Michael Johnson
Technical Editor
May 1, 2001

Step By Step

View Photo Gallery
ZEX’s “smart” nitrous system features a nitrous-management unit that houses its major components. Since we’re installing it on our sleeper LX, this made it relatively easy to hide. One thing we couldn’t hide was the horsepower this kit makes—that is, until we blew a head gasket (see Head Gasket Diaries sidebar). This preproduction ZEX kit was designed for import applications. We called Nitrous Works (706) 864-7009; www.nitrousworks.com to get 75, 100, and 125hp jets for this install. Photo: Chuck James
Mounting the nitrous-management unit under the mass air meter should hide the fact we’re running the laughing gas. The nitrous feed line from the bottle plumbs nitrous to the unit; it’s directed from there to the air intake hose.
There are three outgoing ports found on the nitrous-management unit. One is for the nitrous line to the air intake hose. The other two are routed to the fuel-pressure regulator and intake manifold, respectively.
Three wires exit the bottom of the unit. One is for a ground and the other two attach to the throttle position sensor and the nitrous arming switch. Here, Bart has scotch-locked the white wire to the appropriate TPS wire.
This coupling is used to fasten the nitrous feed line to the air-intake hose. Notice how the discharge points toward the engine. You want the nitrous to travel with—not against—the flow of air. Yes, this is elementary, but Bart says he has people who didn’t realize this call him regarding nitrous-delivery problems.
Bart mounts the ultra-cool, aircraft-style arming switch way out of sight below the dash. It’s still readily accessible, but no one will ever see it by simply looking in the car. The cover keeps us from accidentally arming the system. However, when we’re done playing with the laughing gas, we can simply snap the red cover and push the switch in the off position.
Bart routed the nitrous feed line through this hole from the nitrous bottle toward the front of the car. You can either route it straight along the floor or you can follow the path of the fuel lines, tie-strapping them to the lines for safety.
The nitrous bottle is bolted to the trunk floor to keep it from becoming a deadly projectile should the unexpected happen. The bottle includes straps that help secure it, and make it easier to remove for refilling. 5.0

We wanted to see how much power we could reasonably produce with a stock-appearing Mustang. Previously, we've installed a Comp Cams Extreme Energy cam. With the addition of the cam, we were putting 244 hp and 297 lb-ft of torque to the rear wheels.

To recap, our sleeper also features Power Heads' CNC-ported stock heads, an Extrude Honed Holley SysteMAX lower and stock upper, BBK headers and a 65mm throttle body, and Comp Cams roller rockers and replacement lifters. At this point we're quickly running out of performance components that fit within our sleeper concept (except for pulleys--see Pulleys, Finally sidebar), but we're not about to give up now. When you've exhausted every other option, a little laughing gas never hurts--at least in most cases.

We were curious to find out if we could install a nitrous kit that was hidden from view--no solenoids easily seen, nitrous and fuel nozzles out of plain sight, and the arming switch buried way under the dash. No, this would not be an easy task, but we knew Unlimited Performance's Bart Tobener (yes, that Bart Tobener) could perform the job admirably. Bart has a background in automotive sound systems.

We also knew most nitrous kits on the market would be equally hard to hide, so we decided to give the Comp Cams new ZEX Complete Nitrous System ($595) a try. The ZEX kit is known as a "smart" nitrous system because it uses bottle pressure to regulate the nitrous- to-fuel ratio, thereby optimizing the mix. This reportedly keeps the system from becoming too rich or too lean, which means you should always have the right amount of fuel, no matter what horsepower jets you may be using. ZEX made the system this way because other kits on the market don't take bottle pressure into account. Bottle pressure does change, making a dramatic effect on a nitrous kit's performance.

With some kits, ZEX says the nitrous/fuel mix may be off because of changing bottle pressures, potentially causing engine damage. The coolest part of the ZEX system, though, is its nitrous-management unit. With this unit there are no solenoids to give away our power-adder secret. The nitrous-management unit houses the major components and is roughly half the size of an ignition box. The unit's compact size means we can hide it somewhere out of view, fooling onlookers. We could paint the unit red or black and most people would think it's just an ignition box and not even look for the nozzle going into the back of the intake hose.

The ZEX kit is easy to install. In our case, the biggest challenge was trying to find a spot to hide the nitrous-management unit. The bottle mounts in the same manner as other nitrous kits, and the feed line routes like conventional kits as well. Find a spot for the management unit and you have most of the install out of the way. Everything else is rather straightforward.

Follow along for the skinny on the installation.

Horse Sense: Nitrous Oxide (N2O) is comprised of two parts nitrous and one part oxygen. That one part oxygen allows an engine to burn more fuel and thus make more power. Its chemical change from liquid to gas provides a pleasant, cooling side effect, which also helps produce more power.