Abstract: A carburetor comprises an air passage containing a hollow toroid having nozzles therein from which fuel/water is injected into the air passage along the periphery thereof. Both the fuel and the water are fed from the pumps and needle valves and respectively control fuel and water flow to the toroid. The position of one fuel control needle valve is determined by the vacuum in the air passage and that of the other fuel control needle valve by the setting of the butterfly valve. An overflow line leads away excess fuel that cannot pass the fuel needle valves.