What Can the Turbocharger Do for the Engine?

The turbocharged engine, by operating at intake and discharge conditions several times higher than atmospheric pressure, is capable of increasing its specific output to several times that of its naturally aspirated version, and at better fuel economy. Successful integration of the turbocharger requires recognition of the interrelation and interaction of both reciprocating and turbo machines and changes in their performance characteristics.

This paper discusses the relation of intake manifold pressure to engine load and speed as a function of turbocharger performance, and methods of improving performance of the engine at part speed without excessive overboosting at rated speed.