Advanced numerical models have been developed for better understanding of how adding mixed alcohol fuels to stock fuels affects octane number and emissions. For predictions of combustion and emissions, a reduced chemical kinetic mechanism has been developed for fuel mixtures with components including isooctane, n-heptane, methanol, ethanol, n-butanol, and propanol. The model predictions show a boosted octane number with the addition of alcohols and reduced emissions of both carbon monoxide (CO) and nitrogen oxides (NOx). The numerically predicted trends are consistent with experimental data from the Cooperative Fuel Research (CFR) single-cylinder engine, and the reduced chemistry can be readily implemented into 3-D simulations.