Abstract
It is shown from curves illustrating the effect of pressure ratio on charge density for various compressor adiabatic efficiencies that the efficiency of the pressure-charging system has a great influence on engine output. The Roots blower has been the accepted component for pressure charging for many years, but because of its low efficiency attractive engine outputs have not been obtainable. It is also very noisy and not easy to drive, so its use has been unpopular.
To eliminate the shortcomings of the Roots machine the ‘Bicera’ compressor was designed, and the operation of this novel form of pressure charger is described. Test results are given which prove the performance to be superior to that of the Roots type, and when fitted to an engine showed that a pressure-charged four-cylinder engine can give the output of a six-cylinder, naturally aspirated engine, and can be as economical in fuel consumption.
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