HOW RACING HAS IMPROVED ENGINE DESIGN.

HOW RACING HAS IMPROVED ENGINE DESIGN.

Speaking at a meeting of the Society of Automobile Engineers at Indianapolis, Mr. Dusenberg explained how the rule limiting cubic inch piston displacement in American racing events had resulted in reducing the size of engines from 600 cubic inches displacement in 1911 to the present size of 122 cubic inches, and predicted a further reduction to 91 cubic inches.

With these reductions in size, the average speed of cars in the 300 mile races has increased from about 75 miles per hour in 1911 to 127 miles per hour in 1925, whilst the number of cylinders has increased from four to eight. Given correct streamlining and gear ratios, said Mr. Dusenberg, the 122 cubic inch engine would be able to equal the Beach *record of 156.56 m.p.h. made with a car fitted with two 300 cubic inch engines.

Superchargers were fitted to the cars in 1924, and in April last year De Paolo established a lap speed of 139.7 m.p.h. on the Culver City track, whilst more recently Earl Cooper improved the figure to 141.6 m.p.h. In trials, these engines have attained a speed of 5,500 r.p.m., and Mr. Dusenberg predicted that within three years the 91 cubic inch engine would equal the speed of the present engines measuring 122 cubic inches.

NUMBER PLATES.

The R.A.C. has been advised that the police are displaying a certain amount of activity in regard to the back number plates of cars.

On a large number of vehicles the petrol tank is carried at the back of the car, and is cylindrical in shape; it has been the custom of certain owners either to paint the back number on this tank, or to bend the plate so as to conform to its shape.

It may be argued that such practices are not in accordance with the regulations, and traders should note the fact, both for their own and their customers’ benefit.

MR. S. J. BASSETT, who, well known in trials and. racing events, is now technical superintendent in charge of the ” Brooklands ” Austin Seven Department for Messrs. Gordon England, Ltd. The illustration shows the minute proportions of the Austin Seven crankshaft.