Breaking Down the Nitrous Valve System

Feb 19, 2010

When it comes to performance racing, the industry wants the most reliable and responsive nitrous valve system the market can offer. As installers know, there are multiple choices to consider, making it tough to settle on a single system.

Despite the variety, all the systems have one characteristic in common. At the heart of every nitrous oxide system is the solenoid valve, a small-yet-powerful electromechanical gatekeeper.

In a nitrous valve system, the solenoid valve is electrically controlled by a micro-switch, found beneath the accelerator, and a contact switch, controlled by the driver. The micro switch makes sure the NOS injector is triggered at full throttle while the contact switch avoids accidental activation of the NOS injector.

The Solenoid Valve’s Place

Solenoid valves, although seemingly simple in their makeup, are actually designed to operate through a series of gate-keeping steps.

First, solenoid valves use electricity to open and close an orifice in the valve body, allowing a medium to flow through the valve. In the case of a nitrous system, the medium is the fuel and nitrous oxide.

In its simplest form, a solenoid valve is opened and closed by a plunger, which moves because the solenoid is energizing and de-energizing it. The solenoid’s coil creates a magnetic field to turn the valve’s stop into an electromagnet, attracting and raising the steel plunger.

A corresponding spring then compresses as the plunger lifts, exposing the orifice. Finally, when de-energized, the spring returns to its original position, forcing the plunger back onto the orifice and shutting off the flow.

Overall, the solenoid valve delivers the nitrous and fuel into the engine’s intake tract. Nitrous oxide enhances the combustion process to enable the pistons to work harder and faster. Therefore, the valve helps the system achieve faster speeds. Realistically, selecting a NOS system by focusing on the solenoid valve is the most logical choice.

Yet, there are various ways the valve can help accomplish faster speeds. Specifically, its place within the nitrous system can differ and therefore NOS designs vary as well. In fact, engineers can design a nitrous system around the valve to meet an installer’s NOS wish list.

A Wet or Dry Approach

Nitrous oxide can be supplied via wet or dry systems. When integrated with a range of engine types, these diverse system designs can yield increased horsepower.

With wet NOS systems, the throttle body receives nitrous oxide and fuel through a nozzle, also referred to as a fogger. There are three different design possibilities with wet systems:

• Single Point. This version uses a single nozzle (i.e. fuel injection system) to spray both nitrous and additional fuel into the engine’s intake tract to make it “wet” with fuel.

• Direct Port. Using multiple nozzles, this system design makes it possible to spray both nitrous and additional fuel into individual intake runners. The direct port allows an equal distribution of nitrous and fuel to each of the engine’s cylinders and yields the highest horsepower gains.

• Spray Bar Plate. A spray bar plate (i.e. carburetor system) is installed between the carburetor and manifold. The plate has machined holes that spray both nitrous and additional fuel into the intake air stream.

In a dry NOS system, the engine receives fuel through the fuel injection system. Dry systems come in primarily one design standard:

• Electronic Fuel Injection. Using a single nozzle, electronic fuel injection only sprays nitrous oxide into the engine intake, leaving it dry of fuel. Additional fuel is introduced by increasing injection system pressure or by tweaks to the vehicle’s computer to allow more fuel through the injectors.

Although these systems vary in design, they have one thing in common-additional fuel and nitrous oxide are introduced during the engine’s combustion process. As a result, nitrous oxide delivers additional oxygen and, when combined with the fuel, increases the fuel burn, resulting in greater horsepower gains.

When choosing one of these designs, an installer would need to consider several points. The customer’s budget can limit the choices to just the dry and single-point wet systems. Usually the most cost-effective solutions, these systems have limited horsepower gains (35-150 hp). Costlier systems can achieve even higher horsepower gains (250-1,000-plus hp) with the help of various accessories and higher-quality materials.

Additionally, the compatibility of the nitrous system with the engine design can further narrow the range of choices. When armed with a big budget and ambitious driving plans, drivers can choose a system based on the engine’s maximum achievable horsepower and desired horsepower gain.

Consider the End Result

Installers can easily find solenoid valves from an authorized nitrous system dealer or the nitrous system manufacturer. However, creating the dream NOS valve system may require the efforts of a valve engineer.

NOS valve systems can be custom-designed to fulfill an OEM’s wish list of preferred features. Not all valve systems are designed to withstand the same pressures or achieve the fastest acceleration.

Ultimately, the car owner values the result; therefore selecting a valve system based on features is the most logical approach. The valve engineer can design an appropriate valve based on the OEM’s list of preferred features such as:

• Fast response time. The nitrous valve system should create that added boost to the engine within a specified response time. Valves with short strokes (distance of plunger travel) tend to respond the fastest. Response time is critical to achieve the quickest acceleration once the nitrous system has been activated.

Recommendation: Many variables determine the overall response time of each system. Generally, systems that can use electronic control (i.e. progressive controller) such as direct port respond most quickly.

• Durability. Nitrous valves take a great deal of punishment, which takes its toll on the internal parts of the valve. A more durable valve means a longer life and fewer repairs and replacements. Nitrous solenoid valves are exposed to extreme cycling, pressures and heat. These conditions can easily wear down the internal components of the valve and shorten coil life. The robustness of the valve design plays a large part in extending the longevity and downtime of the system.

Recommendation: One system design is not necessarily more durable than another. Consider the system’s weakest component to determine how durable the valve is under constant pressure. 

• Fast Supply of Flow/Ability to Handle Maximum Pressure. The valve should deliver a certain volume within a specific timeframe while handling maximum pressure. The nitrous system must be fine-tuned with the engine. Solenoid valves are a critical element in dispensing the correct volume of fuel and nitrous in a timely fashion to yield increased horsepower on demand.

Recommendation: System designs vary so there are many options to consider. Systems with a purge valve allow a driver to clear gaseous nitrous from the nitrous bottle supply lines before the system is engaged. This brings pure liquid nitrous to the solenoid valves and ensures initial peak performance. 

• Avoiding Explosive Issues. Nitrous valve systems exist within a volatile environment and must deliver under extreme pressure. Adding nitrous oxide to the mix creates a completely new set of challenges such as explosive decompression, which can cause seal and valve failure. The valve’s dynamic and static seals are critical to avoid media compatibility issues that may result in leakage and valve inoperability.

Recommendation: Nitrous systems must be designed to handle extreme pressure, because the nitrous supply tank stores nitrous in a liquid form at high pressures (i.e. 1,000 psi). The best systems can handle the supply tank’s extreme pressures and avoid a potentially explosive scenario.

Solenoid valve selection is critical to achieving peak performance and longevity of nitrous systems. Once you know the desired result, you can select the appropriate NOS system by focusing on the solenoid valve’s purpose.