Air intake system for an internal combustion engine with at least two cylinder banks

The induction manifold (2) is fitted to a V-6 or flat-6 internal combustion engine. It has two banks of three cylinders (4,6) supplied by individual manifold branches (11-16). Two cross-pipes (18,20) connect the distributor portions supplying the branches for the two banks of cylinders. A single inlet (30) is divided (28) into two channels (25a,25b) leading to a throttle valve (22) in the first cross-pipe. The second cross-pipe has a centrally mounted throttle valve restricting the flow of mixture between the two ends.