Bentley 4½ Litre

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The Bentley 4½ Litre is a British car based on a rolling chassis built by Bentley Motors.Template:Sfn Walter Owen Bentley replaced the Bentley 3 Litre with a more powerful car by increasing its engine displacement to Script error: No such module "convert".. A racing variant was known as the Blower Bentley.

Bentley buyers used their cars for personal transport and arranged for their new chassis to be fitted with various body styles, mostly saloons or tourers.Template:Sfn However, the publicity brought by their competition programme was invaluable for marketing Bentley's cars.Script error: No such module "Unsubst".

At the time, noted car manufacturers such as Bugatti and Lorraine-Dietrich focused on designing cars to compete in the 24 Hours of Le Mans, a popular automotive endurance course established only a few years earlier. A victory in this competition quickly elevated any car maker's reputation.

A total of 720 4½ Litre cars were produced between 1927 and 1931, including 55 cars with a supercharged engine popularly known as the Blower Bentley. A 4½ Litre Bentley won the 24 Hours of Le Mans in 1928. Though the supercharged 4½ Litre Bentley's competitive performance was not outstanding, it set several speed records, most famously the Bentley Blower No.1 Monoposto in 1932 at Brooklands with a recorded speed of Script error: No such module "convert"..

Background and development

File:1929 Bentley 4 12 litre Thrupp & Maberly tourer 3829555062.jpg

1929 4½ Litre with original Thrupp & Maberly four seat coachwork

File:1929 Bentley 4.5 Litre Thrupp & Maberly Tourer - rvl.jpg

Very few vintage Bentleys have survived with their four-seater coachwork intact

Bentley at the 24 Hours of Le Mans

The 24 Hours of Le Mans endurance race is a 24-hour race around the Circuit de la Sarthe. The inaugural race was held 26–27 May 1923, and attracted many drivers, mostly French.Template:Sfn There were two foreign competitors in the first race, Frank Clement and Canadian John Duff, the latter winning the 1924 competition in his personal car, a Bentley 3 Litre.

"Made with precision and the finest material,"Template:Sfn and with recent success, the luxurious Bentley cars attracted attention. After two years without success, Bentley convened a group of wealthy British men, "united by their love of insouciance, elegant tailoring, and a need for speed," to renew Bentley's success.Template:Sfn Both drivers and mechanics, these men, later nicknamed the "Bentley Boys", drove Bentley automobiles to victory in several races between 1927 and 1931, including four consecutive wins at the 24 Hours of Le Mans, and forged the brand's reputation.Template:Sfn Template:Sfn

It was within this context that, in 1927, Bentley developed the Bentley 4½ Litre. Two cylinders were removed from the 6½ Litre model, reducing the displacement to 4.4 litres.Template:Sfn At the time, the 3 Litre and the 6½ Litre were already available, but the 3 Litre was an outdated, under-powered model and the 6½ Litre's image was tarnished by poor tyre performance.Template:Sfn Template:Sfn Template:Sfn

Tim Birkin and the Blower Bentley

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File:Birkin Bentley 4½ Litre Blower.jpg

Tim Birkin's Bentley Blower No.1, shown at the 2009 Pebble Beach Concours d'Elegance

Sir Henry "Tim" Birkin, described as "the greatest British driver of his day" by W. O. Bentley, was one of the Bentley Boys.Template:Sfn He refused to adhere strictly to Bentley's assertion that increasing displacement is always preferable to forced induction. Birkin, aided by a former Bentley mechanic, decided to produce a series of five supercharged models for the competition at the 24 Hours of Le Mans;Template:Sfn Mercedes-Benz had been using superchargers for years.^[1]

Thus the 4½ litre Blower Bentley was born. The first supercharged Bentley had been a 3-litre FR5189 which had been supercharged at the Cricklewood factory in the winter of 1926/7.Script error: No such module "Unsubst". The Bentley Blower No.1 was officially presented in 1929 at the British International Motor Show at Olympia, London. The 55 copies were built to comply with 24 Hours of Le Mans regulations.Template:Sfn Birkin arranged for the construction of the supercharged cars having received approval from Bentley chairman and majority shareholder Woolf Barnato Template:Sfn Template:Sfn^[2] and financing from wealthy horse racing enthusiast Dorothy Paget.Template:Sfn Template:Sfn Template:Sfn Development and construction of the supercharged Bentleys was done in a workshop in Welwyn Garden City by Amherst Villiers, who also provided the superchargers.Template:Sfn

W.O. Bentley was hostile to forced induction and believed that "to supercharge a Bentley engine was to pervert its design and corrupt its performance."Template:Sfn Template:Sfn However, having lost control of the company he founded to Barnato, he could not halt Birkin's project.Template:Sfn

Specifications

File:Bentley 4 12 Litre Spa 6-hours 2009 4879560364.jpg

Engine near-side

File:1929 Bentley 4½-litre engine.JPG

Engine off-side

Although the Bentley 4½ Litre was heavy, weighing Script error: No such module "convert"., and spacious, with a length of Script error: No such module "convert". and a wheelbase of Script error: No such module "convert"., it remained well-balanced and steered nimbly.Template:Sfn The manual transmission, however, required skill, as its four gears were unsynchronised.Template:Sfn

The robustness of the 4½ Litre's lattice chassis,Template:Sfn made of steel and reinforced with ties,Template:Sfn was needed to support the heavy cast iron inline-four engine.Template:Sfn

The engine was "resolutely modern"^[1] for the time. The displacement was Script error: No such module "convert".: Script error: No such module "convert". bore and Script error: No such module "convert". stroke. Two SU carburetters and dual ignition with Bosch magnetos were fitted. The engine produced Script error: No such module "convert". for the touring model and Script error: No such module "convert". for the racing model. The engine speed was limited to 4,000 rpm.^[1]Template:Sfn A single, crossflow, overhead camshaft actuated four valves per cylinder, inclined at 30 degrees. This was a technically advanced design at a time where most cars used only two valves per cylinder in a side-valve cylinder head.Template:Sfn Template:Sfn The camshaft was driven by bevel gears on a vertical shaft at the front of the engine, as on the 3 Litre engine.Template:Sfn

The Bentley's tanks – radiator, oil and petrol – had quick release filler caps that opened with one stroke of a lever. This saved time during pit stops.Template:Sfn

This 4½ was equipped with a canvas top stretched over a lightweight Weymann body.Template:Sfn The hood structure was very light but with high wind resistance (24 Hours Le Mans rules between 1924 and 1928 dictated a certain number of laps for which the hood had to be closed). The steering wheel measured about Script error: No such module "convert". in diameter and was wrapped with solid braided rope for improved grip.

Brakes were conventional, consisting of Script error: No such module "convert". drum brakes finned for improved cooling and operated by rod. Semi-elliptic leaf springs were used at front and rear.Template:Sfn Template:Sfn

fixed head coupé by Harrison 1928
File:1928 Bentley 4 12 litre Harrison Flexible Coupe 3828699267.jpg
File:1928 Bentley 4 12 litre Harrison Flexible Coupe 3828692303.jpg
File:1928 Bentley 4 12 litre Harrison Flexible Coupe 3829500136.jpg

Blower Bentley

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Front of a "Blower Bentley", showing the supercharger in front of the grille

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Intake manifold of a "Blower Bentley"

The essential difference between the Bentley 4½ Litre and the Blower was the addition of a Roots-type supercharger to the Blower engine by engineer Amherst Villiers, who had also produced the supercharger. W. O. Bentley, as chief engineer of the company he had founded, refused to allow the engine to be modified to incorporate the supercharger. As a result, the supercharger was placed at the end of the crankshaft, in front of the radiator. This gave the Blower Bentley an easily recognisable appearance and also increased the car's understeer due to the additional weight at the front.Template:Sfn A guard protected the two carburetters located at the compressor intake. Similar protection was used, both in the 4½ Litre and the Blower, for the fuel tank at the rear, because a flying stone punctured the 3 Litre of Frank Clement and John Duff during the first 24 Hours of Le Mans, which contributed to their defeat.^[3]Template:Sfn

The crankshaft, pistons and lubrication system were special to the Blower engine.^[1] It produced Script error: No such module "convert". at 3,500 rpm for the touring model^[4] and Script error: No such module "convert". at 4,200 rpm for the racing version, which was more power than the Bentley 6½ Litre developed.Script error: No such module "Unsubst".

In 2019–2020, Bentley scanned all 630 components that made up the Blower so that they could digitally re-create it and create 12 new models.^[5]^[6]^[7] In December 2020, Bentley Blower Car Zero, the first example of the Blower Continuation Series was presented. The car was built in Crewe according to the historic specifications and based on the production processes of that period.^[8]

4½ Litre supercharged cars
Supercharged engine MS3948, a late 1931 replica-bodied car in the Beaulieu National Motor Museum (see external link below)

Supercharged engine MS3948, a late 1931 replica-bodied car in the Beaulieu National Motor Museum (see external link below)
Photograph of the dashboard of a Blower Bentley

S/c engine MS3948 dashboard
S/c engine MS3948 Another view of the grille, supercharger, and inlets

S/c engine MS3948 Another view of the grille, supercharger, and inlets
A Blower Bentley from the collection of Ralph Lauren

A Blower Bentley from the collection of Ralph Lauren.

Competition performance

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Bentley racing car "Mother Gun", built 1927, 4.5 L engine.

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Bentley 4½ Litre No. 10 took third at the 1929 24 Hours of Le Mans

Between 1927 and 1931 the Bentley 4½ Litre competed in several competitions, primarily the 24 Hours of Le Mans. The first was the Old Mother Gun at the 1927 24 Hours of Le Mans, driven as a prototype before production.Template:Sfn Favored to win, it instead crashed and did not finish. Its performance was sufficient for Bentley to decide to start production and deliver the first models the same year.^[1]

Far from being the most powerful in the competitions, the 4½ Litre of Woolf Barnato and Bernard Rubin, raced neck and neck against Charles Weymann's Stutz Blackhawk DV16, setting a new record average speed of Script error: No such module "convert".; Tim Birkin and Jean Chassagne finished fifth. The next year, three 4½ Litres finished second, third, and fourth behind another Bentley, the Speed Six, which possessed two more cylinders.^[2]Template:Sfn Template:Sfn

The naturally aspirated 4½ Litre was noted for its good reliability. The supercharged models were not; the two Blower models entered in the 1930 24 Hours of Le Mans by Dorothy Paget, one of which was co-driven by Tim Birkin, did not complete the race.Template:Sfn In 1930, Birkin finished second in the French Grand Prix at the Circuit de Pau behind a Bugatti Type 35.Template:Sfn^[2]Template:Sfn Ettore Bugatti, annoyed by the performance of Bentley, called the 4½ Litre the "fastest lorry in the world." The Type 35 is much lighter and consumes much less petrol.Template:Sfn^[1] Blower Bentleys consume 4 liters per minute at full speed.Template:Sfn

Despite the Blower's record of poor reliability, Mildred Bruce, a British female racer, achieved a 24-hour distance record at Montlhéry in one, attaining an average speed of Script error: No such module "convert"..Template:Sfn In 1930, the Daily Herald offered a trophy for the fastest driver at an event at Brooklands. The first year, Tim Birkin and Kaye Don competed and Kaye Don won with a speed of Script error: No such module "convert".. In 1932, Tim Birkin won driving his red Blower "Monoposto," clocking Script error: No such module "convert"..^[9]

Bentley 4½ Litre at Le Mans
Year	Competition	Position	Drivers	Team	Model
1928 Script error: No such module "Check for unknown parameters".	24 Hours of Le Mans Script error: No such module "Check for unknown parameters".	1 Script error: No such module "Check for unknown parameters".	Template:Flagicon Woolf Barnato Template:Flagicon Bernard Rubin	Template:Flagicon Bentley Motors Ltd.	Bentley 4½ Litre
1929 Script error: No such module "Check for unknown parameters".	24 Hours of Le Mans Script error: No such module "Check for unknown parameters".	2 Script error: No such module "Check for unknown parameters".	Template:Flagicon Jock Lawson Dunfee Template:Flagicon Glen Kidston	Template:Flagicon Bentley Motors Ltd.	Bentley 4½ Litre
		3 Script error: No such module "Check for unknown parameters".	Template:Flagicon Dr. Dudley Benjafield Template:Flagicon André d’Erlanger	Template:Flagicon Bentley Motors Ltd.	Bentley 4½ Litre
1930 Script error: No such module "Check for unknown parameters".	French Grand Prix Script error: No such module "Check for unknown parameters".	2 Script error: No such module "Check for unknown parameters".	Template:Flagicon Sir Henry (Tim) Birkin	Template:Flagicon Bentley Motors Ltd.	Blower Bentley
	500 miles of Brooklands Script error: No such module "Check for unknown parameters".	2 Script error: No such module "Check for unknown parameters".	Template:Flagicon Dr. Dudley Benjafield Template:Flagicon Edward R. Hall	Template:Flagicon Bentley Motors Ltd.	Bentley 4½ Litre

End of production

File:1930 Bentley 4.5 Litre Supercharged Kop Hill 2013.jpg

Supercharged car GN1767
mounts Kop Hill 22 September 2013

In November 1931, after selling 720 copies of the 4½ Litre – 655 naturally aspirated and 55 supercharged – in three different models (Tourer, Drophead Coupé and Sporting Four SeaterTemplate:Sfn), Bentley was forced to sell his company to Rolls-Royce for £125,175, a victim of the recession that hit Europe following the Wall Street crash of 1929.^[1]^[10]

Current status

File:Stahls Automotive Collection December 2021 111 (1928 Bentley 4.5 Liter Vanden Plas Tourer).jpg

1928 Bentley 4½ Litre at Stahls Automotive Collection

since 2013^[update]Template:Dated maintenance category (articles)Script error: No such module "Check for unknown parameters"., Bentley 4½ Litre automobiles from this inter-war period – the "Belle Époque" of the automobile for some Template:Sfn – sold for around €1,000,000. Blowers can fetch more than €7 million^[11] and are coveted by collectors despite never winning a single race.^[1]Template:Sfn Template:Sfn For many, the 4½ Litre is to automobiles what the Spitfire is to aircraft.^[1]Template:Sfn

Popular culture

James Bond drives a 1930 Blower Bentley in Ian Fleming's first three novels featuring the character, Casino Royale, Live and Let Die and Moonraker.Template:Sfn In the books, Bond drives one of the last Blower Bentleys built, a battleship grey Convertible Coupé, with French Marchal headlamps.

Notes

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