Lower Intake Manifold

The Lower Intake Manifold is the lower intake collector and the final step in the intake air's path before it reaches the cylinder head.

Function & Location

The Lower Intake Manifold is located between and above the two cylinder heads, and underneath the Upper Intake Manifold. It provides mounting points for the fuel rail and has ports allowing injected fuel to enter the combustion chamber via the cylinder heads. It also provides a mounting point for the upper timing belt idler pulley & stud.

Versions

There are two versions of the Lower Intake Manifold, which correspond with the phases for Fuel Injectors.

	Non-Turbo	NA (Convertible)	Twin Turbo
Phase I	1990-1992	1993	1990-1994
Phase II	1993-1996	1994-1996	1995-1996

When retrofitting Phase II injectors into a Phase I engine, a traditional way of adaptation was to machine the Lower Intake Manifold to accept a Phase II fuel rail. Today, there are adapter kits and alternative fuel rails available which make retrofitting a drop-in replacement job.

Associated Seals & Gaskets

The Lower Intake Manifold has three surfaces which require gaskets or seals:

• Upper Intake to Lower Intake Plenum Gasket.
• Lower Intake to Head Gasket.
• Fuel Rail Insulators.