The ordinary diesel fuel was obtained from the TUPRAS-Petroleum Corporation. Biodiesel was purchased from EKO Biodiesel, a commercial supplier. Some properties of the both fuels are shown in Table 3. The fuel properties of biodiesel are slightly different from those of diesel. The lower heating value (LHV) of the biodiesel is approximately 9.78% lower than that of diesel fuel. The cetane number is approximately 6.9% higher than that of diesel fuel. The viscosity, density and flash point of the biodiesel are higher than those of diesel fuel. The biodiesel has a narrow boiling range which is boiled off between 331 C and 348 C. The nomenclature BX represents a blend including X% biodiesel i.e., B5 indicates a blend including 5% biodiesel and B100 represent pure biodiesel. Fuel properties significantly affect engine performance and exhaust emissions. In this regard, not only pure fuels (biodiesel and diesel) but also their proportions of different mixtures such as B5, B20 and B50 were used in experiments. The ORG nozzle hole diameter and INHN of test injector used in the engine are 240 mm and 4. The nozzle tips used in the experiments were mini sac type tips. The injector nozzle hole size and number combinations used in the experiments included 340 2 (340 mm diameter holes with 2 holes in the nozzle), 240 4, 200 6, and 170 8. The flow areas for the selected injector nozzles are nearly same. All the injector nozzles used in the presented study have 125 included spray angles.