How Nitrous Oxide Works

In terms of percentages, nitrous oxide works out to 64 percent nitrogen and 36 percent oxygen. The atmosphere we breathe has 23 percent oxygen and approximately 72 percent nitrogen, so in other words, nitrous oxide has more oxygen by volume than air. When nitrous is ingested by the engine, it goes from a liquid to a gaseous state. When the temperature reaches about 570 degrees Fahrenheit in the combustion chamber, the nitrogen and oxygen molecules separate. This is how more oxygen is added to the cylinder. As a result, more fuel must be added with nitrous to maintain the desired air/fuel ratios and stable combustion. It's not nitrous, but fuel that adds power.

In fact, a commonly asked question is why not inject pure oxygen to burn extra fuel? First, remember that combustion in the chamber isn't an explosion. It is, in fact, a controlled burning process that starts at the plug electrode at ignition and burns out to the opposite side of the chamber, forming a flame front. Anyting that destabizes the burning porcess, like detonation or pre-ignition, reduces power and leads to engine damage.

According to NOS, if you add pure oxygen combustion would be uncontrolled, and you couldn't add enough fuel fast enough to stabilize it. If the proper amount of fuel wasn't there, the mixture would be lean, which would make the chamber temperature very hot and eventually damage the engine. So the presence of nitrogen reduces peak combustion temperature and provides a stable combustion environment.

NOS offered several nitrous technical details. It takes approximately a pound of N20 (plus appropriate amount of fuel) to generate 100 horsepower for a 12.90 second quarter-mile run. If you flow two pounds of ntirous (plus fuel of course) in the same period, your power will double. Another feature of nitrous is that when it changes from a liquid to a gas it expands and absorbs heat. As a result, nitrous cools the engine intake. A dyno rule of thumb has a one percent gain of power for every 10 degree drop in temperature. Typically, a NOS system delivers a 40 degree Fahrenheit temperature drop and that alone is good for 15-20 horsespower!

Tuning Nitrous Oxide

While nitrous oxide is simple in producing power, there are tuning details for maximum performance. Nitrous, stored under pressure, is a liquid. As soon as it undergoes a pressure decrease exiting the nitrous solenoid, it turns into a gas, and it's ingested into the engine. The nitrous bottle is most typically intstalled in the trunk and the line is plumbed from there to the engine compartment. In the car, the nitrous switch is wired to the solenoids. Also, an electric fuel pump and line are installed to deliver fuel to the fuel solenoid. When the sytem is activated, the nitrous solenoid opens, allowing the liquid nitrous oxide to flow. Exiting the solenoid, it turns into a gas. In addition, the fuel solenoid is opened, and this allows extra fuel to be added. Another detail for maximum performance is rpm. NOS explains that nitrous can be engaged past 2500 prm in WOT applications. Properly installed, nitrous oxide is safe for catalytic converters and some NOS systems are 50-state smog legal.