Inherent requirement of high specific power of downsized gasoline engine makes turbocharger became a core component in its system. However, delay of response under transient operation due to turbocharger inertial loss and increase of knocking tendency due to high pressure and temperature in cylinder were always pointed out as main draw backs.
In this study, potential benefits of low inertia titanium aluminum (TiAl) turbine wheel turbocharger under steady-state and transient conditions were studied. Transient response reduction by using low inertia turbine wheel turbocharger was experimented and analyzed. In addition, fuel consumption of TiAl and conventional Inconel turbine wheel turbocharger under same torque condition was compared. The results showed that low inertia TiAl turbocharger reduced around 22 % reduction of transient response. However, fuel consumption under steady-state boosting condition with TiAl turbocharger was deteriorated due to lower turbine efficiency. In order to find the way to improve steady-state fuel consumption with TiAl turbocharger, intake valve timing was changed to find out the in-cylinder scavenging benefit of low inertia turbocharger under limited valve overlap period. The results showed that TiAl turbocharger have more fuel consumption benefit under limited valve overlap period than that of conventional one.