A carburetion system for an internal combustion engine wherein the cooperation of throttle blades with the throttle body forms channels for high velocity fuel/air mixture flow at part throttle conditions. Fuel is introduced into air flowing through the main intake passage upstream of throttle blades. At partial throttle conditions, the fuel/air mixture flows substantially only through the channels. Fuel/air mixture emerges from the channels at high speed. The channels can be configured such that the emergent fuel/air mixture streams from the channels are directed on convergent paths. Converging streams from the channels collide in the air intake downstream from the throttles, where the severe turbulence resulting from the convergence causes liquid fuel to be finely atomized and evenly suspended in the intake air. Some of the liquid fuel from the mixture may separate onto the walls of the throttle body as a result of passage through the channels or turbulence from the region of convergence. The throttle body may be heated to assist in vaporizing separated liquid fuel.