Biodiesel and ethanol are known as the typical alternative and renewable fuels that can replace fossil and mineral fuels; however, they can affect combustion due to their undesirable innate traits. The investigation is a numerical attempt to compare the synthesized blended fuels of diesel–ethanol (DE) and diesel–biodiesel (DB) and pure diesel (D100) when combusted in a high-speed direct injection (HSDI) diesel engine. The blends are B10D90, B50D50, E05D95, E10D90, and E85D15. In the initial condition of the code, the fuel is defined as multi-component and the share of each component is determined. The results are indicative of lower ethanol-blended fuel’s mean spray droplet (SMD), thus lower CO2 and soot emissions although it is afflicted with low engine output in terms of power and efficiency. The interaction of SMDE85D15 = 2.5 µm and LHVE85D15 = 31,045.3 kJ/kg with the SMDB50D50 = 2.664 µm and LHVB50D50 = 40335 kJ/kg, droplet diameter is more efficient in emission reduction in better spraying, and on the other hand fuel’s intrinsic heat value is more significant for power generation.
