Flat 12

A flat-12 is a 12-cylinder internal combustion engine in a flat configuration. Rarer, wider, and less tall than a V12, the flat-12 design was used in Formula One and Endurance racing and some exotic sports cars.

Flat-12 engines are generally not true horizontally opposed engines (boxer), but rather 180° V-engines. A true boxer has one crank pin per piston, while in the 180° V-engine, two opposing pistons share the same crank pin. The engine also has a naturally lower center of gravity than a V12, but, with the exception of the Mercedes-Benz C291, is usually mounted somewhat higher in the engine bay to provide clearance for the exhaust system.

Ferdinand Porsche can be credited for creating the first flat-12 engined car, the supercharged Porsche 360 / Cisitalia Grand Prix, near Gmünd in 1947.

In 1964-65, Ferrari introduced a flat-12 in the Ferrari 1512 F1 car and won the F1 world championship with a flat-12 layout in the mid and late 1970s with the Ferrari 312T. However, when wing-cars requiring air-flow venturis came along in the late 1970s, the wide flat shape obstructed the airflow and was considered obsolete. A 4.4-5.0 L 180° flat-12 was also introduced by Ferrari in some of their production models, including the Berlinetta Boxer and Testarossa.

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