Nowadays optimization is increasing in experiments on the engine tests studies. In this study, the test fuel obtained by mixing isopropanol with n-heptane fuel under various engine conditions in HCCI mode was examined combustion, performance and emissions. The study was carried out both experimentally and statistically. Set as engine parameters, different engine speed, test fuel with isopropanol (IP20-IP40) and excess air ratio for experimental study. Engine speed is 800 rpm -1200 rpm, excess air ratio is 1.6 and 2.8, and isopropanol ratio in test fuel of 20% and 40%. From the experiment, investigations were made on effective torque, indicated mean effective pressure, indicated thermal efficiency, maximum pressure increase rate, start of combustion (SOC), combustion duration, COVIMEP, HC, CO and NOx. Before the experiments, experimental series were determined with Response Surface Method, Central Compound Design matrix. Experiments were carried out with the experimental series obtained and the data were analysed. Counter charts, ANOVA results and quartic models were obtained by entering the combustion, performance and output of the HCCI engine into the RSM interface. Then, the targeted response parameters were entered and optimization was made to determine the optimum input parameter. Response parameters under optimum operating conditions Effective Torque 11.438 Nm, IMEP 4.366 bar, MPRR 2.747 bar/°CA, COVIMEP 4.364%, CA10 2.315 °CA, CA50 7 °CA, CA10-CA90 36.245 °CA, UHCs 324.562 ppm, CO 0.0118% and NOx 2.549 ppm were determined.
