Without attempting a scientific discussion of supercharging, the paper presents historical data concerning engines in which the supercharging principle has been employed, such engines being those which utilize special means whereby the cylinder charge is increased beyond the normal charge obtained by filling the cylinder at atmospheric pressure. The object of supercharging is to obtain a greater output of horsepower, due to the greater quantity of fuel mixture consumed and the resulting additional heat-units set free during combustion.
The piston-pump, the vane-pump, Roots blower, and the turbo-compressor are the four types of pump used to supply the required quantity of gas-and-air mixture, a pump of some suitable design being an essential feature. Supercharging methods are outlined, including forced and supplemented induction, scavenging and the use of the two-stroke cycle.
With respect to the different methods used in supercharging different designs are illustrated and their special features are explained. The historical data presented include stationary as well as automotive engines and show that supercharging in some form or other has been employed as far back as the gas-engine can be traced. Aircraft, Diesel and racing engines are considered, as well as those for passenger cars.
Regarding supercharger development for passenger-car engines, the author suggests the possibility of designing a supercharger that will produce greater torque at low speed and enumerates some of the advantages that would result if this were accomplished.