Technical Paper
Coordinating Research Council Trends in Octane Number Requirement Increase
1989-09-01
892036
The Coordinating Research Council, Inc. has studied the octane requirement increase (ORI) of cars and light duty trucks since 1971. This paper investigates ORI trends and influencing effects for over 600 1980 through 1988 model-year vehicles. An analysis of these vehicles shows them to have an average ORI of 3.8 (R+M)/2 measured with refinery-like fuels, and suggests the average ORI decreased from 1980 through 1986, followed by a possible, but statistically uncertain, increase starting in 1987 or 1988. A number of factors have contributed to lower ORI, including higher compression ratios, use of aluminum cylinder heads, multiport fuel injection, and three-way catalyst systems. SPARK KNOCK IS THE NOISE produced by the auto-ignition of the air-fuel mixture in the end gases of the spark-ignition engine.
