AFTER outlining the effects of improper distribution of fuel mixture in an internal-combustion engine and stating how the distribution of a gas is governed, the author discusses motor-fuel condensation and states that, since preheating the air is objectionable and hot-spots do not supply sufficient heat to vaporize the fuel completely, the induction system must distribute wet mixtures; and the partial or complete solution of this problem ordinarily is the result of experimenting with different designs for any particular engine.
Regarding the manifold action with wet fuel-mixtures, it is stated that the phenomena occurring in manifolds which distribute such mixtures are complicated and unstable but some insight into them can be obtained by studying the action in a two-cylinder engine. Analysis shows that the even distribution of wet mixtures is extremely difficult. As to the possibility of securing even distribution by heating the fuel without heating the air, the fuel can be vaporized rapidly by a small quantity of high-temperature heat and then mixed with cool air to form a fog which can be inducted into the cylinder before it can condense.
No complete agreement seems to exist regarding the best form of inlet manifold, although it is generally conceded that sharp turns and sudden enlargements should be avoided, that the various branches should have the same length, that the induction impulses should occur at equal intervals alternately on each half of the manifold and that the gas velocity should be high enough to avoid excessive condensation without causing too high a frictional loss.