Knock Analysis for the Optimization of Water Injection

To reduce both harmful emissions (CO, HC, NOx, etc.) and gases responsible for greenhouse effects (especially CO2), gasoline engines must run efficiently (i.e. with low fuel consumption) and with stoichiometric air to fuel ratio in order maximise the conversion efficiency of the three-way-catalyst. In-cylinder gas temperature is one of the main factors which limits combustion efficiency and the area of the engine map in which a stoichiometric mixture can be used. At low engine speed, knock occurrence requires a late combustion phasing while, at high speed, it is often necessary to enrich the mixture for components protection.