Over the course of the last year, our ’00 F-250 has been subjected to a long list of modifications. Hybrid injectors, an upgraded fuel supply system, higher volume HPOP, fire-ringed heads, GTP38R turbo, built 4R100 transmission, and custom tuning have all made their way onto the truck in an effort to help the build live up to its name: Project 600 HP 7.3L. To ensure we get as close to our horsepower goal as possible, we’re throwing one last power-adder at the 7.3L Power Stroke this month: nitrous oxide.


Designed for diesels with factory to moderate fuel systems, the Stacker 2 nitrous system from Nitrous Express is a safe, cost-effective way to add up to 150 hp to your combination. The NX kit employs a 0.093 orifice Lightning series solenoid, -4 AN braided stainless feed lines, a 15-pound nitrous bottle with NX’s 45-degree bottle valve, and all fittings and necessary installation hardware. The Stacker 2 system retails for $641.63.


For an even distribution point, we planned to have the nitrous enter the 7.3L engine’s intake stream through the intake Y that feeds boost to each cylinder head. With boosted air already having been routed through the intercooler by the time it reaches this point, we believe it’s the best place to introduce nitrous.


We began the install by threading the N2O filter fitting into the inlet port of the Lightning solenoid. This fitting’s screen-type filter is good insurance against any debris making it into the solenoid, as any trash that makes it into the solenoid can hang it open. It’s also important to note that Teflon tape should not be employed when installing the nitrous solenoid fittings into the solenoid. Nitrous Express supplies its own thread sealer with each Stacker kit it sells.


As for wiring up the system, NX supplies a wiring harness that accommodates a 30-amp relay. The relay controls the opening and closing of the solenoid, while a micro switch (also included) activates the relay traditionally at wide open throttle. Since we wanted to be able to turn on or off the nitrous whenever we felt the need, we decided to use our own switch, you’ll see it later on. The relay is basically a remote switch so you don’t have to run large wires into the cab and back out to the solenoid. In order for it to work it needs a supply of power from the battery; a ground to chassis; a lead to the solenoid; and a feed in from the switch in the cab.


Both the solenoid and relays were grounded using an existing ground on the firewall.


Before we mounted the relay and secured the wire harness where we wanted it (out of harm’s way and away from additional sources of heat), the wiring was wrapped in plastic wire loom. This added a layer of protection to our wires, but also made for a clean look. We don’t want to call attention to anything other than the nitrous solenoid. At this point we also ran the remaining wire (switch) through the firewall into the cab to be hooked up later.


In an install such as this, it’s important to mock up the solenoid, fittings, feed line(s), and wire routing before you decide to mount anything. We ended up mounting the aforementioned solenoid relay and its respective wiring harness next to the brake fluid reservoir.


Once we’d decided where the nitrous solenoid was going to go (above the A/C receiver-dryer), we fabricated a quick mounting bracket using some 2-inch aluminum flat stock. Two Phillips head machine screws secure the solenoid to the mounting bracket.


With the solenoid mounted, the supplied inlet and outlet fittings were installed next. After that, one end of the -4 AN braided stainless feed line that spans from the solenoid to the engine (labeled “out”) was attached to the solenoid.


Wiring up the Lightning solenoid is very basic. The unit has just two wires: one for the switch and one for ground. The switch wire we then ran to the relay.


By incorporating a raised inlet and bottom exit feature into its Lightning solenoids, NX eliminates up to four 90-degree turns and one expansion area in this solenoid body. No sharp bends or expansion areas mean nitrous doesn’t have a chance to become gaseous. Instead, it stays in liquid form longer—which means more power can be made. It’s worth mentioning that, while the included thread sealer was used to install the inlet and outlet port fittings into the solenoid, none should be used when the feed lines are attached to the fittings. Before moving forward with the install we pressurized the system (with the solenoid off of course) with the 15-lb NX bottle and checked for leaks with a little soapy water. No bubbles means no leaks.


The wire we ran earlier into the cab will be tied in now. It needs a positive voltage signal in
order to activate the solenoid. So we grabbed a “key on” power source from a wire running to
the radio, ran that to the arming switch (the one with the red cover for safety), from that switch
we ran it to this pistol grip style hand held switch for easy activation on the track. This way the
system will only work if both switches are on.


With everything wired up and mounted, it was time to test the solenoid to ensure it’d been installed (and would work) properly. After confirming the nitrous bottle was off and that no pressure was present in the supply line, we toggled the arming switch to the on position and activated the system until we heard the solenoid click. And then, well, because we just couldn’t wait (do not do this), we cable-tied the line from the solenoid, opened the bottle and pressed the button a couple times.


Last connection under the hood was plumbing the feed line from the solenoid into the intake. We used a plug from Riffraff Diesel that installs in place of the IAH to tap into said intake. The kit comes with different size jets designed to restrict nitrous flow in varying levels, they get installed here between the line and fitting on the intake.


The Lightning 500 bottle valve is about as good as it gets when it comes to nitrous oxide technology. It features a 0.500-inch lift stem assembly, a large 5/8-inch siphon tube, 45-degree outlet for ultimate flow, and dual gauge ports. A -4 AN bottle nipple comes standard, but -6 AN, -8 AN, and -10 AN nipples are also available.


For convenience and concealment, we decided to mount the 15-pound NX bottle in our toolbox, next to our Snow Performance water-methanol reservoir. However, we made sure that once it was installed we would still have plenty of room to access the bottle valve.


The bottle brackets supplied in the NX Stacker 2 system incorporate stainless steel, T-bolt clamps with wing nuts for quick removal and installation of the bottle. Mounting the brackets called for four 3/8-inch holes being drilled after checking to ensure no obstructions existed beneath the area of the bed we elected to drill through.


After using the supplied mounting hardware to secure the bottle brackets in place, we installed the bottle. The final step of the install entailed routing the nitrous supply line up to the solenoid on the engine.


Before routing the feed line from the bottle’s mounting location in the bed to the solenoid under the hood, we capped off the end so no debris could enter the line. The feed line was secured via zip ties wherever possible and was routed as far away from heat sources as possible. We then drilled a ¾-inch hole in the bottom of the toolbox (and the bed) near the bottle nipple’s location for the feed line to pass through.


Arguably no other method of adding power to a diesel is as cost-effective as NO2—and no one understands this better than the folks at Nitrous Express. The company’s “Stacker” systems were specifically designed for diesel vehicles, and can provide between 50 and 300+ additional horsepower. For that little something extra, we opted to run one of NX’s Stacker 2 kits—a system capable of adding another 150hp to the mix. Once everything was buttoned up, it was time to face the music in the form of strapping the truck to the chassis dyno. Follow along for the install and the data we collected on the rollers. DW


The moment of truth for our 600hp build arrived when we strapped the truck to the chassis dyno. After producing 502-rwhp on fuel, we made sure ample bottle pressure was on tap, armed the NX system, and made a pass on spray. Thanks to the nitrous and with a 0.078 jet installed, we picked up 94 hp at the wheels and squeezed 596 hp out of the 16 year old 7.3L. As you can see the nitrous cleaned up the smoke almost completely, so we’re sure that with some tuning for more fuel and a step up in the nozzle size, we’ll be able to get every last drop of NX’s 150 hp rating with numbers closer to 650 hp. With adequate traction at the track our near-600hp Super Duty should be capable of running a mid-12 in the quarter-mile.