Piston/liner configuration coordination in a piston pump

A method for minimizing resistance to aspirated fluid flow in a liquid pump, the liquid pump comprising:

• a pump liner defining a central longitudinal bore and a transverse inlet bore communicating with said central bore for conveying a liquid through said pump housing, said transverse inlet bore having a diameter centered around a centerline intersecting with a centerline of the central longitudinal bore;
• and
• a pump piston axially and rotatably slidable within said central longitudinal bore for pumping the liquid from said transverse inlet bore, said pump piston having a centerline intersecting with the centerline of the transverse inlet bore,
• the method comprising:
• forming a flat surface on the piston parallel with said piston centerline at a distal end of the piston, the flat surface being formed at a distance from the centerline of the piston greater than or equal to ½ of the diameter of the transverse inlet bore of the liner, said flat surface defining a cut-out portion of the piston, said cut-out portion having a hydraulic diameter Dh defined as Dh=4 A/P, where A is a cross-sectional area of the cut-out portion and P is the perimeter of the cut-out portion;
• and
• forming a diameter of the inlet bore in the liner equal to the hydraulic diameter of the cut-out portion.