The significance of octane numbers to drive cycle fuel efficiency

Abstract

Modern spark-ignition engines are knock-limited over a significant fraction of their operating map. The efficiency loss induced by knock mitigation depends on both the fuel octane quality and driving conditions. This paper quantifies the relevance of the Research Octane Number (RON) and Motor Octane Number (MON) to the knock-limited fuel efficiency losses (KLFEL) of a mid-size sports utility vehicle operated in several standard drive cycles. The Octane Index model, OI = (1-K)·RON + K·MON, is used with K as the weighting factor to evaluate the relative importance of RON and MON. The K-map recently obtained for a gasoline turbocharged direction-injection engine (Zhou et al., Fuel 290 (2021) 12..