Abstract

An arrangement for inducting auxiliary heated air into the intake manifold of a carbureted internal combustion engine in an efficient, optimal manner, which achieves substantially complete vaporization of the fuel with a relatively low volume of auxiliary air. The arrangement includes an air induction tube receiving filtered air, which tube is connected to a heater tube disposed within the interior of the exhaust system or to a hot water heat exchanger to heat the auxiliary air, which is then inducted into the engine intake manifold via an insulated double wall tube and a metering block which produces a controlled flow of the heated air into a pair of distributor tubes extending from the metering block into branch cavities of the engine intake manifold. Each distributor tube is centered within a respective manifold cavity and is formed with a hole pattern which produces a uniform diffuse flow of the heated air drawn into the intake manifold by the manifold vacuum so as to produce an optimal flow of heated air. The temperature and flow rates are determined for a particular engine configuration by measuring the fuel flow consumed by the engine at idle at various flow rates and temperatures of the inducted air and selecting the optimal flow rate and temperature.