Internal combustion engine with blow-by gas recirculation system

An automotive internal combustion engine comprises an engine main body including a cylinder head having intake ports, and a cylinder head cover. Fuel injector valves are disposed to be directed respectively to the intake ports. An intake manifold is installed to a side surface of the cylinder head and outward curved to define a space between the intake manifold and the cylinder head. A blow-by gas recirculation system is provided for feeding blow-by gas introduced out of the cylinder head cover to each cylinder of the engine main body through an intake system. The blow-by gas recirculation system includes a blow-by gas piping which extends from the cylinder head cover to the intake ports for the cylinders. The blow-by gas piping is accommodated within the space defined between the intake manifold and the cylinder head.