Frank H. Cicerale
September 1, 2008
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.

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.

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.