Handbook of Turbomachinery Second Edition Revised - Ventech!

Figure 11c G-Lader supercharger is driven by the engine’s crankshaft via a
toothed belt drive. Air is taken in at the top of the supercharger. The compressed air
leaving the central port passes through the air-to-air intercooler in the lower center of
the picture. (Courtesy Volkswagen AG.)
Because the centrifugal supercharger runs cooler than an exhaustdriven
turbocharger, an intercooler may not be needed. Also, heat shields
and other thermal protection provisions associated with the installation of a
turbocharger are not required. Most important, the centrifugal compressor
provides virtually a near-instant boost without turbo lag. Finally, unlike
many positive-displacement superchargers, the centrifugal supercharger is
immune to backfire problems.
Maximum Compression Ratios
The boost pressure resulting from supercharging or turbocharging
effectively increases the pressure in the cylinders. This has the same effect
as increasing the compression ratio. There is a maximum compression ratio
for spark ignition engines because excessive combustion chamber pressure
can lead to denotation and potential engine damage (Fig. 13). This problem
Copyright © 2003 Marcel Dekker, Inc.