Page:International Library of Technology, Volume 93.djvu/168

 AUTOMOBILE AND MARINE ENGINES

FOUR-CYCLE GASOLINE ENGINES

WATER-COOLED AUTOMOBILE ENGINES

CLASSIFICATION OF AUTOMOBILE ENGINES

1. The broad classification of gas engines into stationary, marine, and automobile engines stands for differences in design and construction. As the stationary engine is intended, first of all, to realize high fuel economy, and to last for many years with but a nominal amount of care bestowed on it, it is made slow running and substantial in all its parts. In small and medium sizes, it weighs anywhere from one to several hundred pounds per horsepower.

The marine engine occupies an intermediate position. If intended for use in a working boat, as for oyster dredging or the like, or for long cruises, it is heavily built and run at a comparatively low speed. If, on the other hand, it is intended for racing, or for light and high-speed boats, it is built as light as possible. In the modern high-speed automobile boats, as they are sometimes called, the weight of the engine is considerably more than that of the hull, and as much as 100 horsepower has been put into a boat not more than 40 feet long over all. Such marine engines are made to run as fast as possible, durability being a secondary consideration; nevertheless, the skill that has been brought to