Mercedes D.III
The Mercedes D.III, or F1466 as it was known internally, was a six-cylinder SOHC valvetrain liquid-cooled inline aircraft engine built by Daimler and used on a wide variety of German aircraft during World War I. The initial versions were introduced in 1914 at 160 PS (118 kW), but a series of changes improved this to 170 PS (125 kW) in 1917, and 180 PS (132 kW) by mid-1918. These later models were used on almost all late-war German fighters, and its only real competition, the BMW III, was available only in very limited numbers.