Subscribe to the Free

Nitrous Oxide Systems Facts - The ABC's Of Nitrous

What You Need To Know About Laughing Gas

Chuck Jenkes Mar 1, 2003 0 Comment(s)
Sucp_0303_01_z Nitrous_oxide_system_facts Nitrous_kit 2/18

What is Nitrous Oxide?


Sucp_0303_03_z Nitrous_oxide_system_facts Wet_systems 3/18




Sucp_0303_04_z Nitrous_oxide_system_facts Dual_stage 4/18



Sucp_0303_05_z Nitrous_oxide_system_facts Single_stage 5/18




Nitrous Systems

Sucp_0303_09_z Nitrous_oxide_system_facts Pressure_relief 9/18

Safety pressure-relief burst panels are necessary to protect the nitrous system from over pressurizing. Sanctioning bodies require pressure-relief burst panels to be attached to the bottle valve assembly.

Carbureted V-8 applications most frequently use a plate mounted under the carburetor, which has a spray bar that delivers the additional fuel and the nitrous oxide. A typical plate system uses a pair of 12-volt solenoids to control the release of the additional fuel and the nitrous oxide. The nitrous is plumbed directly to the nitrous solenoid. Fuel is supplied from the fuel supply feed line. Changeable jets control the amount of fuel and nitrous oxide fed to the spray bar.

The electric solenoids can be wired to a momentary push button in the interior of the car. An arming switch controls the power to the system so that it cannot be accidentally activated, as well as a full-throttle switch at the carburetor or throttle position switch.

Nitrous oxide is stored in the bottle under high pressure. A full 10-pound bottle will have approximately 800 to 900 psi at room temperature. At this pressure the nitrous oxide is stored as a liquid. Nitrous bottles must always be mounted at an angle with the outlet facing forward and down. This allows the siphon tube to pick up the liquid from the bottom of the bottle.

Sucp_0303_11_z Nitrous_oxide_system_facts Proper_temperature 10/18

Maintaining the proper temperature of nitrous in the bottle ensures peak performance. However, overheating can be dangerous. Always use a bottle-warming kit that includes a relay, a pressure sensor shutoff, pressure-relief burst panels, and a safety vent tube.

Producing more power requires a stronger engine. This is especially true when considering engines injected with nitrous oxide. If your engine is in need of repair, then adding nitrous will not help; in fact, it can make things worse.

Nitrous oxide injection has the capability to produce sudden power with increased combustion pressures and temperatures. This necessitates the addition or improvement of the engine and its support systems. How much nitrous oxide you can add depends on what type of engine you have. If you have a stock V-8 engine and a stock fuel system, you should limit your power increase to a 125hp kit.

Obviously, it's wise to be realistic when considering the amount of power an engine, transmission, and driveline can handle. A strong engine coupled to a weak transmission or differential will obviously deliver a lot of disappointment sooner or later. Even if the engine is equipped with the best ignition and fuel systems, its internal components have to be capable of coping with the increased loadings associated with producing more power. Adding a 300hp nitrous oxide kit to a production small-block Chevrolet will not last long. It's better to be a little conservative and gain greater reliability and longer component life.

Fuel It
One of the most important considerations when using nitrous oxide is the selection of a top-notch fuel system. A lack of fuel is the quickest way to damage a nitrous-injected engine. Starved of the necessary fuel, combustion temperatures will soar. Extreme temperatures cause catastrophic damage to pistons and other parts in the combustion chamber and lead to massive engine failures.

To prevent this, the fuel system must be able to handle both the normal engine requirements as well as the additional demands created by the nitrous system. You must immediately upgrade the fuel system if there's the slightest hint that the fuel supply is insufficient.

Sucp_0303_10_z Nitrous_oxide_system_facts Nitrous_works_bottle 11/18

There are two options available to remedy the situation. One solution is to beef-up the existing fuel system. The preferred method, though, is to have two independent fuel systems: one that serves the engine and another dedicated solely to the supply of fuel for the nitrous system. This is ideal because it protects the engine from spikes in pressure-an undesirable characteristic that can occur when using nitrous oxide. Additionally, this will allow you to make the flow test of the fuel system easier.

Note that the fuel supply (pressure and volume) must be checked at wide-open throttle, since you may have plenty of fuel pressure at idle, but at speed, with the button pushed, pressure could drop dramatically. (Remember, fuel pressure and volume are NOT the same!)

Sucp_0303_12_z Nitrous_oxide_system_facts Nozzle 12/18

Light the Fire
Increased combustion pressures often require a more powerful ignition system than that on a non-nitrous engine. This is especially true on kits for late-model, fuel-injected production cars. Since many ignition systems are only powerful enough to operate under the conditions they were designed for, increased combustion pressures may exceed the limits of the original ignition system. A lack of spark can cause drastic reductions in power and allows the unburned, highly atomized air/fuel mixture to enter the exhaust system, which can lead to explosive backfires.

Sucp_0303_16_z Nitrous_oxide_system_facts Bottle_mounting 13/18

Proper bottle mounting is a must. The bottle valve's outlet should point downward (angle mount) or forward (vertical mount), ensuring that the siphon tube is positioned to remove the majority of the liquid nitrous oxide.

Ignition Timing
Timing also plays a key role in the performance of a nitrous kit. Due to the increased cylinder pressures, it's unnecessary and inadvisable to advance the timing as much as a normally aspirated engine. Overly advanced timing leads to detonation and can cause severe damage to the engine's internals. As with jetting, start conservatively and gradually progress to optimum performance. The following adjustments will serve as a general rule of thumb:

Sucp_0303_14_z Nitrous_oxide_system_facts Wiring 14/18

Proper wiring of the nitrous system is critical to safe operation. These wiring schematics illustrate the correct way to wire a single- and a dual-stage nitrous system.

Safety First
After the kit is installed and plumbed, but before the bottle is installed, the first step is to check the operation of the solenoids. Arm the system and press the button. An audible click should be heard from both solenoids.

Next, run the vehicle and check for fuel leaks. Now, with the fuel system pressurized and the car idling, raise the engine speed, arm the system, and tap the button momentarily. The engine speed should drop as soon as the button is pushed, indicating the extra the fuel was injected.

Now install the bottle. With the engine off, open the bottle valve and check for leaks. If there are no leaks, you are now set to go to the drag strip to try your system.

It is best to initially activate your nitrous system at wide-open throttle (WOT). Using nitrous at too low of an engine speed can cause detonation, so it is best to be careful. Never activate the nitrous system with the engine not running. If you do, an explosive backfire could occur on start up. If you accidentally activate the system with the engine off, pull the coil wire off or disconnect the power to the coil, and crank the engine over for 30 seconds to clear the nitrous from the cylinders.

Sucp_0303_15_z Nitrous_oxide_system_facts Nitrous_pumbing 15/18

The plumbing system for a nitrous system is important. Applications that have the potential of producing in excess of 125 hp should have a dedicated fuel system to support the nitrous system. This requires a separate pump, regulator, and filter. Depending upon the pump selected, a bypass line may be required.

Bottle Basics
As previously stated, nitrous oxide is stored as a liquid under high pressure in the bottle. Bottle pressure will vary with temperature. If heat were continually applied to the bottle without a safety release, the bottle would explode. The explosion would be so violent that it could destroy the car that the bottle was mounted in. While each bottle is equipped with a 3,000-psi pressure relief to prevent explosions, care should be taken not to allow the bottle to be overheated.

The fitting on the valve in the upright position is the pressure relief. Should the cylinder exceed 3,000 psi, this relief fitting is where the cylinder will empty. If the car is to be used in IHRA competition, the rules dictate this relief fitting be vented to the outside of the car, a good idea in any situation. Relief valves with a threaded housing that accepts an -8 AN hose end are available.

Bottle pressure is also a key to nitrous system performance. Nitrous kits are usually jetted for optimal performance at a bottle pressure of between 950 and 1,000 psi. If the bottle pressure is higher, the mixture could be too lean, and if the bottle pressure is lower, the mixture is too rich. This is why nitrous racers are always concerned about bottle pressure.

Sucp_0303_21_z Nitrous_oxide_system_facts Backfire 16/18


EFI Systems


Finishing Lines

Sucp_0303_19_z Nitrous_oxide_system_facts Nitrous_plate 17/18


Top Ten Nitrous Mistakes






Sucp_0303_18_z Nitrous_oxide_system_facts Cutaway_nozzle 18/18









Connect With Us

Get Latest News and Articles. Newsletter Sign Up

sponsored links

subscribe to the magazine

get digital get print