Gasoline Combustion System Development for Volvo Cars All-New Engine Family

Volvo Car Corporation has recently launched the first three members of a completely new engine family called Drive-E. It consists of four gasoline and four diesel engines that are characterized by high specific performance, low friction and low fuel consumption. The number of cylinders is limited to four, which implies that these down-sized, boosted engines will replace present five and six cylinder engines. This paper focuses on the development of the Drive-E gasoline combustion system, characterized by a centrally-mounted direct-injection fuel injector in combination with high-tumbling intake ports. The break-down of the large-scale tumble motion into a high level of turbulence leads to fast and stable combustion as well as excellent air/fuel mixing and limited wall wetting. The four gasoline engines span a wide range of power levels. This means that the engine at the entry power level needs to breathe less air than the 2.0 L engine at the highest power level (225 kW, 306 HP). Consequently, intake port design was an important part of the combustion system development. Different intake port geometries are applied at the different power levels, and this paper describes the trade-off between a design that sets up a strong tumble motion (leading to fast combustion and thus reduced fuel consumption), and a design that optimizes engine breathing (enabling class-leading specific power, while keeping fuel-efficiency at a good level).