The impact of varying spark timing at different octane numbers on the performance and emission characteristics in a gasoline engine

► The influence of ST on a diesel engine using different RON gasoline was examined. ► Tests were carried out at different STs, RONs and engine speed. ► BTE increased while BSFC, CO and HC decreased with the ORG ST for 95 RON gasoline. ► Best results were observed at increased the ST for high RON gasoline.