By C.Asaravala

Your Car on Steroids
I used to not respect enthusiasts that chose nitrous as their means for achieving horsepower. I felt it wasn't a "real" power adder; that it was chemical enhancement like steroids are to the athlete. I held the position that if the power isn't obtained mechanically, through cubic inches or belts and pullies, then it isn't "real". Needless to say I got into many arguments with those in the nitrous camp. But I am here to admit that I've since changed my position - I have come to really like nitrous. Let me explain why, and justify where some of that early negativity came from.

I had experimented with nitrous on several cars over the last ten years. All of my early attempts at nitrous shared a couple things in common - first, the kits were an installation nightmare. Most systems, carbureted or EFI, required extensive wiring and mounting of solenoids, relays, a throttle position switch, a master arming switch, among other ancillary components. The installation took the better part of a day to accomplish, and left a mess of wires strewn across the engine bay. I may sound like I'm whining but there are many novice horsepower junkies out there who haven't purchased a nitrous kit for this very reason. The second issue had to do with tuning. Early "plate" based nitrous systems were not consistently effective at mixing the nitrous and fuel charge. If bottle pressure was slightly low you immediately had a rich condition. On EFI systems such nitrous systems were prone to fuel puddling in the intake manifold due to poor atomization. I recall many drag strip passes where my car ran inconsistent ET's because the bottle pressure was slightly different than the previous run.

Reinventing the Nitrous System
So what changed my mind? Evolution. A company has finally figured out how to make nitrous systems better. A few years ago Comp's master cam designer Billy Godbold and engineer Matt Patrick were testing some of Comp's new Nitrous HP camshafts. Matt noticed that engine performance would vary significantly due to very minor changes in nitrous bottle pressure. As he looked into the root cause he discovered the poor ability of fuel to stay properly atomized in the nitrous plume. The existing spray bars and nozzles simply shot a stream of fuel towards the nitrous spray and hoped for atomization. These kits deliberately over-compensated on the fuel jetting to "play it safe" and avoid a potential lean situation. Yet ask any EFI guy who has had a nitrous back fire and they'll tell you that it wasn't due to a lack of gasoline. The problem with adding excess fuel as a safety buffer in a nitrous system is that it can have the exact opposite effect. The additional volume becomes even more difficult to atomize and tends to drop out of the gaseous mixture, forming puddles in the intake. The nitrous gas effectively moves forward into the cylinders without the fuel and a lean condition is created.

A new nitrous division, ZEX, was formed within the Comp Performance Group and they began researching and testing new nozzle designs. They knew they had struck gold when, as Matt told us, "the air-fuel ratio on our dyno engine stayed constant even as the nitrous bottle pressure dropped." What Matt had developed was a nozzle design that delivered unprecedented levels of fuel atomization - consistently and accurately. Their patented nozzle features a stainless steel fuel transfer tube in the center of a cup. As high pressure nitrous gas passes out of the cup and over the tube it draws the fuel out into the highest pressure area of the gas plume. The fuel is actually sheared in ultra thin layers resulting in a super fine mist. This design is so sensitive that fuel enrichment is adjusted in correspondence to the vacuum created over the transfer tube by the nitrous gas. The amount of vacuum created is in direct proportion to the nitrous bottle pressure. According to Matt, the Active Fuel Control Technology can adjust fuel 3% in either direction. "It's not going to solve a situation where bottle pressure is at 500psi," comments Matt, "however it will easily adjust to the normal pressure drop in the bottle after a drag strip pass." As bracket racers well know, this type of pass to pass consistency is crucial the difference between between going on or going home.

With the fuel atomization issues resolved, ZEX turned their attention to addressing the wiring and installation shortcomings. The outcome of their efforts was the Nitrous Management Unit. This purple box, about the size of a kids carton of milk, houses both nitrous and fuel solenoids, relay, and associated logic processor for the activation switch. By putting everything inside the box and adding digital processing, all that is required for installation is a ground and switched hot lead plus tapping into the throttle position sensor (TPS). On Ford EFI systems, for instance, a signal from 0 to 1V indicates a closed throttle, while 4.5 to 5V indicates wide-open throttle. By tapping into this signal the ZEX nitrous management unit knows exactly when to activate the solenoids. There are no mechanical micro-throttle switches to deal with.

Installing ZEX on Project '67
It's learning about this technology that got me excited about installing nitrous on our Project 67. Yes it is a little detour from the blower that are planning, but rest assured the nitrous will work well the the future blower as it helps cool the hot blower air. As you'll see and read, the installation is very simple (compare it to the Nitrous Works install we did a couple years back on our 2001 Mustang GT) and the power output is consistent and spot on the advertised rating for our jet combinations.

I. Mounting the Bottle and Nitrous Management Unit

We like to begin any nitrous system install by first mounting the nitrous bottle. Use the supplied bottle brackets so that the bottom of the cylinder is angled downward and facing the back of the car. This way gravity and acceleration will force the nitrous liquid to the bottom of the cylinder where the pickup tube is positioned.

The nitrous cylinder must be securely mounted. We drilled through the trunk floor and secured the brackets with the supplied nuts and bolts. It goes without saying that you must take caution not drill into the fuel tank.


(ZEX Nitrous Installation)

In This Article:
Nitrous kits have had their shortcomings when it comes to fuel atomization as well as system installation. ZEX however has made some major improvements. We take a close look at their innovation and install their EFI wet system and LED purge on our Project 67 Mustang.

Shown is ZEX's universal EFI wet system (PN: 82023). "Wet" means fuel is injected along with nitrous. Dry systems only inject nitrous and use the engines fuel injectors to increase fuel correspondingly. ZEX has dry systems also for certain applications.

Clearing the nitrous lines of air is important in avoiding a rich surge and poor performance. In this article we'll also install the cool ZEX LED purge kit (PN: 82010B). The blue LED illuminates the nitrous purge cloud for a little wow factor. Be sure to check out the video later in this article.

ZEX reinvented nitrous delivery by designing a nozzle that atomizes fuel consistently and effectively. The Fuel Shear Technology™ works when high-pressure nitrous oxide gas exits through the outer edge of the nozzle and shears away the fuel passing though the transfer tube. Since the fuel is drawn out by the vacuum caused by the gas moving over the tube orifice, change in bottle pressure results in a corresponding change in vacuum and fuel draw. This is ZEX's patented Active Fuel Control.

This purple box is what makes ZEX nitrous systems so superior to other kits on the market. The box conveniently houses both nitrous and fuel solenoids, as well as the throttle activation circuit. On EFI dry systems the box also utilizes a patented nitrous pressure reference to signal fuel enrichment to the fuel pressure regulator. ZEX boils down the wiring to three simple connections.
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