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High Flow Upper Intake Plenum

Crazy Mater Fab

  • $200.00

Our exclusive laser cut, hand-fabricated high-flow plenums for 6.2L and 6.5L diesels.  These come in multiple versions to support many different configurations.  Perfect for mechanical or electronic injection trucks with no extra fab work required to figure out where sensors will go.

On most engines, especially those with upgraded turbos, you will instantly notice less cruise boost, lower EGT and lower IAT.  This all happens due to removing the restriction present in factory plenums so the turbocharger is not constantly pushing air up against a "wall".

We can also add WMI ports (Water Methanol Injection) during fabrication to accommodate your 1/8" NPT nozzles!  If you don't have an aftermarket WMI kit then please disregard this option.

Curved Outlet - 3" tubular connection to side-mount turbo with an integrated hose retention flange.

Intake Base Plate Option:

  • 6 bolt F Code 6.5L flange. 3/8" thick. Compatible with non-egr intake manifolds ONLY
  • 2 bolt J Code 6.2L flange. Also fits non-egr 6.2 intakes that have the same bolt pattern as the J Code. Requires RTV to seal

Turbocharger Connection Option:

As of May 2023, the base plenums are all fabricated in the same configuration and you have to select what connection kit you need for different turbochargers. This allows you to install with a stock turbo now and upgrade in the future by only changing the coupling kit.

  • Stock GMx turbo. GM3/4/5/8
    • We'll include the silicone reducer coupling and clamps to connect your stock turbo to the high flow plenum
    • It is required to re-clock the compressor cover for this application
    • The extra cost for this option is due to a custom extended length silicone coupling
  • Holset Style Turbo with v-band flange in-tact
    • We'll include our CNC billet aluminum adapter, o-ring, silicone coupling and associated clamps for a leak-free seal
  • Quadstar Super 54 or Super 60 with v-band flange in-tact
  • Exclude Connection Kit
    • Nothing will be included to complete the turbocharger connection

Sensor Style Option:

If you are unsure, trucks built before 1994 had mechanical injection. 1994 and newer trucks have electronic injection with a PMD.

  • DB2 - Mechanical Injection - 2x 1/8" NPT sensor bungs with plugs.
  • DS4 - Electronic Injection - 2x 1/8" NPT bungs, MAP Sensor Flange, and IAT sensor bung. The only simple BOLT-ON plenums for DS4 injection trucks
  • Neither style requires a "boost bolt" since the ports are built into the flange for you!

New flange bolts and gasket are included with all styles.

*These are fabricated to order and can take up to a week to ship.

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