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DEVELOPMENT OF 1917 AUTOMOBILE DESIGN
Q. Name some of the latest improvements in design.
A. Prominent among these may be mentioned the eight and twelve cylinder V motors, the universal adoption of electric starting and lighting systems, the use of cantilever springs, and wide introduction of the Stewart vacuum feed fuel system.
Q. What are the advantages of the eight cylinder V motor over the "all-in-line form"?
A. The announcement of a prominent motor-car maker in the late fall of 1914 that it was to market an eight cylinder motor vehicle in 1915 created a furor in the automobile trade. This type of motor appealed strongly to the motorist as well as to the manufacturer, as is evidenced by the announcement of the production of eight cylinder models by more than a dozen makers. That manufacturers of engines anticipate a general demand for eight cylinder types can be judged by the fact that all of the leading engine builders are developing eight cylinder engines. Those who have followed the development of the gasoline engine will recall the arguments that were made when the six cylinder motor was introduced at a time that the four cylinder type was considered standard. The arrival of the eight cylinder has created similar discussion of its practicability.
The reason the V type shown at Fig. 330-A is favored is that the "all-in-line form” which is shown at Fig. 330-B is not practical for motor vehicles because of its length. Compared to the standard four cylinder engine it is nearly twice as long and it required a much stronger and longer crank shaft. It will be evident that it could not be located to advantage in the automobile frame. These mitigating factors are eliminated in the V type eight cylinder motor, as it consists of two blocks of four cylinders each, so arranged that one set or block is at an angle of forty-five degrees from the vertical center line of the motor, or at an angle of ninety degrees with the other set. This arrangement of cylinders produces a motor that is no longer than a four cylinder engine of half the power would be.
Q. Is the eight cylinder V engine a new or untried type?
any means, although it is not generally known to automobilists. It has been a standard power plant for aeroplanes for many years, leading exponents being the Antoinette, the Woolsley, the E. N. V. in Europe and the Curtiss in the United States. Messrs. De DionBouton, a leading French automobile manufacturer, is credited with being the first to produce an eight cylinder motor as a commercial proposition. Many racing cars have been built with eight cylinder motors, notably the Rolls-Royce, the Darracq and Winton. The eight cylinder V type has also been widely used in racing motor boats and gasoline propelled railway coaches. It was not a surprise, therefore, to those who were familiar with internal combustion engineering when the eight cylinder engine was applied for automobile propulsion.
Q. What are the real advantages of the eight cylinder engine?
A. Apparently there is considerable misconception as to the advantage of the two extra cylinders of the eight as compared with the six cylinder. It should be borne in mind that the mul.
TOROUE IN INCULATORQUE IN INCH-LA TORQUE NDCR-LA
ON CRANKSIUN TON CRANKSHAN TON CRANKSUIT
eigt frLINDER | TORQUE, DIAGRAM
00 120 150 100 210 240 270 300 350 360* 30 60 90
60 180* 210 240* 270 300 380 560 Comparative torque diagrams of four, ax and alght-cytinder moton, showing Increase in uniformity with added cylinden
Fig. 331.-Curves Showing Torque of Various Engine Types Demon
strate Graphically Marked Advantage of the Eight Cylinder Type.
tiplication in the number of cylinders noticed since the early days of automobile development has not been solely for increasing the power of the engine, but to secure a more even turning movement, greater flexibility and to eliminate destructive vibration. The ideal internal combustion motor would be that which more nearly conforms to the steady running produced by a steam turbine or electric motor. The advocates of the eight cylinder engine bring up the item of uniform torque as one of the most important advan. tages of the eight cylinder design. A number of torque diagrams are shown at Fig. 331. While these appear to be deeply technical, they may be very easily followed when their purpose is explained. At the top is shown the torque diagram of a single cylinder motor of the four cycle type. The high point in the line represents the period of greatest torque or power generation, and it will be evident that this occurs early in the first revolution of the crank shaft. Below this diagram is shown a similar curve except that
Fig. 332.-Front View of the King Eight Cylinder V Engine with
Cover Removed from Timing Gear Case to Show Use of Silent
it is produced by a four cylinder engine. Inspection will show that the turning moment is much more uniform than in the single cylinder; similarly, the six cylinder diagram is an improvement over the four, and the eight cylinder diagram is an improvement over the six cylinder.
Q. Why is better torque obtained with an eight cylinder engine than with a four or six?
A. The reason that practically continuous torque is obtained
in an eight cylinder engine is that one cylinder fires every ninety degrees of crank shaft rotation, and as each impulse lasts nearly seventy-five per cent of the stroke, one can easily appreciate that an engine that will give four explosions per revolution of the crank shaft will run more uniform than one that gives but three explosions per revolution, as the six cylinder does, and will be twice as smooth running as a four cylinder, in which but two