The Bentley 4½ Litre was developed by Walter Owen Bentley in 1927 to replace the aging 3 Litre. By removing two cylinders from the existing 6½ Litre engine and reducing displacement to 4.4 litres, Bentley created a nimble but powerful inline-four machine capable of competing at Le Mans. The engine displaced 4,398 cc with a 100 mm bore and 140 mm stroke, producing 110 hp in standard touring form and 130 hp in race specification. It featured a single overhead camshaft operating four valves per cylinder — technically advanced for an era when most production engines used side-valve cylinder heads.
The car sat on a robust steel lattice chassis reinforced with ties, necessary to handle the weight of the cast-iron engine. Despite tipping the scales at 1,625 kg, the 4½ Litre handled nimbly. Drum brakes, semi-elliptic leaf springs, and an unsynchronised four-speed manual gearbox were standard equipment. Quick-release filler caps on the radiator, oil, and fuel tanks sped up pit stops during endurance racing.
The supercharged Blower variant was born from a disagreement between the company's founder and one of its most celebrated drivers. Sir Henry "Tim" Birkin, described by W. O. Bentley as "the greatest British driver of his day," believed forced induction could unlock more performance than simply enlarging displacement. W. O. Bentley was fundamentally opposed, famously stating that to supercharge a Bentley engine was to "pervert its design and corrupt its performance." Having ceded control of the company to majority shareholder Woolf Barnato, however, he could not stop the project.
Birkin secured financial backing from wealthy racehorse enthusiast Dorothy Paget and set up a development workshop in Welwyn Garden City, run by engineer Amherst Villiers, who designed and supplied the Roots-type supercharger. Because W. O. Bentley refused to permit modification of the engine internals, the supercharger was mounted at the front of the crankshaft, ahead of the radiator — giving the Blower its unmistakable appearance. The additional weight at the front increased understeer, but also created one of the most recognisable silhouettes in racing history.
The Blower's engine produced 175 hp at 3,500 rpm in touring form and up to 240 hp at 4,200 rpm in racing specification — more than the larger Bentley 6½ Litre. Fifty-five examples were built to satisfy Le Mans homologation requirements; the first was officially presented at the 1929 British International Motor Show at Olympia, London.
The Blower's racing record was marked by unreliability. The two cars entered by Dorothy Paget's team at the 1930 24 Hours of Le Mans, one co-driven by Birkin, retired without finishing. The naturally aspirated 4½ Litre fared better in endurance racing — a car driven by Woolf Barnato and Bernard Rubin finished second at the 1928 Le Mans, setting a new average speed record of 111.12 km/h while running neck and neck with a Stutz Blackhawk.
Birkin found more success in sprint events. At the 1930 French Grand Prix at the Circuit de Pau, he finished second behind a Bugatti Type 35 — prompting Ettore Bugatti's famously acidic description of the 4½ Litre as "the fastest lorry in the world." In 1932 at Brooklands, Birkin drove his personal red single-seat Blower Monoposto to a recorded speed of 222.03 km/h (137.96 mph), winning the Daily Herald trophy. This set one of the most famous speed benchmarks at Brooklands.
British female racing driver Mildred Bruce achieved a remarkable 24-hour distance record at Montlhéry in a Blower, recording an average speed of 89.4 mph — a significant result for a car widely considered unreliable.
Bentley sold the company to Rolls-Royce in November 1931 after financial pressures following the Wall Street crash forced the sale, ending production at 720 units. Despite the Blower's lack of outright victories, it became one of the most coveted collector cars of the pre-war era. By 2013, Blower Bentleys were fetching upwards of seven million euros at auction.
The Blower achieved additional cultural prominence as the preferred mount of James Bond in Ian Fleming's first three novels — Casino Royale, Live and Let Die, and Moonraker — where Bond drives a battleship-grey Convertible Coupé 1930 Blower, one of the last built. In 2019 and 2020, Bentley scanned all 630 components of the original car to create a digital re-creation, using it as the basis for a twelve-car Continuation Series produced in Crewe to original specifications.
The Blower Bentley remains one of the defining symbols of British inter-war motorsport: flawed, magnificent, and unforgettable.