The Rest of the Engine for Project WRX

  As with many of our builds, we used Kings XP rod and main bearings.  We have had extremely good luck with these bearings in the most extreme use conditions. The XP bearing uses Kings P-Max black tri-metal construction a steel backing is covered with a hard intermediate layer with a high tin and copper content for superior load-bearing capacity. This is covered with an overlay with a 2-3% copper content which is harder than typical for excellent load-bearing capacity.  This intermediate layer and overlay result in a bearing with 24% more load capacity and 17% more fatigue resistance than its competitors. The upper main bearings that are grooved have King’s U-Groove oil groove design, this design has a deeper but more narrow oil channel that allows for good oil distribution while giving more bearing surface area for better load-bearing capacity.

King XP bearings are coated with their pMaxKote nanoparticle coating.  pMaxKote is a ceramic nanoparticle enhanced polymer coating.  The coating provides increased wear and seizing resistance while increasing the bearing’s load capacity.  We have torn down some long-term race motors that have run this coating and were amazed to find the bearings looking like new.  King Bearings use an eccentric profile for a better hydrodynamic oil wedge formation. The bearings also use King’s radial lock method to provide a better press fit for more spin resistance and better heat transfer from the bearings surface without bearing surface distortion in the area where the shells come together.

To assure good oil pressure we selected a new OEM 10mm oil pump.

For longer life, better fatigue strength, and cooler running, we WPC treated our oil pump gear.

We will be using a Fluidampr harmonic balancer instead of the OEM Subaru part. Conventional OEM harmonic dampers typically have a hub attached to the crank with a mass damper bonded to the hub with an elastomer. The weight of the mass damper is tuned to help attenuate vibrations in a certain range. A bonded rubber damper can only be tuned to work in a narrow RPM range. The Fluidampr gets around this by being amplitude sensitive instead of frequency sensitive.  A Fluidampr has a steel flywheel housed in a laser-welded housing that is attached to the crank.  The housing is filled with a silicone goo that acts as a shear layer between the housing and flywheel. The silicone absorbs the torsional vibrational energy, the more the torsional movement, the more the silicone absorbs the force.  This is independent of the frequency of the vibration.


  1. I’m surprised that your high-mileage S20 heads were rebuildable. No cracking in the spark plug thread area?

  2. Love the cam choice. I definitely feel like these motors are often undercammed given their displacement. Where are you looking for the powerband to be?

      1. Im from Europe and I would like to rebuild 2.0 turbo 130kw (EJ205) Forester SG motor. Is it possible to have any consultations via email etc ?? It is not possible for me to ship my engine to USA and then back.

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