Octane Requirement Increase of 1983 Model Cars.
COORDINATING RESEARCH COUNCIL INC ATLANTA GA
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Octane requirement increase ORI was determined for seventy-nine 1983 model cars operated on unleaded gasoline. The data base consists of information volunteered by participants. All ORI values were determined from the increase in maximum octane requirements irrespective of whether requirements were obtained at full- or part-throttle. At 15,000 miles, the mean ORI for all cars with full-boiling range unleaded FBRU fuels was 4.4 Research octane numbers RON, 2.9 Motor octane numbers MON, and 3.7 RM2 numbers. At 15,000 miles, the mean ORI with FBRU fuels for the sixty car subset tested on all three reference fuels was 4.4 RON, 2.7 MON, and 3.6 RM2 numbers. At 15,000 miles, the mean ORI for sixty cars with full-boiling range high sensitivity unleaded fuels was 4.7 RON 3.3 MON and 4.0 RM2 numbers. At 15,000 miles, the mean ORI for sixty cars with primary reference fuels was 3.9 ON. Compared with 1982 models 115 cars, the mean ORI for all cars in the 1983 program with FBRU fuels decreased 0.5 RON, 0.1 MON, and 0.2 RM2. In general, the mean ORI unweighted with FBRU fuel exhibits a slight downward trend for the 1975 through 1983 model cars.