The research of renewal energetics resource has increased substantially in the last decades, the oil reserves are not enough, and the pollution generate since at the fossil fuels burn has alert to industrialized countries on the development of alternative fuels. Colombia is not indifferent to this situation and has found on the natural gas a transition fuel before of massive implementation of biofuels. Conversions of gasoline engines to natural gas (NG) have entrance massively on the vehicle park of the country since facilities on availability of fuel, prize respect to gasoline, and technical support. However, a lot of dismount of equipment is occasioned because the mixer does not accomplish with the proper design for each engine type. This research paper is evaluated the fluid-dynamic behavior of an Air/Natural Gas mixer employing computational fluids dynamics (CFD) to find the constructive parameters that generate the most homogeneous mix in the entrance to intake manifold of a Mazda 323NX engine. An experimental design was made to do the simulations where the factors and their levels are calculated by the Mitzlaff and Agudelo Methodologies. In concluding this research is found that the Agudelo methodology with a venture diameter of 54 mm and gas outlet in groove form generates a 93% of the homogeneous mixer