The present application relates to rib structure on cylinder block. A cylinder block having a top surface, an inner bottom surface, a cylinder opening on the top surface, and a head boss positioned on the top surface, centered on a first axis, and configured to engage with a fastener at an initial position, which defines a first depth. The cylinder block includes a first main boss positioned on the inner bottom surface, centered on a second axis, and configured to engage with a first main fastener at a first end position, which defines a second depth. The cylinder block includes a second main boss positioned on the inner bottom surface and configured to engage with a second main fastener at a second end position, which defines a third depth. The cylinder block includes a first rib path extending from the first depth to the second depth and a second rib path extending from the first depth to the third depth.

The present disclosure relates to an engine assembly for a vehicle. The engine assembly comprises an engine including a cylinder head and an engine block. The engine block comprises a cylinder block and a crankcase having a crankshaft. The engine may be used in different models of the vehicle having different characteristics by interchanging or replacing the cylinder head from a plurality of cylinder heads and/or a cylinder block from a plurality of cylinder blocks, while keeping one or more engine components such as the crankcase, a timing chain, or a valve cover the same. Accordingly, the engine is adaptable to different vehicles.