Liberty 12 Model A, V-12 Engine

Type: Reciprocating, 12 cylinders, V-type, Liquid-cooled

Power rating: 298 kW (400 hp) at 1,800 rpm

Displacement: 27.0 L (1,648.92 cu in)

Bore and Stroke: 127 mm (5 in.) x 178 mm (7 in.)

Weight: 383 kg (844 lb)

The Liberty engine was America's most important contribution to aeronautical technology during World War I. Jesse G. Vincent of Packard and Elbert J. Hall of Hall-Scott co-designed it between May 30 and June 4, 1917 for the U.S. government, which wanted a standard design in 4-, 6-, 8-, and 12-cylinder versions that could be quickly mass-produced to equip U.S. combat aircraft. To ensure a workable engine in the shortest possible time, they used only proven components, with features from both Hall-Scott and Packard. They succeeded, with the first 8-cylinder engine delivered in early July.

However, demand for lower-power engines was already being met, and wartime experience showed the need for high power. Liberty-12s powered many aircraft types, but most were built for the de Havilland DH-4. Automakers Ford, Lincoln, Packard, Marmon, and Buick produced 20,748 Liberty 12s, with varying quality, before the Armistice, which insured their widespread use into the 1920s and '30s.