Zex Is For Nitrous

Trunk space in the convertible is next to nil, so our choices of where to mount the nitrous bottle were limited. Being that this is a daily driver, removing the spare tire was not an option. Instead we pulled the rubber plug on the passenger side to allow us to route the nitrous feed next to the stock fuel lines. We also cut the rubber plug and wrapped it around the feed to prevent chaffing from metal-on-metal contact.

This was the most time-consuming part of the install. Dropping the tank only required removing two bolts from the tank strap and pulling out the fuel-tank sleeve. The easiest way to do this is to first make sure the tank is nearly empty and use a jack to support the weight. Once it was loose, we did a mock-fit of the brackets with the bottle mounted, then drilled out the four holes needed for the mounting bolts and nuts. Notice how we cut the carpet to fit around the brackets.

We routed the nitrous line along the stock fuel line and then plumbed the final segment through the fenderwell and into the engine bay.

Ideally, the nitrous nozzle should be 6 to 8 inches from the throttle-body. We placed ours just outside of the bend in the inlet elbow. And since we had a metal elbow, we placed a piece of masking tape to prevent the drill from getting out of control while we drilled a 7/16-inch hole to mount the bulkhead fitting. While we could have drilled a 1/4-inch hole and used the tap to screw in the nozzle, we felt using the bulkhead would keep the nozzle from moving. Either way, just be sure the nozzle opening faces the throttle-body.

Most people probably wouldn’t give the NMU a second look and just assume it’s some aftermarket ignition box. However, to tuck it away from view, we drilled four holes (arrows) on the cowling and mounted the unit upside down to expose the nitrous feed from the bottle (A), AN-3 line to the nitrous nozzle (B), hose to fuel regulator (C), and intake/fuel jet housing to vacuum port on manifold.

Using the same 7/16-inch drill bit, we made four more holes along the firewall to route the hoses and braided lines to the NMU. The feed line and the three NMU wires enter and exit here (A). Coming out of the NMU, the -3 braided line is connected to the nitrous nozzle (B). The vacuum hose is connected to the fuel pressure regulator (C). The vacuum hose is connected to the intake manifold in order to vent unused nitrous-control pressure (D).

It only takes three wires to fire up the NMU—black is the ground, the red goes into the arming switch, and the white wire (arrow) attaches to the green wire of the throttle-position sensor. No need to worry about adjusting a full-throttle nitrous arming switch. The white wire leading into the sensor will activate the solenoid only when it detects a wide-open throttle position. We also used a small piece of hose wrap to show how easily you can camouflage the system. If we really wanted to fool someone, we would have placed the nozzle under the elbow (hint, hint).

That 7/16-inch bit came in very useful again when we used it to drill out the hole for the trick aircraft-style arming switch supplied with the kit (arrow). The switch comes complete with the necessary wiring, including an inline fuse. Just plug the fuse side to a 12-volt switched-ignition power source and use the other wire to connect to the red wire on the NMU.

There it is—complete and ready to go. The funny looking contraption wrapped around the bottle is the Zex Nitrous Bottle Heater. This ensures we maintain optimal bottle pressure on those not so warm days in the high desert. It has dual thermostats and automatically turns the heater on and off to maintain the correct bottle temperature. The gauge (arrow) keeps tabs on bottle pressure; it’s best kept between 800- to 1,000-psi to give you the maximum punch. Anything below 800 psi means a loss of up to 20 lb-ft and 10 hp. Anything above 1,000 psi can result in a stuck solenoid from the high pressure.

We’re willing to bet most of you have never heard of Zex. As a matter of fact, it was news to us when we saw the press release. But what enticed us the most was the phrase “world’s only smart nitrous system.”

Unlike virtually every other nitrous kit we’ve seen, the Zex Nitrous System is completely self-contained with all the necessary ports extending from a black box controller. The unit relies on bottle pressure to regulate the nitrous-to-fuel ratio. Inside the weatherproof box, the Nitrous Management Unit (NMU) has a bleed orifice that measures bottle pressure and regulates fuel enrichment according to that reading. This means the engine always gets a perfect nitrous-to-fuel mixture no matter what the bottle pressure is. The dry system that we installed on our ’88 5.0L Mustang simply fogs the manifold with nitrous rather than dumping both fuel and nitrous into the intake. To get the extra fuel enrichment needed to make the power, the NMU measures bottle pressure and then sends a vacuum signal to the stock fuel regulator to spike up the fuel pressure and increase fuel delivery through the engine’s stock injectors. With all that thinking going on, it’s a pretty remarkable system.

The Zex kit is rated to produce from 75 to 125 hp depending on the jets you install. And while they don’t supply you with the additional nitrous/fuel jets, a little birdie told us that the Zex Nitrous System can safely give you up to a 200hp increase with a proper fuel system consisting of a better fuel pump and larger injectors to meet the demand of this power increase.

Installing the Zex Nitrous System on our car was a cinch. It could have taken as little as two hours to install if not for the excruciating job of dropping the fuel tank (which you have to do with any nitrous kit) to mount the nitrous bottle correctly in the trunk. We probably could have gotten away with mounting it behind the passenger seat (the back seat is never used), but since the Zex system is such a nice unit, it deserved to be installed with style—even if it meant we had to get a little dirtier. We even took it a step further and hid the NMU under the front cowling, so unless you knew what you were looking for, you would never suspect this topless cruiser packed a punch. Read on to see how simple it really is!