Prior to assembly we sent our crank, rings, oil pump gears, camshafts, cam followers, valvesprings, and block off to be WPC treated. WPC treatment is a Japanese-born process, where metal surfaces are bombarded with a very tiny ceramic shot at extremely high velocities. Special antifriction additives like tin or zinc powder and molybdenum disulphide are added to the mix and embedded into the surface. The result is an extremely smooth, friction-free surface with self-lubrication properties. The shot also compresses the metal on a molecular level near the surface, refining the grain, and creating a zone where it's very difficult for micro fatigue cracks to propagate. In this way WPC works very much like shot-peening for increasing fatigue strength of parts but on a finer scale. When applied to the crank, WPC improves upon the surface finishing of the journals and toughens the fillets of the crank, where most failures occur. On the cylinder walls, WPC reduces friction and the micro dimpled surface helps the rings seat instantly. The dimples hold oil, which helps ring and bore life, and reduces friction as well.

WPC is a little known secret that sees a lot of use in Champ Car, NASCAR, JGTC, and F1, where it's highly effective in reducing friction and improving the life of parts. A drawback is that the process is somewhat expensive and costs around $800 to apply to all of the engine's rubbing parts. While this isn't needed for a budget motor, we've heard very favorable reviews of the process increasing both power and component life from our friends at XS Engineering, Cosworth, and in the professional racing world. When we received our parts back from WPC we were amazed by the silky smoothness that they exhibited. We can hardly wait to see how this process works.

We used Calico-coated Clevite bearings for the rod and main bearings, using SR20DET bearings for the mains to make use of the extra oiling holes and regular SR20 bearings for the connecting rods. Our friends in the world of professional racing had good things to say about the Calico bearings so we decided to give them a try. Clevite bearings are tri-metal, meaning that lead, copper, and zinc are alloyed in various ratios and applied in layers to the steel shell to create a bearing with a wide range of characteristics. This creates a hard bearing for superior load that can still be embedded like a soft bearing to make it a little more forgiving for dirt and contaminates. The bearings then have Calicos CT-1 coating applied in a 0.0004-inch thick layer to provide additional protection and friction reduction. The CT-1 dry-film lubricant coating is technically engineered to withstand extreme performance pressure. CT-1 coated engine bearings are claimed to increase horsepower and efficiency while extending bearing life.

Strangely enough, most Nissan engine bearings were Clevite but in an effort to become a more green company by eliminating the use of lead, Nissan discontinued their use in the early '90s. The new bearings, with less potential for pollution, are vastly inferior for performance, especially in regards to temperature resistance. The eco-friendly Nissan bearings begin to deteriorate with oil temperatures as low as 280 degrees. It's common for an SR driving at the track on a hot day to see sump temps in the 300-degree range!

With the Calico-coated bearings, our bearing clearance worked out to be slightly at the tight side of the middle for factory spec-perfect and actually pretty normal for a typical slow-wearing used SR motor.