Experimental study on combustion and emissions of an SI engine with gasoline port injection and acetone-butanol-ethanol (ABE) direct injection

•High ratio and early direct injection timing (DIT) of ABE can obtain higher IMEP.•GPI + ABEDI can reduce CoVIMEP and CA0-90 especially at lean burn condition.•Late DIT can effectively reduce NOx while early DIT is beneficial for lower HC.•40% or 60% of ABEDIr with early DIT can effectively reduce the particle number.•80% of ABEDIr combined with DIT = 300° CA BTDC can be regarded as best condition.