Renault Billancourt engine

Billancourt engine
	File:Renault Logo.svg Renault logo
Company type	Engine
Industry	Automotive
Founded	1947
Founder	Renault
Defunct	1985
Fate	Replaced by Cléon-Fonte engine
Successor	Cléon-Fonte engine
Headquarters	Billancourt, Paris, France
Area served	Worldwide (Renault vehicles)
Key people	Fernand Picard (engine development)
Products	Inline-4 automobile engines (603 cc to 845 cc)
Owner	Renault
Parent	Renault
Website	www.renault.com

{{Infobox automobile engine |name= Billancourt engine |aka=Ventoux engine, B-Type engine |image=Renault Ventoux engine (1956).jpg |manufacturer=Renault |assembly=Île Seguin, Billancourt, Paris, France |production=1947–1985 |successor=Cléon-Fonte engine |configuration=Naturally aspirated Inline-4 |block=Cast-iron |head=Aluminium |valvetrain=OHV |displacement= |bore= |stroke= |compression=9.2:1 |power= |torque=

The Billancourt engine was a power unit developed by Renault specifically for the Renault 4CV, manufactured between 1947 and 1985. Known internally as the "B" engine due to its association with the Billancourt factory, its sportier version was marketed under the name Ventoux engine.

History

This inline four-cylinder, liquid-cooled engine incorporated a cast-iron block paired with an aluminium cylinder head, featuring a three-main-bearing crankshaft and an 80 mm piston stroke. It employed a lateral camshaft to actuate overhead valves and also powered the cooling fan belt.

In 1940, Renault appointed engineer Fernand Picard as deputy technical director overseeing automobile engines. Throughout World War II, he spearheaded the development of a compact vehicle that culminated in the Renault 4CV and its Billancourt powerplant, which was functional by 1943. Eventually, the Billancourt engine was superseded by the more contemporary Cléon-Fonte engine.

Produced in various displacements from 603 cc up to 845 cc, the engine’s capacity was primarily altered by modifying cylinder bore size. This power unit served numerous Renault models over nearly forty years, highlighting its pivotal role in Renault's postwar lineup and commercial success.

760 cc

Debuting in 1947 with the Renault 4CV, the initial Billancourt engine delivered a displacement generating SAE power ratings. In 1950, a variant producing SAE power was introduced exclusively for that year's Renault 4CV Grand Luxe.

747 cc

October 1950 saw the introduction of the 747 cc version, which replaced the earlier 760 cc by slightly reducing bore diameter while retaining the same stroke length. This modification enabled Renault to enter racing classes restricted to engines below . The 747 cc model offered six different power outputs ranging up to SAE, all classified at 4 fiscal horsepower.

782 cc

Released in 1971, this variant increased bore size while maintaining the original stroke. It was available in two power levels: and hp SAE. The lower-powered option was installed in the Renault 4L (1971–1980), whereas the higher output powered the Renault 5 (1972–1976).

845 cc

The largest displacement within the Billancourt family appeared in 1956 with the Renault Dauphine, boasting . Rear-engine configurations carried the code 670, while front-engine, front-wheel-drive versions such as the Renault 4 (from 1964) and base Renault 6 used the 800 designation. Bore diameter increased to , producing between and hp SAE for standard models.

The ultimate version reached up to hp and Nm torque at 2,500 rpm through enhancements including cylinder head re-machining, valve upgrades, and improved cooling systems. This iteration powered models like the Renault 5L (1977–1984) and was identified as B1B under Renault's revised engine coding system.

603 cc

The most budget-friendly option in the Billancourt engine lineup featured a smaller bore, resulting in a total displacement of 603 cc. This powerplant delivered up to 21 hp SAE (19 hp DIN) at 4,800 rpm, with a peak torque of 40 Nm. It was exclusively installed in the Renault 3 model (1961–1962), which was a very basic version of the Renault 4.

Ventoux Engine

The Ventoux engine, named after the Mont Ventoux Hill Climb event, represented a sportier iteration with notable performance upgrades.

747 cc Ventoux

This enhanced version was utilized in vehicles such as the Alpine A106 and Renault 4 CV R1063. It incorporated reinforced duralumin connecting rods, an improved camshaft, larger valves, and Solex carburetors. Power output varied from approximately 29 hp SAE for the standard R1063 to over 40 hp SAE for competition models, reaching as high as 49 hp SAE on the A106. Certain A106 engines were tuned to produce 55 hp SAE and favored Solex twin-choke carburetors rather than Weber units.

Ventoux Gordini

Amédée Gordini upgraded the original engine by machining angled valve seats, enhancing cylinder head cooling, and fitting a new 32 mm Solex carburetor. These modifications, combined with an increased compression ratio, elevated power to 37 hp SAE at 5,000 rpm and torque to 62.8 Nm at 3,500 rpm. Launched in late 1957, this engine saw further refinement by 1959, boosting output to 40 hp SAE and leading to the introduction of the Dauphine Gordini (type R1091) in that year.

The power increase to 37 hp SAE allowed a top speed of 126 km/h thanks to a redesigned cylinder head, higher compression ratio, and enlarged intake and exhaust ports. Early changes such as the vertical outlet cylinder head were abandoned due to cost constraints. By 1960, power rose by an additional three horsepower; the Dauphine Gordini was available from 1957 until 1963 and reissued in 1965.

Subsequent enhancements in both 1960 and 1965 improved torque figures. A more potent variant included a new camshaft, upgraded valves, a Solex double-body carburetor measuring 32 mm, and a compression ratio of 9.2:1, which raised maximum power output to 55 hp SAE (49 hp DIN).

Ventoux 1093

Renault tasked Amédée Gordini with developing the high-performance Dauphine 1093 (type R1093), introduced in late 1961. Key engine improvements comprised pistons with convex heads raising compression to 9.2:1, a reversed Solex twin-choke carburetor (32 PAIA 3), a specialized camshaft, double valve springs, and Autobleu intake and exhaust manifolds. Strengthened sprockets and clutch components supported an output of 55 hp SAE (49 hp DIN), enabling speeds up to 140 km/h.

The transmission featured a modified fourth gear distinct from that of the Dauphine Gordini. Braking was enhanced through front drum cooling fins; suspension employed shorter springs without reducing ride height. The 1093 was unique in France for offering a 12-volt electrical system—aligning with export specifications instead of the standard domestic six volts.

Visually distinctive elements included large-diameter US-style headlights measuring 180 mm, a "Réjane" white cream exterior adorned with two blue stripes running lengthwise along the body, and "1093" badges positioned on both the rear and front wings. Inside, an additional tachometer calibrated up to 180 km/h complemented the speedometer.

While sporty within its category, the Dauphine 1093 required further development to remain competitive under racing regulations that limited displacement and restricted component modifications from 1960 onward. Approximately 2,140 units were produced across two series: an initial run of about 1,650 for homologation purposes and a subsequent batch of around 490 featuring disc brakes and "Valois" gray paint responding to customer requests. Today, the Dauphine 1093 is regarded as the most collectible Dauphine variant; roughly one hundred survive worldwide with about half still operational.

The Dauphine 1093 participated in events such as the 1962 Tour of Corsica Rally; however, its late market debut combined with modest performance improvements limited its impact in motorsport. It serves as an important link between the artisanal Renault 4CV R1063 and the groundbreaking R8 Gordini in touring car racing history.

Succession

The engine known as the Sierra, which was later renamed the Cléon-Fonte engine, made its initial appearance in 1962 on the Renault Floride S and Renault 8 models. This powerplant was notable for incorporating a five-bearing crankshaft, a novel feature at the time. Positioned as a mid-sized engine, it did not supersede the Billancourt engine, which remained in use for entry-level vehicles. Over time, as automobiles increased in weight and demanded greater efficiency, Renault gradually discontinued the Billancourt engine by 1980, subsequently redefining the Cléon-Fonte as an engine with small displacement.

Designed entirely anew by engineer René Vuaillat, the Cléon-Fonte was not a derivative of the Billancourt engine. Although both engines utilized a lateral camshaft driven by either a chain or sprocket, their similarities were minimal and largely superficial.

Models equipped with this engine

Cylinder dimensions and displacement

Engine types	690	662-2 - 680	662-1	839	B1B - 670 - 800 - Ventoux1093
Bore	49 mm (1.93 in)	54.5 mm (2.15 in)	55 mm (2.17 in)	55.8 mm (2.20 in)	58 mm (2.28 in)
Stroke	80 mm (3.15 in)
Displacement	0.6 L (603 cc)	0.7 L (747 cc)	0.8 L (760 cc)	0.8 L (782 cc)	0.8 L (845 cc)