Comparison of passive and active methods for improving transient performance of turbocharged engine systems

The drive to reduce engine emissions has placed an emphasis upon turbocharging especially with the
trend of engine downsizing (C. Macrae, (2006), A. Lefebvre et al. (2005)). Turbocharged vehicles
exhibit a weak point of poor drivability under transient running conditions. Previous work by Y. Matsura
et al (1992), has reviewed various methods of improving the transient engine performance. This paper
compares the passive method of reducing the inertia of the compressor wheel and the active method
of injecting air into the inlet manifold. The work has shown that both these methods improve the
transient response of the turbocharger. The effect of the active system is shown to be greater than
that of the passive method.