Mike Sayers

4½-litre

BLOWER BENTLEY

The Doncaster show is the place to keep up with progress on Mike Sayers’ 4½-litre Blower Bentley engine. It is being built to 1:3 scale. All components are constructed as exact replicas of the original by using either works drawings of original components as reference. No castings are used and everything is machined from solid using manual rather than CNC machining.

Mike’s much acclaimed first model Bentley engine was a 3-litre, which famously powered the marque’s first winner of the Le Mans 24-hour race. His current project is a 4½-litre ‘Blower’ engine, designed by W.O. Bentley. With the original un-blown 4½, Bentley was looking to produce a more powerful car by increasing the engine displacement. That brought success in three more Le Mans races, 1928-30 in normally aspirated form.

The supercharged version was unveiled at the Olympia Motor Show in 1929. Some 55 examples were built, to comply with Le Mans regulations. W.O. Bentley was not in favour of supercharging his engines, but by then he had lost control of the company to Woolf Barnato, the majority shareholder and chairman. Dorothy Paget financed the Blower project, a change from her great passion of horse racing for which she was famous for many things, including ownership of Golden Miller, the winner of five Cheltenham Gold Cups and a Grand National. She also bred Arkle, regarded by many as the best ever racehorse.

The Blower was essentially a Bentley 4½ with the addition of a Roots-type supercharger made by Amherst Villiers. W.O., still chief engineer at the company, had refused to allow the engine to be modified to incorporate the supercharger. Consequently, it was placed at the end of the crankshaft in front of the radiator, which also made it immediately recognizable. Two carburettors on the intake were protected by a guard. The crankshaft, pistons and lubrication system were unique to the Blower. It produced 175hp at 3500rpm, but in racing form produced 240hp at 4200rpm. Sadly, the company was a victim of the recession and was bought by Rolls-Royce in 1931 for just £125,000.

Photos by Roger Froud.

https://www.sarikhobbies.com/model-engineer-builder/

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