Octane Requirement Increase of 1981 Model Cars.
COORDINATING RESEARCH COUNCIL INC ATLANTA GA
Pagination or Media Count:
The need to study octane requirement increase ORI with unleaded fuel became evident in 1970 when manufacturers announced that cars would require catalytic converters and use unleaded gasoline of at least 91 RON quality to meet future emission standards. Since that time, manufacturers have made many engine modifications to meet both exhaust emission and fuel economy standards. Because of these engine design changes and the increasing use of unleaded gasoline, the Coordinating Research Council, Inc. CRC initiated a series of ORI programs in 1971. This report will summarize ORI data for 1981 model cars. Findings include Octane requirement increase ORI was determined for eighty-six 1981 model cars operated on unleaded gasoline. At 15,000 miles, the mean ORI for all cars with full-boiling range unleaded FBRU fuels was 5.1 Research octane numbers, 3.3 Motor octane numbers, and 4.2 RM2 numbers At 15,000 miles, the mean ORI for seventy-four cars with full-boiling high sensitivity unleaded FBRSU fuels was 5.2 Research octane numbers, 3.6 Motor octane numbers, and 4.4 RM2 numbers At 15,000 miles, the mean ORI for seventy-four cars with primary reference fuels PRF was 4.1 octane numbers Compared with 1980 models 120 cars, the mean ORI for all cars in the 1981 program with FBRU fuels was the same on a RON basis, and 0.1 MON higher In general, the mean ORI with FBRU fuels has not changed appreciably for the 1975 through 1981 model cars and ORI decreases about 0.2 to 0.3 octane number per octane number increase of initial octane requirements.
- Surface Transportation and Equipment