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Handbook of Turbomachinery Second Edition Revised - Ventech!

Handbook of Turbomachinery Second Edition Revised - Ventech!

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INTRODUCTION<br />

13<br />

Automotive Superchargers and<br />

Turbochargers<br />

William D. Siuru, Jr.*<br />

U.S. Air Force, Colorado Springs, Colorado, U.S.A.<br />

Supercharging uses a mechanically driven ‘‘air pump’’ to artificially supply<br />

the engine cylinders with a greater amount <strong>of</strong> air/fuel mixture than would be<br />

taken in under normal atmospheric conditions. The basic concept in most<br />

supercharging devices is to increase the outlet pressure over the inlet<br />

pressure and therefore the density <strong>of</strong> the air delivered to an engine above<br />

ambient atmospheric conditions. This in turn increases the mass <strong>of</strong> air<br />

drawn into the cylinders during each intake stroke. Then, if the optimum<br />

air-to-fuel ratio is still maintained, more fuel can be combusted to produce<br />

more power output.<br />

A supercharged engine <strong>of</strong> a given displacement size can produce<br />

significantly more power and torque compared to the same engine when<br />

normally aspirated, that is, not supercharged. Conversely, a smaller and<br />

* Retired<br />

Copyright © 2003 Marcel Dekker, Inc.

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