Combined Technologies for Efficiency Improvement on a 1.0 L Turbocharged GDI Engine
Cooperated with a local Chinese brand, Geely, the goal of this research is to improve the thermal efficiency on an extremely downsized 3-cylinder 1.0 L turbocharged GDI engine. Effects of compression ratio, low pressure cooled EGR, valve timing and viscosity of oil on fuel economy were studied. The results show that increasing compression ratio (from 9.6 to 12) can improve fuel economy at relative low load (below 12 bar BMEP), but has negative effect at high load due to increased knock intensity. EGR can significantly reduce the pumping loss at low load, optimize combustion phase and reduce exhaust gas temperature. Therefore, the fuel consumption is decreased at all test points. The average brake thermal efficiency (BTE) benefit percentage is 3.47% with 9.6 compression ratio and 5.33 % with 12 compression ratio. However, at higher load (over 18bar BMEP), EGR needs to be reduced to reach the target load, which would affect its beneficial to efficiency.