Nitrous Oxide Systems Facts - The ABC's Of Nitrous

What You Need To Know About Laughing Gas

Chuck Jenkes Mar 1, 2003 0 Comment(s)
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What is Nitrous Oxide?
Nitrous oxide (N2O) is a compound that contains one oxygen atom and two nitrogen atoms. Nitrous oxide as a gas is colorless and odorless and has 36 percent more oxygen by weight than air. The English scientist, Joseph Priestly, first identified nitrous oxide in 1772.

One of the main factors that determine how much power an engine can produce is how much oxygen it can draw in during the induction cycle. There are several ways to pack more oxygen into the cylinder: add a supercharger or a larger camshaft, improve flow of the cylinder heads, or add nitrous oxide. Nitrous oxide is often the easiest method of adding power to your engine.

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Nitrous oxide was most probably used for the first time in combustion engines after World War I but was used extensively in piston-driven aircraft by both the Allies and the Axis in World War II.

Nitrous oxide, when compressed to 600 psi at room temperature, becomes a liquid. As nitrous is introduced into the intake tract, the pressure drops and the liquid boils to a gas. When the liquid nitrous changes to a gas, it drops to approximately -129 degrees Fahrenheit.

Performance nitrous systems keep the nitrous in a liquid state until it is near the intake manifold and then inject the gas so that the nitrous is as cold as possible inside the engine. This "supercools" the intake charge. A cooler intake charge packs more air into the cylinder, which also increases power. In general, you will see a 1 percent power gain for every 10-degree drop in inlet air temperature. This is a power gain even before the nitrous gets into the cylinder!

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Dual-stage nitrous systems use separate fuel and nitrous solenoids to gain added power. They come in either single-bar or crossbar configurations. Timers trigger the second stage.

If oxygen is what we are after, why not inject pure oxygen into the cylinder instead of nitrous? Injecting pure oxygen would create such violent, uncontrolled combustion that even small amounts could be catastrophic. With nitrous oxide, the heat of the combustion breaks the chemical bond that holds the two nitrogen atoms and the oxygen atom together. Without heat, the three atoms would remain bonded, and consequently, the oxygen atom would be unavailable to play its role in the combustion process. This is why inhaling nitrous is dangerous, leading to fatal asphyxiation, even though it has a higher oxygen content than air: Your body cannot produce the heat necessary (approximately 565 degrees Fahrenheit) to break the bond between the nitrogen and the oxygen, leaving the oxygen unavailable for respiration. Since the ignition process must start before the oxygen from the nitrous can be released, the net affect is a more controlled release of oxygen and a stable combustion process.

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Single-stage kits for carbureted applications cover a wide power range. An entry-level kit like the NitrousWorks 10010 kit can deliver from as little as 75 hp to as much as 200 hp. Other kits can deliver up to 400 hp. The difference is in the jetting and the configuration of the bar spray patterns.

The optimal air/fuel ratio for complete combustion of gasoline is 14.7:1 (commonly referred to as the stoichiometric ratio). However, gasoline engines produce the best power at an air/fuel ratio of 12.5:1-13:1. Because nitrous is more oxygen-rich than air, the chemically correct air/fuel ratio becomes 9.65 parts of nitrous to 1 part of fuel (9.65:1). Additional fuel beyond 9.65:1 should be added to make maximum power and to prevent detonation (an air/fuel ratio of 8.0:1-8.2:1).

That means when oxygen-rich nitrous is introduced to an engine, additional fuel must also be supplied in order to maintain the correct air/fuel ratio. Without the additional fuel the mixture would become dangerously lean-circumstances that will almost always lead to severe and expensive engine damage.

Nitrous Systems
Nitrous is stored in a bottle, which should be mounted in the trunk area or somewhere out of the driver's compartment. It is then transferred to the engine compartment via a stainless braided high-pressure line to the engine compartment.