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 about the Lagonda V12 for the Le Mans race.
| Identifier | ExFiles\Box 128\3\ scan0051 | |
| Date | 13th June 1939 | |
| The Motor 110H 740 June 13, 1939. DEVELOPMENT. The engine of the new car is substantially standard but has revised carburation, higher compression and a sump deepened, by the use of a plastic distance piece, shaded black in the drawing, to give better cooling and greater oil capacity. Lagonda for Le Mans First Details of Two Streamlined 4½-litre V12 British Entries CARBURATION. Below can be seen the layout of the two S.U. carburetters which are used on each bank of cylinders. An exhaust hot spot is used with cross connection from one bank to the other, the flow being derived from pulsations in the manifolds. FOR months past the Bentley-designed Lagonda entry for the Le Mans 24-Hour race has been the subject of discussion amongst enthusiastic motorists. This is not without justification, for the last British car to win this race was a Lagonda in 1935, and W. O.{Mr Oldham} Bentley’s designs were victorious no fewer than five times, in the years 1924, 1927, 1928, 1929 and 1930. Yet it should be emphasized that this latest venture is in the nature of an experiment with a view to trying out the product and collecting data for an intensive effort next year. This notwithstanding, everything possible has been done to prepare the cars which will thoroughly and adequately represent the best in British automobile engineering. The 12-cylinder engine and chassis has, of course, been chosen as a basis, its power unit being particularly suitable for development in sports car racing. It has small cylinders with high bore : stroke ratio (1 : 1.13), and, therefore, a capacity for developing high r.p.m. and considerable b.h.p. per litre. In standard form the engine gives approximately 175 b.h.p., and this has been raised to between 200 and 220 b.h.p. by various modifications. The compression ratio has been raised somewhat, but more important is the completely new induction system. Whereas the standard car has two downdraught S.U. carburetters, the Le Mans model has four S.U. L.4 types, these being disposed two to each bank of cylinders, as can be seen from one of our illustrations. Air silencers have, of course, been deleted, and as a further interesting point the cross section and area of the manifolds have been reduced. This, in conjunction with modified valve timing, gives not only an increase in output at over 5,000 r.p.m., but also improved low end torque, with consequent benefit to acceleration. On a circuit through a number of slow corners rapid pick-up is, of course, vital, and, with this in view, no effort has been spared to reduce the all-up weight of the car by every possible expedient. To this end, the box section frame members are drilled out, as are the wishbone arms, brake drums and sundry other components. In addition, much lightening has gone on by details, modifications and changes in material. Thus, the steering box, to cite one example, has been slimmed to the extent of 17 lb. In consequence, the final weight has been cut down to 27 cwt., a figure which compares very favourably with the standard chassis weight of 29 cwt. The weight-reduction process has, of course, been extended to the bodywork, this and the streamlined mudguards being made entirely from hand-beaten aluminium panels. In contradiction to the anticipation of many, the body has a fine streamline form, there being a long tapering tail with fairing behind the driver containing a petrol tank with a capacity of 38 gallons. This should give the car a range between refuelling of approximately 300 miles. A20 | ||