of 6.85:1.
[1] The core of the engine was a forged steel crankcase which enclosed the three piece two-throw crankshaft.
The cylinders were arranged equally around the crankcase, with each row off-set by 16.3636.° to ensure cooling airflow.
Accessories similar to other Cyclone engines were arranged around the rear face of the crankcase and a 0.333:1 planetary reduction gearbox at the front.