Martin 4-333, Inverted In-line 4 Engine

Type: Reciprocating, In-line, Inverted, 4 cylinders, Air-cooled

Power: 89.5 kW (120 hp) at 2,100 rpm

Displacement: 5.47 L (333.98 cu in.)

Bore and Stroke: 114 mm (4.5 in.) x 133 mm (5.25 in.)

Weight: 120 kg (265 lb)

The Chevrolet Brothers Aircraft Company, owned by Swiss immigrants Arthur and Louis Chevrolet, well known designers of automobile engines and drivers of race cars, designed this in-line, inverted four-cylinder aircraft engine. In advertisements, Louis Chevrolet was quoted as saying "Upside down is right side up." For among the advantages of the design were improved pilot visibility and propeller ground clearance. Designated Model D-4, the engine was certificated in December 1929, and became known as the Chevrolair. A D-4 engine powered Travel Air low-wing aircraft won first place in its class at the September 1930 Cleveland National Air Races.

Subsequently, the Chevrolet Brothers Aircraft Company failed and the engine design sold to the Glenn L. Martin Company of Baltimore, Maryland. Uprated and renamed Martin 333, it was recertificated in July 1930, and powered the Martin 162A Tadpole Clipper and various Driggs aircraft.