Abstract: An integral cylinder block is provided having features which enhance structural stiffness, thereby reducing noise emissions. The block includes an upper portion with cylinder bores and a lower portion forming at least a part of a crankcase. At the upper and lower portions of the block, the casing has sculpted wall portions with a curved, undulate shape. At a side of the cylinder block, a closed oil cooler cavity is formed. A wall is provided to generally separate the oil cooler cavity from the water jacket defined within the block. An opening is provided in the wall, but the opening is distally located relative to a water pump outlet that provides a flow of coolant into the cavity, thereby improving the flow direction of coolant across the oil cooler. Also, an opposite side of the cylinder block includes a closed tappet cavity to accommodate pushrods.