An intake manifold with a swirl system for an internal combustion engine having a number of cylinders; the intake manifold has, for each cylinder, an intake conduit connecting the intake manifold to the cylinder and in turn having two parallel channels; the swirl system has, for each intake conduit, a throttle valve housed inside a channel of the intake conduit to vary the air flow section of the channel, and which has a throttle mounted to rotate about an axis of rotation.