2005 Pontiac GTO Nitrous Kit - Gen IV Juice

The nitrous feed line needs to be run to the bottle in the trunk; it was routed along the brake lines next to the passenger-side exhaust manifold to the underside of the car...

...Underneath, the nitrous line is zip-tied to the brake and fuel lines and follows them along the framerail, over the subframe and axle assembly, and to the back of the car, where it enters the trunk compartment through a convenient factory opening behind the right rear wheel.

On to the wiring: the heavy black wire of the NX wiring harness goes to the positive side of the battery (or the positive side of the fuse block if you prefer).

While the NX harness includes the male end of Weatherpak connectors for the wiring going to the solenoids, female ends need to be assembled onto the wiring coming from the solenoids.

To ensure that the serpentine belt immediately below it wouldn't scuff the fuel solenoid wiring, we made sure to zip-tie them to an adjacent power-steering reservoir hose. The fuel solenoid sits rather close to the belt primarily because this system was originally designed for the C6 Corvette's intake system.

In lieu of the NX throttle position activation switch, we used the FJO box exclusively. To get a tach signal for the FJO box, tap into the brown wire with a red tracer stripe that comes from the blue connector of the ECU.

Figuring out which of the GTO's TPS wires to tap into for the FJO's TPS activation signal was tough. NX's instructions for this C6 Corvette kit specified tapping into the purple TPS wire at the lower rear of the plug. We did so when hooking up the FJO box, which resulted in the solenoids rapidly turning on and off--the Goat's wiring is different. A digital multimeter was used to try to figure out the problem, and the voltage read normal. With help from NX's Ricky Stancik, FJO's Gerald Oberbuchner, and TTP's George Benson, Werner concluded that there were two TPS signals--one rising, one falling--and the voltage signal characteristics of each (i.e., whether or not they had some sort of spiking behavior invisible on a multimeter) would be visible only on a scope, which we didn't have. Chris decided to hook up the TPS activation wire to the falling signal, which was the green wire at the top rear of the plug. This worked, and we now had a TPS signal for the FJO box.

The strut tower brace-mounted FJO box is a cinch to program; just hook up the supplied USB adapter to your computer once you install the software. After opening the software and specifying the type of TPS signal (rising or falling), the rpm values at what you want the nitrous system to start and cease operating, and the appropriate rpm multiplier to compensate for the vehicle's rpm signal characteristics (ours was "divide by 2"), just click the Upload button and the FJO box will be programmed and ready to go. The software can also program the FJO box to work with progressive solenoid drivers and a second stage of nitrous, neither of which we were using.

Out back, the bottle is installed and the warmer is added to keep bottle pressure just right. NX's heater is rather unique in that it works off of a bottle pressure sensor rather than a temperature thermostat. This way, the bottle pressure stays exactly between 900 and 1,050 psi, and not merely some guesstimate based on the temperature of the outside of the bottle (as other manufacturers use and measure with thermostats). This is particularly important since a given bottle temperature will not always yield the same bottle pressure since the amount of nitrous left in the bottle will affect this.

No adjustment to the stock timing settings were made; TTP's Matt Sorian was prepared to adjust the fuel jets if the juice turned the mixture lean, but that wasn't the case. The baseline numbers were 338 horses and 340 lb-ft. On the jug, the LS2 belted out 447 ponies and 497 pounds of torque, a gain of 109 hp and a staggering 157 lb-ft at the rear wheels. The stock 11.8:1 air/fuel ratio dropped a touch lower, to around 11.5:1, when the nitrous was flowing. Bring on that juiced LS1!

We installed the switches controlling the nitrous arm, nitrous purge, and bottle warmer in the interior, wiring them into the fuse panel just below and to the left of the steering wheel. A good ignition-switched source (the cigarette lighter fuse) was tapped in to downstream of the 20-amp fuse.

Everything was connected and wired up, and the NX MAF system install was complete. Note the stock breather line attached to the factory intake; this shouldn't impede the use of nitrous, and Chris zip-tied the fitting just to be safe.

With the installation complete, we filled up the bottle and took the Goat over to TT Performance in Clifton, New Jersey, for some dyno time.