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Spark-assisted compression ignition (SACI) leverages flame propagation to trigger autoignition in a controlled manner. The autoignition event is highly sensitive to several parameters, and thus, achieving SACI in production demands a high tolerance to variations in conditions. Limited research is available to quantify the combustion response of SACI to these variations. A simulation study is performed to establish trends, limits, and control implications for SACI combustion over a wide range of conditions. The operating space was evaluated with a detailed chemical kinetics model. Key findings were synthesized from these results and applied to a 1-D engine model. This model identified performance characteristics and potential actuator positions for a production-viable SACI engine. This study shows charge preparation is critical and can extend the low-load limit by strengthening flame propagation and the high-load limit by reducing ringing intensity.

Low pressure (LP) and cooled EGR systems are capable of increasing fuel efficiency of turbocharged gasoline engines, however they introduce control challenges. Accurate exhaust pressure modeling is of particular importance for real-time feedforward control of these EGR systems since they operate under low pressure differentials. To provide a solution that does not depend on physical sensors in the exhaust and also does not require extensive calibration, a coupled temperature and pressure physics-based model is proposed. The exhaust pipe is split into two different lumped sections based on flow conditions in order to calculate turbine-outlet pressure, which is the driving force for LP-EGR. The temperature model uses the turbine-outlet temperature as an input, which is known through existing engine control models, to determine heat transfer losses through the exhaust.

This research describes several data processing and analysis techniques that can be used to quantify indicated torque losses associated with in-cylinder thermodynamic events. The detailed thermodynamic techniques are intended to aid the development of performance engines under high-load conditions. This study investigates potential IMEP gains that could be made to an engine based on evaluating cylinder and manifold pressure data collected during wide-open-throttle operation. Examination of the data can guide engine design changes by exposing inefficiencies that may have otherwise gone unnoticed. Examples of calibration adjustments and physical intake and exhaust manifold design changes are also presented to validate the data analysis techniques presented. The research data sets were recorded using a 5.3L V8 engine in conjunction with a highly-controlled transient dynamometer.