The response surface methodology (RSM) is used in the present research together with a group of variables that have an effect on engine performance and output exhaust from the combustion process. Therefore, the purpose of the current paper is to get efficiency best by using biodiesel fuel and comparative with normal fuel. The variables under consideration include biodiesel ratio, engine load, and injection pressure. The experiments were performed with different engine speeds (1500, 2000, and 2500 rpm) and with different torques (4, 5, 5, 7, and 8 N.m). The biodiesel ratio (at 10%, 20%, and 30%) affects engine performance, power, specific fuel consumption, and mean effective pressure. The comparison is performed in the previous variables according to the gas ratio of the output exhaust (NOX, CO2, CO, HC, and smoke). The experimental work shows the center composite design approach of the response surface methodology. To get the best performance from the engine, the optimal values for the engine factors are 50% per volume, an engine speed of 2500 rpm, and an engine torque of 5.9744 Nm. The optimal engine performance responses depending on these optimal factors have been Power (KW) 2.36665, BMEB (bar) 3.6465, BSFC (g/kWh) 338.131. The exhaust released was 1.7808 (g/kWh). 273.985 (g/kWh) BSCO2, 0.0436773 (g/kWh) BSCO BSHC, NOX (2.48637 g/kWh), and 3.43418 g/kWh smoke.