Abstract: An intake system delivers air into cylinders of an internal combustion engine which are divided into two groups. The cylinders in each group are arranged in one and the same row so that adjoining cylinders in each row do not fire one after another. The intake system has conflux chambers for the cylinder rows, connected to the cylinders by intake passages, and also interconnected to each other by a communication passage having a valve. First and second resonant passages are each connected at one end to the respective conflux chambers and are joined together to communicate with each other at another end, opposite to the one end, in a location at which a throttle body is located. The first resonant passage has a connection point with one conflux chamber closer to an interconnection between both the conflux chambers than a connection point in a lengthwise direction of the second resonant passage with another conflux chamber.

Abstract: An intake system includes two surge tanks for cylinders in first and second cylinder banks of a V-type internal combustion engine which are arranged side by side over one of the first and second cylinder banks in the lengthwise direction of its associated engine and, are preferably formed as one unit and includes intake passages arranged in series in the lengthwise direction, each intake pipe connecting the surge tank with each of the cylinders in the first and second cylinder banks. The outermost intake passages disposed at the opposite ends of the surge tanks extend outward of the surge tanks in the opposite directions and are bent back into a space between the first and second cylinder banks. The remaining intake passages for the cylinders in the first cylinder bank are of C-shaped passage and the remaining intake passages for the cylinders in the second cylinder bank cross inside the C-shaped intake pipes in the space.

Abstract: An internal combustion engine of the in-line type having a surge tank located above the engine. Intake tubes connect the surge tank with the in-line engine cylinders. The tubes extend from one side of the engine body in a direction away from the engine body and are then curved upwardly in a U-shaped manner toward the surge tank. Surge tank openings and the ends of the intake tubes connected together are both formed as ellipses having a major axis lying in a direction parallel to the cylinder axes. The cross-sectional shape of the intake tubes gradually changes from an ellipse into a circle at approximately the middle or bend of the intake tube.

Abstract: An intake apparatus for an in-line type internal combustion engine having an elongated surge tank extending the full extension of the in-line cylinders of the engine. Intake passages connect the surge tank with the in-line engine cylinders. A throttle body is secured to one side surface of the surge tank. The registering and connected surfaces of the surge tank and the throttle body are mutually inclined an angle .theta. with respect to the medial plane or axes of the in-line cylinders.