Good to know: Nitrous Oxide is not a fuel, it is not flamable and is wrong to use the term NOS when talking about it.
Nitrous oxide, also known as dinitrogen oxide or dinitrogen monoxide, is a chemical compound with chemical formula N2O (2 atoms of nitrogen and 1 atom of oxige). Under room conditions, it is a colourless non-flammable gas, with a pleasant, slightly-sweet odor. It is used in surgery and dentistry for its anaesthetic and analgesic effects, where it is commonly known as laughing gas due to the euphoric effects of inhaling it. It is also used as an oxidizer in internal combustion engines.
When an engine pushes the piston down it burns fuel. So, when a car maker or tuner wants to get more horse power makes this pistons beeing pushed with more force, meaning more fuel it will be burn, more oxigen will be used (we all know that the burning process need oxygen). This is exacly that the nitrous oxide do: it allows more fuel to be burned so the system to generate more horse power.
When the engine burns fuel, at a temperature arround 300 degress Celsius (572 Fahrenheit) the nitrous oxide decompose in nitrogen and oxygen. The oxigen that result from the decomposition process will create additional power and more fuel will be burned. But you need to know that Nitrous Oxide without fuel won’t go to any result, because the fuel is the one that generates the power, the Nitrous Oxide only helps to burn a greater quantity of fuel in the same time.
In order to use the Nitrous Oxide in your car, it is compressed at a high pressure (850-1100 PS) so it will take the liquid form (it is acully a gas). The liquid it is put into a nitrous bottle and from where with a high-pressure hose runs up to the engine bay. To release the nitrous into the engine it is used an lectrically controlled valve called a solenoid.
Types of Nitrous Oxide Systems
1. Dry System
A dry nitrous system use an injector (called nitrous-only nozzle) so only the nitrous oxide to be injected in the intake. The additonal fuel needed to create the power is supplied by increasing fuel delivery throught the OEM fuel injectors when the nitrous system is activated.
2. Wet System
A wet system introduces both fuel and nitrous oxide into the intake in the same time using the same nozzle having two solenoids: one for nitrous, one for fuel.
Nitrous has a cooling effect
When nitrous oxide is injected into the intake manifold, it changes from a liquid to a gas. This will reduce the temperature of the nitrous to minus 127 Degrees F and the intake temperature by approximately 60-75 Degrees F, so more power is created ( 350 HP engine with an intake temperature drop of 70 Degrees F, would gain approximately 25 HP on the cooling effect).
How Nitrous Oxide Injection creates torque
Nitrous oxide allows the engine to burn more fuel at a lower rpm range than normal, this way a longer burning period is created and the pistons will be pushed down with a greater average force. In the combustion process the nitrous it is separated into nitrogen and oxygen which is used to burn the additional fuel, while the released nitrogen acts as a buffer against detonation and damps mechanical loads.
A very important thing to know is that you need to have enough fuel to burn the additional oxygen or you will seriosly damage your engie. If the amount of nitrous and the extra fuel is controlled precisely your engine can safely and reliably generate exceptional power increases.
You need to make the difference: nitrous oxide does not burn, it just provides oxygen so more fuel can be burned. In the nitrous oxide molecule the atoms are boud together, so the oxygen is not free but the bond breaks down as temperature rises (arround 565° F). When you add nitrous oxide to an engine, the total amount of oxygen is increased while the volume of nitrogen is decreased. This increase will speed up the burn process. It is easy to run too much ignition advance with nitrous, but too much will not only hurt power, it can quickly bring a nitrous engine into detonation and destroy it.
To control the detonation you must control the extra heat taht nitrous can make by simply adding more fuel. The extra fuel takes away the heat and raises the detonation limit (raising this limit you will allow more nitrous to be used to get more power).
So why not Pure Oxygen?
A very importanty thing to know is that nitrogen does not aid in combustion, it only absorb and carry heat away. So, only the oxygen it helps the combustion process. The more nitrous you add, the more oxygen it will be available for the burning process, but in the same time less nitrogen to absorb heat.
That’s the reason why the nitrous increases engine heat very rapidly. So why not to add only oxygen? Because if we were to add pure oxygen the percentage of nitrogen would fall even lower as more oxygen was added and the engine heat will increase. Only the oxygen takes up more room and reduces normally aspirated power, and the amount of nitrogen from it. But using nitrous oxide, the engine will produce more oxygen atoms.
When to use it?
You can use nitrous oxide only when the engine is in top runing condition and use it in a controlled environment. If you were driving arround on a 40 degress C day and your engine is cooking this is not a good time to make a 20-second nitrous blast
Example of a car having nitrous tank
1997 Toyota Supra
In addtition to the first model from 1979 the new model has a Twin Turbo engine provinding 320-horsepower and a sprint from 0 to 60 in less than 5 seconds.
- Opening Hood, Opening Doors, Opening Trunk, Rear Spoiler
- Stereo System located in Trunk, Changeable Hood and Tires
- Detailed Interior and Dash, Nitrous Tank located between back seats
- 2 TV’s located in Car, Official Logos and Insignias, Baked Enamel Finish
- Precision Diecast Replica, 1:24 Scale Model, 8 Inches Long