Interest is clearly growing in the fiercer type of pre-war car, and this year the Vintage Sports Car Club, which caters for owners of real motor-cars made prior to 1931, has included a class for pre1914 cars at its speed trials.

Obviously, many types were likely to be attracted, from really early lowpowered %roiturettes to ears of considerable performance, such as Chambers’s. 1907 42 h.p. Renault and Clutton’s 1908 60 h.p. Itala. Consequently some form of handicap became essential, and Mr. C. L. Nicholson suggested that account should accordingly be taken of each car’s age, weight, and cubic capacity. Cecil Clutton, Press secretary to the club, has been responsible for working out the formula. The Veteran Car Club PT makes use of the formula R — where P= rated h.p., T = time of run and W =weight. This works well enough when only pre-1905 cars are involved, but is not suited to the requirements of the Vintage Sports Car Club. Clutton consequently decided to use a new value for I’, taking the figure of b.h.p. per litre, working on a basis of one h.p. per litre per year ; i.e., four for 1904 cars, ten for 1910, etc. Applied to existing data however this was not entirely satisfactory, and finally the accompanying graph was evolved. The graph was drawn after careful consideration of existing data, though very few reliable details were to hand, the loss of efficiency through depreciation being an extremely difficult factor to assess. The curve was eased off at the lower end, but even so the formula hardly favours the earlier veterans of low power. The formula is :— P 100

where R = result, P = graph reading of h.p., T = time of run in seconds, x = 3 per annum, starting at in 1915, 3 in 1914, G in 1913,. etc., and W = weight in cwt.

That the formula is extremely effective in general application is demonstrated by the following example. Clutton’s 1908 60 h.p. Itala covers the AstonClinton course in 23 secs. and his father’s 1910 16 h.p. Fafnir in 42 secs. Thus for the Itala the formula comes out as 4.74 30 30

Considering that the Itala is in effect a racing-car while the Fafnir is a touringcar, and considering their differing powers, the result is very encouraging. Before drawing the graph Clutton considered taking P as rated horse-power, but found that performance in sprints does not increase in proportion. He then tried VP, but this unduly favoured the bigger cars. A function of P expressible symbolically was considered, but in the end the. graph was deemed advisable, as so many factors had to be taken into consideration. Actually, the original idea of taking P as b.h.p. per litre estimated at 4 up to 1904, 5 in 1905, 6 in 1900, etc., would probably have proved very satisfactory for pre-1912 cars. Thereafter high-efficiency engines of modern type began to appear, and with the increasing crankshaft speeds strokes became shorter and volumetric efficiency increased, resulting in a rising figure for power output for a given capacity. Clutton is convinced that the better racing engines of this period, such as the Mercedes, Peugeot, Opel, and Sunbeam, were giving around 25 b.h.p. per litre, which rules this basis out as a means of collectively handicapping all pre-war

motors. Clutton has devoted a great deal of his time to evolving a practical formula and one hopes that this winter all owners of pre-war racing and sportingcars will show their appreciation by joining the Vintage Sports Car Club and running their veterans in next season’s speed trials. In the meantime students of history who can wield the slide-rule may care to comment on the formula, which, incidentally, was also used at the Bugatti Owners’ Club’s meeting at Lewes for the veteran class. 23 x 21 9 (23 – – 100 ) 9 x18.17 R = = 4).4 35 35 and for the Fafnir:— 42 x 15N 100 ) 4×8&7 R 4 (42 –