Engine crankcase ventilation system including a blowby gas passage defined between crankcase members

An engine crankcase ventilation system for an internal combustion engine including a plurality of crankcase members jointly defining a crankcase assembly, a cylinder head attached to an upper part of the crankcase assembly defining a cylinder, and an intake system attached to an upper part of said cylinder head;

• comprising:
• a blowby gas passage defined between adjoining crankcase members;
• and
• passages defined in said cylinder head and said intake system for communicating said blowby gas passage to downstream of a throttle valve;
• said cylinder head passage and said intake system passage communicating with each other via opposing openings in mating surfaces of said cylinder head and said intake system;
• wherein said internal combustion engine consists of a multiple-cylinder V-engine, and said intake system is placed between two cylinder banks of said V-engine, said blowby gas passage being communicated with said cylinder head passage via a communication passage defined in a ridge formed in a corresponding part of said cylinder bank, and said intake system is provided with a recess for receiving said ridge.

An engine crankcase ventilation system for an internal combustion engine including a plurality of crankcase members jointly defining a crankcase assembly, comprising:

• a blowby gas passage extending in parallel with a crankshaft axial line along a first side of a lower part of said crankcase assembly;
• and
• a fresh air passage extending in parallel with a crankshaft axial line along a second side of a lower part of said crankcase assembly;
• said blowby gas passage and fresh air passage being defined between adjoining crankcase members independently from each other, and extending from an axial end of said crankcase assembly to another end.