Mapping K factor variations and its causes in a modern, spark-ignition engine

The Research Octane Number (RON) and the Motor (MON) are primary fuel properties that characterize gasoline’s knock resistance in spark ignition engines. utility of these two metrics, however, has been questioned with advancements engine technologies significantly change thermochemical environment inside cylinder. Index, OI = (1-K)·RON + K·MON, therefore proposed to modern engines where K weights relative contribution RON MON is primarily determined by design operating conditions. Quantifying factor central understanding a fuel’s anti-knock performance spark-ignition (SI) engine. This work determines map over conditions for 2-litre, 4-cylinder turbocharged, gasoline direct-injection To achieve this, novel blending system reference fuels (PRFs) was developed determine matching 91.6-RON certification PRF at each condition. values normal high intake air coolant temperatures. At temperature, negative most knock-limited conditions, consistent previous findings, whereas temperatures, mostly positive and, indeed, exceeds 1 near 8 bar BMEP 3000 RPM, demonstrating relevance some practical significance. Further analysis conducted via simulations examine relationship between end gas strong correlation observed unburned temperature later stages combustion. argued have sound physical basis engine’s thermochemistry, supporting this method.