Intake manifold with variable runner area

A tunable intake manifold for directing a flow of air between a plenum and an internal combustion engine, said tunable intake manifold comprising:

• a manifold housing defining an interior, said manifold housing having a runner wall extending through said interior between an opening and an opposite intake port;
• a slider having a slider wall extending through said interior of said manifold housing, said slider wall cooperates with said runner wall to define a runner having a defined cross sectional area for transporting the flow of air therethrough, said slider slidably engaged with said manifold housing for moving said slider wall relative to said runner wall to selectively change said defined cross sectional area of said runner, such that the volume of air passing therethrough changes with said movement of said slider;
• and
• a diffuser member pivotally coupled to said slider adjacent said intake port, said diffuser member including a cam surface in continuous contact with said manifold housing for pivoting said diffuser member in response to movement of said slider wall relative to said runner wall and a diffusing surface variably extending from said slider wall into said intake port in response to said pivotal movement of said diffuser member to smooth the flow of air from said runner through said intake port.