An improved multi-fuel supply and co-injection system and method for powering internal combustion and turbine engines, whereby various combinations of fuels, both liquid and gaseous, may be mixed together and fed into the system, under the real-time control of a microprocessor responding to a variety of sensors and acting on a variety of control devices, all working together in a manner designed to enhance the utilization of the thermal content of the various fuels, and in particular to enhance the combustion efficiency and increase the power output while decreasing the consumption of fuel, calculated both by quantity and by cost and whereby the liquid fuel lubricates the moving parts of the injection system.