An engine assembly includes a cylinder block having at least one cylinder. The engine assembly includes at least one cylinder head coupled to the cylinder block, and at least one intake port coupled to the cylinder head, at least one exhaust port coupled to the cylinder head, and at least one fuel injector coupled to the cylinder head. The engine assembly includes a head cooling extension protruding from the cylinder head. The head cooling extension includes at least one extension wall and defines an extension cooling passageway at least partially enclosed by the at least one extension wall. The extension cooling passageway is at least partly disposed between the exhaust port and the fuel injector in order to create a thermal barrier between the fuel injector and the exhaust port when the coolant flows through the extension cooling passageway.