The R-1820 Cyclone 9 represented a further development of the Wright P-2 engine dating back to 1925. Featuring a greater displacement and a host of improvements, the R-1820 entered production in 1931. The engine remained in production well into the 1950s.
The R-1820 was built under license by Lycoming, Pratt & Whitney Canada and also, during World War II, by the Studebaker Corporation. The Soviet Union had purchased a license for the design, designated M-25, and the Shvetsov OKB was formed to further develop the engine.
The R-1820 was used on many famous aircraft including B-17 Flying Fortress, Douglas Dauntless, Douglas C-47, North American T-28B, Grumman Tracker and Grumman Albatross.
The B-17 made use of a turbocharger, in which the exhaust gases were directed through a turbine that drove a compressor to boost the air pressure being delivered to the carburetor. This system caused higher back-pressures in the exhaust manifold, requiring more expensive materials to withstand the heat. However, it allowed the engine to deliver high power at the high altitudes that the long-range bomber required.
Using 100/130-grade fuel the Cyclone engines in the B-17 developed 1200 hp at 2500 RPM for takeoff. The engine was also developed for use in a US tank at 900 hp. Power output increased from 575 hp (429 kW) in early models up to 1525 hp (1138kW) in the last model.