Perhaps the worst-kept secret among “the right crowd” in motor sport circles in 1929 was the development of the supercharged Bentley. As early as 1 January, 1929 the “Morning Post” suggested that two UK companies would be entering supercharged cars for Le Mans that year and in July 1929, when the “Morning Post” announcement had proved premature, “The Autocar” reported: “It is no secret that experiments have been carried out for a very long time with 4.5-liter Bentleys and a supercharger.”
The inspiration behind the “Blower” Bentley was the legendary Tim Birkin whose family Nottingham lace business struggled to finance his motor sport aspirations. W.O. Bentley never supported the development of the supercharged car and is quoted as saying how much he “disliked the easy short cut provided by the supercharger,” preferring the addition of liters, as evidenced by the 6.5-liter and eight-liter cars, and the increasing use of Elektron castings to reduce front end weight. Nevertheless “W.O.” did not control the purse strings at Bentley Motors Ltd. and the influence of Birkin, backed by the fabulously wealthy Woolf Barnato, saw the supercharged 4.5-liter Bentley come to fruition.
The first production model, Chassis no. SM 3903, a sporting four-seater by Vanden Plas was exhibited on Stand 130 at The Motor Exhibition at Olympia in October 1929, a car which was to be retained as the Company demonstrator. Similar in many respects to the standard 4.5-liter car, the new car was however immediately distinguishable by the massive supercharger protruding at the base of the radiator.
Amherst Villiers had been commissioned by Birkin to design a supercharged unit, Birkin no doubt having noted Villiers’ successes with the supercharged Vauxhall Villiers and feeling that here was the answer to racing success. The cars were fitted with an Amherst Villiers Supercharger Mark IV, Roots-type, with twin paddle rotors, drawing mixture from twin S.U. carburetors and driven off the front of the crankshaft. The crankshaft itself had been substantially strengthened to accommodate the power of the new car.
The supercharger was to the design of Villiers’ engineer and draughtsman Murray Jamierson, who later claimed fame in racing circles with the diminutive supercharged monoposto Austin 7’s, a far cry from the mighty 4.5-liter Bentley. With 9.5 lbs boost at 3,500 rpm the blown Bentley developed 175 bhp and with 10 lbs boost at 3,900 rpm, 182 bhp was produced. Writing of a supercharged Bentley in 1931 “Motor Sport” related: “The supercharging has made possible remarkable acceleration, and when a stretch of open road appears, and the gears are used as they should be, the car momentarily doffs its sheep’s clothing and reveals its ancestry of well-tried racers.”
This car was completed in August 1930 and retained by Bentley Motors Ltd. as the second showroom demonstrator. Some 50 supercharged production Bentleys were built to comply with homologation rules for Le Mans, and some 34 were furnished with Vanden Plas coachwork of which 26 were sports tourers. This car carries its original lightweight fabric covered four-seater tourer coachwork by Vanden Plas (Body No. 1682), although the original flowing wings were replaced by the existing cycle wings over 50 years ago. The car with its original wings is illustrated in “Bentley – The Vintage Years” by Michael Hay, p.146. Bentley records indicate that the company sold the car in 1932 to P. Chandler and the car had four further pre-war owners.
In 1943 the car was acquired by its previous owner and remained in his hands for a remarkable 51 years. Found in a Colnbrook Orchard in 1943 at a time when its new owner, an aeronautical engineer, was employed by Napier at Acton, a deal was struck and the car was to be used almost every day.
The car was in constant use during that period of 51 years and was maintained by its qualified aeronautical engineer owner, who until recent years flew his own Tiger Moth and counted Amherst Villiers among his circle of engineer friends.
The original fabric body has been retained and has a delightful patina of age with isolated areas of aircraft fabric and dope patching reflecting its previous owner’s other passion.
In recent years, the gearbox has been rebuilt, the crown wheel and pinion fitted with new bearings and reground crankshaft were installed in the engine some years ago. The body has never been removed from the chassis during the last 50 years and one or two modifications have been fitted by the previous owner such as new mixture control flow levers from a Tiger Moth, a switched electric fan, two BTH CISE 12-S magnetos, two SU HGV5 carburetors, an oil cooler and some aircraft instrumentation.
Earlier this year the car was driven to Goodwood for the Festival of Speed Press Day, behaving impeccably and making an impressive climb of the hill.
This well known car, one of the most original of the surviving “Blowers,” will grace the best stocked motorhouse, will leave almost all vintage cars at the traffic lights, will take the fast route to the Cote d’Azur and would surely by a “preservation class” winner in a Concours d’Etat.