A Study on the Intake Pressure Wave Actions and Volumetric Efficiency-Speed Characteristics of Multi-Cylinder Engines
Presented in this paper is the relationship between intake pressure wave actions and the gen eral volumetric efficiency-speed characteristics of multi-cylinder engines. Coupling of primary pipes at the plenum produces a variable pressure boundary at the entry of primary pipes. The plenum pressure fluctuations directly superimpose on to the inlet Port pressure and in this way the volumetric efficiency curve is modified over that of the open primary pipe system. In speed domain the plenum pressure fluctuations experience a change of favorably to unfavorably phased, and the amplitude from significantly large to relatively small. Corresponding to that, the general volumetric efficiency characteristics of multi-cylinder engine can be divided into three sub-regions: (1) it is boosted over that of open primary pipe system; (2) it dips towards and down below that; (3) it follows the trend of that but with lower amplitude. Those three sub-regions are divided by the intake system tuning and de-tuned speeds which can be quite accurately predicted by a synthesis wave action model derived from this study.
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