Abstract: Device for the injection in internal combustion engines of combustible emulsions with a readily variable ratio, constituted by a hydrocarbon phase and a component poorly miscible with it, which comprises a positive-displacement pump driven by a portion of the delivery of the injection pump fed with the hydrocarbon phase, said positive-displacement pump carrying out the pumping of the other component of the emulsion; the two components of the emulsion are combined in the injector, which incorporates a static emulsifying device upstream the same injector.