Project 350Z: Building a New Engine – Part 1


Since our poor rod bearings were really hammered, we replaced them with high load heavy duty King XP tri metal parts as well.
To improve cooling, we replaced the long suffering stock radiator with a Koyo Racing radiator. The Koyo radiator features 100% TIG welded aluminum construction with brazed in fins and tubes for a long high pressure leak free life. We opted to get the radiator with Koyo’s HyperV core and improved cross-flow design. The Hyper V core is 36mm thick and has a new fin design that allows better air flow through the radiator while still providing increased surface area for radiating heat. The new cross-flow design changes the OE down coolant flow to a horizontal side to side flow. This lengthens the coolant’s path, greatly increasing heat dissipation.
Koyo also offers high pressure radiator caps that increase pressure to 19 psi. This is easily done when you don’t have plastic end tanks that can slit or blow off!  A higher pressure increases the boiling temperature of the coolant, greatly improving cooling efficiency. A 19 psi cap will increase the boiling point to 268 degrees or 56 degrees more than the normal boiling point of water.
The Koyo radiator has a machined radiator cap flange for a very positive and long lasting seal, even with stiff high pressure radiator caps.  All of the locator pegs are in the exact same as stock configuration for a perfect fit in the stock chassis.
Though the Koyo radiator also has all of the correct tabs for the OEM fans/shrouds, it will require a little trimming of the plastic shroud in order to achieve a perfect fit. Nothing a novice can’t take care of with a dremel. The altered, but more efficient horizontal flow of the Koyo cross-flow radiator required the inlet and outlet to be moved, so you will need to trim the lower driver side corner of the shroud in order for it to clear the new radiator outlet location.
JWT recommended that we go with PPE Engineering’s long tube headers with their bigger cams so we could get the top end benefit of the bigger intake cam without losing bottom end torque.
You can see the difference in header primary length compared to our current DC headers.

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