The Pacific War Online Encyclopedia

The Pratt & Whitney R-1830 Twin Wasp was an air-cooled supercharged radial aircraft engine with fourteen cylinders arranged in two rows. Bore and stroke were both 5.5 inches (140mm). It was first introduced in 1932 and had a high compression ratio (6.5) requiring very high octane gasoline. Successive models progressed from single-stage to two-stage supercharging and then to turbosupercharging. The R-1830 was efficient and mechanically reliable and was used on a large number of aircraft models. The -43 and -65 marks have been described as "probably the most realiable air-cooled radials ever built" (Simons 2012). The later models could sustain a maximum 2400 rotations per minute and weighed around 1470 lbs (667 kg). Total production was 178,000. Over 13,464 were built for the C-47 alone.

Model	Horsepower	Wattage	Notes
9	1000 hp at 11,500 feet 900 hp at 12,000 feet	750 kW at 3500 m 670 kW at 3700 m
17	1200 hp takeoff 1050 hp at 10,000 feet	890 kW at takeoff 780 kW at 3000 m
57	1200 hp	890 kW
64	900 hp takeoff 850 hp at 8000 feet	670 kW takeoff 630 kW at 2400 m
65	1200 hp at 26,500 feet	895 kW at 8077 m
76	1200 hp takeoff 1000 hp at 19,000 feet	890 kW at takeoff 750 kW at 5800 m	First aircraft engine with two-stage supercharging
90D	1200 hp	890 kW
92	1200 hp 1000 hp at 19,000 feet	890 kW 750 kW at 5800 m
G205A	1200 hp	890 kW
S3C4G	1200 hp	890 kW