16. Calculation of O.N. - Bracketing Procedures
16.1 Calculate the average knockmeter readings for the sample fuel and each of the PRF blends.
16.2 Calculate the O.N. by interpolation of these average knockmeter readings proportioned to the O.N. values of the bracketing PRF blends in accordance with the example shown in Fig. 7 and Eq 4:
17. Report
17.1 Research O.N. of Spark-Ignition Engine Fuels:
17.1.1 Report the calculated bracketing procedure or the C.R. procedure result as Research O.N.
17.1.1.1 For ratings below 72.0 O.N., report the value to the nearest integer. When the calculated O.N. ends with a 0.50, round off to the nearest even number; example, round 67.50 and 68.50 to 68 O.N.
17.1.1.2 For ratings from 72.0 through 103.5 O.N., report the value to the nearest tenth. When the calculated O.N. ends with exactly 5 in the second decimal place, round to the nearest even tenth number; example, round 89.55 and 89.65 to 89.6 O.N.
17.1.1.3 For ratings above 103.5 O.N., report the value to the nearest integer. When the calculated O.N. ends with a 0.50, round off to the nearest even number; for example, round 105.50 and 106.50 to 106 O.N.
17.1.2 Report which procedure is used to determine the O.N.: bracketing-equilibrium fuel level, bracketing-dynamic fuel level, or compression ratio.
17.1.3 Report the engine room barometric pressure at the time of the rating.
17.1.4 Report the IAT used.