NOS Three-Valve Kit Test - Liquid Displacement

A pretty strong case can be made for Ford's modern Mustang machinery. While we all look back fondly on the musclecar era of yesteryear, the reality is that nostalgia has altered our perception somewhat.

Who doesn't love a thumping Cobra Jet fastback or a high-winding Shelby small-block? As great as these classics are, time and technology have marched on so that a modern modular motor not only offers every bit as much performance (actually more), but it does so while delivering a combination of driveability, fuel economy, and reduced emissions only dreamed of by their carbureted counterparts.

I don't think its sacrilegious to say that the current 4.6L offerings are the most powerful (and impressive) Mustang powerplants ever offered. That the new 5.4L GT500 motors offer over 540 hp (550 hp in the now-defunct Ford GT) while still managing to knock down as much as 25 mpg on the freeway--I know this firsthand from a recent cross-country trip--is a testament to the new design. The GM boys used to cry foul and say Ford had to resort to forced induction to achieve these numbers, but just look at what's powering the new ZR1.

Nevertheless, there are always ways to improve power output, right? Forced induction is one route, as are basic bolt-ons. Yet another route, pioneered by the German Luftwaffa and made popular by street racers across the nation, is nitrous oxide. Originally designed to enhance the power output, (and therefore, the flight ceiling), many German (and later, British) pilots relied on the power-enhancing compound for their very lives: Winning bragging rights or even a fist full of cash at some street race hardly compares to the rush of saving your hide and living to fight another day.

For those modern Mustang owners unfamiliar with nitrous oxide, the compound contains both nitrogen and oxygen (similar to the air you and your motor already breathe). It is actually the oxygen contained in the nitrous-oxide compound that is responsible for the additional power.

Blame both TV and movies for the common misconception that nitrous oxide is highly explosive or even flammable. It would take a nitrous bottle stuffed to the regulator with C4 explosives to produce the kind of explosions seen on the big screen. The door-blowing explosions and singed eyebrows accompanied by fireballs that send the aforementioned street racer's ride to a fiery grave are noticeably absent.

It should be noted that the oxygen in the nitrous-oxide compound is extremely flammable--the compound itself is not. Only after the oxygen molecules have been released from the nitrogen compound will they be allowed to burn. Fortunately for enthusiasts, it requires a great deal of heat (to the tune of 572 degrees) to liberate the oxygen molecules. This tremendous oxygen-liberating temperature is supplied by the combustion process. Technically speaking, nitrous oxide is not a fuel, but rather an oxidizing agent. Once released, the free oxygen molecules support (or enhance) the combustion process, which requires the burning of some other fuel--in this case, gasoline.

If the release of the power-producing oxygen molecules isn't enough to win you over, additional power gains are realized by the reduction in inlet-charge temperature. For automotive use, nitrous is stored under pressure as a liquid; when injected into the engine, the nitrous is converted into a gas, a process called boiling. The liquid-to-gas conversion absorbs a great deal of heat from the surrounding area (the inlet air). Though we normally associate a boiling point with heat (converting liquid water to steam at 212 degrees), the boiling point of nitrous oxide is a chilly -129 degrees.