EXCESS POWER

Manawatu Times, Volume XLIX, Issue 3493, 1 November 1926, Page 14

EXCESS POWER

USE OE SUPERCHARGERS. Steady progress has been made in the application of superchargers of various designs to racing cars, and undoubtedly it will not bo long until devices of this kind aro adopted as standard equipment on passenger automobiles, writes C. W. Iseicr, research engineer of the General Motors Corporation. Advantages gained by the use of the supercharger arc increase in power, mechanical efficiency, flexibility, fuel economy, and speed. Furthermore, it is possible to build the engine with a compression ratio that is lower than the highest possible ratio that can be used without detonation and yea obtain a surplus of power. Owing to the increased quantity of mixture per charge, it is possible to open the exhaust valves later, thus utilising more fully the amount of work available during the expansion stroke. In the supercharged engine, the mixture Is forced into the cylinder irrespective of the rate of valve opening, hence the lift of flic valve may be more gradual. Moreover, smaller valves that are lighter and less likely to overheat than the larger ones can be used. As a consequence, the total weight of the valve mechanism can be reduced and lighter valve springs used, thereby decreasing the wear of the parts as well as the noise of operation. An onsrino of small piston qisplacement can bo used, as the supercharger is the means of providing Ihe excess power needed for acceleration and hill-climbing. The most important of the many advantages derived from the use of a smaller engine is the reduced fuel consumption. Since the power that can be developed by the, average modern automobile engine is greatly in excess of the power required to drive the car along the level road at constant speed, it is .necessary to throttle the engine or run under part load. The most economical rates of fuel consumption are obtained under full and three-quarter load conditions, and the consumption increases rapidly as the load decreases.