om617 HE221 (T25) Installation Kit for Holset Turbos - 12AN
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om617 HE221 (T25) Installation Kit for Holset Turbos - 12AN

Mounting a Holset HE221 or other T25 frame turbo to your om617 can be a total pain...

om617 HE221 (T25) Installation Kit for Holset Turbos - 12AN

Mounting a Holset HE221 or other T25 frame turbo to your om617 can be a total pain in the ass but it doesn't have to be!  The BenzForce HE221 Installation Kit for the om617 takes the headache out of the physical connections.  All that is needed is a 4AN feed line and a 12AN drain hose. Please note that this kit does not connect directly to the intake manifold - there is an offset.  The main intent is to be used in injunction with our intake manifold adapter to route your compressed air through an intercooler.


** Turbo not included

Here is what is included: 

Wastegate Installation Instructions:

  • Remove the wastegate hose
  • Remove the wastegate actuator. After pulling the internal pin allowing the compressor housing to rotate independently, just remove to cotter pin on the wastegate (or a C-clip on the 5.5 cm2 models) and the two bolts holding the wastegate on the turbo.  This will allow you to completely remove the wastegate.
  • Mount the bracket.  Remove the turbo from the T25 flange.  Place, or replace, a new T25 gasket on the flange.  Then install the wastegate bracket, followed by another T25 gasket.
  • Install the turbo
  • Reinstall the actuator.  Rotate the actuator 180 degrees from its original position.   Put the end over the pin on the turbine housing and install the original cotter pin or c-clip.  Then pull the actuator and insert the original two bolts through the bracket and through the stock actuator bracket.  The actuator comes pre-loaded from the factory so pulling the actuator should put the same amount of tension on the actuator as the original configuration.  Use the included copper exhaust nuts to secure the actuator to the BenzForce bracket.
  • Install boost hose.  Depending on how the turbo is clocked, you can either reuse the existing boost hose or you may require a new one.  Regardless, reinstall the hose so the actuator will see boost from the compressor housing.

Note that the HE221 has clocking pins inside the turbo.  Both the compressor and turbine housings pins will need to be removed in order to rotate the core

The HE221 must have at least 30 degrees angle off the horizontal which is about the perfect setup after clocking the core for the drain to clear the wastegate.  With 2 x 60 degree 12AN fittings, you can build the perfect drain hose!  Getting the threads started on the fittings may take some muscles but it will look absolutely awesome!

On the w123 chassis, the engine support mount may be in the way.  We have seen at least two suspension types so please look at the last picture to determine if that will meet your needs before ordering.

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