Why is this upgrade essential for your Nissan Z?
Traditionally, most vehicles utilize an air-to-air intercooler to cool the hot air generated by turbochargers before it enters the engine. Hot air can be detrimental to an engine, increasing the likelihood of detrimental detonation and reducing power output. The cooler the intake air, the more power the engine can produce. For the Nissan Z, equipped with an advanced turbocharged engine, efficient cooling is critical. 

When Nissan created the 3.0L VR30 twin turbocharged engine, it decided to use a water-to-air intercooler located directly on top of the engine. By utilizing a water-to-air intercooler Nissan was able to reduce costs and make the packaging of the engine and its turbochargers very efficient by eliminating a lot of "intercooler" piping that would have been necessary to get the air from the turbocharger, to the front of the vehicle where an air-to-air intercooler would be located, and then back to the engine. It is common to have a total of 10+ feet of intercooler piping that air travels through in a vehicle with an air-to-air intercooler. With the water-to-air intercooler in the Nissan Z, the air coming out of the turbochargers almost instantly feeds into the water-to-air intercooler where the air is cooled, and then the air nearly instantly (within inches) is feed into the engine. This reduction in piping allows the car to have essentially no "turbo lag" for instant engine power and response.

How does a water-to-air intercooler cool itself?

A water-to-air intercooler needs cool fluid to pass through the "water" side of the intercooler to keep the intercooler cool. A water-to-air intercooler uses an electric water pump to circulate fluid from the water-to-air intercooler to a heat exchanger. The heat exchanger is basically a "revers" water-to-air intercooler. The factory heat exchanger is located at the front of the vehicle where cooler outside air passes through the heat exchanger, and this outside air cools the heat exchanger. The fluid runs through the heat exchanger (similar to how a radiator works). The fluid, once it passes through the heat exchanger, is "cooled" and makes it was back to the water-to-air intercooler. This "cooled" fluid now become the mechanism that cools the water-to-air intercooler. So when the air from the turbocharger passes through the water-to-air intercooler the air will now be cooled. 

What happens when a water-to-air intercooler is not properly cooled?

Without cool fluid passing through the "water" portion of the water-to-air intercooler, the air portion of the intercooler would not cool the hot air passing through it from the turbochargers. This hot air would not only then make its way to the engine, this hot air would itself increase the temperature of the water-to-air intercooler creating what is referred to as "heat soak". Once a water-to-air intercooler is heat soaked, not only does the engine receive air that is too hot, the fluid in the water-to-air intercooler can boil. This boiling will create air pockets in the water system that will then cause the electric water pump to fail. 

The downfall of a water-to-air system:

It is much harder to keep a water-to-air intercooler cool when it is located inside the engine bay vs. an air-to-air intercooler which is located outside of the engine bay at the very front of the vehicle. The factory Nissan Z heat exchanger is significantly undersized, when the Nissan Z is driven quickly the factory heat exchanger becomes heat soaked, and this is why there is a high failure rate of the factory electric water pump. Solution - Upgrading the factory heat exchanger with a higher capacity, better designed for performance heat exchanger. With extensive testing, we found that the factory Nissan heat exchanger not only does a bad job of cooling, it also restricts coolant flow. This slows the flow of fluid though the water-to-air intercooler, which reduces the cooling of the air going to your engine, and make the factory electric water pump work harder. Significantly increasing the internal tube area in the AAM Competition Nissan Z 3.0T High Capacity Heat Exchanger  allows the system to run at lower pressure. This lower pressure allows the water pump to operate under less stress and therefore increases its long-term reliability. In addition, our heat exchanger features an all-aluminum, TIG-welded construction for improved durability, as well as a captive bleeder valve to help with installation."