We slapped Zex's new Perimeter...
We slapped Zex's new Perimeter Nitrous Kit on a carbureted '89 Mustang GT. The result was 430 rwhp and 500 lb-ft of rwtq at the press of a button. Nitrous is cool!
Whenever the MM&FF staff goes to a restaurant, we usually end up being served plates overflowing with food-lasagna, chicken parmesan; you name it. Once the dinner is over and the dessert is skipped (yeah, right), we head to our homes, loosen our belts, and sit in our chairs-fat, happy, and stuffed like a Thanksgiving turkey.
It was sort of the same thing after we finished wrenching on Chris Winter's '89 Mustang GT at Crazy Horse Racing, except this time it was the Fox-body that was feeling fat and happy from the Zex nitrous kit we installed and the subsequent influx of power.
You're probably saying, "C'mon, it's just another nitrous install." While that may be the case, this time we installed Zex's new Perimeter Plate nitrous system, made specifically for carbureted cars. Bet your ears just perked up, didn't they?
While superchargers and turbochargers aren't only great for power, but also for putting up a big mark on the "wow" scale, there's nothing that compares to the on-demand power of a nitrous hit. Nitrous oxide (N20) is a chemical makeup of two parts nitrogen and one part oxygen. Since the engine breathes in 78 percent nitrogen, 20 percent oxygen, and 2 percent other gasses, any additional oxygen that the engine can ingest can be countered with an increase in fuel, and, obviously, extra horsepower will result. Engines burn only the oxygen in the air (and fuel) so adding more oxygen is always a plus.
 The Zex carbureted wet kit...  The Zex carbureted wet kit comes complete with a 10-pound (unfilled) bottle, bottle brackets, lines, wires, hardware, and the unique carb plate. |  Since we were planning on...  Since we were planning on taking a stab at the quarter-mile later on down the road, we swapped out the 4.56 gears that were in the car for a set of 4.10s we picked up from Down's Ford. With the extra power on tap, running the 4.56s means running the car way out of the engine's usable power range when we press the nitrous system's "on" button. |  The kit comes with two solenoids...  The kit comes with two solenoids capable of supporting up to a 300hp shot. Each solenoid is clearly marked, and comes with mounting brackets to mount them securely. |
Most nitrous kits are uniform across the board, coming in either two styles (wet or dry), as well as being made up of a similar construction. A wet nitrous system is a kit that delivers both the nitrous and fuel directly into the intake tract together. A dry nitrous kit delivers just the nitrous, leaving the fuel system to supply the additional fuel to maintain the correct air/fuel ratio. This can be done by an increase in fuel pressure to, say, the fuel injectors, or it can be done by increasing the pulse width in EFI applications.
When pressurized, nitrous oxide becomes a liquid. When the liquid nitrous is moved from the bottle to the engine via a nitrous feed line, solenoid, and nozzle or carburetor plate, the nitrous is converted to a gas. When it reaches the combustion chamber, it's compressed, and when introduced to heat, the compound breaks down, releasing the lone oxygen molecule from the pair of nitrogen molecules.
 Here you can see how Zex's...  Here you can see how Zex's plate injects the nitrous mixture into the engine. Along the sides, as well as in the corners, are the orifices. The nitrous enters the back of the plate, the fuel enters the front of the plate, and after mixing inside along the perimeter, the mixture is injected into the powerplant. |  The plate that comes with...  The plate that comes with the Zex kit is unique in that there are no spray bars injecting the nitrous and fuel into the engine. Instead, the plate is lined along its perimeter with orifices that, according to Zex's Matt Patrick, distributes the nitrous/fuel mixture evenly to all eight intake runners. |  |
With this extra oxygen molecule available to be burnt, extra fuel is added to compensate for the extra oxygen, and the resulting influx makes for a more powerful combustion process. When done right, this results in greater cylinder pressure, which forces the piston down the cylinder bore with greater thrust on the power stroke, thus making more power overall than the engine could make on its own.
When it comes to a carbureted application in particular, when running a plate-style system, the ice-cold nitrous also provides a cooling effect to the intake charge, in addition to the plate itself acting as an intake spacer. Having done numerous fuel-injected nitrous applications recently, we decided to tackle a carbureted nitrous install and see how much power we could make with the new kit Zex offers.
 The basis for our nitrous...  The basis for our nitrous install is the 306ci engine under the hood of Chris Winter's '89 Mustang GT. The small-block Ford showcases World Products Windsor Sr. iron heads, an Edelbrock Victor intake, and a host of other goodies. While the compression ratio on this pushrod powerplant is a stout 13:1, relegating the car to ingest racing gas, it served as the perfect basis for our install. |  Our fears of having ignition...  Our fears of having ignition problems were quickly alleviated when we saw the car was already equipped with an MSD 6AL box and Blaster 2 coil. According to Patrick, anytime you hit an engine with a 300-or-more-horsepower shot of nitrous, it's highly recommended you upgrade to this style of ignition system. |  We began the install by removing...  We began the install by removing the fuel inlet lines to the carburetor, followed by loosening the four bolts on the carb flanges. Once loose, we removed the worked-over 750-cfm Holley carb and set it aside. |