In order to reduce the BSFC of supercharged Miller cycle engine

a 1.5L turbocharged direct injection gasoline engine was modified to improve its compression ratio and intake tumble. A comparative experimental study on reducing BSFC by electric supercharging and exhaust gas recirculation (EGR) was carried out. The experimental results show that the high compression ratio EGR scheme can significantly reduce the BSFC of the engine

the BSFC decreases by 5% to 13.6%

and the maximum effective thermal efficiency reaches 41.2%

which is mainly due to the reduction of heat transfer loss

air exchange loss and the increase of expansion work. Increasing EGR rate can reduce the heat transfer loss and advance the combustion center

which is the main reason for the decrease of BSFC

and the key to improve EGR tolerance is to optimize combustion structure to reduce ignition delay and combustion duration.