1982 CRC FUEL RATING PROGRAM: ROAD OCTANE PERFORMANCE OF OXYGENATES IN 1982 MODEL CARS

Because of the widespread interest in the use of alcohols and ethers as gasoline blending components, the road octane rating program reported here was conducted to evaluate the effects of several oxygenates on gasoline octane performance and to evaluate the effects of car design features such as engine and transmission type. Twenty-eight unleaded fuels, including four hydrocarbon fuels, two hydrocarbon fuels plus toluene, and twenty-two oxygenated fuels, were rated in duplicate in thirty-eight cars. Five oxygenates were evaluated at two nominal concentrations, 5 and 10 volume percent, at both regular- and premium-grade octane levels: methanol, ethanol, isopropanol, tertiary butanol, and methyl tertiary butyl ether. A blend of 5% methanol and 5% tertiary butanol was also tested at both octane levels. Two different techniques were used to analyze the data obtained in this program: the conventional method, used in all previous programs, which analyzed data from all of the fuels together; and a different approach whereby road octane number prediction equations were developed for each car and for all cars using only the six hydrocarbon fuels. It was found that the addition of oxygenates caused nonlinear increases in all the octane numbers: Road octane number, Research octane number, and Motor octane number. The effects tended to level off with increasing concentration. A new term, Road Octane Performance, was devised to represent the Road octane number performance of the oxygenates as compared with hydrocarbon blending components. In the regular grade fuels at full throttle, all the oxygenates showed improved Road Octane Performance. Oxygenates in regular-grade fuels had highly significant beneficial effects in six cylinder engines as a group, whereas the four-cylinder and V8 engines showed smaller, and non-significant, effects. With the premium fuels, none of the engine types showed significant effects; however, the V8s showed significantly poorer responses than the other engine types. There was no significant effect of transmission type.

• Corporate Authors:

  Coordinating Research Council, Incorporated

  219 Perimeter Center Parkway
  Atlanta, GA  United States  30346
• Publication Date: 1985-7

Media Info

• Features: Appendices; Figures; Tables;
• Pagination: v.p.

Subject/Index Terms

• TRT Terms: Data analysis; Engines; Ethanol; Ethers; Fuel additives; Gasoline; Mathematical analysis; Methanol; Octane number; Performance evaluations; Transmissions
• Uncontrolled Terms: Isopropanol; Methyl ether; Oxygenates
• Old TRIS Terms: Octane rating; Tertiary butanol
• Subject Areas: Highways; Safety and Human Factors; Vehicles and Equipment;

Filing Info

• Accession Number: 00495549
• Record Type: Publication
• Source Agency: National Highway Traffic Safety Administration
• Report/Paper Numbers: CRC Rept No. 541, HS-039 421
• Files: HSL, USDOT
• Created Date: Jul 31 1990 12:00AM