From stoichiometry to ultra lean burn in a direct injection spark ignition engine model

In an internal combustion engine, whenever complete combustion can be achieved, indicated torque production is directly related to fuel rate. This premise is exploited to extrapolate a public-domain, homogeneous charge, spark ignition engine model to the stratified charge regime. The extrapolation is based on published, functional forms for indicated torque and friction torque in a direct-injection, spark ignition engine. The extrapolated, control-oriented model is "validated" through comparisons to both published results and expected behaviors. The dynamic model is illustrated through step responses in fuel and throttle flow rate.