The Billancourt engine was an automotive engine designed by Renault for the Renault 4CV, used subsequently until 1985. It later received the internal code "B", for Billancourt. The "sport" version is called Ventoux engine. History The engine is liquid-cooled, with four cylinders in line. It is also characterised by its three main bearing design and its piston stroke of . It has a cast-iron block, aluminium cylinder head and uses a lateral camshaft to operate overhead valves, which also operated the fan belt on its other end. In June 1940, Louis Renault appointed Fernand Picard who became deputy technical director in the automobile engine department. During the World War II, he participated in the study of a small car: the future 4CV. Its engine was ready in 1942 and a year later, it first turned a wheel. Renault replaced this engine with the Cléon-Fonte engine, a completely new design. This engine designed by Fernand Picard was produced from 1947 to 1985, in displacements of , , , and . These differences were carried out by changing the cylinder bore diameter Different displacement 760 cc Commercialized in 1947 with the Renault 4CV, the first version of the "engine Billancourt" was a of SAE. In 1950, a SAE version was fitted to the Renault 4CV Grand Luxe, produced only in 1950. 747 cc In October 1950, the replaced the . The slightly lower displacement was obtained by slightly reducing the size of the bore from , while the stroke remained unchanged. This change was decided by the leaders of Renault in order to be able to use this extremely undersquare engine in competitions where it was necessary to stay below to homologate the car in its category. This new displacement offered six power levels, from SAE, all of 4 fiscal horsepower. 782 cc In 1971, the appeared with an increased bore, from , always with an unchanged stroke of . This engine was proposed in both variants developing . The less powerful one was mounted under the hood of the Renault 4L produced between 1971 and 1980, while the variant developing was used on the Renault 5 produced between 1972 and 1976. 845 cc The highest engine capacity of the Billancourt engine appeared in 1956 at the launch of the Renault Dauphine, one of the main models equipped with this engine; it displaces . The rear-engine version was codenamed 670. It also