Abstract: A piston for an internal combustion engine includes a piston body forming a crown portion and a skirt portion. The skirt portion includes a bore that receives a pin for connecting the piston to a connecting rod, and the crown portion forms a bowl surrounded by a flat crown surface having an annular shape and disposed along a plane. The bowl and the flat crown surface meet along a circular edge surrounding a rim of the bowl. The piston further includes an annular protrusion disposed within the bowl adjacent the rim. The annular protrusion has a generally convex shape in cross section created by an upper, inwardly extending surface and a lower, inwardly extending surface that meet along a convex apex. The piston further includes an airfoil surface formed in the flat crown surface. The airfoil surface has a convex shape and extends annularly around the rim of the bowl.

Abstract: Various methods are provided for characterizing fuel injector operation. In one embodiment, a method of characterizing fuel injector operation comprises determining a flow error of a single fuel injector of two or more fuel injectors positioned in a first fuel rail by comparing a sum of each of a plurality of injector commands for the single injector to a fuel amount pumped into the first fuel rail, the fuel amount being predetermined.