Chapter Four - Turbocharged Engines

Abstract

Publisher Summary This chapter presents the principles of mechanically driven superchargers and exhaust-gas driven turbochargers. The objective of supercharging or turbocharging is to increase the power output of an internal combustion engine. This is accomplished by using a compressor to raise inlet air density, so that a greater mass of air enters the cylinders during the induction process. With more air in the cylinders, more fuel can be burnt to achieve a higher power output. Increased power output reduces the cost, weight, and volume per unit power of an engine. Subsidiary benefits include increased efficiency or reduced exhaust emissions. Turbocharging is now a widely used method of increasing the performance of gasoline and diesel engines. On turbocharged gasoline engines, exhaust systems are more compact and have reduced thermal inertia to increase turbine inlet temperature more rapidly. In the case of gasoline engines, turbocharging continue to be used for high performance sports vehicles. Turbochargers are more firmly established on diesel engines, where their impact on performance, fuel economy, exhaust emissions, and total cost are more than with gasoline engines. The ratings of truck diesels are steadily increasing by turbocharging and better charge air cooling. Variable geometry turbochargers are also being used on some truck and bus engines.