Combustion Modeling of Internal combustion engines is still a complex matter, requiring further developments to better simulate the performance and emissions of different fuels. In order to study the influence of gasoline-ethanol blends on a Flex-Fuel engine, a computer model was designed to simulate the experimental conditions using Fractal combustion and Woschni based heat transfer models. The simulations were validated with engine dynamometer experimental tests. In-cylinder maximum pressure, IMEP and emissions data were calculated for different gasoline-hydrous ethanol blends at different engine conditions. The computer model presented a predictive behavior and a good agreement with experimental data for in-cylinder maximum pressure and IMEP. Regarding emissions, the simulations of some pollutants could not match precisely the experimental data, showing the need for additional combustion modeling improvements.