Abstract: A three plenum air distribution manifold for intake air to internal combustion engine with long, narrow runners leading from first and second spaced side plenums for delivery of air and recirculating exhaust gases into corresponding combustion chambers of the engine. One end of the spaced side plenums are connected by an acoustically balanced cross over passage selectively closed by a manifold tuning valve for improving engine output torque during low engine speed. A third plenum is positioned intermediate the two side plenums to communicate with the combustion chambers in bypass relation to the side plenums thereby directly supplying air to the combustion chambers through short runners which are selectively opened by valves to optimize engine torque over a higher range of engine speeds. The manifold tuning valve and short runner valves are controlled by an onboard electronic controller responsive to signals from the engine corresponding to parameters such as engine speed.

Abstract: A three plenum air distribution manifold for intake air to internal combustion engine with long, narrow runners leading from first and second spaced side plenums for delivery of air and recirculating exhaust gases into corresponding combustion chambers of the engine. One end of the spaced side plenums are connected by an acoustically balanced cross over passage selectively closed by a manifold tuning valve for improving engine output torque during low engine speed. A third plenum is positioned intermediate the two side plenums to communicate with the combustion chambers in bypass relation to the side plenums thereby directly supplying air to the combustion chambers through short runners which are selectively opened by valves to optimize engine torque over a higher range of engine speeds. The manifold tuning valve and short runner valves are controlled by an onboard electronic controller responsive to signals from the engine corresponding to parameters such as engine speed.