4. Reduce pollutant emissions and fuel consumption

4.1 Definition of dilution

An internal combustion engine operates with dilution when combustion no longer takes place under stoichiometric conditions, or when it takes place with an oxidant whose composition is no longer that of pure air. Dilution may be provided by an excess of air (richness less than 1, in which case we refer to it as air dilution), but it is more commonly accepted that the nature of the gases used for dilution will be derived from the result of combustion.

Exhaust gas recirculation can be internal, defined by the acronym "IGR" for Internal Gas Recirculation. This is the most common dilution technology, as it can be used in conjunction with variable valve timing systems. In this case, valve timing is used to achieve the best possible engine...