Abstract: An intake manifold system for a V-type multiple cylinder engine comprising an upstream intake passage, a plenum intake chamber, an intake manifold and downstream intake passages. The upstream intake passage which is directly connected to a throttle body curves downwards towards the intake chamber while the downstream intake passages are connected to the upper end of the intake chamber by way of the intake manifold and after being curved in the shape of inverted letter U are connected to the intake ports of the engine. The intake manifold system as a whole can be accommodated within a gap defined between the two cylinder banks of the engine in a highly compact manner. The advantageous arrangement of the overall intake passage produces favorable ram effect and assures high volume efficiency particularly in low speed range of the engine.

Abstract: An intake manifold for a V-type internal combustion engine with supply tubes in the shape of a horse-shoe. Branch tubes are integrally formed with the supply tube to provide communication between the supply tube and the cylinder intake port. Fuel injection nozzle mounting holes are formed in the branch tubes at a point just above each cylinder intake port.

Abstract: A blow-by gas passage system for an internal combustion engine of the V-type wherein longitudinally spaced passages are formed on each side of, and parallel to, the cylinders in each cylinder bank. Corresponding passages formed in each cylinder head allow for communication between the crankcase and a cavity formed in the space between the two banks of cylinders. An oil separator with a plurality of baffles arranged in a labyrinth-type fashion is mounted on top of the cylinder block and over the collection cavity. An intake manifold is mounted atop the oil separator and has an internal passage formed therethrough corresponding to the exit port of the oil separator. The other end of the intake manifold internal passage is fitted with a PCV-valve which is attached to a pipe leading to the engine air inlet passages of the intake manifold.

Abstract: An improved intake manifold structure for internal combustion engines includes a distribution chamber having an upper sub-chamber leading to a carburetor and a lower sub-chamber communicating with the upper sub-chamber through a communication hole. A plurality of branch passages extend from the lower sub-chamber to a plurality of combustion chambers. An air-fuel mixture fed from the carburetor to the distribution chamber is expanded successively in two steps to promote its atomization as it passes through the two sub-chambers, thus improving uniform distribution of the mixture to the respective branch passages. Engine exhaust gas is returned to the upper sub-chamber to further promote the atomization of the mixture.