Chart 1: The Maxima was dyno'd...
Chart 1: The Maxima was dyno'd prior to installation of the air filter or activation of the nitrous kit. This run (made with the HKS exhaust) would serve as a baseline for the other components. The car put down 190.2 hp, which is less than the previous run made in the same trim. The most likely cause of this is the switch to bigger, heavier wheels, which require more energy to turn.
For our throttle in a bottle, we went with ZEX because of its easy-to-install design. The key is the integrated design of the system's distribution block. On one side of the block, there are three wires, a power wire, ground wire and the activation wire that leads to the Throttle Position Sensor (TPS). There is also a port for incoming nitrous that connects to the bottle. On the other side of the block are ports labeled Intake, Regulator and Nozzle. The Regulator port is joined to the fuel pressure regulator to ensure a bump in pressure when the system comes online, while the Intake port ensures that any excess pressure, in case of a spike, is bled off and routed into the intake system so when the throttle plate is closed, fuel pressure returns to stock levels. The Nozzle port funnels the nitrous to the engine. The nozzle itself is fitted with jets that determine the amount of nitrous oxide introduced to the combustion chamber and, consequently, the amount of power that the system will generate.
We employed KG Precision Engineering to handle the installation. Popping the hood, the Maxima looked to be a tough nut to crack because of its crowded engine bay. Hondas have a grip of space on the firewall to mount ignition boxes, relays or the ZEX distribution block. A creative place was found and the block was secured. Grafting the power wire into the mix and securing the ground wire was simple. The only real hurdle we faced was the TPS. The ZEX solenoid must see 4.5 volts from the TPS before it will fire. The Maxima's TPS generated only 3.98 volts at WOT when first wired to the system. Using the TPS adjustment screws, the KG crew was able to realign the TPS so it would generate the proper voltage.
We elected to play it safe and run the smallest jet in the lot-a .38. The ZEX kit can be configured to deliver up to 75 hp while using the stock fuel system. Even considering KG's vast experience with nitrous systems, the install was swift. In about an hour, the Maxima was ready to laugh and we were off to XS Engineering for some dyno pulls. We retested the baseline of the Nissan with the HKS exhaust and netted 190.2 hp and 179.6 lbs-ft of torque. This was a bit less power than before. The only reasons we can come up with for this discrepancy are the wheels. The Volk IIIs are bigger and therefore heavier than the stockers and require more kinetic energy to turn, hence the lower power figures.
When installing the K&N filter, we were shocked to see how much dirt was on the OE element. A 2-minute swap later, the rollers were spinning and the Maxima laid down 194.2 hp. One hundred twenty seconds is a darn fast way to gain 4 hp at the wheels. We decided to make a pull with no filter and the V6 made 194.6; we were impressed with a filter that flowed .4 hp less than an open intake.
Chart 2: The K&N filter produced...
Chart 2: The K&N filter produced 194.2 hp, a 4 hp gain. This is a pretty good deal, considering the drop-in replacement element took seconds to install.
Chart 3: We were curious...
Chart 3: We were curious how good a replacement-style filter can be. We were shocked when the open box resulted in a microscopic .4 hp gain.
Chart 4: Activating the ZEX...
Chart 4: Activating the ZEX nitrous system jumped power to 220.1. The full potential of the kit was not realized because Nissan pumps are capable of generating only 60 psi (compared with 80-plus psi for a Honda) and less fuel means less power. Even with this shortfall, the Maxima still responded eagerly on the street when the chemical supercharger was engaged.