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The effects of exhaust gas recirculation (EGR), late intake valve closure (LIVC) and high compression ratio (HCR) on the performance of a 1.6L multi-point injection (MPI) gasoline engine at 2000rpmwere investigated in this paper. Compared to the baseline engine, The improvement of fuel consumption is about 1.4%∼4.5% by using EGR only because of a reduction of pumping loss(PMEP). Nevertheless deterioration of combustion is introduced at the same time for high specific heat of EGR. The maximum EGR rate introduced in this system is limited by cyclic variations of indicate mean effective pressure (COVIMEP) at low load and fresh charge to achieve enough output power at high load. After combined LIVC and HCR, the improvement of fuel consumption is about 3.5%∼9.6% compared with the baseline engine at the same operation conditions because of significant PMEP reduction, increasing of effective compression ratio (ECR).

In order to improve the fuel consumption and expand the range of low fuel consumption area of a 1.5L Atkinson cycle PFI engine, the effect of the intake manifold length and chamber shape on the engine performance is investigated by setting up a GT-power (1-D) and an AVL-Fire (3-D) computational model which are calibrated with experimental data. After this the new engine was transformed to the test bench to do the calibration experiment. The results demonstrate that the intake manifold case_1 (the length is 300mm, side intake form) matched with a new designed chamber improves combustion in cylinder with a range 1.6∼7.4g/(kW•h) reduced in fuel consumption of speed that has been studied; the case_3 (the length is 100mm, intermediate intake form) matched with the new designed chamber with a range 3.86∼7g/(kW•h) reduced in fuel consumption of speed that has been studied. Both case_1 and case_3 expand the range of low fuel consumption area significantly.