Evaluation of Organic Octane Improvers for Gasoline Fuels: Performance and Environmental Considerations

Improving gasoline octane quality is essential for modern spark-ignition engines, as increased knock resistance supports better efficiency, optimized combustion, and reduced fuel consumption. Environmental concerns have increased the demand for cleaner organic alternatives instead of conventional metallic octane boosters. This study evaluated selected organic octane improvers for commercial gasoline fuels, focusing on isopropanol (IPA), N-ethylaniline (NEA), and their binary blends. Fuel samples were prepared by controlled dosing of additives into base gasoline, followed by homogenization and determination of octane number using a portable fuel analyzer. Both additives increased gasoline octane rating, but their effectiveness depended on chemical type and dosage. NEA showed stronger octane-enhancing performance, whereas IPA provided a moderate improvement and potential combustion benefits associated with oxygenated fuel components. The investigated IPA–NEA binary blends increased the research octane number by up to 3.5 units at 3 vol.% additive concentration. Engine bench testing demonstrated reductions in CO emissions of up to 60%, in HC emissions of up to 40.8%, and in fuel consumption of up to 4.7% under selected operating conditions. Distillation characteristics remained within acceptable gasoline quality limits, indicating that the investigated additives did not adversely affect fuel volatility.