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How To: Install ZEX dry nitrous kit

12883 Views 12 Replies 9 Participants Last post by  kapster76
Installation of ZEX dry nitrous kit.

I have had 4 PM's this week about this so I figured I would post it as a how-to.

OK. Here goes...

Will fit on a 1999 with return style fuel system ONLY. You can tell if you have a return style fuel system by looking under the throttle body. There will be either one or two metal fuel lines running underneath into the engine block. If you have two lines, it will work.

10lb nitrous bottle.
Bottle mounting brackets.
Control box.
Intake nozzle.
Thread tapper for intake nozzle.
Jets for 35HP, 55HP, and 75HP. (You can buy larger ones if you want.)
2 steel braided nitrous feed lines.
2 Vacuum line hoses.

The nitrous bottle mounts in the trunk. I put mine on the left side kinda tucked into the curve in the trunk so it is out of the way. Mount it so that the nozzle of the bottle is towards the front of the car, and the label is up. It is done this way so that the nitrous flows towards the tube inside the bottle when you are accellerating. From there, you just run the longer of the two N2O feed lines through the trunk floor and under the car into the engine bay. I used zip ties to hold mine in place. You can come up to the top of he engine bay right through the front by the radiator. Once this is run, you have to install the control box. The control box mounts in the engine compartment. The nitrous feed line that you just ran from the trunk goes into one side, and the shorter nitrous line connects to the other side. Run the short N2O line up to the intake and drill a hole. I think it's 3/8". Install the nozzle by threading the intake with the supplied threader and then just screwing it in. Make sure that the nozzle is pointed towards the engine. Connect the short nitrous line to the intake nozzle and the nitrous hose installation is done. The electrical wiring is pretty simple also. There are only 3 wires. Power, ground, and signal. The ground wire obviously gets grounded. Just drill a small hole in the engine bay and ground it there. The signal wire hooks into the TPS wiring harness on the very top of the engine on the right side. There are 3 wires that are in the harness - they are yellow, white, and brown. Splice the white wire and the sensor is hooked up. The power wire gets run through the firewall into the driver's compartment. Decide where you want to mount the arming switch and hook the power wire into one of the wires from the switch. The second switch wire goes to a power source. You should probably use the ignition as a source, but if you don't want to go through the hassle you can run it to any source that is turned off when the car is off. Example: Stereo power wire. After this is done, the electrical part is finished. The only thing left to do is tap into the fuel pressure regulator. This is kinda a pain in the ass. You have to take off the upper intake manifold. There are 6 (I think it's six, might be 8 though) bolts on the very top of the upper intake manifold. They are in plain sight. Just take those out and make sure that everything else is disconnected before you lift the manifold out of place. The easiest way to do it is to only slightly move the intake manifold instead of taking it completely off. That way you don't have to mess with taking the throttle body apart or anything. Just undo the bolts and disconnect the tube underneath the manifold. Make sure you take this off cause it is plastic and will break! After that is disconnected, just lift the manifold up about 2" and you will see the fuel pressure regulator on the right side underneath where the manifold was. You can identify it by it's shape. It looks like a big donut that has a vacuum hose (looks almost like a wire) comming out of the top of it. Disconnect the line. Run one of the vacuum hoses from the zex control box to the fuel pressure regulator, and one to the line that used to come from it. Put the upper intake manifold back into place and re bolt it in. You are finished with the installation!!!

The first thing that you have to do is program the control box to detect the correct voltage for turn on. There is a little black button on the side of the control box. Turn the key to the on position (Not started, but the radio and windows work) and have someone sit in the car and floor the gas pedal. While it is floored, go under the hood and press the button. (Make sure that you do this without the nitrous line hooked up to the bottle!!!) It should start to flash from green to red. When it does this, turn the key off and let go of the gas pedal. It should now be programmed to activate only when at WOT. The nitrous jets that came with the kit are 35HP, 55HP, and 75HP. They work in different combinations to adjust the air/fuel/nitrous level. Start off with the 35HP jets. One will mount in the nitrous nozzle where the feed line connects, and the other will mount in the fuel pressure regulator line that is connected to the control box. There will be a diagram with the kit that tells you which jets to use for what HP. So, insert the combination for the 35 horse power shot at first and take it for a test drive. Before you take it for a spin though - make sure that you are using copper core spark plugs that are 1 or 2 steps colder. All that you do to activate the nitrous is turn the arming switch on and floor the gas. It responds the best above 3500RPM. When you run the nitrous for a little bit, pull back in the garage and take a look at your spark plugs. If the tips are all colorful and weird looking, you are running too lean. If they are covered in black residue, you are running too rich. If all is ok, you can start to install bigger jets for more HP. Don't be disappointed on your first ride too... The 35HP jet is a lot different from the 75HP jet! Plus, you have to learn how to use it to get the best response. Let me know if I missed anything, but I think that should pretty much cover it. Good luck, and let me know if I can help!
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1 - 13 of 13 Posts
RE:Installation of ZEX dry nitrous kit.

wow that's a great how-to. It makes me want to buy a zex kit right now!

RE:Installation of ZEX dry nitrous kit.

I have an 2001 with a returnless fuel system. Anyone know of a how-to for the wet system? By the way that is a great how-to, good job!
RE:Installation of ZEX dry nitrous kit.

actually I have to correct zexcougar: he is correct in saying there are 3 size jets but they are not 35hp 55hp and 75 hp. They are 55hp 65hp and 75 hp. I am going to be installing a dry kit on my car this winter. Ill be using the 75hp jets. I hope to gain atleast 60hp if not more once we get done retuning the motor. I will say this tho your how to is very detailed and descriptive. I appreciate the how to thanks
RE:Installation of ZEX dry nitrous kit.

Oops... My bad! Since day 1 I have thought they were 35, 55, and 75! I even double checked the website and indeed, you are correct!
RE:Installation of ZEX dry nitrous kit.

I was always under the impression that a 75hp shot would be very, very bad for a stock this true?
RE:Installation of ZEX dry nitrous kit.

from what I know from talking to the people at zex they say if you use it properly it will not damage ur car
Originally posted by: enahs
I have an 2001 with a returnless fuel system. Anyone know of a how-to for the wet system? By the way that is a great how-to, good job!
Or a 2002, figured the 01's and 02's are equal.
Originally posted by: 123
from what I know from talking to the people at zex they say if you use it properly it will not damage ur car
You could use a 150 shot 'properly' and not damage the car....initially.

You've got to remember our engines aren't set up for forced induction - the higher shot you use and the more you run it, the more you increase the wear and tear on your engine. A shot here and there won't kill it, but if you plan on becoming a nitrous junky like most people, it wouldn't hurt to upgrade your internals and shoot for lower compression...fortify the rest of the engine so it will last longer.
the NX Wet System is 35-50-75-100-150 HP and it cost $579 shipped... i was looking at it and it seemed like it would be worth it for the HP gains it shows there... but how long do these nitrous bottles last and how much maintaince do they require to use?

Sorry i'm still a newb :p
Once the kit is set up, there isn't any maintainance at all. All that you need to do is keep filling the bottle up. It unhooks really quickly. There is financial maintainance though... It costs about $35-40 for a bottle that will only last for a few sprays. With a 75HP shot, I usually get about 10 sprays out of it until I start to notice a loss in power when I lose pressure. A bottle heater will increase the uses per bottle though. Also, get used to buying premium gas too... I use premium gas at every fill up, along with an $8 bottle of octane booster if I am going to be using the nitrous. Plus, with the colder spark plugs, your gas mileage will be around 15MPG or so. So, there are financial requirements to be fulfilled if you want to play with N2O, but it isn't too bad if you don't use it all the time. That way it only costs you extra money when you want to go fast.
Thats a great how to Zex. Nice work..Now I'm thinking about getting one :)
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