An experimental and theoretical investigation to evaluate the effect of diesel fuel produced in Iraq and blended with ethanol of four stroke single cylinder direct injection diesel engine was conducted. This study focused on the development of an empirical ignition delay equations based on engine experimental data and to analyse the dependency of ignition delay on equivalence ratio, engine brake power fraction, effect of engine speed, and cetane number .The experimental measurements was performed at compression ratio of 22:1 at engine speed ranging from 1100 to 2600 rpm with an increment of 500 rpm, and engine torque ranging from 2 to 10 N.m with an increment of 2 N.m. The experimental data from engine during test have been saved on the computerized program (ECA 100, VDAS) connected to the unit.The results show that the empirical equations of delay period are resulted as a function of ignition pressure, ignition temperature, fraction brake power with better agreement with the experimental data than an empirical equations of delay period which are resulted as a function of ignition pressure, ignition temperature, equivalence for all fuels at all speeds. E0 Basra has the highest value of the cylinder pressure with low speed at variable torque. E10 blended fuel has recorded the lowest value of ignition delay period in all speeds. The experiments also show that the ignition delay period has been found to be decreased with increase of cetane number, ignition pressure, ignition temperature, equivalence ratio, and the fraction brake power.