ANSYS Forte’s SI engine capability employs both a flame-propagation model (using the G-equation approach) and detailed chemistry. The G-equation determines where the flame resides at each time step and a chemical-equilibrium assumption is used on the flame front. Everywhere else, detailed chemistry is employed. In this way, we can predict knocking from auto-ignition outside of the flame front (e.g., in the “end gas”) due to compression by the flame propagation. Forte’s G-Equation model accommodates multi-component fuels and is fully integrated with Forte’s detailed kinetics solvers.