GAC Group has set up two modular engine families, G and GS, for various vehicle classes equipping demands. G family engines, which have already gone through three generations, target for the higher torque and power, the lower fuel consumption and the future strict emission standards. For the latest generation, new technologies were added to achieve the development goals based on the previous modular engines. For example, miller combustion cycle with increased compression ratio is introduced in the newer engine combustion system. Additional key technologies such as 350 bar injection system and high tumble intake ports are also applied.
The combustion system development, which established on the GAC Combustion Controlling System (GCCS), was facilitated by integrated use of advanced optical measurements and computational fluid dynamics for improving the in-cylinder flow, fuel sprays and the interaction between them. This paper presents the analytical work done to develop the combustion systems. A higher tumble intake port design enhances the motion in intake process, the well-organized in-cylinder flow may bend over the sprays and keep them from interacting with the cylinder. The redesigned spray structure and piston bowl could do good for a reasonable mixture formation, which decreases the soot and HC emissions, especially for the cold-start conditions. Results from engine test bench experiments show that all of the new generation of the 0.5L/cylinder turbocharged DI gasoline engines can meet the strict legislation for nearest or some considerable time to come.