Piston and bowl for gasoline direct injection compression ignition (GDCI)

A piston for use in a GDCI engine, the piston cooperating with the wall of a cylinder defined in the engine and with a cylinder head to define a combustion chamber, the surface of the piston that faces the cylinder head defining a bowl configured to receive fuel dispensed from a fuel injector located in the cylinder head substantially along the central axis (A) of the cylinder, wherein the bowl is configured such that substantially all of the injected fuel associated with a combustion event reaches a localized equivalence ratio greater than 0.0 and less than or equal to 1.2 at a time immediately preceding initiation of the combustion event;

• wherein the bowl is configured such that stratification of the localized equivalence ratio is achieved at a time immediately preceding initiation of the combustion event with a first portion of the injected fuel at a localized equivalence ratio of less than 0.3, a second portion of the injected fuel at a localized equivalence ratio greater than 0.3 and less than 0.7, and a third portion of the injected fuel at a localized equivalence ratio of greater than 0.7.