Dollar for dollar, it’s tough to beat the value proposition offered by nitrous systems when you’re looking for ways to shave tenths of a second off your elapsed time. But like any power adder, efficiency and tuning are crucial factors in not only the potential performance benefits but the ability to use the system safely and reliably on a regular basis, as well. That last part goes double for spray – without proper fuel delivery, a sudden influx of nitrous can cause a lean condition and some serious drama for your engine. That’s why we opted to install a ZEX LS Series Perimeter Plate Blackout Nitrous System on this 2007 Corvette.
The mildly warmed-over C6 was good for passes in the high 12s when it rolled into our shop, but we were confident that we could cut those times down significantly without sacrificing longevity with a bit of help from the bottle.
Here we’ll take a closer look at the LS Series perimeter plate system, go through the installation and setup process, and get some insight from the folks at ZEX about makes this kit a compelling option for enthusiasts who are looking for a big performance bump at a very reasonable cost.
“One of the things that’s kind of unique about our street EFI kits is that they are direct fit systems,” says Matt Patrick, Director of Product Development for COMP Performance Group and ZEX. “We actually design these systems for particular vehicles. So with the LS Series perimeter plate systems, all the lines, all the wiring – everything’s sized to bolt right into any kind of modern Corvette or Camaro. Obviously, the system will work great with GM trucks, as well, and it’s just nice to not have to go hunting around the auto parts store for fittings, hose clamps, or anything like that. We include everything in the kit, so it’s pretty much a turn-key deal.”
While that certainly takes a lot of guesswork and potential hassles out of the install, what really sets the system apart from the competition are the patented perimeter plate technologies that ZEX employs in its design.
“The perimeter plate system has three key technologies going for it,” Patrick explains. “Perhaps the most important of the three is the Perimeter Injection tech. Unlike other designs you’ll find on the market, we went through the process of developing a manifold around the perimeter of the plate which provides twelve separate injection points. So with that design the nitrous and fuel are mixing all around the opening of the throttle body, which provides an unparalleled mixture distribution – you get a really nice fog going into the plenum of the intake manifold.”
Patrick says that mixture distribution is crucial for two key reasons. “First, it’s great for making power because when that fuel, nitrous, and air mix together better, it will absolutely translate to higher output. But it’s also important from a distribution standpoint because you don’t want one cylinder running lean and another one running rich. Because the fuel is mixed so nicely, we tend to get much more consistent air-fuel ratios across the cylinders, and that in and of itself allows the system to function more efficiently and build more power. It’s not uncommon for folks to switch over from, for example, a single nozzle setup to our plate system and pick up some ET and some horsepower with no other changes.”
We went through a year of research and testing to land at a design that evens out the spray pattern, so you get the exact same amount of nitrous out of each one of those slots. It sounds pretty simple in theory, but in practice, it’s actually very difficult.
He adds that the development of the injection technology goes far beyond merely drilling a dozen holes in the plate. “If you look closely at the plate you’ll notice that each individual slot is sized a little bit differently from one another. We went through a year of research and testing to land at a design that evens out the spray pattern, so you get the exact same amount of nitrous out of each one of those slots. It sounds pretty simple in theory, but in practice, it’s actually very difficult – if you just put twelve identical slots in there, the flow tends to load up on one side of the plate, and the distribution is horrible. There’s actually a mathematical formula that we developed early on with our carburetor plate system which gets us close, and then we tweak it from there to dial in the flow pattern for this system.”
But the injection technology is only one piece of the puzzle. Patrick says, “The Airflow Enhancement technology is very important too. When you spray nitrous in a consistent pattern around an opening, whether it’s a square opening like our carburetor plates or a round opening like the LS plate, it creates a very intense low-pressure area behind the throttle body, and it helps to induce greater airflow. I wouldn’t go so far as to call it a mild form of supercharging, but it’s a way of utilizing the chemistry of the nitrous to enhance the airflow into the engine.”
And as we’re all well aware, heat is typically the enemy of engine performance. That’s where the company’s Cryo-Sync technology comes into play. “Because we flow that chilled nitrous through the plate before it gets released into the air inlet of the engine, within a few seconds that plate becomes a very effective heat sink,” Patrick tells us. “That helps to pull heat away from the throttle body and help to cool it as you’re going down the track. All three technologies work together to squeeze more efficiency out of the system, so when you compare it on a per-pound of nitrous usage versus our competitors, you’ll find that these systems will make more power.”
OK, so we’ve established that the ZEX LS Series Perimeter plate system has some pretty cool tech going for it. But does that translate to a more involved install? “It’s very simple actually,” says Patrick. “Typically where you’d start off is locating a spot in the trunk to mount the bottle. That’s critical because you’ve got have it mounted where the bottle valve is facing forward, that way while the vehicle is accelerating the liquid nitrous in the tank is always pushing toward the siphon tube at the very bottom of the nitrous cylinder.”
From there you’ll run the nitrous feed line from the trunk to the engine bay, either running along the frame rail or under the carpeting if you want to keep it away from the elements, attaching the line with either Adel clamps or zip ties. “At that point, you can select where you want to place your nitrous solenoid,” Patrick notes.
“Typically you’ll find something on the intake manifold where there’s an extra bolt or something like that, and you would mount your solenoids up. At that point, you would connect your nitrous line, fuel feed line, and also locate your -4AN fuel tap on the fuel rail, if you want to measure your fuel pressure externally. We include a tool to remove the Schrader valve core out of that port, and that becomes a perfect tap spot.”
The next step is to use the included gaskets to sandwich the plate between the throttle body and the intake manifold. “One item of note is that our perimeter plate system comes with a fitment ring on the inside, and it slides out if you don’t need it,” Patrick points out. “Our plate is designed for the common 102mm opening with the fitment ring removed, but if you have a 90mm opening, this aluminum ring shrinks the plate down to fit that opening. And since that’s a solid aluminum ring, if a builder wants to port match that to their manifold there’s no reason they can’t do that.”
Setting Up For Success
Patrick also offers a few tips to ensure that builders get the most out of the system while ensuring the well-being of the engine. “The number one accessory I’d recommend a customer to get would be a bottle pressure gauge. Bottle pressure is crucial to get the most amount of safe, consistent power out of the nitrous system. We generally recommend a range of about 900 to 1000 psi. We rate our systems at 950 psi, but we’ve found that even if the bottle pressure varies 50 psi here and there, the reality is that it will flow about the same. When you start to go above 1000 psi or below 900 psi, your mass flow starts to change pretty drastically, and you will start to see things that affect power.”
He says that many racers tend to jack up their bottle pressure for a strong initial punch, but that initial surge can be misleading. “You’ll get a flow spike for maybe one or two seconds that will hit really hard, but then what happens is that the nitrous flow actually starts to bleed down very quickly, and within a few seconds you’re flowing about the same volume of nitrous as if you would have just set it to 950 or 1000. That’s one of those things where the seat-of-the-pants testing can be misleading, and the downside is that you’re running lean at the worst possible moment.”
A purge kit is also a good idea. “It basically relieves all that excess vapor in the lines and gives you a good solid flow of liquid nitrous right at the solenoid so that when you go to launch the car you have instant power,” he adds.
But beyond system accessories, Patrick reminds us that getting the engine itself ready for nitrous is also very important. “When you bolt up a nitrous system, you generally want to switch over to spark plugs that are two steps colder in heat range. It’s very important because you’re going to have a lot more heat volume in the combustion chamber and the plug needs to match that. If the plugs can’t lose the heat fast enough, the tip will melt, and it will cause pre-detonation. You also want to dial in 2-degrees of ignition retard for every 50 horsepower worth of nitrous you put in the engine, so if you’re going to spray a 150-shot of nitrous on an LS, start off by retarding the ignition timing by about 6-degrees.”
Want to surprise the guy in the other lane at your next grudge match race? Give the folks at ZEX a buzz to safely and reliably add spray to your arsenal, then get ready to watch those ETs drop in short order.