Bentley 3 Litre

Bentley 3 Litre
Blue label tourer by Park Ward 1924
Overview
Manufacturer	Bentley Motors Limited, Cricklewood, London
Production	1921–1929 1622 produced
Designer	Walter Owen Bentley
Body and chassis
Class	Sports car
Body style	as arranged with coachbuilder by customer
Powertrain
Engine	3.0 L OHC 4-valve I4
Dimensions
Wheelbase	108 in (2,743 mm) 117.5 in (2,984 mm) 130 in (3,302 mm)
Chronology
Successor	4 1⁄2 Litre

The Bentley 3 Litre was a car based on a chassis manufactured by Bentley. The company's first car, it was introduced in 1919 and the chassis was made available to customers' coachbuilders from 1921 to 1929. The Bentley was larger than the Bugattis that dominated racing at the time, but strength and innovative technology compensated for the extra weight. The 4000 lb (1800 kg) car won the 24 Hours of Le Mans in 1924, with drivers John Duff and Frank Clement, and again in 1927, this time in Super Sports form, with drivers S. C. H. "Sammy" Davis and Dudley Benjafield. Its weight, size, and speed prompted Ettore Bugatti to call it "the fastest lorry in the world."

The 3 Litre was delivered as a running chassis, with Bentley referring many customers to Vanden Plas for standard bodies. Most were tourers, but some variety was inevitable with custom coachwork. Customers included Prince George, Duke of Kent, Gertrude Lawrence, and Beatrice Lillie.

The 3.0 L (2,996 cc or 183 cu in) straight-4 engine was designed by ex-Royal Flying Corps engineer Clive Gallop and was technically very advanced for its time. It was one of the first production car engines with 4 valves per cylinder, dry-sump lubrication and an overhead camshaft. The four valve SOHC Hemi design, with a bevel-geared shaft drive for the camshaft, was based on the pre-war 1914 Mercedes Daimler M93654 racing engine. Just before the outbreak of the war Mercedes had placed one of the winning Grand Prix cars in their London showroom in Long Acre. At the suggestion of W.O. Bentley, then being commissioned in the Royal Naval Air Service, the vehicle was confiscated in 1915 by the British army, dismantled at Rolls-Royce and subjected to scrutiny. A notable difference to both the Mercedes and the aero engines was the cast-iron monobloc design, and the fully Aluminium enclosed camshaft, which greatly contributed to its durability. But having the valve-head and block in one-piece made for a complicated and labour intensive casting and machining. This was a feature shared during that time by the Bugattis which the car was later to compete with. The engine was also among the first with two spark plugs per cylinder, pent-roof combustion chambers, and twin carburetters. It was extremely undersquare, optimized for low-end torque, with a bore of 80 mm (3.1 in) and a stroke of 149 mm (5.9 in).