1928 Bentley 4½-Litre Supercharged Tourer
Only 50 examples of the supercharged 4½-Litre Bentley were built, produced specifically to homologate five Birkin team racing cars, and among the few road cars of their day capable of reaching 100 mph, they remain among the most coveted British automobiles ever made.
The project was driven by Bentley Boy Sir Henry Tim Birkin, who wanted a British car capable of holding its own against faster continental rivals. W.O. Bentley himself never approved, preferring larger displacement over forced induction, but Birkin’s partnership with the wealthy Dorothy Paget carried the program forward regardless.
The Amherst Villiers Mark IV supercharger, a Roots-type unit with twin lobed rotors, sits prominently ahead of the radiator and draws mixture from twin SU carburetors. Driven off the front crankshaft, the blower raised output from the standard car’s 110 horsepower to approximately 175 bhp at 9.5 pounds of boost.
The crankshaft and internal components were strengthened to handle the added load.
Birkin demonstrated the car’s potential by finishing second at the 1930 French Grand Prix at Pau against a field of purpose-built monoposto racers. First shown publicly at the 1929 London Motor Show, the Blower Bentley has been referred to by Motor Sport as a car for the connoisseur of sporting cars.
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