Abstract
Boosting of gasoline engines is gaining increasing importance. Mechanical supercharging and turbocharging are the two main competing systems. In the past turbo charging was mainly targeted at increasing rated power while transient behaviour was one of its weak points - often described by the so called turbo lag. Nowadays much more attention is paid to improved low-end torque and to immediate response to the driver´s demand for rapid acceleration, i.e. elasticity. Both characteristics are seen as enablers for downsizing concepts.
In the following the current state of the art for turbocharged engines will be shown and steady-state and transient performance will be demonstrated. Looking for further improvements, advanced charging technologies with variability on turbine or compressor side will be evaluated. The potential of the most promising variant will be tested under steady-state as well as under transient conditions using the same base engine hardware.
Gasoline Direct Injection in combination with dual continuously variable cam phasers is another competing technology and will be analyzed. At the end all systems will be compared. The most beneficial application for each technology will be shown and an outlook of further improvements will be given.
KEYWORDS - gasoline engines, turbocharging, variable turbine geometry, gasoline direct injection, cam phasing