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Wet vs Dry Nitrous - How To Choose - Nitrous 101

By: Jeremy Stoermer07/17/2018 < Back to Blog Home

When you hear racers talk about Nitrous, ears perk up, eyes widen, and imaginations run wild!  Nitrous Oxide is nothing more than a gas that contains a higher oxygen concentration than atmospheric air alone.  It’s typically stored under high-pressure as a liquid in specialized bottles. Some Dentists even use nitrous oxide as a sedative, we know it better as Laughing Gas but it’s not quite the same as what we use for engines.  Automotive grade nitrous contains a small amount of sulfur mixed in and can be harmful if not used properly! Nitrous Oxide can be injected into an engine in either liquid or gas form. As a liquid, it must first change states from a liquid to a gas before it can be used to make power. Extreme heat  within the combustion chamber causes the nitrous molecule to split. The extra oxygen that’s left over from this separation allows you to burn more fuel, which in turn makes more horsepower. There’s also another advantage to Nitrous! The change in state from a liquid to a gas is known as vaporization. The actual vaporization process causes a rapid drop in temperature making the incoming air/fuel mixture much denser, which also helps to make more power. These benefits along with the ease of installation, makes nitrous oxide a very attractive power adder. But before running out and buying that nitrous plate or direct port system, there are a few things you’ll need to know.


Two terms you’ll probably hear when talking about nitrous are “Wet” and “Dry” systems. These terms refer to the method in which the additional fuel is added when a nitrous system is activated. A “Wet System” adds additional fuel with a separate pump through the same plate or nozzle, supplying the nitrous oxide. The complete system is activated by a switch, either controlled by the driver or set up on the throttle linkage, the switch activates a set of solenoids for both the nitrous and the fuel. The amount of fuel added is determined by the “Jet” size installed in the plate or nozzle. This “Jet” is basically a calibrated restriction that can be swapped-out for a different size orifice in order to obtain the desired Air/Fuel ratio. “Wet” nitrous systems are typically used on carbureted engines, but many EFI applications also use this design since you usually don’t have to make significant and sometimes expensive changes to your existing fuel system.

A “Dry” nitrous system relies on the existing fuel system, whether it’s fuel injected or carbureted, to supply the additional fuel needed when the nitrous system is activated. This means the nitrous plate or nozzle only supplies nitrous oxide, no additional fuel is added here unlike a “Wet” kit.  A “Dry” nitrous system can be activated with a switch like much like the “Wet” system, but typically it’s controlled by the fuel injection controller or ECU. This allows the EFI system to calculate and determine when and how the additional fuel is added. More advanced systems, such as the Holley Dominator and HP EFI systems can pulse, delay or otherwise control the nitrous solenoids based on a multitude of pre-determined parameters that you can set within the ECUs programming.


Knowledge is a must when it comes to determining which system best fits your needs. Start with your current set-up and determine what expectations you have. Take into account your budget, mechanical abilities, and system limitations when you’re selecting a kit that’s right for you. Don’t forget to think about your future plans, this can help avoid any unnecessary upgrades and modifications, should you choose to increase that nitrous shot in the future.


Whether you need a complete “wet” or “dry” nitrous system or you’re just looking for a few pieces to upgrade your current set-up. With a huge variety of options and applications, look no further than NOS your nitrous leader.

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