CarBrandLogos archive · Bentley · 1927

Bentley4½ Litre

A bigger bore, heavier bodies, and the supercharger its creator never wanted.

Photo: Hugh Llewelyn · CC BY-SA 2.0

The story

A defining chapter in Bentley history.

Explore the ideas, engineering and context that shaped the Bentley 4½ Litre, then continue into its specifications and place in the marque's lineage.

Origins

By 1927 the coachbuilt bodies customers were ordering had outgrown the three-litre engine, so W.O. Bentley enlarged his four-cylinder to 4,398 cc, keeping the single overhead camshaft and four valves per cylinder. Woolf Barnato and Bernard Rubin won Le Mans with one in 1928, and the model became the backbone of the racing programme.

1929 Bentley front 34 right · Sfoskett · CC BY-SA 3.0

Design and engineering

The version everyone remembers is the one the company's founder disliked. Tim Birkin wanted forced induction; Bentley believed the answer to power was capacity, and had built the 6½ Litre on exactly that principle. Birkin went ahead anyway, funded by the heiress Dorothy Paget, with an Amherst Villiers supercharger mounted out in front of the radiator between the dumb irons, and a small run of blown cars was built to satisfy racing regulations.

1929 Bentley 4½ Litre Blower · exfordy / Brian Snelson · CC BY 2.0

In production

The Blowers were fast and unreliable. They never won Le Mans, where the unsupercharged cars did the winning, but Birkin's single-seater took the outright lap record at Brooklands, and that protruding supercharger became the defining image of a Bentley, which is not the outcome W.O. would have chosen.

"Blower" Bentley 4 litre · Hugh Llewelyn · CC BY-SA 2.0

Legacy

Around 720 were built to 1931, the year the company ran out of money and was bought by Rolls-Royce. Bentley returned to the design in 2019, building twelve continuation Blowers to the original drawings, using the surviving team car as the pattern.

At a glance

The facts that define it.

Produced

1927–1931

Units built

720

Engine

4.4 L SOHC straight-4

Designer

Walter Owen Bentley

Technical specification

The 4½ Litre, in detail.

Production: 1927–1931 ; (supercharged model from 1929) ; (720 units) ; 2019–2020 ; (12 units)
Class: Sports car chassis
Body style: as arranged with coachbuilder by customerSfn; VBO; 2006
Layout: FR layout
Engine: 4.4 L SOHC straight-4; I4; 4.4 L supercharged SOHC straight-4; I4
Transmission: 4-speed manual
Designer: Walter Owen Bentley
Assembly: United Kingdom: Cricklewood
Manufacturer: Bentley Motors Limited