Vegetable oils may be used with dilution modification technique as an alternative diesel fuel. rn this study, a used sunflower oil-diesel fuel blend (20:80 v/v%) was investigated in a Pancar Motor E-108-type diesel engine to observe engine characteristics and exhaust emission. The effect of the compression ratio on ignition delay characteristics and smoke emissions of blend fuel was determined in this CFR engine. The results of fuel blends were compared with the reference grade No. 2-D diesel fuel.