Bentley 3 Litre

Bentley 3 Litre at a glance

Development: 1919 to the first delivery

English Wikipedia credits the car to Walter Owen Bentley, with a chassis derived from a Humber design by Frederick Tasker Burgess and an engine designed by Clive Gallop. English Wikipedia notes that the engine was based on the 1914 Mercedes racing engine.

The chassis appeared at the London Motor Show in 1919, but the engine was not ready; German Wikipedia describes the first exhibit as a non-running mock-up shown in May 1919. Perfecting the engine took two years, and the first customer car was delivered in September 1921. Bentley sold rolling chassis and usually sent buyers to Vanden Plas for the body. Most cars were bodied as open tourers, and some dealers ordered short runs of identical bodies. Customers included Prince George, Duke of Kent, and the actresses Gertrude Lawrence and Beatrice Lillie.

The 16-valve engine

The engine was a cast-iron monobloc four with a bore of 80 mm and a very long stroke of 149 mm, giving 2,996 cc. A single overhead camshaft, driven by bevel gears, opened four valves per cylinder in hemispherical, pent-roof combustion chambers. Each cylinder had two spark plugs, and two carburettors fed the engine, which used dry-sump lubrication.

English Wikipedia gives about 52 kW (70 hp) for the untuned engine. The 1927 Le Mans entry list rated the 3-litre racing engines at 66 kW (88 bhp). With a weight of about 1,800 kg, the standard car had around 29 kW per tonne, and our power-to-weight calculator shows how far that is from a modern sports car. Ettore Bugatti called the 3 Litre "the fastest lorry in the world", a remark the company took as a compliment.

A four-speed gearbox drove the rear wheels. Until 1924 only the rear wheels had brakes; four-wheel brakes arrived that year. In the winter of 1926–1927 the factory service department fitted a Roots-type supercharger to chassis 220, driven from the crankshaft, two years before Tim Birkin's supercharged Bentleys.

Blue, Red and Green Label versions

The radiator badge told buyers which version they had, although customers could order other colours.

German Wikipedia describes the 100 mph Super Sports as the fastest series production road car in the world at the time, a title later taken by the 4½ Litre.

Le Mans: 1923, 1924 and 1927

Bentley entered the first 24 Hours of Le Mans, on 26–27 May 1923, with one 3 Litre for John Duff and Frank Clement. A stone broke a headlamp before midnight, and just before midday another punctured the fuel tank near Arnage. Clement walked back to the pits and returned with fuel on a gendarme's bicycle; the repair, with a cork in the hole, took about two and a half hours. The car still finished fourth equal with 112 laps and set the fastest lap at 107.33 km/h (66.69 mph).

A year later, on 14–15 June 1924, Duff and Clement won the race outright in car number 8, the only entry from outside France. It was not easy. At about 2 am a gearbox blockage took half an hour to trace to a stray staple in the electrics, and at 2:30 pm a precautionary wheel change turned into a half-hour delay when one rear wheel would not come off. Under the new rules the final laps fell below the required average and were not counted, but the 120 laps completed before the long stop were enough: the Bentley finished one lap ahead of the Lorraine-Dietrich of Stoffel and Brisson. English Wikipedia counts 41 starters, of which 12 completed the 24 hours. In 1927 Bentley sent three cars. At about 9:40 pm, as drizzle began, a spinning car blocked the road at the Maison Blanche curves and eight cars collided, among them all three Bentleys. Sammy Davis hit the wreckage sideways in the 3 Litre known as "Old Number 7", drove to the pits and repaired the car in about 30 minutes. With Dudley Benjafield he went on to win by 20 laps, covering 137 laps of the 17.3 km circuit with damaged steering that pulled to the right.

Rolls-Royce era and surviving cars

When Rolls-Royce bought Bentley in 1931, it acquired the remaining 3 Litre stock as well. German Wikipedia records that in 1936 four used 3 Litres were rebuilt from stock parts, given new "RC" chassis numbers and Vanden Plas bodies, and sold with a five-year warranty. The full story of the marque is in our history of Bentley Motors, and the takeover from the other side in our history of Rolls-Royce.

The oldest surviving production Bentley is chassis 3, with engine 4 and a body by R. Harrison & Son, registered AX 3827. A 1927 Speed Model, chassis 1209 DE, is in the Simeone Foundation Automotive Museum in Philadelphia, and a 1924 car has been on show at the Shepparton Motor Museum in Victoria, Australia, since July 2019.

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