The quest for enough horsepower is a frustrating one. It seems like no matter how much we get, we just end up wanting more. What seemed like enough power a year ago, just isn't as satisfying today. This desire to have our engines pump out more ponies generally leads to bigger cams, higher-flowing heads, and a host of other upgrades. The only problem is, this extra power comes at a cost. Maybe it's worse gas mileage or a cam that's so lopey that the car becomes a pain to deal with on the street. On a newer car, it might mean running afoul with the smog police. Enter nitrous oxide: that magical combination of molecules that lets the user run a relatively mild engine and still put down some serious power with the flip of a switch.
Nitrous oxide (also know as dinitrogen monoxide or dinitrogen oxide in the scientific world) works by introducing extra oxygen into the intake charge, which in turn, allows for a greater amount of fuel to be added and converted into energy. This can greatly increase the power produced by the engine. Another benefit is since nitrous oxide is stored as a liquid, the evaporation of it in the intake manifold helps drop the intake charge temperature. This cooling causes a denser charge and can increase power output as well as reduce detonation.
But, like everything in life that sounds perfect, there's a cost involved. That cost is vigilance. When using nitrous you have to be very careful with bottle pressure, fuel pressure, timing, and a host of other things. If all is set up right, then it's a beautiful thing. If not, then a fragged engine and tears looms on the horizon.
Our LS3-powered '01 project car, Black Betty, puts 403 hp to the tires, but these days that's just not enough to get the job done. So we decided to try out one of the systems from ZEX. They have a sweet new perimeter plate that mounts just behind the throttle body and it's adjustable from 100 to 250 horsepower. With a ZEX kit from Summit Racing in hand, we headed over to our friends at Don Lee Auto to get our Z28 plumbed for some giggle juice.
01 This kit from ZEX (PN 82195, $812) had everything we needed for a basic nitrous install. It included the bottle, valve, basic bottle mounts, supply lines, solenoids, brackets, TPS controller, gaskets, switches, wire, perimeter plate, and enough hardware to get it all working.
02 If the nitrous bottle is ever overfilled or overheated, then this safety blow-down kit (PN 82099, $50) will save our bacon. Besides, it's required at most tracks and sanctioning bodies. If an overpressure event occurs, the safety disc bursts and the gas is vented outside the car. We've heard it's pretty spectacular.
03 First up was finding a spot to mount the bottle. The easy place is in the recess under the hatch designed to hold the T-tops. The problem is that it takes up valuable storage space, and besides, we like to be a little stealthy. Instead, we decided to put the bottle in the spare-tire well. We used some cardboard to help make a template for the mounting plate.
04 The standard bottle brackets are fine, but removing the bottle for refills can be a bit of a pain. This billet nitrous bottle bracket kit (PN 82171, $194) looks great, but more importantly, it will make messing with the bottle a painless and tool-free endeavor. You can also see the slick mounting plate that the guys over at Don Lee fabbed up and rattle-canned black.
05 This heater (PN 82006, $154) will help to increase bottle pressure and keep it in the optimal range of 900-1000 psi. This is really important if we want to race on a cold day and not have to constantly top off our bottle.
06 Here you can see how we mounted the blow-down tube. It required bending the tube, which wasn't easy, but the end result was a super-clean install that will pass tech at any track. We also added a ZEX pressure gauge (PN 82005, $44), but we had a hard time clocking it so we could get a decent view. Bottle pressure is critical, so a gauge of some sort is needed.
07 Here's the installed assembly. The heater has a built-in thermostat that helps maintain optimum bottle pressure. All the electrical components, such as the relay, are molded into the heater. The bottle heater wires were run under the car then up into the interior so they could be attached to the supplied switch and the nitrous line was ran under the car to the engine bay. It was nice that ZEX included more than enough wire and braided line to route the system on our Camaro.
08 The heart of the ZEX system is this trick perimeter plate. It's designed for LS applications and fits directly behind the throttle body. Arranged around the perimeter of the plate are 12 injection ports. This provides a very even distribution of nitrous oxide and fuel to the engine, resulting in more power. Also, since the chilled nitrous travels through the plate, it drops overall charge temperatures during use resulting in a denser charge. The plate is tunable for a 100-250hp shot of nitrous and can be used on large-bore intakes like the FAST 105mm piece or a step-down ring can be added for use on 90mm intakes like our factory LS3 version. This perimeter plate technology is also available for carbureted applications.
09 Moving to the engine bay, we bolted on the plate and mounted the fuel solenoid. Where it ended up was slightly determined by the length of the supplied line and we used the easy-to-bend bracket to get it in the best location. If you have more time and want to make up some custom lines, then you can certainly make the install stealthier.
10 For fuel, we tapped into the front of the GM fuel line on our LS3. The ZEX kit included the tool needed to remove the valve, and we then simply secured the supplied feeder line. Fuel pressure is critical, so we're glad we installed a fuel pressure gauge a couple of months ago.
11 The purge kit (PN 82010, $104) makes it easier to clear unwanted vapor out of your system before use so that you're delivering pure, cool nitrous when you engage the system. The purge kit also clears excess nitrous out of the lines after use.
12 Here you can see were we mounted the nitrous feed solenoid. You can also spot (red arrow) where we attached the line for the purge solenoid.
13 Finding a good spot to mount the nitrous purge solenoid was sort of a pain. It needed to be in a spot away from heat yet close enough to the cowl area were we wanted the purge hard line to exit. In this location we didn't even have to drill any holes. The two wires from the purge solenoid were then run into the interior of the car so they could be wired into the supplied momentary switch and a 12V power source.
14 The system is capable of 100-, 150-, 200-, and 250hp shots of nitrous. This is achieved by installing various jets. The writing on them is uber tiny, so make sure you install them correctly or your first pass may not go exactly as planned. We decided to start off with a conservative 100 shot.
15 Here you can see the plumbed-in ZEX perimeter plate. The hex bolts supplied in the kit were incompatible with our Holley throttle body, so we had to go to the hardware store and pick up some longer Allen-head fasteners. We also had to shorten the brass fitting for the vacuum hose since it collided with the nitrous-inlet port on the plate. In our case, we didn't need to shorten the air intake to account for the added thickness of the plate.
16 We also added a ZEX nitrous traction control window switch (PN 82085, $163), the programmable switch will let us select the rpm range where the nitrous will activate for both lower and upper rpm limits. This is critical since we don't want the system spraying below 2,600 rpm or spraying on the rev limiter since both situations can cause engine damage. It will even allow us to block out First gear activation so we can keep from igniting the tires. It's weatherproof, so we mounted it in the engine bay right under the main nitrous control module.
17 This trick ZEX gauge just hit the market, so we thought we would try it out. It's main function is to give you an idea of how much nitrous is still in your bottle. It does this with a math calculation based on how long the solenoids are open, and according to the engineers at ZEX it's pretty darn accurate. It integrates to the system via five wires and will handle bottles from 1-30 pounds and systems up to 500 hp. It also auto-dims for night use. The guys at Don Lee fabbed up this sweet panel to hold the gauge along with the master arm switch, bottle heater switch, and momentary purge button. We also liked how the gauge shows us that the system was armed.
18 And with that, we were done. The installation wasn't rocket science, but it took awhile to neatly hook up and run the wires (some corrugated plastic wire loom from the local parts store helped). Total install was about 11 hours.
19 On the Westech dyno our best pre-nitrous pull was 404 hp and 413 lb-ft of torque. With the 100-shot that number shot up to 511 hp and 576 lb-ft of twist. That's a lot of added performance available with just the push of a button. For this run we pulled two degrees of timing since detonation and nitrous is not a happy marriage.
20 To go easy on the engine, we engaged the nitrous at 4,000 rpm and held it to just over 6,000 rpm. The initial hit produced the expected torque spike, but once things calmed down, torque, like horsepower, was up by just over 100 points. Once the weather clears we'll hit the dragstrip and see how this newfound power helps our times, and maybe we'll even try a 150 shot. What's the worst that could happen?