A Fierce Debate

W.O. Bentley v Louis Coatalen on the Worth of the Specialised Racing Car

Back in 1924 a very intriguing discussion broke out in the correspondence pages of The Autocar between Walter Bentley, who had raced and broken records with special DFP cars before the war, before designing his masterly three-litre Bentley, and Louis Coatalen, the celebrated Chief Engineer of the STD concern, who loved motor racing and would go to exceptional lengths to enable a Sunbeam to win a Grand Prix. It all began when W.O. wrote expressing the view, unwisely it may seem, that the well­worn sentiments that racing improves the breed and that the racing car of today was the touring car of tomorrow were both equally and utterly untrue, in the context of racing with specially-designed cars.

Quite what prompted W.O. to make these debatable statements is difficult to decide. It may have been that Sunbeam was able to advertise victory in the 1923 French GP and in the 1922 IoM TT a fairly standard Bentley had come home behind a twin-cam straight­racing Sunbeam. W.O. no doubt regarded the Sunbeam as a rival make for his three­litre Bentley, and about to take over, perhaps, that role from the ageing 30/98 Vauxhall. If this was so, he must have been aware that a new three-litre super-sports Sunbeam was on the stocks, which would use a racing­type six-cylinder engine. Could this have prompted him to write this now classic letter to our leading weekly motor journal; he could not have known that the new Sunbeam would not be ready for Le Mans in three months' time, nor make its debut at Kop hill-climb at about the time this letter was published -although in 1925 a three­litre Sunbeam was second in the Le Mans 24-hour race in which all the Bentleys retired..

Whatever the reason, W.O. stirred up a hornet's nest. W.O. was careful to make it clear that he had nothing against the racing of special GP cars and he hoped Sunbeam would again win the Grand Prix but that to pretend such cars were directly useful to touring-car development was "simply ridiculous". Moreover, argued Mr Bentley, an unbeaten racing car is a magnificent, if ephemeral, form of advertisement... He really took the bull by the horns when he declared that if motoring history was properly read it would be apparent that all the things that might be credited to the specialised racing car, like high-speed engines, multiple valves, dual ignition, forced lubrication; etc, were introduced originally for conferring benefits on touring cars! Maybe W.O. was thinking of one touring chassis in particular when he wrote that (he never called his three-litre a sport$ car in the beginning), for he immediately called it a rather sweeping and controversial statement and qualified it by naming front-wheel brakes, adopted first on touring cars, only later for racing. There was more in this vein, for W.O. described as a fallacy that did not exist for a single minute the idea that the racing car had contributed better steels and other materials to the touring car. He suggested that returning large batches of faulty material intended for a touring car had a better stimulus on the steel industry does one read into this a plug for the careful checks made in the Bentley factory? W.O. then spilled much ink suggesting that special racing cars were built in separate factories from production models, by special personnel, and while granting "their technical interest and their prodigious fascination", he did not grant their utility, not even their indirect utility, and he stated that the only useful racing was that done with standard "production" cars.

Louis Coatalen, proud of the Sunbeam success in the previous year's Grand Prix and the long association of his name with racing successes, lost no time in replying. Coatalen in fact didn't mince matters. He said he strongly disagreed with Mr Bentley's views and was very much surprised that he should have started the argument. First, because W.O.'s firm was one of the youngest in the industry and therefore his experience of making racing cars to his own design must be somewhat limited, secondly, because the three-litre Bentley was practically a standardised form of special racing car as used in the 1914 TT(!). As all Mr Bentley's cars were very largely of racing type it was easy for him to have faith in racing only standard cars and Mr Coatalen suggested that on this score his judgement was too biased to carry much weight. After all, he added rather unkindly, one of the objects of a racing programme was to win races...

The legendary Louis went on to say that although W.O. posed as an authority on the history of automobile engineering he was not quite prepared to accept his theory that racing did not benefit the touring car in the specialised fields named by the Bentley designer. These were mostly failures when applied to touring chassis, and only rendered practical by racing. Coatalen cited the side-valve Sunbeams that finished 1,2,3 at Dieppe in 1912, their engines running at the then quite absurd speed of 2,700 rpm, commonplace for ordinary cars in 1924. The high-speed engine was, said L.C., purely a racing product, without which the modern economical, reliable, efficient and light car would be impossible of realisation (was he thinking of the 8 hp and 10/23 hp Talbots?). He went on to say he thought he was correct in thinking W.O. used a dry-sump lubrication system and a nickel-chrome crankshaft, both developed by Sunbeam's (the latter through Vickers) for their racing engines. (Here, surprisingly, Coatalen was wrong, for W.O. had abandoned the drysump, although using this system for his experimental engine of 1919), and he quoted special valve steels and six-cylinder engines (with smoother torque and freedom from vibration -a nasty crack, because the 3-litre Bentley was a "four", Coatalen's forthcoming 3-litre sports car a "six") and asked if the combustion chamber with four­valves-per-cylinder of the Bentley originated for touring or was first exploited on a racing car!)

Coatalan then forced home his message by saying that as a result of racing experience he had abandoned the Hotchkiss drive in favour of the torque-tube and the separate gearbox for a unit gearbox and he 'felt sure that if Mr Bentley had built special racing cars he would have done the same, for fast sporting cars. But, said L.C., "His own car is today almost exactly the same as it was in 1919. No wonder he cannot see the advantage of research by means of special racing cars; he has had no experience of it. Coatalen then disposed of W.O.'s idea that Sunbeam racing cars were the products of separate factories and personnel. They were, he explained, under the control of the technical committee and allocated to the experimental department, which forms an integral part of the Sunbeam and allied factories. There was more, giving Sunbeam's a nice boost, but one feels sorry for W.O., who was undoubtedly thinking of how the 1914 TT Sunbeam was a Peugeot crib and how Coatalen had obtained the services of the great Fiat engineer to design the 1923 GP­winning Sunbeam and the new 3-litre sports model, and how, since the STD amalgamation, L.C. had the use of factories at Suresnes, Wolverhampton and Acton and allowed his special cars to race as Sunbeams, Talbots or Talbot-Darracqs, as expedient...

Coatalen ended his letter by saying that if W.O. wanted to race standard cars, that was his own affair, which he had no intention of attacking, but that he preferred a policy that gave dependable results rather more rapidly and effectively, the end justifying the means, and as a last prod he asked W.O. to think in terms of the 2-litre 14 hp Sunbeam GP engine,which was giving about 140 bhp with a mep hitherto unapproached, yet was not at all freakish-two valves and one plug per cylinder. Furthermore, what about six­cylinder engines? Has it not been abundantly shown by racing that the sporting car of the future must have at least six cylinders? (What a plug for the 3-litre twin-cam Sunbeam!)

Poor Mr Bentley, you. Might have said. But he fought back. First he complimented his famous adversary and made it clear that he had the highest respect for STD racing performances; in fact, by saying the argument as to whether the racing of GP-type cars was of any benefit to touring cars was purely academic rather weakened the point of the very long letters that were appearing, early in 1924. It was for others to decide who was right, said W.O., who put his further case by saying he had no intention of designing a special racing car, that the fact that his firm was a young one showed how far it had got without assistance, and he challenged Mr Coatalen that the Bentley was "a standardised form of racing car"; they had made a few "speed models" but the bulk of Bentley output was chassis intended to carry closed touring bodies. In 1919 he had laid down a touring car that on occasion should be equal to racing work, an ideal way of ascertaining its weaknesses. W.O. refrained, perhaps foolishly he said, from using front brakes in the 1922 TT for one reason only, namely, they were not standard fittings, which was at least consistent. They raced with a standard chassis that could be bought by the ordinary public, as a standard product.

As for Coatalen's 2,700 rpm in 1912, W.O. Bentley was racing a car with a standard sv engine that turned at 3,400 rpm, so he saw L.C.'s engine speed as "very moderate". (He did not say for how long his DFP ran at this rate, but the Sunbeams lasted the length of the Coupe de L'Auto race...). W.O. said multiple valves called for no special pleading and reminded L.C. that in one of his aero-engines he used six per cylinder but in his current GP engine only two. Why? queried W.O.; four would clearly be better. After a further "puff' for the Bentley's multiple valves, the merits of which were apparent without having to build a special racing engine, W.O. wrote similarly of his use of dual ignition, and he explained that he used a normal low­pressure lubrication system. As for nickel­steel crankshafts, they were excellent for aero-engines, where light weight counted, but "simply unnecessary" for cars; mild steel was better for the bearings, too. In fact, W.O. was not interested in the special steels about which Coatalen was so fond, saying Bentleys had stainless steel valves, even in the cars they raced, which never gave any trouble", because we like small valves and two of each. Did L.C. use these special steels in his production cars? If not, why not? And, asked W.O., did he not find them "a little inclined to vary in quality?".

Having thus justified his rather out-dated design, even to saying if he had to design a motor-bus engine he would give it four valves per cylinder, W.O. got in a rather severe crack at Coatalen by asking whether, as he emphasised the influence of racing car design on aero-engines, and as previous to the war "he had a unique racing car experience", this should have enabled him to produce "a predominant aircraft engine". Did it?, asked W.O., presumably thinking pf some less-successful Sunbeam engines of 'this kind! W.O. then disposed of detachable wire wheels and the Hotchkiss drive as not necessarily stemming from racing, saying the 1906 30/35 hp Hotchkiss had it and he believed the 42 hp live-axle Daimler at that time and De Dion and Renault probably even earlier.

If L. C. was so keen on the torque-tube, why had he not adopted it years before, after Ford and other American cars had shown the feasibility of this and unit construction, and why did the 24/70 hp Sunbeam still have Hotchkiss drive, the most elaborate and expensive in the Sunbeam range? Bentleys had an open prop-shaft because it reduced prop-shaft length, reducing vibration. Bentley insisted on a high standard of gearbox quietness and unit construction with a torque tube would have hampered this aim -presumably because a noisy gearbox could not be changed so expeditiously. (Coatalen might surely have remarked that quietness should be built into a gearbox before it was fitted to the car and that his 24/70 hp model was rather dated by 1924 and I feel he might have questioned W.O.'s assumption that torque-tube drive was cheaper -Ed.). Weight distribution was named by W.O. as favouring a separate gearbox. Finally, W.O. again generously praised the fine power of the GP Sunbeams but said he had no interest in building such cars. Incidentally, in querying why L.C. put his 140 bhp racing engine into a short­wheelbase chassis with half-elliptic springs all round surely W.O. was making the way easier for Sunbeam's to introduce the twin­cam 3-litre with its long wheelbase and cantilever back springs?

By now other letter-writers were joining in the discussion, some siding with W.O., others with Coatalen, but nothing very significant emerged. W.O. plucked up courage to remark that were he building special racing cars he "would try to get the best man from Fiat or Sunbeams and give him a free hand" (!). But he must have winced when no less a person than H. R. Pope, writing from Cannes, said he had been very surprised to read in W.O.' s letter the statement that "I still maintain that to pretend racing is directly useful in the development of the touring car of the immediate future is simply ridiculous" because on the first page of the instruction book that had come with a friend's Bentley (a car Pope's mechanic was decarbonising to obviate the necessity, implied in that book, for taking the car back to the works in England for this servicing to be carried out) he had just read: "The Bentley chassis contains many features which have hitherto been associated with racing cars in the minds of the average motorist"! W.O.,' it seems, did not read his own instruction books...

If the Bentley engine with its fixed head was difficult to decoke, another correspondent pointed out that he had found a separate gearbox to reduce repair charges by 10% to 15% over those for cars with unit gearboxes; this might be of interest even today, should anyone be investing in a vintage car he intends to keep long enough for major overhauls to eventually become due. Coatalen was allowed the last word in this battle with W.O. and he ingeniously pointed out that the Sunbeam that had won the 1922 TT had four-valves-per-cylinder, a separate gearbox, and the torque and thrust of the have learnt a great deal since then.” Would Mr Bentley point out the difference between the special racing Sunbeam and the so-called "standard" Bentley? And to show he knew about a more refined form of multi-valve head, Coatalen told W.O. of the current Sumbeam Condor aero-engine in which the four valves were disposed symmetrically in a hemispherical combustion chamber, with their axes convergmg towards the axis of the cylinder, a layout too cumbersome for full advantage in racing engines to the 2-litre formula, but "very much better than four valves in two parallel pairs". Coatalen remarked that "just as the Bentley is a modification of accepted old-type racing practice, which merely by increasing the compression-ratio and fitting a different-camshaft he can make into an out-of-date racing car", so "the new 3-litre Sunbeam is a modification of new-type racing practice". One feels apt to say again, "poor Mr Bentley".

I recall part of this aged argument not with the intention of taking sides for the Sunbeam or the Bentley, but in the hope that, as there is still rivalry between vintage models of these illustrious makes, it will provide some amusement to those not previously conversant with it. – W .B.