Abstract: A piston for an internal combustion engine includes a piston wall defining an outer perimeter of the piston, and a piston face located at an end of the piston wall. The piston face includes a radially-extending outer face, and a combustion bowl formed therein and recessed from the outer face. The combustion bowl includes an upper bowl including a flat upper bowl radial surface recessed from the outer face a distance in the range from 3.5 to 4.5 millimeters, and a lower bowl including a lower bowl surface recessed to a maximum bowl depth from the flat upper bowl axial surface in the range from 10.4 to 13.4 millimeters. The piston face is axisymmetric about a piston central axis.