The Nissan P engine is a large overhead valve, inline-six cylinder engine manufactured by Nissan Diesel Motor Co., Ltd. from 1959 to 2003 and used in light-duty trucks by Nissan, as well as in the Nissan Patrol. It replaced Nissan's older, sidevalve engines with which it shared its dimensions. This series of engines were based on the pre-war Type A engine, which was a license built Graham-Paige design.

NAK

Introduced in 1950, this is a 3670 cc petrol inline six-cylinder engine which produces 75 hp. This was directly derived from Nissan's pre-war A engine, a license-built Graham-Paige unit. Applications:

NB

Introduced in 1953, this is a 3670 cc petrol inline six-cylinder engine which produces 95 hp. Applications:

NC

Introduced in 1955, this is a 3956 cc, sidevalve petrol inline six-cylinder which produces 105 PS at 3,400 rpm. Bore and stroke are 85.7x114.3 mm. It was used in various buses and trucks as well as in early Nissan Patrols. Applications:

P

The P is a gasoline-powered, overhead valve 3956 cc inline six-cylinder with 125 PS at 3,400 rpm initially. Bore and stroke are 85.7x114.3 mm. Later with 135 PS, further modifications in 1965 increased the power to 145 PS. Later variants were called P40, reflecting the engine displacement in liters (4.0). A variant especially for fire-fighting duties, with a stronger alternator, an engine block heater, and various other improvements, was called the PF engine. Applications: