How Nitrous Oxide Works and What You Need to Know

If you’ve ever watched a Fast and Furious movie, you’ve seen a car with nitrous. Nitrous oxide is arguably the most cost effective way to increase horsepower. It is a very popular mod because with the flip of a switch your car could make an extra 100hp or more!

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But how does nitrous actually work? What is wet vs dry nitrous system, and will this blow up your engine? Well, these are just a few of the topics we’ll discuss in this blog post.

What Is Nitrous Oxide?

Nitrous oxide, also known as laughing gas, is two parts nitrogen and one part oxygen or N2O if you prefer chemistry. Nitrous oxide has several uses. It was first used recreationally in the 18th century for its laughing gas traits, and today it is used in the medical field as a sedative. Nitrous oxide used for performance cars is a different grade of N2O. It has sulfur added to prevent substance abuse.

Nitrous oxide was first used in engines during World War II. The Germans discovered that injecting this substance into the engine would increase its performance. It was especially useful in high altitude situations with low oxygen content.

When Nos, as its commonly called, is stored in a tank when it is used on cars. The Nos inside the tank is in a liquid state. This is because the nitrous is usually under a high pressure of around 900 to 950 psi when its in a bottle. At atmospheric conditions N2O is a gas. Its important to note that nitrous oxide is not flammable

How Does Nitrous Increase a Cars Horsepower?

Simply put nitrous is sprayed into a car’s intake to create more horsepower. It does this by splitting into nitrogen and pure oxygen. The added oxygen improves combustion and you can inject more fuel into your engine while using Nos. This will substantially boost horse power while the Nos is being sprayed.

As nitrous oxide leaves the bottle, it leaves a pressurized environment that get it condensed as a liquid. As it leaves the bottle, the N2O expands and becomes a gas. So now that the Nos is in a gas state, all that’s left is to separate the nitrogen from the oxygen atoms. This is done by adding heat. When nitrous is to approximately 570 degrees F, it splits into nitrogen and oxygen atoms.

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Another way nitrous oxide boost performance is by its cooling effect. As nitrous oxide is injected into the intake manifold it vaporizes, and while its vaporizing, it significantly drops the temperature of the incoming air. This is important because colder air is denser. In other words more air fits inside the same volume of space. By cooling the air via Nos, you are not only adding oxygen from the splitting of N2O but you are also adding more air from the engine’s intake because you increased the air density by cooling.

How Long Does Nitrous Last?

How long your nitrous last depends on the size of your bottle and the amount of shot your spraying. For example a 100 shot is spraying enough nitrous to increase your engine’s horsepower by approximately 100 hp. The bottle Nos size is measured in pounds. So for this example we will use a 10lb bottle with a 100 shot.

A standard rule of thumb is that 1lb of nitrous will give you ten seconds of spray for a 100 shot. So a 10lb bottle will give you 100 seconds of continuous spray. In other words you should be able to do a solid 3-5 quarter mile runs. Then after that the nitrous benefit will drop off slightly, but you still be able to do a few more decent runs before the bottle is empty.

Wet vs Dry Nitrous Systems

When picking a nitrous system for your car its important to understand the difference between a wet and dry system. A wet system not only adds nitrous, but it also adds additional fuel with the Nos. This added fuel and nitrous is sprayed into the intake.

A dry system only adds nitrous to the intake. No additional fuel is added with the Nos. However in order to avoid a lean mixture, the fuel pressure is increased. The increased fuel pressure allows for more fuel to be injected with the added oxygen from the nitrous. If you’re running a dry setup, the amount of nitrous you can inject will be determined by your fuel injector size and fuel pump.

Dry kits are easier to install, and they don’t require you to run additional fuel lines. Wet kits do not increase fuel pressure, but they do require you to run a fuel from the fuel rail’s schrader valve (where fuel pressure is measured) to the fogger nozzle. The fogger nozzle is the nozzle which injects both fuel and Nos into the intake.

Wet nitrous allows accurate tuning of air to fuel mixtures, which is necessary if you’re going for high horsepower numbers. However, if you’re only looking at adding 60-100hp a dry nitrous kit is simpler to install, use, and safe to use.

Does Nos Destroy Engines?

There is a myth that nitrous oxide will destroy your engine, and the truth is that people destroy their engines. There is no reason a healthy engine should blow up with a 60 shot of nitrous, but if you take a stock block and add 400 shot of nitrous, you’re just asking for a bad day.

Most engine damage due to Nos is because of an improper air to fuel mixture. If you add to much air, but don’t compensate with extra fuel your engine will run lean. This can be deadly to your engine.

Overall nitrous is not anymore dangerous for you engine than a turbocharger or supercharger. The way to stay safe is to understand how your nitrous kit works, keep a healthy air to fuel ratio, and don’t put spray more shot than your block can handle.

How Much Nos can a Stock Engine Take?

The amount of Nos your engine can take will be determined by your engine’s health and size. Generally speaking bigger heavier engines can handle more spray than smaller engines with less cylinders.

A 4 cylinder engine shout be able to easily handle a 40-60hp shot, while a small block v8 could likely handle 100hp without modification. If you want to get bigger horsepower mods, you will probably need increase the structural integrity of your engine. This could include switching from cast pistons and crankshaft to forged components.


Nitrous oxide is one of the cheapest and easiest ways to get big horsepower gains. With proper knowledge adding and using Nos is as safe as other performance modifications like turbos and superchargers. If you are a quarter mile racer looking for a simple and cost effective way to make a lot of horsepower this might be the mod for you!