The Duesenberg brothers introduced the first successful straight-eight racing engine in 1920, when their 3 L engine placed third, fourth, and sixth at the Indianapolis 500. The following year one of their cars won the French Grand Prix, while two others placed fourth and sixth in the race. Based on work the company had done on 16-cylinder aircraft engines during World War I, the overhead camshaft, three-valve-per-cylinder engine produced at 4,250 rpm, and was capable of revving to an astonishing (at the time) 5,000 rpm. No Grand Prix engine before the war had peaked at more than 3,000 rpm.