An Introduction to How Low Speed Pre Ignition Affects Engine Components 2017-01-1042

Current market demands in conjunction with increasingly stringent emission legislation have vehicle manufactures striving to improve fuel economy and reduce CO2 emissions. One way to meet these demands is through engine downsizing. Engine downsizing allows for reduced pumping and frictional losses. To maintain acceptable drivability and further increase efficiency, power density increase through the addition of boosting is employed. Furthermore, efficiencies have been realized through the use of high gear count transmissions, providing an opportunity for manufactures to effectively down speed the engine whilst still achieving the desired drivability characteristics. As a result of these efficiency improvements, gasoline turbo charged direct injected (GTDI) engines are developed for and tend to operate in low engine speed, high torque conditions . This operating condition results in an environment within the combustion chamber which has the propensity to experience a disruptive abnormal combustion event known as low speed pre-ignition (LSPI). This phenomenon has the potential to catastrophically damage the power cylinder unit (PCU); therefore, engine manufacturers and suppliers are working to eliminate LSPI or design components to survive LSPI events if they occur.

This paper is the first of a series of papers that will discuss MAHLE’s LSPI research, focused on power cylinder unit (PCU) components and systems designed to withstand LSPI events, as well as minimizing or eliminating the propensity of LSPI to occur.