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OCTANE

CRC Project No. CM-137

Leader:      J. J. Simnick

Scope and Objective

The objectives of CRC Project No. CM-137 are to conduct a survey of the octane number requirements of current production automotive vehicles, to develop methods for measuring vehicle octane number requirement, and to determine effects on octane number requirement of variables such as mileage accumulation and altitude.

Current Status and Future Program

Fuel Antiknock Quality Program

The objective of this program is to assess the relative importance of Research Octane Number (RON) and Motor Octane Number (MON) in current and future fleets.  Given these results, it may be possible to ascertain whether the arithmetic average of RON and MON, (R+M)/2, is still the best way to determine the Antiknock Index (AKI). 

Shell Oil data indicate that recent production European and Japanese vehicles are more responsive to RON than MON.  They found that for a given RON, a fuel of lower MON had better road octane performance and gave better power and acceleration. All vehicles were equipped with knock sensors and 93% were equipped with manual transmissions.  This RON sensitivity differs from historical U.S. data, which showed a pronounced sensitivity to MON.  The Octane Group plans to develop a program that verifies and expands on the Shell research, testing vehicles representative of the current and future U.S. fleet. 

In October 2005, the Octane Group published CRC Report No. 643 that recorded the results from an acceleration octane test round-robin program. The report included a brief description of the work done within CRC with the Octane Acceleration Technique, the difficulties encountered with the data analysis of the CRC Interlaboratory study, the variability among laboratories in conducting the testing, and specific recommendations for an improved test procedure.  Report No. 643 is available on the CRC website.

The group sought OEM support for a test program emphasizing the fuel economy potential that could accrue from changes in fuel sensitivity (RON-MON).  A letter was issued to the CRC OEM members of the Performance Committee requesting statements of interest in participating in testing engines at their respective laboratories and reporting summary data back to the committee to assess octane response of their engines.  The Performance Committee organized a panel to identify the test fuel set for the study and agreed to begin the project with even a limited number of participating laboratories.  A second invitation was sent to several OEMs outside of CRC and one independent laboratory, but no parties other than Chrysler expressed interest.  A detailed program plan has been reviewed and approved by the panel. A Request for Proposal (RFP) for test fuel blending has been issued by CRC and awarded to Dow Chemical (Haltermann Products).  Test fuel blends are underway before larger drum quantities of the test fuels are prepared.  The project will start with testing at Chrysler's engine laboratories once the drums of test fuels are blended and shipped.

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