Nitrous Oxide Injection Systems

To understand how nitrous oxide injection impacts and engine, let's examine how an engine works. An engine creates power by transfering energy created by fuel combustion. Combustion is a form of rapid oxidation, which requires oxygen as the name dictates. The amount of oxygen determines how much fuel can be burned, and the more fuel that is burned, the more power is created.

Nitrous Oxide is a chemical that is rich in Nitrogen and Oxygen. Injecting nitrous oxide increases the oxygen density of the intake air. Nitrogen is a cryogenic liquid with a very high vapor pressure. It must be kept at a minimum of 745 psi to remain a liquid at room temperature.

Since the vapor pressure is so high as a liquid at room temperature, when nitrous oxide is released into the atmosphere, there is a very rapid expansion as it metamorphoses from a liquid to a gas. There is a large amount of evaporative cooling that takes place as the liquid evaporates, drastically reducing the temperature of the surrounding air.

When this chemical reaction is added to the intake air of a combustion engine, you get a double effect of an oxygen rich intake charge and supercooled, dense air. The higher air density and oxygen percentages allow for more fuel to burn, creating large amounts of power. This cooler air lowers the chances of premature detonation which can be damaging to internal engine components. Just the cooler air alone can increase horsepower by about 5 percent.

As stated earlier, you must have extra fuel for the combustion to occur properly because with an oxygen rich and dense intake charge, you will find yourself running dangerously lean under the conditions of nitrous oxide injection. To obtain more fuel, there are several tricks that can be done.

First, you can add an aftermarket fuel pressure regulator for nitrous systems. These regulators will clamp the return fuel line under nitrous injection, raising the fuel pressure to the injectors which will provide more fuel. Others have added a fuel cell which is a small additional "tank" of fuel, usually filled with race or higher octane fuel, that will engage and supplement the factory fuel settings to kep the air/fuel ratio in the optimum zone for the maximum amount of power.

You can't just squeeze every ounce of power out of your engine without some faily major modifications to its internals though. On a standard engine with no modifications, it is recommended to stay within a maximum of 40% of the rated horsepower of your vehicleon the amount of horsepower shots, and keep the shots to less than 10 seconds per shot. More than this on a standard motor and you could get yourself in big trouble. I know of several istances where more than the recommended horsepower shot was used, only at the sacrifice of blown rings or a blown off intake manifold.

There are several types of systems which will be covered int he next few posts, such as mild street setups, dry single point injection, wet single point injection, direct port injection, and two stage race applications.

Hopefully this has helped you better understand how nitrous oxide injection works, so we can focus on the actual systems in the future.