What the Diesel engine has done, its possibilities of development and future application to automotive service are major topics of the paper. When modified for automotive use, the author asserts that the Diesel engine would not only allow the burning of cheaper fuel and provide greater fuel economy, but give immediate opportunity to use the two-stroke cycle; that is, it would generate about twice the power for an equal weight of mechanism, compared with present power attainment. In addition, the two-stroke cycle makes possible partial or entire elimination of exhaust-valves, exhaust through ports being better in every respect, and the Diesel-engine principle affords the possibility of a two-stroke-cycle double-acting engine in which, theoretically, four times the power of the present gasoline engine would be available.
Fuel injection provides other advantages, such as the elimination of crankcase-oil dilution and the fact that no fuel is present in the cylinder until the instant of combustion, just enough fuel then being fed continuously to keep the fire going. But the author says that we must consider injection engines as being slightly more expensive than carbureting engines at present, and that it is the possible ultimate use of the two-stroke-cycle engine which would make it less expensive.
The growth of the Diesel engine in size is traced, some of its history and some applications being described in conjunction with illustrations. The status of large Diesel engines is outlined in like manner, the heat flow in these large units is explained and high-speed injection-engines are analyzed, since they already have broken into the automotive field for use on motor rail-cars and small locomotives.
In this Country, three classes of railroad service exist to which the Diesel engine is applicable: Self-contained rail-car units of up to 100 hp. having from 40 to 80-passenger capacity, a “short-haul” unit of about 300 hp. capacity and a large locomotive of 1000 hp. or greater capacity for freight and passenger service to haul standard car-equipment. Diesel engines have been built for the last two classes but, for the present, the first class has been left to the gasoline engine.
Research is being conducted to fit the Diesel type of engine to the power demands of the automobile, the motor truck, the tractor and the airplane. After describing special types of engine that utilize the Diesel principle, the author states that the paper aims to present the position the Diesel engine is likely to occupy as a prime-mover within the next few years.