Emphasizing the necessity of persuading fuel manufacturers to improve the suitability of internal-combustion engine fuel by the mixture of other materials with petroleum distillates, and realizing that efficiency is also dependent upon improved engine design, the author then states that results easily obtainable in the simplest forms of automotive engine when using fuel volatile at fairly low temperatures, must be considered in working out a future automotive fuel policy.
The alternatives to this as they appear in the light of present knowledge are then stated, including design considerations. The principles that should be followed to obtain as good results as possible with heavy fuel in the conventional type of engine are then described. These include considerations of valve-timing and fuel distribution. Valve-timing should assist correct distribution, especially at the lower engine speeds. Manifold design should include a steady up-grade from the carbureter to the inlet valves and the manifold should be compact on multi-cylinder engines; the best manifold shape must be worked out for each particular engine. The final requirement in utilizing the heavy fuel of low volatility successfully is heat, but for good distribution the less the amount of heat used the better, because high temperatures reduce volumetric efficiency.