Intake Manifold

Intake Manifold - L81:

The SUV L81 intake manifold is a two-piece magnesium variable runner length intake manifold. The top cover can be removed to gain access to the internal vacuum chamber, fuel rails and fuel injectors. The internal vacuum chamber stores vacuum to be used when Engine Control Module (ECM) requests increased runner length. Two shafts that are mounted internally to the manifold achieve this increased runner length. On command by ECM, a solenoid is activated allowing vacuum from the chamber to pull closed two vacuum diaphragms (mounted on the end of the intake manifold), mechanically drawing both internal shafts (with flaps) closed, causing air to route through the increased runner length to the combustion chamber.