WPC is very secretive about their exact process but we have been able to glean a few important details from indirect observation and our own personal experience with the process. Contrary to popular belief, WPC is not a coating; it is closely related to shotpeening except WPC is done in a very different manner. Like shotpeening, WPC involves impacting a part with spherical projectiles to produce surface compressive stress, plastic deformation, and grain refinement. Again, much like shotpeening, this action greatly improves fatigue strength and stress corrosion fracture resistance. However, WPC differs from shotpeening in that the peening media is several orders of magnitude smaller, much harder and the impact velocities are much higher. WPC now offers CTP’s cryo services in the same location so getting both of these treatments in the same place is a great time saver!
The freshly aligned honed main bores are all signs of IAG’s great machine work.
Our IAG cases were then shipped back to IAG for assembly into our super Subaru EJ257 engine.
That is a quick overview of what it takes to correct a lot of the EJ257’s inherent design and dimensional problems. It also shows that yes, IAG can build it better than the factory and should silence all of those built engine Subaru internet engineering experts. Stay tuned, in our next segment we will cover the rest of our IAG Engines bottom-end parts.
Read all about project STI and the other chapters of this engine assembly!
8 comments
Hi Guys,
Love this article – I’ve got one question about the sequence of steps, specifically the CTP Cryogenics treatment step coming in after the torque plate hone/bore. If the tensile strength of the metals are going to be increased would that mean that the same torque rating on the head studs would create less distortion and negate some of the benefits of using a torque plate while machining?
Thanks,
Nick
No.
Our Cryogenic services should come after rough boring, if needed, but before final honing.. Torque ratings should not be altered from specs.. All building techniques should be done to the highest standards not matter what. It is the same as procuring the highest quality parts one can despite sending parts for DCT (deep Cryo Treatment) and other enhancements such as WPC or DLC..etc
As a note, we did not measure any dimensional differences in our cases before and after cryo treating.
Do you notice any differences between the machine work done by Outfront on the video build and and IAG on this one? if so which would you recommend for a Subaru engine build?
They are both high quality jobs but from seeing the process firsthand, IAG has more control over their processes and more state-of-the-art machining centers. IAG also uses deck reinforcements using the same cast metal as the block which is more thermally compatible with the original case. IAG has the 14mm stud option vs 12.5mm. IAG has the receiver groove for O-Rings. These are incremental differences.
What effect , if any does the wpc treatment have on oil retention on the bores?
The dimpled texture probably improves it.