•Performance of gasoline engine fuelled with ethanol blend has been investigated.•Hydrocarbons and NOx emissions were influenced by engine operation and fuel type.•Gasoline/ethanol blend showed improvement in engine torque and brake power.•Break thermal efficiency was increased when gasoline/ethanol blend was used. The aim of this study was to investigate the range of opportunities and future prospects of presenting a blend of gasoline/ethanol fuel to run a gasoline engine. Biofuel’s advantages involve emission of low quantities of contaminants to the atmosphere and its renewable character in order to trim down dependency on gasoline as a fuel. Analyses have been carried out to show the influence of compression ratio on engine performance and tailpipe emissions by using unleaded gasoline and gasoline blends with (10 and 20%) pure ethanol SI (spark ignition) engine having a variable compression ratio with the air-cooled single-cylinder engine. Experiments were conducted on five different compression ratios (CRs) of 4:1, 5.5:1, 7:1 8.5:1, and 10:1 with a wide-open throttle. Two combinations of blended fuels were compared to the unleaded gasoline. The results showed that the BMEP (brake mean effective pressure), BTE (brake thermal efficiency), and BSFC (brake specific fuel consumption) obtained with the use of gasoline blends at all CRs were generally higher in comparison to those of pure gasoline. In general, gasoline blends provided a lower exhaust emission compared to gasoline’s emissions at all CRs. Furthermore, NOx emissions were affected much more than other exhaust emissions when changing the compression ratios compared to unleaded gasoline.