Forced-Induction Possibilities for Automotive Vehicles 340120
IT is always the automotive engineer's endeavor to improve automotive vehicular performance. Greater acceleration and higher speeds have been accomplished by a continuous increase of engine sizes, until today further increase by this method is not logical.
We are today turning to dual axle ratios and streamlining to accomplish further increases; the former to allay the disastrous effects of the drooping torque-curve at high engine speeds, and the latter to reduce the power to propel the vehicle.
Reduction of engine-speed wheel-speed ratios is ideal for high speed but represents a loss in acceleration at intermediate speeds. Reduction of wind resistance of the vehicle, only valuable at high speeds, permits only a slight increase in top speed because of the rapid reduction in power at high engine speeds.
Thus a dilemma exists, which can be avoided by forced induction, or supercharging. Forced induction with dual axle ratios and streamlining produces the only complete picture.
Of three general types of compressors adaptable to automotive engines-the vane, Roots, and centrifugal types-the last is best adapted for present-day engines. Actual tests show, in addition to a remarkable improvement in performance, a sizable reduction in specific fuel consumption.
Centrifugal compressors are least expensive, most silent, involve the fewest problems, have the greatest production possibilities, and can be adapted to present engines in a number of satisfactory ways.