Tuneable intake manifold

Claim 1

An intake manifold for an internal combustion engine having an intake valve port, comprising: an air inlet coupling at one end of the manifold for connection to a source of at least air and an outlet coupling at an opposite end for connection directly to the intake valve port of the engine; at least one intake runner having opposite open ends, connected at one end to receive said air from said air inlet coupling and connected at its opposite end to said outlet coupling and thereby directly to said engine for conducting said air to the intake valve port of the engine; said intake runner being defined by and having side walls forming an inlet passageway having a central axis extending along the path of air flow through the passageway; at least one of said walls of said passageway being mounted via a mounting for movement towards and away from said central axis of said passageway to effectively decrease and increase the through flow cross sectional area as measured in a plane perpendicular to said axis throughout the length along said passageway, respectively, with said mounting including a pivotal connection, about a pivot axis generally perpendicular to the adjacent portion of said central axis and spaced therefrom for the end of said movable wall adjacent said air inlet coupling to said runner; and spring means biasing said movable wall about said pivot axis in the direction to decrease the through flow cross sectional area of the passageway for maintaining said movable wall in an adjusted position automatically in response to engine speed.