Unique block rib geometry for reducing liner distortion

An apparatus comprising:

• an engine block for an internal combustion engine, the engine block having a cylinder bore surrounded by an inner cylinder bore wall, the inner cylinder bore wall having a mid-portion that spans between an upper end and a lower end of the inner cylinder bore wall, the mid-portion including a liner stop mechanism positioned a distance from the upper end of the inner cylinder bore wall, the liner stop mechanism locates and supports a liner in the cylinder bore, the engine block having an outer cylinder block wall that surrounds at least a portion of the cylinder bore wall, the outer cylinder block wall includes a first outer cylinder block wall and a second outer cylinder block wall, each of the first and the second outer cylinder block walls includes a first rib positioned above the liner stop mechanism and a second rib positioned below the liner stop mechanism relative to a cylindrical axis of the cylinder bore, wherein the first rib is located below the upper end of the inner cylinder bore wall and the second rib is located above the lower end of the inner cylinder bore wall, wherein each of the first and the second outer cylinder block walls includes a head boss positioned between the first ribs and the second ribs.