Intake system for an automotive engine

Claim 1

An intake system for an automotive engine having cylinders, comprising: primary intake ports communicated with said cylinders; secondary intake ports communicated with said cylinders; each of said primary and secondary intake ports being communicated with a corresponding cylinder at a common intake valve; each primary intake port being disposed in a tangential direction so as to provide a swirl of induced mixture; a primary intake manifold communicated with said primary intake ports; a secondary intake manifold communicated with said secondary intake ports; a primary carburetor having a throttle valve provided in said primary intake manifold; a secondary carburetor having a throttle valve provided in said secondary intake manifold; said throttle valve of the secondary carburetor being so arranged to be opened after the throttle valve of the primary carburetor has been fully opened; a control valve provided in each branch of said secondary intake manifold for controlling a counter flow of inducted mixture; means for opening said control valve in dependence on increase of engine speed, and wherein said means comprises actuating means for actuating said control valve, sensing means for sensing engine speed and load on the engine, control circuit means responsive to outputs of said sensing means for operating said actuating means so as to open said control valve as engine speed and load increase.