Bentley 4,5 Litre Supercharged Le Mans SWB
|
Car producer : |
Bentley |
|---|---|
|
Model: |
4,5 Litre Supercharged Le Mans SWB |
|
Year: |
1929-1931 |
|
Type: |
Roadster |
Based in Crewe, England, Bentley Motors Limited was founded by W. O. Bentley on 18 January 1919 in Cricklewood near London and was acquired by Rolls-Royce in 1931.
The original model was the 3-litre, but as customers put heavier bodies on the chassis, a larger 4½-litre model followed. Perhaps the most iconic model of the period is the 4½-litre "Blower Bentley", with its distinctive supercharger projecting forward from the bottom of the grille. Uncharacteristically fragile for a Bentley it was not the racing workhorse the 6½-litre was, though in 1930 Birkin remarkably finished second in the French Grand Prix at Pau in a stripped-down racing version of the "Blower Bentley", behind Philippe Etancelin in a Bugatti Type 35.
The 4½-litre model later became famous in popular media as the vehicle of choice of James Bond in the original novels, but this has been seen only briefly in the films. John Steed in the television series The Avengers also drove a Bentley.
The new 8-litre was such a success that when Barnato's money seemed to run out in 1931 and Napier was planning to buy Bentley's business, Rolls-Royce purchased Bentley Motors to prevent it competing with their most expensive model, Phantom II.
The Bentley 4½ Litre was a British car based on a rolling chassis built by Bentley Motors. Walter Owen Bentley replaced the Bentley 3 Litre with a more powerful car by increasing its engine displacement to 4.4 L (270 cu in).
Bentley buyers used their cars for personal transport and arranged for their new chassis to be fitted with various body styles, mostly saloons or tourers. However, the publicity brought by their competition programme was invaluable for marketing Bentley's cars.
At the time, noted car manufacturers like Bugatti and Lorraine-Dietrich focused on designing cars to compete in the 24 Hours of Le Mans, a popular automotive endurance course established only a few years earlier. A victory in this competition quickly elevated any car maker's reputation.
A total of 720 4½ Litre cars were produced between 1927 and 1931, including 55 cars with a supercharged engine popularly known as the Blower Bentley. The 4½-Litre was produced for four years, all but nine made being built on the 3-Litre's 'Long Standard', 10' 10"-wheelbase chassis. A 4½ Litre Bentley won the 24 Hours of Le Mans in 1928. Though the supercharged 4½ Litre Bentley's competitive performance was not outstanding, it set several speed records, most famously in 1932 at Brooklands with a recorded speed of 222.03 km/h (138 mph). The original 4½-Litre car, nicknamed by the team 'Old Mother Gun' and driven by Frank Clement and Leslie Callingham, promptly set the fastest race lap of 73.41mph before being eliminated in the infamous 'White House Crash' multiple pile-up.
Although the Bentley 4½ Litre was heavy, weighing 1,625 kg (3,583 lb), and spacious, with a length of 4,380 mm (172 in) and a wheelbase of 3,302 mm (130.0 in), it remained well-balanced and steered nimbly. The manual transmission, however, required skill, as its four gears were unsynchronised
The robustness of the 4½ Litre's latticed chassis] made of steel and reinforced with ties was needed to support the heavy cast iron inline-four engine
The engine was "resolutely modern for the time. The displacement was 4,398 cc (268.4 cu in): 100 mm (3.9 in) bore and 140 mm (5.5 in) stroke. Two SU carburetters and dual ignition with Bosch magnetos were fitted. The engine produced 110 hp (82 kW) for the touring model and 130 hp (97 kW) for the racing model. The engine speed was limited to 4,000 rpm. A single overhead camshaft actuated four valves per cylinder, inclined at 30 degrees. This was a technically advanced design at a time where most cars used only two valves per cylinder. The camshaft was driven by bevel gears on a vertical shaft at the front of the engine, as on the 3 Litre engine.
The Bentley's tanks - radiator, oil and petrol - had quick release filler caps that opened with one stroke of a lever. This saved time during pit stops.
This 4½ was equipped with a canvas top stretched over a lightweight Weymann body The hood structure was very light but with high wind resistance (24 Hours Le Mans rules between 1924 and 1928 dictated a certain number of laps for which the hood had to be closed). The steering wheel measured about 45 cm (18 in) in diameter and was wrapped with solid braided rope for improved grip.
Brakes were conventional, consisting of 17-inch (430 mm) drum brakes finned for improved cooling and operated by rod. Semi-elliptic leaf springs were used at front and rear.
Sir Henry "Tim" Birkin, described as "the greatest Briton of his time" by W.O. Bentley, was one of the Bentley Boys. He refused to adhere strictly to Bentley's assertion that increasing displacement is always preferable to forced induction. Birkin, aided by a former Bentley mechanic, decided to produce a series of five supercharged models for the competition at the 24 Hours de Le Mans Mercedes-Benz had been using superchargers for years.
Thus the 4½ litre Blower Bentley was born. The first supercharged Bentley had been a 3 litre FR5189 which had been supercharged at the Cricklewood factory in the winter of 1926/7. The Bentley Blower No.1 was officially presented in 1929 at the British International Motor Show at Olympia, London. The 55 copies were built to comply with 24 Hours de Le Mans regulations Birkin arranged for the construction of the supercharged cars having received approval from Bentley chairman and majority shareholder Woolf Barnato and financing from wealthy horse racing enthusiast Dorothy Paget Development and construction of the supercharged Bentleys was done in a workshop in Welwyn by Amherst Villiers, who also provided the superchargers.
W.O. Bentley was hostile to forced induction and believed that "to supercharge a Bentley engine was to pervert its design and corrupt its performance."However, having lost control of the company he founded to Barnato, he could not halt Birkin's project.
The essential difference between the Bentley 4½ Litre and the Blower was the addition of a Roots-type supercharger to the Blower engine by engineer Amherst Villiers, who had also produced the supercharger. W. O. Bentley, as chief engineer of the company he had founded, refused to allow the engine to be modified to incorporate the supercharger. As a result, the supercharger was placed at the end of the crankshaft, in front of the radiator. This gave the Blower Bentley an easily recognisable appearance and also increased the car's understeer due to the additional weight at the front. A guard protected the two carburetters located at the compressor intake. Similar protection was used, both in the 4½ Litre and the Blower, for the fuel tank at the rear, because a flying stone punctured the 3 Litre of Frank Clement and John Duff during the first 24 Hours of Le Mans, which contributed to their defeat
The crankshaft, pistons and lubrication system were special to the Blower engine. It produced 175 hp (130 kW) at 3,500 rpm for the touring model and 240 hp (180 kW) at 4,200 rpm for the racing version, which was more power than the Bentley 6½ Litre developed
Despite representing the epitome of 'Boys Own' motoring and providing the heart and soul of the hobby, selling the requisite fifty cars that had needed to be built in the dire economic climate of the late 1920s proved hard work for Bentley Motors. As a result of this, though it may seem improbable today, not all were sporting tourers. Some 17 were delivered as drophead coupes and even closed Saloon cars. Among the few cars that were capable of 100mph on the open road. Blowers have always been regarded as the Supercars of their era. In period the British magazine Motor Sport spoke of the Blower's 'remarkable acceleration' and 'ancestry of well-tried racers' calling it 'a car for the connoisseur of sporting cars...' - Nothing has changed today!
