In the late 1950s, Renault engineering, led by the engineer Fernand Picard, decided to develop a modern version of the "Billancourt engine" from the Dauphine for the future Renault 8 model. The engineer René Vuaillat designed an all-new small four-cylinder engine which would eventually evolve from . Consisting of a cast iron block topped with an aluminum cylinder head, this engine was characterized by its camshaft placed high in the block with short pushrods, and, unusually for the time, five crankshaft bearings. From the first test, it showed more torque and considerably more power than the "Billancourt", whose design dated back to 1944. It was baptized the "Sierra", because at that time, Renault had not yet adopted its later scheme of designating each engine design with a letter. It was later that it took the name "Cléon", referring to the plant where it was made, combined with "Fonte" (meaning "cast-iron" in French) to distinguish it from the aluminum-block Renault 16 Cléon-Alu engine; it was later shortened to the "C engine."