The Main Squeeze

The Basics

For a given internal combustion engine to make more power, it must burn greater quantities of fuel and air, and do it at a faster rate. Turbos and superchargers accomplish this by mechanical means, using an exhaust or crank-driven impeller to pull great gobs of air into the engine; the carburetor or injector system adds the proper amount of fuel, and you're off to the races. Nitrous basically does the same thing, only chemically, hence another nitrous nickname--chemical supercharging.

An engine needs more air and fuel to make more power. N20--nitrous' chemical formula--takes care of the former. Here how it works: In the bottle and under pressure, N20 turns into a liquid. Once released from the bottle, the liquid returns to a gaseous state, but at a greatly reduced temperature. This is benefit No. 1: Nitrous can lower the incoming air temperature by as much as 65 degrees F. Cooler air is denser, bringing us closer to our goal--more power.

The N20 makes it's way into the combustion chamber where the extremely high temperatures separate the oxygen and nitrogen molecules. The oxygen molecule is then free to help burn more fuel. The two nitrous molecules also come in handy--they're each largely made up of oxygen themselves, so this also provides more air to burn. Nitrogen also moderates the pressure gains when the enhanced air/fuel charge is burned, which is easier on the engine.

Of course, that's only part of the equation. The combustion process requires fuel as well as air, so all nitrous systems make provision for adding the necessary fuel in the proper amount. Whether it's a wet system (both fuel and N20 are injected) or a dry system (N20 is injected directly, while the vehicle's own systems add extra fuel), maintaining a proper air/fuel ratio is absolutely essential. In fact, many systems come with a safety switch that shuts the nitrous system down if it senses a lean mixture.

Another issue to consider is ignition timing. Under nitrous, cylinder pressure rises much more quickly than usual. Over-advanced timing at this point has the engine working against itself, with the combustion process starting too early. That means less power, and it's not good for those piston tops, either. Done properly, however, a good jolt of nitrous gives you an even better jolt of power.

Beyond the Basics

Nitrous is cheaper than a turbo or supercharger. What we don't want to do, however, is oversimplify the process. Done wrong, nitrous-oxide injection can ruin an engine. That's why, when shopping, you'll want to take a systems approach to nitrous. You will certainly need a bottle, a bottle heater and opening >> valve, the injectors and lines for both N20 and fuel, solenoids to release both into the engine, and an arming switch.

Beyond that, there are a number of items that can help keep your newly squeezed ride safe. You'll want to look at beefing up your fuel delivery system to guard against a lean mixture, and an improved ignition system will make sure every molecule gets burned for power. Safety measures are also good--a switch to shut down the system if the mixture goes lean is always a good idea, as is a fuel-pressure gauge. There are also various retard switches that can ensure proper timing when you're on the squeeze. And, of course, you'll want a switch that controls when the juice actually comes on, whether it be a simple wide-open throttle switch or an rpm-activated window switch. If you remember that you're buying a system, not just a bottle and injectors, you'll be OK.

What we've done here, in the space allotted, is give you a very basic look at how nitrous oxide adds power to an internal combustion motor. If you do your homework, follow manufacturer recommendations on engine modifications, and buy smartly, nitrous oxide is the bang-for-your-buck king of power adders. The fun lasts as long as you can afford to fill the bottle. CHP