Impact of Fuel Detergent Type and Concentration on the Rate and Severity of Stochastic Preignition in a Turbocharged Spark Ignition Direct Injection Gasoline Engine 2021-01-0490

Stochastic Preignition (SPI) is an abnormal combustion event that occurs in a turbocharged engine and can lead to the loss in fuel economy and engine hardware damage, and in turn result in customer dissatisfaction. It is a significant limiting factor on the use and continued downsizing of turbocharged spark ignited direct injection (SIDI) gasoline engines. Understanding and mitigating all the factors that cause and influence the rate and severity of SPI occurrence are of critical importance to the engine’s continued use and fuel economy improvements for future designs. Previous studies have shown that the heavy molecular weight components of the fuel formulations are one factor that influences the rate of SPI from a turbocharged SIDI gasoline engine. All the previous studies have involved analyzing the fuel’s petroleum hydrocarbon chemistry, but not specifically the additives that are put in the fuel to protect and clean the internal components over the life of the engine. In this study, the fuel detergent types and concentrations are compared to a baseline fuel to understand the impact of the detergent itself on the rate and severity of SPI events. The results showed that the rate of SPI increases above the baseline fuel when the concentration goes above the TOP TIER level, no matter what the detergent type. The effect of fuel detergent types and concentrations on SPI severity is found to be more complex. Despite some indications of severity reduction from one of the fuel additives at different concentrations, the variation in the behavior of base fuel with respect to the SPI severity casts doubt on the extent of this effect.