Dual fuel supply system and method for an internal combustion engine

A method of operating an internal combustion engine of the type having a plurality of combustion chambers and an intake manifold through which fuel is delivered to said combustion chamber, said method comprising:

• providing a source of gasoline fuel;
• providing a second source of alcohol fuel separate from said first source consisting of less than 195 proof alcohol;
• adding a corrosion inibitor free of nonvolatile mineral salts to said alcohol fuel;
• delivering said gasoline fuel to said intake manifold in a predetermined amount;
• heating said alcohol fuel prior to delivery into said intake manifold to enhance the vaporization thereof;
• delivering said alcohol fuel to said intake manifold in a predetermined proportion to said amount of gasoline fuel at all engine loads;
• supplying said alcohol in proportions of 11 to 25 percent of said total fuel amount over the range of said engine loads;
• vaporizing said fuels in vapor phase prior to combustion in said combustion chamber;
• introducing water vapor into said combustion chamber with said gasoline and alcohol in the ratio of 0.5 to 2.5 percent;
• and
• including in said corrosion inhibitor a cationic surfactant having substantivity to metal surfaces and being active in both the solute and vapor phase to effectively protect exposed air spaces in addition to the liquid space of said alcohol fuel.