Single cylinder CFR test method

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In the single-cylinder CFR test procedure , the RON (researched ( researched ) octane number ) or MOZ (engine octane number) is determined, this is the octane number at which a gasoline sample begins to knock in a continuously compressible knocking engine . There must be a constant ignition setting, a speed of 600 rpm and an air preheating of 52 ° C (this applies to the RON). With the MOZ, the measurement is carried out at 900 rpm and a mixture preheating of 149 ° C. The octane number is now determined by changing the mixing ratio of isooctane to heptane until the test engine exhibits characteristic knocking behavior.

The test engine and procedure were first defined by the Cooperative Fuel Research Committee of the American Society of Automotive Engineers ( SAE ).

Procedure for determining the octane number : The engine mentioned above has several fuel tanks that are arranged in a circle around the engine and can be switched over while the engine is running. The unknown gasoline sample is filled into a storage container and defined octane-heptane mixtures are filled into the other containers. Now the compression is continuously increased on the engine until the combustion starts to knock with the fuel sample. Then you switch to a known octane-heptane mixture and, if the engine exhibits the same knocking behavior as with the sample, its octane number is found.

Determining the octane number can take a long time and is associated with many imponderables. For this reason, blank samples are distributed once a year to refineries and university institutes, which independently determine the octane numbers of the fuel samples. The engine industry controls the information from the mineral oil industry on the octane numbers of their fuels. This leads z. B. the car industry through so-called ring tests, in which each participant (car manufacturer) takes a portion of the fuel according to a precisely prescribed procedure and passes the barrel on to the next participant. The engine industry compares the control values ​​obtained for the octane number with the specified values ​​(RON or MON) from the fuel manufacturer in the mineral oil industry. An octane number is then assigned to a blank sample, which is strictly statistically relevant with a minimal square deviation.

origin of the name

CFR test engine (Cooperative Fuel Research Committee of the American Society of Automotive Engineers).

literature

  • Hans-Hermann Braess, Ulrich Seiffert: Vieweg manual automotive technology. 2nd edition, Friedrich Vieweg & Sohn Verlagsgesellschaft mbH, Braunschweig / Wiesbaden, 2001, ISBN 3-528-13114-4