Abstract: A cylinder block structure includes a plurality of mounting bolts extending through a plurality of bearing caps and through a crank case to fix a crank shaft in a cylinder block. During operation, the crank shaft transmits detrimental horizontal stress to the bearing caps, the mounting bolts, and the crank case. A bulge portion, a plurality of reinforcing ribs, boss portions, and reinforcing oil transport structures extend away from the cylinder block to resist the horizontal stresses and prevent deformation of the mounting bolts and the bearing caps. An engine mount bracket secures the cylinder block structure to an external position and provides additional rigidity. The bulge portion, reinforcing ribs, boss portions and other structures minimize vibration and allow close tolerances by providing rigidity to the cylinder block structure without increasing wall thickness.

Abstract: A cylinder block structure includes a plurality of mounting bolts extending through a plurality of bearing caps and through a crank case to fix a crank shaft in a cylinder block. During operation, the crank shaft transmits detrimental horizontal stress to the bearing caps, the mounting bolts, and the crank case. A bulge portion, a plurality of reinforcing ribs, boss portions, and reinforcing oil transport structures extend away from the cylinder block to resist the horizontal stresses and prevent deformation of the mounting bolts and the bearing caps. An engine mount bracket secures the cylinder block structure to an external position and provides additional rigidity. The bulge portion, reinforcing ribs, boss portions and other structures minimize vibration and allow close tolerances by providing rigidity to the cylinder block structure without increasing wall thickness.