Bentley at 100: Looking back on the Blower
Bentley turns 100 this year, and to celebrate its centenary, the venerable automaker sent a Blower Bentley out for some beauty shots on a road course, where it belongs. By the looks of it, the Blower is basking in the light at Silverstone.
Company founder W.O. Bentley did not take kindly to racing hero Sir Henry “Tim” Birkin suggesting that he add a supercharger to the Bentley 4½ Litre. Bentley’s engine was quite advanced for its time, with a single overhead camshaft and four valves per cylinder. Fitted with twin SU carbs and dual Bosch magneto ignition, the engine made 130 horsepower in racing trim.
Though a privateer won the second 24-hour race at Le Mans in a 3.0-liter Bentley, the company’s cars were not successful at the next two races. Other manufacturers were catching up to Bentley’s technical prowess. The addition of a supercharger to the 3.0-liter engine allowed Bentley to take another win in 1927, but by then W.O.’s engine was nearing the end of its product cycle.
Bentley had raced his 6½ Litre six but even the best tires of the time couldn’t handle the mass of a car weighed down by huge cast iron engines. (Ettore Bugatti called the six-cylinder Bentleys the world’s fastest trucks.) W.O. solved the problem by lopping off two cylinders. The 4½ Litre model won the 1928 Le Mans race with Woolf Barnato and Bernard Rubin driving.
Barnato and Rubin were among a group of wealthy British men W.O. Bentley brought together to race and wrench his cars. Like many inventors, W.O. Bentley believed his creations were exactly as they should be. If they needed more power, he favored increasing displacement, not adding forced induction.
Tim Birkin, whom Bentley considered the greatest British racer of his day, disagreed. By the late 1920s, Mercedes-Benz had been supercharging its racing engines for years. By this time, W.O. had lost financial control of his company to financier and Le Mans winner Barnato, who approved the construction of 55 supercharged models to homologate the car. Birkin directed the development of the supercharged Bentley, with the financial backing of Dorothy Paget, a wealthy horse racing enthusiast.
Amherst Villiers made the superchargers, powered them off the front of the crankshaft, and assembled the modified cars in his workshop. The official introduction of the “Blower Bentley” occurred at the 1929 British International Motor Show.
Blower Bentleys were big cars, 172 inches long with a 130 inch wheelbase and a curb weight of 3583 pounds. They were also very fast, and set a lap record at the Brooklands course. The front-mounted supercharger boosted output to 175 horsepower and gave the car a distinctive look. As fast as they were, though, the Blower Bentleys were not reliable.
Had Birkin been less of a flat-out racer and more concerned with preserving his machines, he might have had more wins and lived longer. Neither driver finished the race, but his 1930 Le Mans duel with Rudolf Caracciola at the wheel of a Mercedes-Benz has become the thing of legend, with Birkin making a high speed pass on Caracciola with two wheels off of the track, on grass. By then, tires had improved a bit and Barnato won the race in a Bentley Speed Six.
To take on the Brooklands banked track, a Blower Bentley was rebodied as a single-seater and power was increased to 240 horsepower, allowing Birkin to achieve a 137.9 mph lap average in 1932, then a record. Birkin was a World War One combat veteran, an adrenaline addict, and a fearless racer. Contemporary observers to the Brooklands record attempt said he was frequently airborne due to the uneven track surface.