First start of the Continental R975-C4 after rebuild. This engine is going soon into the Sherman M4A1 76mm HVSS completely rebuild. The Wright R-975 Whirlwind was a series of nine-cylinder air-cooled radial aircraft engines built by the Wright Aeronautical division of Curtiss-Wright.
image/text credit: harentrois
These engines had a displacement of about 975 in³ (16.0 L) and power ratings of 300-450 hp. They were the largest members of the Wright Whirlwind engine family to be produced commercially, and they were also the most numerous.
During World War II, Continental Motors built the R-975 under license as a powerplant for Allied tanks and other armored vehicles. Tens of thousands of engines were built for this purpose, dwarfing the R-975’s usage in aircraft.credit: (wikipedia).
After the war, Continental continued to produce its own versions of the R-975 into the 1950s; some of these produced as much as 550 hp (410 kW).The R-975 is most famous for being used as the power plant for the M18 Hellcat tank destroyer, the fastest and most efficient American tank killer of World War II.