Nitrous oxide: the chemical compound that invokes fear into the hearts of some while raising the hair on the back of the neck of those who have felt its unruly power. Despite the horror stories, most likely well-exaggerated, nitrous oxide can be as safe as any other form of power adder and by far the greatest bang –for-the-buck modification. So why do so many fear the juice? Presumably, it is due to lack of understanding and a wealth of misconceptions and myths on the streets. Whatever the case may be, the key to running a safe and dependable set-up is knowledge. Here were going to install a basic wet nitrous system, compliment it with a stand-alone fuel supply and a host of accessories for a trick set-up that safely adds 125 extra tire-melting ponies.
The subject chosen for the giggle gas mod is a 2003 Dodge Ram with the 5.7L Hemi engine. For some the stock 345 horsepower would be sufficient, but when is factory horsepower ever enough? For the nitrous system we went with the new Zex Hemi kit, which can be used on all year 5.7 Hemi trucks thanks to Zex’s innovative fuel line adapter, which provides a source of fuel on ’06 and later trucks that do not have a factory fuel rail test port. For the fuel supply on this install, however, we’ve consulted the expertise of the pros at Aeromotive so we can feed the beast with race gas while on the bottle as opposed to pump gas from the tank. The higher octane fuel is for both performance as well as a safety; the increased compression provided by the nitrous thrives on slower burning fuel thus making more power, and the high octane will help us avoid detonation.
This system we’re installing is more complex than most, yet can be completed in the typical 20x20 garage in less than a weekend’s time. However, the basic Zex nitrous systems can be installed on any truck, gas or diesel, in a few hours using common hand tools. Whether you’re an accomplished pro or a budding gearhead, you can turn your truck into a rubber-shredding freak in a single afternoon without sacrificing driveability or the headaches of tuning a supercharger/ turbo.
Part One: Mounting the Hardware
- The first step is mounting the Zex NMU. Carefully choose your location for the NMU being sure you will be able to reach the air intake tube once mounted. On this truck the Airaid filter housing served as an excellent location.
- Mounting the fuel pressure regulator close to the NMU makes for a clean install, avoiding fuel lines zig-zagging across the engine bay. Mount the Auto Meter fuel pressure sending unit to the regulator and double-check clearance for lines and wiring harnesses then mark and drill your locations.
- Install -6 hose ends on bulk lengths of -6 fuel line. Be sure to use steel-braided line for the pressure side and, at a minimum, rubber fuel injection hose for the return line. The pressure line will need to handle 80 psi and the return line will be 30 to 40 psi, so keep this in mind when buying your bulk line.
- Install a -6 tee to the inlet side of the regulator and
attach the steel braided hose. On the third end of the tee, use a
- Select a location for the purge solenoid close to NMU. Before mounting, check the supplied -3 line in the Zex purge kit will reach from the tee on the NMU to the purge solenoid. Once you have this verified, install the fittings on the purge solenoid and mount in place with the supplied hardware.
- Reinstall the housing back on the base and route the lines down between the firewall and splash shield. Route the lines through the body mounts back to the bed. Be sure to secure with zip ties.
- With all the hardware mounted under hood, start in the bed by mounting the bottle brackets with the supplied hardware. Be sure to verify you have a clear shot under the chosen location so lines and wiring are clear of suspension pieces and you will be able to access the bolts for tightening. Once the bottle is positioned, drill a 1” hole for the nitrous feed line and wiring.
- Choose a location for the fuel pump. The pump is gravity fed,
so ideally this will be under the bed and clear of moving suspension
pieces, the differential and spare tire/ winch. Install the filter on
the inlet side of the pump with the -10 adapter and fit a
Mount the pump with the supplied bolts and insulated brackets – use blue thread locker on the mounting bolts. Install a -6 hose end on the pressure line coming from the engine compartment and thread onto the pump outlet. Be sure to support the fuel line as needed to keep it clear of the differential.
- Choose a location for the fuel cell factoring the routing of the return line as well as the routing of the supply line to the pump. Also, choose a location that will accommodate easy refilling. To mount the fuel cell, we picked up some bulk aluminum and 3/8” bolts, nuts, lock washers and fender washers. Measure twice and bend once as the aluminum can only be formed one time without sacrificing its rigidity. Mount the cell in place and drill a 1” hole for the supply line to the pump in the floor of the bed. Double-check under the bed to avoid drilling into suspension pieces or double-walled bed reinforcements.
- Drill another 1” hole near the cell inlet port for the return line. To keep hoses in the bed to a minimum, we routed the line between the inner and outer bedside panels. Be sure not to drill the access hole too close to the cell inlet to avoid sharp bends or kinks in the line. Install a grommet in the access hole for insulation and a -6 hose end and attach to the cell inlet port. Install a -6 cap on the unused inlet port if your cell is equipped with dual inlets.
- So we can open and close the bottle on the fly, we’re installing Zex’s remote bottle opener. Install by removing the manual handle and installing the opener gear. Slide the collar over the bottle and using the supplied clamp, fasten the bottle opener to the collar.
- Install a single port -4 bottle manifold to the bottle port and thread the Auto Meter nitrous pressure sending unit into the manifold. Use Teflon tape or putty on the NPT thread to avoid leaks.
- Ideally bottle pressure should be between 900 to 1050 psi., so to keep our bottle in the sweet spot we’re using Zex’s bottle heater with an integral thermostatic control. Affix the heater to the bottle and fasten the bottle in the insulated brackets.
Part Two: Wiring
14. To monitor the system, we’re using electric fuel and nitrous pressure gauges and a air/ fuel gauge from Dynotune to ensure we don’t run lean while on the gas. Auto Meter also offers a trick 3-gauge dash pod to cleanly mount the three gauges in the otherwise useless dash cubby.
15. We can pick up fused 12V power and ground for all three gauges by t-tapping into the two wires leading to the cigarette lighter.
- Rather than mounting a plethora of gauges in the cab, we picked
up this
- We sourced power for the
- The NMU is triggered by a wide-open-throttle switch. The Hemi trucks do not use a throttle position sensor, so WOT voltage can be picked up from the pedal position switch on earlier-model Hemi trucks. T-tap into the #5 pin on the harness located under the battery tray.
- To keep from running large amounts of voltage through the
- To control the fuel pump, we used the toggle switch supplied in
the Zex kit (not used because of the
- With everything wired, it’s time to fill the cell and hook up the bottle to test for leaks. To avoid detonation when spraying nitrous we’re using C12, a 108-octane unleaded fuel designed for a wide variety of applications from VP Racing.
- After verifying there are no leaks the final step is to set the pressure on the regulator. The regulator does require a vacuum source, lucky for us there happens to be a spare port located on the brake booster. Zex tests their fuel injection systems at 58 psi, so we set fuel pressure at 60 psi. Adjusting the regulator is easy; just loosen the lock nut and turn clockwise for more pressure or counterclockwise for less.
- The final step in finishing the nitrous system is mounting the Zex nozzle. Zex recommends placing the nozzle 6” to 18” away from the throttle blade to allow for proper atomization of the nitrous. Using an 11/32” bit, mark your location and drill the intake tube. Using the supplied tap, thread the hole for the nozzle and install the proper jets for the selected horsepower (75, 100, or 125).
- As a precautionary measure, Zex recommends running colder
plugs to further resist detonation. On this Hemi, we’re installing
NGK’s 4306 plugs which are one heat range colder than the stock 5306
plugs. As well, we will run a slightly tighter gap: .040” as opposed
to the factory-recommended .044”. To ensure we have sufficient
spark, we’re also installing a set of
- (Image 025) – Before remounting the Shaker hood, we fabricated the purge lines using bulk 3/16 brake line from the local auto parts and a handful of compression fittings. The sky is the limit on the purge set-up, just be sure to route the lines so that the nitrous cloud is visible from the driver’s seat. Here we routed the lines through the Shaker base plate and out the openings on each side of the scoop.
The Final Word:
On track performance yielded over a second drop in 1/4 –mile ET with the truck in full street trim. However, there was more to be lost as the factory speed limiter ended the fun early on the nitrous runs. Extending the speed limiter and adding some sticky rubber could easily turn this mid-14 second street truck into a nasty 12-second screamer thanks to Zex.
How Much Did It Cost?
Zex Bottle Warmer : $125.95
Zex Bottle Opener: $224.99
Zex Dual Outlet Purge: $115.95
Aeromotive Pump: $305.95
Aeromotive Regulator: $168.79
Auto Meter Gauges: $379.90
Dynotune A/F Gauge: $89.00
Dynotune Nitrous
Jaz Products 1-Gallon Fuel Cell: $134.99
VP Racing C12 Fuel (5-gal): $40
Nitrous (10 lbs.): $45
Fuel Lines and Fittings: $281.49
Total:
$2631.96
Sources:
Zex
www.zex.com
Aeromotive
www.aeromotiveinc.com
Auto Meter
www.autometer.com
Henson Motors
Dynotune
www.dynotunenitrous.com