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.

The Renault 4CV is a car produced by the French company Renault from August 1947 through July 1961. It is a four-door economy car with its engine mounted in the rear and driving the rear wheels. It was the first French car to sell over a million units, and was superseded by the Dauphine.