Engine block for internal combustion engine

An internal combustion engine comprises a siamese engine block having cylinders defined by cylinder walls arranged in series with adjoining cylinders sharing a common wall. The engine block has a coolant jacket defined by a coolant jacket wall radially positioned parallel to and outboard of the cylinder walls to define a coolant passage for coolant flow through the engine block. The coolant passage includes an arc passage and a V-bend passage where the V-bend passage is adjacent the common wall of the adjoining cylinders. The V-bend passage is configured as a narrow rectangular portion having a coolant pocket projecting inboard from the rectangular portion into the common wall to provide heat transfer from the common wall of the cylinder. The cylinder wall includes a protrusion extending into the arc passage and disrupts flow from about the upper one-half of the coolant pocket.