In this study, the best ignition timing for an SI engine with the use of E10 ethanol blend was experimentally investigated. Ignition timing was retarded successively by 2 degrees up to 6 degrees at most (denoted as -2, -4 and -6 respectively) and then advanced by 2 degrees successively up to 6 degrees (denoted as +2, +4 and +6 respectively) with respect to the advance values realised with gasoline (termed as 'original advance values') at full load operation. It was generally observed that overall efficiency increases with advanced ignitions. The best performance and emissions were obtained with +4. This increase amounts to 6% for 4 degrees advanced ignition at 3000 rev min(-1). Advanced ignition timing resulted with increase in NOx emissions, while CO and CO2 remained relatively unaffected. Increasing retard in ignition timing caused poorer combustion and hence more fuel consumption but less hydrocarbon emissions.