He, Y., Liu, Z., Stahl, I., Zhang, G. et al., "Comparison of Stochastic Pre-Ignition Behaviors on a Turbocharged Gasoline Engine with Various Fuels and Lubricants," SAE Technical Paper 2016-01-2291, 2016, doi:10.4271/2016-01-2291.
Stochastic pre-ignition (SPI) has been commonly observed in turbocharged spark-ignition direct-injection (SIDI) engines at low-speed and high-load conditions, which causes extremely high cylinder pressures that can damage an engine immediately or degrade the engine life. The compositions and properties of fuels and lubricants have shown a strong impact on SPI frequency. This study experimentally evaluated SPI behaviors on a 2.0-liter 4-cylinder turbocharged SIDI engine with China V market fuel and China fuel blended to US Tier II fuel specifications. China V market fuel showed significantly higher SPI frequency and severity than China blended US Tier II fuel, which was attributed to its lower volatility between 100 °C to 150 °C (or lower T60 to T90 in the distillation curve). Two different formulations of lubricant oils were also tested and their impact on SPI were compared. Lubricants formulated with lower Calcium, more Molybdenum, and reduced propensity to absorb fuel are effective in significantly reducing SPI frequency and severity. This study provided important insights into the fuel differences in various regions and their impact on SPI behaviors on the same engine with the same controls and calibrations.