All Zexed Up: LS1 Camaro Nitrous Install

There is no disputing that nitrous is a great modification for a daily driver that sees time at the track. You can drive the car normally, and when the mood suits you, a flip of a switch will give you an additional 50+ horsepower. Using a 2001 Camaro SS, we will show you exactly how easy it is to install a nitrous system with a Zex High Output kit, complete with a window switch.

The History of this Cold Concoction

There is nothing new about nitrous. Nitrous oxide is the chemical compound N2O. Originally synthesized in the 1770s by English chemist and minister Joseph Priestley, he initially believed that it could be used as a preserving agent. After attempts to use it in this manner failed, others began to experiment with N20.

During the 1790s, British scientist Sir Humphry Davy started running experiments with the gas, giving it to those who would come into his institute, in order to study its effects on respiration. After noting that people would laugh and act silly after inhaling it, Davy began to call N2O “laughing gas,” and soon people were using it recreationally.

Nitrous oxide began to be used as a dental anesthetic in the United States during the 1840s, due in large part to demonstrations by American lecturer Gardner Quincy Colton on its anesthetic properties.

Fast forward to World War II and its first recorded use on combustion engines in high altitude Luftwaffe planes such as high-speed bombers and interceptors.

The use of nitrous in racing applications became popular in the 1970s. Though originally intended for use in race cars only, it didn’t take long for the development of street systems that could be used in everyday vehicles.

F Stands for Fun: Jose’s ’01 Camaro SS

Jose de Anda, owner of this 2001 Camaro SS, wanted additional power that could be turned on and off with ease. His modified Camaro had 410 horsepower and 367 ft/tq naturally aspirated with a 13:1 air/fuel ratio. The modifications on Jose’s car are as follows:

• Centerforce Dual Friction Clutch and Billet Flywheel
• Pro 5.0 Shifter
• Pacesetter Long Tube Headers
• Flowmaster Muffler
• 85 MM Air Lid and MAF
• FAST 90 MM Intake and Throttle Body Combination
• MS3 Cam
• Dual Valve Springs, Hardened Push Rods
• MSD 8.5 MM Plug Wires
• 25% Underdrive Pulley
• HP Tuners, Tuned By CMS

There are a fair amount of F-body guys out there who don’t like pulling their engines apart. Part of an F-body’s engine sits under the dash, and the average enthusiast wants as much easily accessible bolt-on power as they can get. Once those bolt-on parts are exhausted and you develop that taste for speed, it’s time for a big jump in power. Thus, Jose chose to go for the Zex High Output nitrous installation.

Zex Gen III LS Based High Output Nitrous System

When most people think of Zex, they think of that purple box that houses all the key components of the nitrous kit, the Nitrous management Unit (NMU). Inside the NMU, you will find all the solenoids and electronics that key into the throttle position sensor for nitrous activation.

This kit works well when you are looking for a maximum of 175 horsepower. To exceed those numbers, you need larger (external) solenoids that can flow the higher quantities of fuel and nitrous. According to Matt Patrick of Zex, “To get more performance out of a given solenoid, you just have to make it bigger outside the standard NMU ones.”

The High Output system looks more like a “traditional” nitrous kit, with separate fuel and nitrous solenoids. Zex has developed a way to control the activation via TPS, using the same technology as the NMU kits in an external box. “We took all the same electronics out of the NMU box and put them into a standalone unit, done remotely but in the same fashion,” says Matt.

The F-body system is specifically made for that car. Zex has a smaller module that hooks in between the solenoids for activation – a classic look with modern electronics.

Zex specifically designed jetting for the LS engines through dyno testing. They also developed a fuel rail fitting that makes tapping for fuel a breeze. They supplement them with custom line lengths and fittings to make it a bolt-and-go installation. The rest of the kit still uses a conventional ten pound bottle, brackets, single nozzle, relays, and wiring.

Zex’s Big Shot system still comes with the traditional TPS activation that Zex offers with their traditional kits.

I asked Matt if there were any plans for a plate kit and he remarked, “We are about halfway done on our plate kit development. It is a round design of our perimeter plate system found on our carburetor kit, that sprays around the entire plate and not through the middle like a spray bar configuration.”

Top Setup Tips From the Mouth of Matt Patrick

The right gas – Use the appropriate octane level fuel. If you have a 500 horsepower LS1 and you want to spray a 250 shot to it, it is probably a good idea to get some racing fuel.

The right ignition – Next you have to get the correct spark plugs. Typically, we recommend one to two step colder heat range plugs as you step up nitrous power. When you start approaching 700+ horsepower, you want to go beyond those plugs and begin looking into racing plugs. They have a shorter ground strap and a much better design for high horsepower racing use.

We are installing the Zex window switch that allows for engagement in a chosen gear.

You need to be retarded – We generally recommend retarding two degrees of ignition timing for every 50 horsepower worth of nitrous. When you’re thinking of a 250 shot as ten degrees of retard it is a safe place to start from, though it sounds excessive to a lot of people.

Installation of the Kit – Solenoids and Lines

The first items we installed were the solenoids. Searching for a place that we wouldn’t have to drill, we found that using the stock coil pack mounting points was going to be a good option.

The tab for the nitrous solenoid was cut shorter, in order to offset the location of the in/outlets and to provide better clearance for the lines. The AN fittings for the solenoids come with sealant on them, so we simply installed them then tightened them down. The outlet side of the solenoids are NPT’s that mate to the AN line and these do require some blue thread lock.

We mounted the solenoids off the coil packs using the existing mounting bolts.

Once the solenoids were installed it was time to do the intake nozzle. Since the Camaro is a mass airflow car, we installed the nozzle in the black coupler that connects the intake pipe to the throttle body.

After drilling out the silicone sleeve, we installed the coupler that holds the nozzle in the sleeve. While tightening it down, the nut began to push through the sleeve because there wasn’t enough grab on the rubber. To solve this, we put a thin washer on each side of the coupler to allow for a much tighter seal. Before tightening everything down, we made sure that the nozzle was installed and facing the throttle body.

We started off with jetting for a 100 shot. Again, remember that you do not use thread sealer on AN fitting threads.

Washers on each side of the nozzle coupler made for a much tighter fit.

The driver’s side fuel rail contains an air bleed valve that you can remove for the fuel solenoid source.

After we secured the nozzle and ran the outlet lines from the solenoids, we started on the fuel feed. Tapping fuel on an LS car is extremely easy. All you have to do is take the cap off of the fuel rail on the driver’s side and use some small needle-nose pliers to unscrew the bleed valve. Make sure that you release the pressure out of the gas tank by taking the cap off, and then attach the other side of the fuel inlet line to the rail. Since the supply line was longer than needed, we wrapped it around the solenoid.

The last item to be hooked up for the solenoids was the line to the trunk that supplies the bottle. We ran the line to the hard fuel lines and secured them behind the heat shield with zip ties. We then ran the line to the trunk underneath the rear seat on the passenger side via a rubber grommet, and pulled the line directly into the trunk from there.

Bottle Mounting Options

We used an aftermarket bracket to mount the bottle in the spare tire area.

When it came time to mount the bottle, we did some research online to find the best location. We learned that the only flat part on the rear deck lid houses the fuel cell underneath. Therefore, the only option for properly mounting the bottle was to install custom mounts to position the bottle either between the rear seats on the hump or in the spare tire area.

Since the owner wanted the bottle to be hidden, the spare tire was removed and in its place we installed a pre-made plate that required two small holes for mounting. Finally, we mounted the Zex bottle brackets, the bottle, and attached the feed line.

Final Steps of the Installation – Wiring

Now that all the hardware was installed, it was time to wire the kit. There is a battery terminal hookup in the driver’s side front that served as a good place to mount the relay.

The battery post supplies the power to our relay, which is mounted directly behind it.

The relay wiring is rather simple. Attach the two blue wires on the electronic throttle activation switch and mount it to Post #1 on the relay. The fuel and nitrous solenoids will both go to Post #3. Solenoids use switchable polarity, so it doesn’t matter which wire you run off the solenoid as long as you ground the opposite wire.

Posts #5 and #2 will go to a 12-volt source, though it is recommended that Post #2 be used as a key-on hot switch. The red wire from the throttle switch will go to the arming switch and the black wire will be your ground.

You will need to install and calibrate your throttle switch before installing the RPM window switch.

Tie the blue wires together off the TPS activation switch and run to post #1 on the relay.

The white wire on the activation switch will go to your TPS switch wire. From there, you are ready to program it. Simply turn the ignition switch to the ‘on’ position (don’t start the engine), flip the activation switch, press the calibration button on the throttle switch, and mash the throttle. When the light blinks ‘red, green, off’ the switch is programmed.

You want to do all of this with your bottle disconnected (unless you want to hurt your motor). Next it’s time to add the window switch.

Zex Traction Control Window Switch

The Zex Traction Control Window Switch lets you select the RPM range that activates your nitrous system in both upper and lower RPM limits. The Traction Control Window Switch also lets you select which gear the nitrous will start to spray in. This will help combat tire spin.

After installing the kit and programming your throttle switch, you are going to want to remove some wiring to make way for the window switch. The installation is easy – the two white wires are going to be used to intersect the power going to the nitrous solenoids. Either white wire will work. Power wires, ground wires, and the green wire for the RPM wire are all that is left. Due to the ignition configuration on LS engines, putting the window switch into four-cylinder mode will give the right RPM read out.

Safety with Colder Plugs

When running nitrous (or any forced induction for that matter) you need colder plugs. A high heat range plug creates higher cylinder temperatures, and even though nitrous cools the incoming charge dramatically, it still creates more energy. This results in more heat during the combustion process.

Colder plugs helps reduce the heat in the cylinder and they won’t melt the electrode as easily as a high heat range plug. The downside to running a colder plug is its inability to clean itself. This means that you will get less life out of the plugs and will be more prone to fouling, especially if you don’t spray often in order to clean them.

Zex spark plugs come pre-gapped so there is nothing to worry about.

Another factor with respect to the plugs is the gap. With increased cylinder pressure, blowing out the spark becomes easier. Decreasing the gap will help solve this problem. For a street car, this means that you want the gap to be in the .028 -.035 range.

We opted for the Zex spark plugs, as they are made specifically for nitrous use. According to Matt, “The primary ground strap that fires when you are at wide open throttle has a copper core. What makes that important is it has much lower resistance. Additionally, it has a much faster heat path. So when the heat starts to rise, the plug is able to maintain its tip temperature much better.”

Dyno Time with Tuner Ryne Cunningham

Baseline before nitrous: 409.84 horsepower and 366.89 ft/tq.

The Camaro already had HP Tuners installed, but they would need to be backed off from the naturally aspirated tune that was in there. We made our base run after Ryne from Cunningham Motorsports made the necessary changes. The Camaro made a healthy 409.84 horsepower and 366.89 ft/tq naturally aspirated with a 13:1 air/fuel ratio.

With the nozzles loaded for a 100 shot, Ryne ran the switch armed and managed a run of 487.36 horsepower and 498.19 ft/tq, an increase of 78 horsepower and 132 ft/tq, while maintaining a 12:1 air/fuel ratio.

Feeling brave, we swapped out the 100 shot jets for the 150 shot to see what the Camaro would do. After a cool down period, Ryne ran it on the rollers once again to see how much power we could make. In the end, the power increased to a staggering 558.45 horsepower and 550.76 ft/tq. This made for an increase of 149 horsepower with 184 ft/tq to the rear wheels – all through a stock block and heads.

About the author

Mark Gearhart

In 1995 Mark started photographing drag races at his once local track, Bradenton Motorsports Park. He became hooked and shot virtually every series at the track until 2007 until he moved to California and began working as a writer for Power Automedia. He was the founding editor for its first online magazines, and transitioned into the role of editorial director role in 2014. Retiring from the company in 2016, Mark continues to expand his career as a car builder, automotive enthusiast, and freelance journalist to provide featured content and technical expertise.
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