1958-01-01

THE EFFECT OF FUEL INJECTION ON KNOCKING BEHAVIOR 580276

A direct comparison of the effects [illegible] systems on fuel and and engine behavior has been made using the same V-8 engine far both systems. Fuel was metered by a standard four-barrel carburetor in one case, and by a timed manifold-port injection system in the other case. With both systems, provisions were made for varying fuel-air ratio.
A major portion of the work was done on an engine dynamometer, with sufficient vehicle testing using the same engine and fuel metering systems to verify the laboratory results.
When only the method of metering fuel was changed, the following results were obtained:
  1. 1.
    Brake horsepower increased slightly when fuel injection was used; the increase varied from zero to a little less than 3 % depending on engine speed.
  2. 2.
    Fuel economy, as measured by brake specific fuel consumption, was the same with both systems throughout the manifold vacuum load and speed range of the engine when each system was operated to provide minimum specific consumption.
  3. 3.
    Wide-open-throttle octane requirements in terms of primary reference fuels were the same with both systems at speeds above 1600 rpm when the fuel-air ratio for maximum power and the minimum spark advance for best torque (mbt) were used. At 800 rpm, the octane requirement with fuel injection was 1.7 octane numbers lower than the requirement with carburetion.
  4. 4.
    Unleaded sensitive-reference-fuel series tended to rate slightly higher with fuel injection at 1600 rpm and slightly lower with fuel injection at 3200 rpm.
  5. 5.
    Leaded sensitive reference fuels rated higher at all speeds with fuel injection equipment. The magnitude of the increased rating was dependent on TEL concentration; the higher the TEL concentration, the greater the increase.
  6. 6.
    The effectiveness of TEL in improving fuel antiknock was enhanced in this engine when fuel injection was used.

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