Study on Fuel Economy and Exhaust Emission of Lean-burn PFI Engines

Lean-burn engines operate at a very lean air-to-fuel (A/F) ratio under light-load and part-load regions, in order to analyze the effect of engine speed and load on the BSFC (Break Specific Fuel Consumption) and exhaust emission of Lean-burn engine, an experimental research was conducted on a 4 cylinder lean-burn gasoline engine using different A/F ratios. The results show that the CO emission level decrease significantly, HC emission level becomes lower at the same A/F ratio, while the NOx emission increases, hence, advanced technologies are needed to carry out the NOx storage and purge operations in the lean-burn engines. Additionally, the experiment also reveals that the BSFC becomes lower as the engine speed and load increase.