The modern Bentley
As the road-test report by A.H. in the colour-section of this issue of Motor Sport is on the Bentley Mulsanne Turbo, it is appropriate to reflect on the Bentleys made by Rolls-Royce Motor Car Division of Crewe.
When it was time to return the test car we went to the Rolls-Royce factory and talked about them with Jack Read (“J.M.R.” by R-R identification), the present Future Projects Manager, who is, by the way, a VSCC member, and Ian J. Adcock, the new R-R Press Relations Manager. The point was made that for some time the once famous Bentley name was losing impact, especially in America and to some extent in Europe, and this the Company, now operating under the Vickers umbrella, was anxious to rectify. (Incidentally, prior to 1926 Vickers had run the Wolseley Company, their most prestigious ’20s model being the 24/30 h.p. six-cylinder Wolseley.) So a move was made to re-establish the Bentley as an exciting, sporting, separate entity when the Bentley Mulsanne 4-door saloon was shown at the 1980 Paris Salon.
We do not know who thought up the type-name “Mulsanne” but it was undoubtedly brilliant, conjuring up as it does memories of Bentley’s finest years at Le Mans, where the old W.O. cars were victorious four years in succession, from 1927 to 1930, with 3-litre, 4½-litre and 6½-litre Speed Six cars, having first won this prestigious 24-hour race in 1924. Incidentally, in view of the importance of American sales it is interesting that the first appearance in racing of a “works” Bentley was at Indianapolis in 1922, when a 3-litre finished 13th in the 500-Mile Race.
Although the Bentley Mulsanne had to be based largely on Rolls-Royce Silver Spirit design and components — and no harm in that, especially in view of the prestige earned by the pre-war R-R-built Bentleys and their splendid showing in the Ulster TT races of 1934, 1935 and 1936 by E. R. Hall’s Derby Bentley — if the present interest in the New Bentley increases and sales successes are achieved, the intention is to diversify away from the Spirit to an even more individually Bentley-like motor-car, under the R-R badge. At present output runs at some 200 Bentleys a year and, asked whether the introduction of the Mulsanne Turbo is likely to reduce sales of the non-Turbo Mulsanne Bentley, in view of the fact that by the end of this year 125 Turbo Bentleys will have been delivered, we were told that customers seem to prefer to take the model available to them, instead of being put on a waiting list, changing to the later model when this is available. We know this, from conversation with R-R owners, to be in the tradition of replacement sales of these cars, some former owners, especially Company-users, ordering a new Rolls-Royce or Bentley without necessarily trying it or even seeing the more recent model.
On specifics of the Bentley Mulsanne Turbo, we asked why turbocharging was adopted, after experiments which began in 1974. Mr. Read told us that it was the test way of obtaining the 50% power output they were looking for, without enlarging the 6.7-litre vee-eight engine — incidentally, they were also aiming for a 5% improvement in fuel consumption. Otherwise, it meant either building a completely new lightweight car or increasing the capacity of the existing engine to some 10-litres, as no increase in crankshaft speed was contemplated. At the time of the Mulsanne Turbo’s introduction no change was made in the compression-ratio of the R-R engine when it was turbocharged, this remaining at 8.0 to 1, although since then the c.r. of the Silver Spirit engine has been increased to 9.0 to 1. The turbocharger was arranged to blow into the Soles 4AI four-choke downdraught carburetter in order to keep the top of the engine unchanged, but it is probable that fuel-injection will be used in the near future. Asked why Rolls-Royce, who have made some very fine superchargers of their own, adopted an American Garrett AiResearch turbocharger, we were informed that this was logical, as Garrett had a wide range of big-output turbochargers available and much technical know-how. In fact, a Holset installation had been experimented with; the present installation involves an air-balance box to adjust turbo-pressure to that of fuel-feed pressure. Shades of Mercedes-Benz having to devise a complicated means of pressurising both carburetter float-chamber and fuel tank, on their vintage sports-cars, in which the accelerator brought in the mechanically-driven supercharger that likewise blew air through the carburetter. . . .
The Bentley Mulsanne turbocharger runs at up to 80,000 r.p.m. but R-R see no problems, either from the bearings or in respect of corrosion of the casings and piping, the materials used ensuring that the installation, and indeed the exhaust-system, should last the life of the car. Turbo-lag has been overcome by providing for turbo speed to be always in advance of the speed of the torque-converter and no particular noise problems were experienced from turbocharging; in fact, in some ways the turbine acts as a noise damper. Looking to the future, we enquired of Mr. Read what size engine he would visualise should a smaller Rolls-Royce or Bentley be made in the future. While his answer must be pure conjecture at this stage, he thought perhaps something in the region of 4-litres, probably in vee-eight form, but that six cylinders might suffice, it being all a matter of litres-per-ton-mile, allied to the required arid essential smooth and quiet functioning.
After talking with Mr. Read the Editor was allowed to drive back to the R-R factory after lunch in an atmospherically-fed Bentley Mulsanne. Here was all the expected Clubland interior and elegance. The winged-B badge no longer rides ahead of one but the dignity and sumptuousness remain. The steering is extremely light and the ride is intended for comfort rather than frantic cornering, although if the customer wants harder springing this can be provided. The big Bentley is remarkably easy to place accurately on the road and when parking, but it was a trifle more audible than tradition tempts one to anticipate; but then if the hush was entirely silent one would not hear it! And when W.B. inadvertently signalled a r.h. turn with the gear-selector lever, this being placed unexpectedly like a steering-column stalk, this merely emphasised the remarkable lightness of even this control. Over, then, to the Test Report on the Turbo on page 550.
Formation aerobatics with smoke, parachuting, ballooning, an autogyro and a selection of historic aeroplanes will combine to make-up the first main air display of 1983 at the Shuttleworth Collection at Old Warden, near Biggleswade in Bedfordshire. The date is Bank Holiday Monday 2nd May, starting at 2 p.m. The attractions will include the Marlboro Aerobatic Team, the famous preserved Fairey Swordfish torpedo bomber and the Hawker Sea Fury carrier fighter from the Royal Navy’s Historic Flight, the diminutive Wallis Autogyro, and numerous unique historic aeroplanes, among them the Bristol Boxkite and Avro Triplane.
There is also the newly completed Richard Shuttleworth Memorial exhibition. To avoid congestion, gates will be open by 9.30 a.m. and visitors are encouraged to arrive early. Other dates in the near future include a Mini-Flying-Day on May 29th, and a Charity Motor Show on Sunday June 5th. June also sees the first of the very popular Flying Evenings, commencing at 7 p.m. on the 11th.