The first part of installing nitrous is the actual plumbing, starting with mounting the bottle in the car. While putting it in the passenger compartment is generally frowned upon, if you've got a Corvette, that's pretty much where it's gotta go. From the bottle, the nitrous passes through a braided-steel line to a solenoid that mounts near the intake manifold. When the solenoid receives an electrical signal, it opens a valve, releasing the pressurized nitrous through another braided line into the perimeter plate, where it's mixed with fuel and sprayed into the intake manifold. Where the line meets the plate, it screws onto a fitting that accepts one of several different jets, or "pills," that meter how much nitrous gets in. These are marked with different numbers, and the kit specifies which one is required, and which fuel jet should accompany it in order to deliver a certain power level.
Traditional "plate" nitrous systems use a roughly half-inch-thick plate that fits between the manifold and the carburetor or throttle body. Generally, the plate has a perforated tube that runs across its middle, and the nitrous/fuel mix is sprayed from that tube. The Zex perimeter plate, however, uses a series of channels machined into the plate itself (actually two pieces screwed firmly together) to mix the fuel and nitrous and then spray the mixture through 12 different ports. The result is more-even distribution. (For those who already have a conventional plate system, the Zex perimeter plate is available separately.)
For fuel delivery, a fuel line must be added to the existing one and run to the fuel solenoid. This was the only necessary component that wasn't included in the Zex kit, likely because fuel-delivery systems vary so much between vehicles. Since this car has a 3/8-inch fuel line, I added a 3/8-inch brass tee to the stock line and ran the additional one from there. When the solenoid is activated, fuel goes through a braided line to the opposite side of the plate; this line screws onto a fitting containing the appropriate jet.
The system is activated by a switch in the cockpit. To install it, you'll need to splice into a source of switched power at the fuse box. This wire will then run to the toggle switch, and from there to a relay mounted in the engine compartment. A relay is generally used when you need to run more power to something than it's safe to put through a simple 12-volt toggle switch. The power required to operate whatever it is--here, the nitrous solenoid--comes from a direct power source, such as the alternator or battery, to the relay. A separate arming switch then "turns on" the relay, which is essentially a heavy-duty switch.
In addition to the power coming in from the alternator and the arming switch in the cockpit, the relay also has a contact for a ground wire, which you'll want to mount to the intake. There's also a contact for the power going out to the solenoids, each of which also will need to be grounded. Although I'm a relative novice at electrical work, the diagram and instructions that come with the kit are quite clear, and I had no trouble putting it all together.
The only other electrical components required are an inline 30-amp fuse for the power coming into the relay, and a throttle switch. Since nitrous can damage the engine if it's run at low rpm, many systems use a microswitch, mounted on the carb or throttle body, that only activates when the engine is at wide-open throttle. This switch is wired into the arming circuit, so that the wire coming from the arming switch in the cockpit goes to one side of the throttle switch, and another wire leads from the other side to the relay. The circuit is only closed when the arming switch is on and the throttle switch is activated.
10 Begin assembling the nitrous...
10 Begin assembling the nitrous solenoid. There's a filter fitting that goes into the inlet, and one of the 12-inch lengths of braided steel -4 AN line will be screwed into the outlet. AN fittings are measured in increments of 1/16-inch, so this one has an inside diameter of 4/16-inch, or a 1/4-inch.
11 With the inlet and outlet...
11 With the inlet and outlet fittings in place, place the solenoid on its mounting bracket. The kit comes with three brackets--one for each solenoid, and one for the throttle switch--made of easily bendable material. These can be oriented in several different directions, thanks to the different hole patterns in the bracket. Mount them to the bottom of the solenoid with the two button-headed screws, using the included hex key.
12 With the solenoid assembled,...
12 With the solenoid assembled, it's time to hook it up to its fitting. But first, check the instructions to find the correct-sized jet. Since I was adding 100 hp, this required a No. 46 jet. Insert the jet with the conical part pointed away from the plate, and screw on the braided line.
13 The nitrous solenoid in...
13 The nitrous solenoid in its final position, mounted with an intake bolt. Note that it's tucked up close under the throttle linkage. Wherever you choose to place it, make sure it will clear all moving parts.
14 Assemble the solenoid...
14 Assemble the solenoid lines and bracket the same way, using the appropriate fuel jet--in this case a No. 43. The inlet fitting is a barb unit; you'll need to install a tee in the main fuel line to get fuel from it to the solenoid. When we installed the inline fitting (with added pressure gauge, safety switch, and warning-light sending unit), we used a 1/4-inch NPT close union to attach it to the solenoid. This was placed on the other end of the inline fitting and attached the fuel line with a hose clamp.
15 You'll need to lower the...
15 You'll need to lower the carb stud to accommodate the reduced hood clearance. With the air cleaner removed, back off the jam nut and lower the stud until you have plenty of clearance. Place putty on top of the stud and slowly lower the hood. Check the putty for clearance, then do the same with the air cleaner on. Use as much clearance as you can get, remembering that the engine moves around significantly when it's running.
16 The final part to be mounted...
16 The final part to be mounted near the carburetor is the throttle switch. Thanks to an unusual throttle-cable bracket, there was no easy way to do this with the supplied bracket, so we used a flat sheet of aluminum to fabricate a mount that puts the switch directly on the carb beneath the air cleaner.
17 Here's a look at the switch...
17 Here's a look at the switch as mounted. Also note the fuel- pressure gauge, which is mounted to an inline fitting connected to the fuel solenoid. This is where we'll affix the low- pressure-light sending unit and kill switch.
18 While the kit comes with...
18 While the kit comes with wire and the appropriate terminals, you'll have to assemble the wiring. Shown here are a wire stripper and crimper, along with the wire, terminal, heat-shrink tape, and toggle switch. Strip the end of the wire, slide the heat-shrink tube over it, insert the wire into the terminal, and crimp in place. Then slide the tube up over the crimped part of the wire and use a heat gun to seal it up.