From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Article from 'The Motor' magazine detailing the five-year performance evolution and modifications of a Forrest Lycett Bentley, accompanied by a wartime cartoon.
| Identifier | ExFiles\Box 160\5\ scan0019 | |
| Date | 30th October 1940 | |
| PAGE 286 Header: The Motor, 286, October 30, 1940. Title: A Record Breaker on the Road . . . . . Contd. Image Caption: FIVE-YEAR PLAN. The external changes in Forrest Lycett's Bentley are clearly shown in the two pictures above, both taken at the Lewes Speed Trials. The left picture shows the car as run in 1934 and the right in 1939. The recorded times for these years make interesting reading viz: in 1934, 25.2 secs.; 1936, 21.89 secs.; 1937, 21.30 secs.; 1938, 21.59 secs.; 1939, 20.69 secs. The latter is a class record representing an average of 36.2 m.p.h. for the third of a mile compared with 47.5 m.p.h. average in 1934. [Column 1] just first-class engineering well carried out. Nevertheless, the merit of its performance in competitions, coupled with its comfort, stability and comfort on the road, certainly gives ground for reflection. Is the modern car, with all its refinements, so great an advance as some think, or are perhaps the Vintage Club right in their dogma, " the production of real motorcars ceased at or about 1930 "? Whatever may be the answer I can vouch for the fact that this particular car is a tribute not only to the merit of the original design, but also to the skill and enthusiasm of Forrest Lycett. It may not be generally remembered now that the 8-litre Bentley was introduced in 1930; the engine is, in effect, a bored-out 6½-litre, but the frame, gear box and chassis parts quite special. It was sold in saloon form at £1,850, and the six-cylinder engine (110 by 140) transmitted the power through a single-plate clutch to a four-speed gearbox which was split on a vertical axis so as to provide for intermediate bearings. The car was capable of 104 m.p.h. on its top gear of 3.53 to 1, 78 m.p.h. on third of 4.75, 58 on second of 6.32; thus the maximum engine speed was about 3,500 r.p.m. The car was made available in two wheelbases 12 ft. and 13 ft. and had a track of 4 ft. 8 ins. The frame was also used on the 4-litre Bentley, of which few were sold to the public, with the difference that the 4-litre had the wheelbase cut to 11 ft. 2 ins. It is this reason that Lycett uses, with, of course, the large engine installed. As will be seen from the illustration, Lycett's car originally had a four-seater touring-type body, and its success in this guise prompted the urge for intelligent modification. It was felt that the engine, although having an overhead camshaft (incorporating highly ingenious drive, embodying triple eccentrics, was not really suitable for a high degree of tuning. The ports were slightly opened up and polished, and the other modifications undertaken which I have previously [Column 2] mentioned, but the gain in power as compared with the standard type does not, I should think, exceed 30 per cent. This is a creditable enough result, implying about 250 h.p., or about 31 h.p. per litre., As the peak r.p.m. have not been shifted much above 3,500, approximately 9 h.p. per litre 1,000 r.p.m. are developed, giving an m.e.p. of about 116 lb. per sq. inch. The frontal area of the car has been reduced by lowering the height of the radiator, and a completely streamlined undertray has been provided. The most fruitful source of endeavour has, however, been in respect of weight reduction. Might I recapitulate from my article of two years ago in itemizing the points, for they are of considerable interest? WEIGHT SAVING Component. | Weight saved. Batteries and mounting | 60 lb. Radiator | 20 lb. Brake drums | 45 lb. Exhaust manifolds | 18 lb. Exhaust pipes | 40 lb. Steering brake servo | 35 lb. Shorter front springs | 40 lb. Flywheel and clutch | 35 lb. Camshaft damper | 12½ lb. Bonnet | 33 lb. Spring gaiters and tie-rods | 20 lb. Brake rods | 17½ lb. Rear spring hangers | 5 lb. Pistons | 6 lb. Total: 487 lb. The original chassis weight was rather under 37 cwt., so, with approximately 4 cwt. removed and a body weighing not much more than 1 cwt., it will be seen that the complete car now scales a figure about 10 per cent. less than the original chassis. Note how this large overall saving is compounded from many details. I cannot think of a better illustration of the fact that progress usually comes not from a single radical change but from adding together a number of small improvements. The saving of weight on the exhaust system (80 lb. in all) is, of course, particularly striking and is achieved by substituting sheet metal manifolds for castings and Burgess silencers in place of the original heavy mufflers. [Column 3] All these things, of course, have enabled considerably higher gears to be used. In place of the standard final ratio of 3.53, a 2.7 gear is now employed, making 3,500 r.p.m. converted to m.p.h. 130 in place of 104, the tyres now being 19 by 7, in place of the original 21 by 7. The intermediate gears have now been modified, and it is interesting to note the new and old speeds and ratios. Ratios | Speed | New | Old | New (Old) Top | 2.8 | (3.53) | 130 (104) Third | 3.42 | (4.75) | 100 (78) Second | 4.7 | (6.32) | 75 (58) Bottom | 6.3 | (11.45) | 50 A very powerful clutch stop is fitted and the right-hand gear lever has a spring bias towards third and top sectors to help changing up, but engaging lower ratios is by no means foolproof. Even the hand of the Master is known to fail! This brings me back once more to the car on the road. It has a plate on the facia panel (slightly modified from the original) reading " Still the world's finest sporting car." I can well imagine owners of Type 57 CS, 57 Cs and 540 Ks, to say nothing of those who own overdriven 4¼-litres from the North or 12-cylinder Vs{J. Vickers} from the Thames (not forgetting a six-cylinder model from Coventry), disputing this statement. All of them have undoubtedly some points in which they excel the car I have just reviewed. Whether they exceed its virtue as a whole, I should not like to say. Suffice it for the moment that this basically 10-year-old model is still one of the world's great cars and one in which driving does beyond doubt take one " Above the smoak and stirr of this dim spot Which men call Earth, and with low thoughted care Confin'd, and pester'd in this pin-fold here Strive to keep up a frail and Feaverish being— " PAGE 283 Header: October 30, 1940., 283, The Motor Title: The Monte Carlo Rally Expert Goes Through [Cartoon signature at bottom left]: Brockbank [Page number at bottom right]: B7 | ||