Internal combustion engine having provisions for heating the fuel-air mixture prior to injection into the cylinders

An attachment to an internal combustion engine having a carburetor means for forming a fuel-air mixture and a butterfly valve, an inlet manifold means for directing the fuel air mixture to cylinders for combustion of the fuel-air mixture and exhaust means for conveying hot combustion gases away from the cylinders, the improvement consisting of a means of injecting a metered quantity of air heated to a temperature of at least 150.degree. F. to the carburetor means in a region in the venturi zone, said region extending from the butterfly valve to a point two inches below the butterfly valve comprising:

• (a) a heater means for heating air to a temperature of at least 150.degree. F.;
• (b) first tube means for conveying said heated air to the carburetor means in said region in the venturi zone from the butterfly valve to a point two inches below the butterfly valve;
• and
• (c) second tube means comprising either a PCV or a vacuum advance line connecting to the first tube means upstream of the point where the first tube means joins the venturi zone;
• (d) a restrictor for metering a quantity of air flowing therethrough positioned in the second tube means comprising a tube with an internal orifice for the passage of heated air from a source of heated air, said tube having an upstream and a downstream end, said restrictor being positioned in said tube means at a pointdownstream of the heater and upstream of the carburetor means, said internal orifice having a diameter of 0.047 to 0.057 inch and said upstream and downstream ends of the restrictor being tapered inwardly to produce a jet action in the flow of heated air thereby causing said heated air to be injected into the carburetor means.