Alternative RON estimation method by using pressure oscillation analysis, serving novel spark ignition fuel development

For almost a century, the knock-resisting ability of a spark ignition fuel has been quantified with the RON and MON indications, conforming to the corresponding ASTM-D2699 and D2700 methods, respectively. These testing methods rely on specific pressure pickup technology that acts like a low-pass signal filter, thereby cutting off high frequency cylinder pressure information. Within a second-generation sustainable naphthenic fuel research framework where many different fuels had to be screened, the need arose to develop a simplified octane rating method for quick, economical and efficient knock-resistance evaluation. The method that was subsequently developed is based on mean average maximum pressure oscillations (MAMPO) and allows for quick octane number verification with a CFR engine equipped with commonly available high frequency pressure measurement equipment. This paper investigates the necessary test parameters to deal with the stochastic nature of knock and to obtain a good correlation, not previously established in literature, between the MAMPO-based octane rating and the well-established RON. A method was found to enable fast and economical RON estimations of novel spark ignition fuels, additionally providing insight in the pressure oscillation behavior of a fuel during knock, enabling the assessment of potential knock-induced engine damage thanks to the use of high-frequency pressure information.