How Does Nitrous Work?
For racing purposes, nitrous oxide is usually contained in an aluminum cylinder, and is available in a variety of sizes ranging from 2.5 lbs to 20 lbs. While retained in the cylinder, the nitrous is in a liquid form and held under high pressure. When it's released from the cylinder into the intake tract, its physical state changes from a liquid to a gas. This transformation occurs as the nitrous is released from an area of extreme pressure (the aluminum cylinders are pressurized to approximately 1000 P.S.I) into the vacuum of the intake manifold. This change in state is usually referred to as the nitrous 'boiling'. Water boils at 212 degrees Fahrenheit or 100 degrees Centigrade. However, if held under pressure in an automobile cooling system, for example, the coolant will remain a liquid, even above boiling point. Though inadvisable, if a radiator cap is removed under these conditions, and the pressure relieved, the water would expand and boil instantly. And so it is with nitrous oxide. While under pressure, nitrous exists in a liquid form. However when exposed to an instant reduction in pressure, the liquid expands and boils and the nitrous oxide is converted to gas. It takes energy to enable the nitrous to expand and boil. This energy is produced by the heat, which is absorbed from the surrounding air/gas in the intake tract. The end result is an intake charge that is cool, dense and oxygen rich - the ideal recipe for producing more power. The additional fuel required for nitrous is introduced in such a way that it is exposed to the full force of the expanding nitrous and it is atomized completely. This promotes improved burning in the combustion chamber and, as a direct result, power-output is increased. Nitrous Oxide (also known by the chemical formula N20) comprises two atoms of nitrogen and one of oxygen. The heat of the combustion breaks the chemical bond that holds them together. Without heat, the three atoms would remain bonded and, consequently, the oxygen atom rendered powerless, and unable to play its role in the combustion process. This is why inhaling nitrous can lead to asphyxiation, even though it has a higher oxygen content than air. Your body cannot produce the heat necessary (about 525 degrees Fahrenheit) to break the bond between the nitrogen and the oxygen, leaving the oxygen content useless for respiration. Gasses are often considered in terms of moles. The definition of a mole is the amount of substance that contains Avogadro's number of atoms or molecules. Though this number remains the same (6.02 x 10 to the power of 23), the weight of a mole can vary depending on the atomic weight of the molecule in question. Because an engine requires volume instead of mass, weight can be dismissed. A mole of any substance occupies 22.4 litres at standard pressure and temperature. The fact remains that all gasses have the same molar volume in similar conditions. So, if a cylinder can draw two moles of air on an intake stroke, it can also consume the same volume of nitrous. By volume, air contains 21 % oxygen compared to nitrous, which is 50% oxygen. For every two moles of Nitrous Oxide (N20) introduced to the cylinder, there are two moles of Nitrogen (N2) and one mole of Oxygen (02), as can be seen in the equation below:
2N2O==> 2 N2 + 102
There lies the hidden advantage of Nitrous Oxide. Since every mole has the same volume, it's clear that two moles of nitrous drawn into the cylinder, becomes three moles through the combustion process. This further raises combustion pressures and increases the power-producing potential of the engine.
Will Nitrous Harm My Stock Engine?
A kit that uses the current NOS brand or NX brand factory calibration will not cause increased wear on your engine. The key is choosing the correct HP for your application. A 4-Cylinder engine normally allows an extra 40-60 HP gain. A 6-Cylinder engine normally allows an extra 75-100 HP gain. An 8-Cylinder engine normally allows an extra 75-150 HP gain. Donít be fooled by cheap imitations. Insist on NOS and NX Brands.
Dry vs. Wet - Which One Do I Choose?
Dry (nitrous only) systems are perfect for adding a quick and safe 40-70 horsepower to a stock or modified naturally aspirated EFI vehicle.
Wet (nitrous mixed with fuel) systems are used on forced induction EFI vehicles or race applications using a direct port or plate system. Wet systems are a little safer in some applications because they add both fuel and nitrous not relying on the stock computer to compensate for the nitrous.
How Long Can I Hold The Nitrous Button Down?
Fifteen continuous seconds at a time, or less, is what is recommended. A typical 50-75 HP kit, with a 10 lb capacity bottle, will usually offer up to 14 to 20 full 1/4 mile passes.
When Is The Best Time To Use Nitrous?
Unless a progressive controller is used, you should only use nitrous with a wide-open throttle. Nitrous can be safely applied above 2,500 RPM, under full throttle conditions.
Are There Benefits To Using Nitrous With A Turbo Or Supercharger Application?
Yes! With the addition of nitrous, turbo-lag is completely eliminated. Turbo and superchargers compress incoming air, thus heating it. Nitrous adds an inter-cooling effect (75 degrees or more). Boost is usually increased as well, adding even more power.
What Do I Need To Modify?
Most systems for stock applications require little, if any, permanent modifications. Most stock fuel pumps will work adequately for smaller nitrous applications. Check to see if your pump can flow enough additional fuel to the nitrous kit, under full throttle conditions. Most late model ignition systems are well suited for nitrous. Only the higher HP cases may require a high output ignition system. Nitrous will not harm the catalytic converter and the stock computer chip will work fine.
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