Bentley 4½ Litre Owner’s Workshop Manual: 1927 onwards (all models, including ‘Blower’)

The 4.5-litre Bentley is still one of the most iconic pre-war cars, and the supercharged 4.5-litre Blower Bentley is one of the most sought-after and most valuable cars for collectors.

The road cars were originally built by Bentley as rolling chassis to be fitted with often bespoke coachwork bodies by their buyers. At a time when their rivals were seeking to gain publicity by taking part in motor-racing events, Bentley decided to put together a competition programme to help to market its cars. The Bugatti and Lorraine-Dietrich companies had focused on building cars to compete in the Le Mans 24-Hour race, which was established in 1923. A victory in the this race quickly elevated any manufacturers position, and so Bentley decided to take on the challenge. A privateer 3-litre Bentley first won Le Mans in 1924, but without success in 1925 and 1926, Bentley decided to recruit a British team of drivers and mechanics “united by their love of insouciance, elegant tailoring, and a need for speed,” to renew the marques success. These characters soon became known as the “Bentley Boys”!

The Bentley Boys, including such characters as Woolf Barnato, Dr. J. Dudley Benjafield, Sir Henry Tim Birkin and Bernard Rubin, won several high-profile races in Bentleys, including four consecutive Le Mans victories between 1927 and 1930, Woolf Barnato and Bernard Rubin winning with a 4.5-litre car in 1928. Bentleys founder, W.O. Bentley took the view that increasing the size of an engine was always preferable to supercharging (which Mercedes had been using for some time), but he was defied by Sir Henry Tim Birkin, who with the aid of a former Bentley mechanic, built a series of five supercharged Blower Bentleys to compete at Le Mans. The first car Bentley Blower No.1 was presented at the British International Motor Show at Olympia in 1929, and 55 copies were built to satisfy the Le Mans rules. These cars were sanctioned by Bentley majority shareholder, and by-now Chairman Woolf Barnato, despite the disapproval of W.O. Bentley, who had lost control of his company as a result of the knock-on effect from The Great Depression.

Because W.O. Bentley, who was chief engineer of his company he had founded, refused to modify the engine to allow a supercharger to be integrated, the supercharger was mounted externally, in front of the cars radiator, and driver from the end of the engines crankshaft, giving the car its instantly recognisable look. The Blower Bentleys Achilles Heel was its reliability, and it never won Le Mans, although Tim Birkin did finish second in the 1929 French Grand Prix.

Today, 4.5-litre Bentleys are highly sought-after, and unsupercharged cars change hands for in excess of £75,000, while Blower Bentleys can fetch more than £2.5 million, despite never winning a race!