Abstract: Methods and systems are provided for coordinated control of a compound boosting system, including a first compressor staged upstream of a second compressor in an engine intake. In one example, a method may include operating the second, downstream compressor in steady-state to achieve an overall pressure ratio across the compound boosting system while operating the first, upstream compressor transiently, based on an airflow shortfall at the downstream compressor. A timing and amount of electric assistance provided to transiently operate the first, upstream compressor may be adjusted dynamically as the pressure ratio across the second compressor changes.

Abstract: Methods and systems are provided for coordinated control of a compound boosting system, including a first compressor staged upstream of a second compressor in an engine intake. In one example, a method may include operating the second, downstream compressor in steady-state to achieve an overall pressure ratio across the compound boosting system while operating the first, upstream compressor transiently, based on an airflow shortfall at the downstream compressor. A timing and amount of electric assistance provided to transiently operate the first, upstream compressor may be adjusted dynamically as the pressure ratio across the second compressor changes.

Abstract: A system and method are disclosed for operating an internal combustion engine in which the intake valves are electromechanical valves and the engine has direct fuel injection. By opening the intake valves during the intake stroke when the piston is moving at its maximum speed, the turbulence through the intake valve is enhanced, thereby increasing combustion speed, and hence combustion stability at low torque, low speed operating conditions. Furthermore, if the fuel injection interval occurs when flow of gases through the intake is highest, air-fuel mixing is improved.