BETTER ACCELERATION

New Zealand Herald, Volume LXXI, Issue 21982, 13 December 1934, Page 7

BETTER ACCELERATION

RATIO OF POWER TO WEIGHT To meet the demand for improved acceleration will not necessarily involve a general increase of engine size. The big engine, while possessing definite advantages, cannot compete with a smaller unit in point of economy. Acceleration is mainly a matter of the relationship between power and weight and can be improved by weight reduction as effectively as by increasing the size of the engine. There are also great possibilities in the supercharger as a means of increasing power and torque without adding appreciably to the weight. It seems highly probable that cars will become a good deal lighter during the next few years by the evolution of more scientific methods of construction and bv an extensive use of light alloys.' To-day, the majority of 4-5-seater saloons rated at 10-12 h.p. weigh over one ton unladen or nearly 14 tons with a full complement of passengers. This represents an altogether excessive load for an engine of limited capacity. Apart from weight and engine giz<\ the efficient utilisation of the power available has a vital influence upon the acceleration attainable. This is the function of the transmission system. Easy-change gearboxes, silent gearing to encourage the use of the lower ratios, and automatic clutches all tend to improve car performance. The next development in this direction will be the more general use of automatic and infinitely variable transmissions which allow the engine to rim at its peak of power output throughout the period in which a car is gathering speed. Such a result cannot be achieved with the ordinary step-ratio gearbox. The question of brakes, although equally important in its bearing upon safety and average speed, is not at the moment so pressing because braking systems in general have reached a high standard of performance. There is, however, room for improvement on the lines of lighter pedal pressures and a bigger margin of safety on greasy roads. Perhaps the road engineers will also play their part by the universal adoption'of safe surfacing materials. At present the wide variation in road conditions makes the provision of a consistently safe braking system almost impossible.