Aviation Fuel Rating

Waukesha CFR F4 (Aviation Fuel Rating)

Matching correct fuel characteristics to engine requirements is critical for aviation applications. The Waukesha* CFR F4 engine is the most widely used aviation fuel rating instrument in the world and the only one that conforms to both ASTM D909 and IP 119 aviation fuel specifications. The technology for determining the supercharge octane number for aviation gasoline is an outgrowth of the original fuel rating technology that was pioneered by GE’s Waukesha gas engines. 

How It Works

The Waukesha CFR F4 unit is a single-cylinder engine that simulates operation of an aircraft engine. Its test process conforms to ASTM D909 for testing aviation gasoline above and below 100 octane to determine the rich-mixture antiknock performance (supercharge octane number) of the fuel.

The method determines the supercharge octane number of a test fuel by comparing its knock-limited power with the knock-limited power for bracketing blends of reference fuels under standard operating conditions.

This is done at constant compression ratio by varying manifold pressure and fuel flow rate and measuring indicated mean effective pressure (imep) to define the mixture response curves for sample and reference fuels.

The test requires critical adjustment of the fuel/air ratio and inlet-manifold pressure to establish the knock-limited power characteristics of the fuel. 

Features and Benefits 

  • Accuracy and productivity: Data acquisition and computerized instrumentation for tight operation control and fewer measurement and recording errors.
  • Precision measurement: Temperature and pressure measurement control and computerized calibration of fuel/air ratios. Displays test method parameters in easy-to-read format.
  • Easy operation: Electronic fuel flow measurement via touch-screen monitor. Dynamometer-based system also controls engine speed.
  • Versatility: Air intake system conditions air to simulate blown or super-charged engines.
  • Easy to service: Simply-designed crankcase for easy measurement and repair of key components.

* Trademark of the General Electric Company

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