Engine intake system with modulated tuning

Claim 1

A modulated tuning intake system for a V-type internal combustion engine having a pair of adjacent longitudinal cylinder banks containing a plurality of cylinders each included in one of two cylinder groups, a longitudinally elongated manifold plenum for each group and runners connecting each plenum with the cylinders of its respective group, said manifold plenums extending longitudinally in laterally spaced side by side relationship with one another and the adjacent cylinder banks, a common chamber for the system, a pair of conduits, one connecting each manifold plenum with the common chamber, said system being tuned to provide an enhanced level of cylinder charging volume in a predetermined lower range of engine speeds, and the improvement comprising a connector laterally joining the dual manifold plenums continuously along at least half their longitudinal extent and providing a large area passage internally communicating the separate plenums to effectively provide a single larger plenum and thereby modify the system tuning so as to provide an enhanced level of cylinder charging volume in a higher range of engine speeds above said lower range, and valve means in said passage and movable to selectively open and close the communication of said separate plenums and thereby respectively provide the lower and higher speed ranges of enhanced cylinder charging for the intake system.