Bentley Speed Six

Somewhere in Motor Racing Heaven W.O. Bentley must be smiling, because, after more than half a century, the company that carries his name (and his brother’s) has been liberated from Rolls-Royce. Of course, neither popular British marque is independent. BMW owns Rolls-Royce, while Volkswagen is the caretaker of the Bentley brand, but there is no doubt that W.O. would have a preference that circumstance to the previous administration in which Bentleys were little more than Rolls-Royces without the famed radiator shell.

Henry Royce and W.O. (he hated his first name Walter)  battled for supremacy in the British luxury car market for more than a decade, and by an odd coincidence, both started their careers as railway apprentices. It is said that Bentley didn’t care much at all for automobiles as a young man, and instead he pursued his ambition of building big locomotives. Only his hobby of motorcycle racing turned him from his passion for railroad engineering and pushed him toward enthusiasm for internal combustion engines.

Bentley rode a Rex at Brooklands in 1909, and then climbed astride an American-produced Indian as his racing exploits widened. Finally, in 1910 he got the car bug, purchasing a Riley V-twin that year, and in the Teens he bought two Sizaire-Naudins.

Immediately,  he let his railway apprenticeship fade, and for a period,  he worked as a mechanic at the National Motor Cab Company, and then he joined his brother, H.M., as a principal in a DFP automobile dealership in London.

An extraordinary car salesperson

Unlike most salespeople, he took a genuine interest in the mechanical facets of the cars he was selling, and soon he was altering them to produce better performance. One of his neatest techniques was to exchange lighter aluminum-copper alloy pistons for the DFP’s standard-issue pistons. Later,  he reconfigured the automobile’s camshaft for racing versions of the car as well.

However, the success with DFP was short-lived because World War I intervened.  In military uniform, Bentley redesigned the French Clerget rotary aircraft engine, equipping it with (not surprisingly) aluminum pistons, and the re-done engine delivered  extremely better performance. In his honor, the new engines he  worked on were designated BR1 and BR2 (for “Bentley Rotary”) and Bentley was promoted to lieutenant.

When the war was finished  and he and the service parted company, Bentley rejoined his brother in the car dealership. But after the success of his mechanical exploits while in the military service, he yearned to do more than peddle cars; he wanted to manufacture them.

Formation of Bentley Motors

In the summer of 1919,  he created a company called Bentley Motors Ltd to do just that. Teaming with Frank Burgess, a former Humber competition driver who had become popular  for drawing up the dual overhead cam engine that competed ably in the pre-war Tourist Trophy races, Bentley formulated a motor car that was quite advanced for the day.

Justifiably, the chassis design owed much to Humber, but the engine was significantly distinctive and the heart of the new car. Though the engine had but one camshaft (driven via a shaft from the crank), it did provide four valves per cylinder, quite a novelty in 1919. It utilized two plugs per cylinder, a more common practice at the time, and its crankcase was cast of light alloy rather than being a steel stamping for rigidity and weight savings. Block and head of the engine were cast in a piece, and the engine had an exceptionally extended stroke of 5.8-inches and a 3.1-inch bore. (This odd combination of bore and stroke was no doubt influenced by British tax laws which calculated taxable horsepower by extrapolating from the engine’s bore, disregarding the stroke altogether.)

Disobeyed the naming convention

Bentley disobeyed with tradition by calling his creation a “3-Litre.” At that time,  it was ordinary  practice for British auto manufacturers to label their cars with their horsepower (the Rolls-Royce Silver Ghost was the formally called the 40/50, for example), but the calculated horsepower for the Bentley was simply 15.9, which would have been marketing suicide and was inaccurate on top of it.  Real horsepower from the sophisticated engine was more than double that figure.

Aside from the engine, the Bentley 3-Litre was traditional in design. Substantial girders  connected by four cross members served as the frame. Semi-elliptical springs were used at all four corners, and the primary wheelbase was 117.5-inches.

The 3-Litre used a 4-speed gearbox operating through a slightly un-modern cone-type clutch. The right-hand mounted gearbox lever was most often affixed exterior of the bodywork in what was apparently a right-hand-drive vehicle. Until 1924, 2-wheel brakes were utilized, and then the Bentley works added drums to the front wheels as well.

Bad finances plagued Bentley

The sad fact that dogged Bentley Motors Ltd throughout its life was its weak financial condition. The company was started on less than $50,000, and it approached automobile manufacture with a cottage industry fashion.   However, the catch-as-catch-can nature of his manufacturing operation didn’t stop Bentley from going racing. In 1922, his 3-car team won the team prize at the well-respected Tourist Trophy race on the Isle of Man, with separate cars  finishing second, fourth, and fifth. This smashing success against the best from England and  the Continent quickly grabbed Bentley Motors some much-needed recognition.

The coup on the Isle of Man was followed two years later by John Duff’s success  in the 24-Hours of Le Mans, but despite racing successes, Bentley’s sales trickled along–21 in 1921, 122 in 1922, 204 in 1923, and 402 in 1924. Still Bentley’s  victory  in motor racing,  as well as what might be the most fabled Le Mans victory of them all–the win by the 4-Litre in 1927 after a crash had seemingly put it out of the race–gave the company panache far outstripping its sales  figures. One has to remember in that time, cars very much like the Le Mans-winning racers could be purchased straight off the showroom floor and driven day-to-day, so the marque’s dominance was a huge marketing device  in moneyed circles.

This esteemed clientele prevailed upon Bentley to build a more extended wheelbase version of the 3-Litre that would accommodate more elaborate bodywork. The outcome  of their lobbying was a 130-inch wheelbase chassis, though that, too, was most often outfitted with a 4-seater open touring body accented by cycle fenders.

Huge plans in the works

Even as the 3-litre was enjoying success, W.O. Bentley was toying with the idea of  producing  a more refined 6-cylinder car, and he had a prototype built with a 4.5-liter in-line 6-cylinder engine built in time for the Le Mans race in 1924. But the car wasn’t built to race in the event; it was produced  so that W.O. could drive it to and from the race course. While in France, the story goes, Bentley was piloting this “one-off” when he encountered another model, the Rolls-Royce Phantom I. The two engaged in some impromptu rivalry, and though the Bentley prototype held its own, W.O. became convinced that more displacement was required  to preserve his winning margin.

The outcome  of those musings was the Bentley 6-Litre, a car with a powerplant of 6597 cc. In spite of Bentley’s affection for racing,  the new version  wasn’t meant to be a racer.   Instead, it was designed to offer  the company’s luxury-seeking clients with a platform for large, comfortable saloons (sedans) and town cars. And from its launch in 1925, through Bentley’s continued success at Le Mans in 1927 and 1928, that’s how things stood until 1929.

Then, with the stock market booming but a crash looming, W.O. Bentley made a decision  to transform the rather staid 6-Litre “Standard Six” into the performance-oriented “Speed Six,” and yet another legendary prototype. Interestingly, the transformation was accomplished with little more than  typical hot-rodding techniques. The compression ratio was boosted and the Standard Six’s Smiths carburetor was substituted by a pair of SUs. Those simple  substitution and modification of a “hotter” camshaft were all that were necessary to bump the engine from an easy-running 140 horsepower to a still largely under-stressed 180 hp. In race trim, with an even more exotic camshaft, the engine was said to supply  200 horsepower. But  equally important, especially for Le Mans-style endurance racing, was the fact that the engine could run hour after hour at speed without over-taxing itself.

This combination confirmed so successful in the 1929 running of Le Mans that the Bentley Speed Sixes won in a cakewalk. In fact, they were so far ahead of their closest competitors  that W.O. Bentley insisted that they slow down. He wasn’t worried about their durability; he simply didn’t want to reveal  to his competitors–especially Mercedes-Benz–just how superior his cars were.

A technique hides their true power

That bit of genius paid off the following year when the self-same Speed Six that had won in 1929 (piloted by Woolf Barnato and Henry “Tim” Birkin) took first place once again (this time with  Glen and Barnato Kidston sharing driving duties.)   Two factors keyed the victory. First, the rival Mercedes-Benz team had used the 1929 Speed Six Le Mans times as their performance bogey, not recognizing that the cars had slowed significantly  once they were certain the game was won. And, second, the Speed Sixes were so heavy duty that all their drivers had to do was wait for the Mercedes-Benzes to break.

Unluckily, the stock market debacle and consequent worldwide Depression also forced Bentley to the breaking point. W.O. Bentley’s ultimate  stab at the luxury car market was his substantial 8-Litre. Essentially,  a bored-out model of the Speed Six, the 7982 cubic centimeter engine produced up to 225 horsepower, but even as the car was being  launched,  receivership was just days away.

After Rolls-Royce absorbed his company, Bentley moved on to Lagonda, where he designed several superior engines, but never again was he able to capture the magic that was the fabled Speed Six.

—© Studio One Networks—

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