NOS Basics and Layout

The basic nitrous oxide injection system, or a NOS kit, is pretty straight forward and easy to grasp. It consists of a nitrous oxide tank to hold the Nitrous, some tubing to route the Nitrous to the intake system, a nitrous solenoid and possibly a fuel solenoid to regulate the system, a toggle switch and throttle position microswitch to activate the system, and jets, a nitrous fogger, a relay, and a distribution block.

NOS Canister

The basic layout or a Wet NOS System

The nitrous tank is a pressurized canister that is used to store Nitrous Oxide in a liquid form. The tank is pressurized as Nitrous Oxide must be compressed if it is to remain in liquid form at room temperature. Remember N2O reaches boiling point and it becomes gaseous at -127° F (-89° C) and more Nitrous Oxide can be stored when it is in a liquid form. At sea level approximately 850 psi of pressure is required to keep Nitrous Oxide liquid at room temperature but the nitrous tank must be pressure tested and certified to withstand 1,800 psi. If the certification on your NOS tank is older than five years, your nitrous dealer will not refill it and you will have to have the tank pressure tested and recertified.

The tank has an internal siphon tube that extends to the bottom of the tank and is connected to the release valve where the Nitrous is released at the top of the tank. The tank must be mounted in the car's trunk at a 15° angle to ensure that the maximum amount of Nitrous Oxide can be released from the tank.

High pressure nylon or Teflon inner-lined braided-steel pipe is used to route the Nitrous Oxide to the engine where it is regulated by the NOS solenoid. The solenoid is an electrically controlled valve which uses a strong electromagnetic field to open a small plunger that blocks the flow of the liquid Nitrous Oxide. In a Wet NOS system, a second solenoid is used to supply extra fuel into the intake system so that the air/fuel mixture remains constant when Nitrous is applied. Both solenoids are controlled by electric switches that activate the electromagnetic field. The NOS system should have at least two switches — a microswitch that is fitted to the accelerator linkage and is only activated at full throttle; and a spring-loaded momentary switch that is activated by the driver. The microswitch on the accelerator linkage ensures that the nitrous system can only be activated at full throttle. Activating the system during part throttle or during a gear change can have very catastrophic consequences. As an added precaution, the oil pressure switch can also be used to ensure that the system can only be activated when the engine is running and there is oil pressure. Starting an engine with NOS in the combustion chamber can also be very catastrophic.

Some more high pressure nylon or Teflon inner-lined braided-steel pipe is used carry the nitrous and fuel (which are still separate at this stage) to the intake manifold where it is released into the engine via two small jets that are located in a special nitrous injector. The jets must be correctly calibrated to release the correct amount of fuel for a given amount of nitrous. In addition, the pressure on the fuel supply side must be adequate and at a constant level to ensure that the air/fuel mixture is correct at all times. This may require the fitting of an electric fuel pump and a fuel regulator.

Metering Jets

Metering Jets

The quantity of the nitrous flow depends on the size of the metering jet fitted. The jet is the same as those used on carburetors and is basically a threaded screw with a whole through the length of it. It's used as a restriction tool depending on the size of the link up orifice. Applying a bigger jet is the easiest way to squeeze a bit more power out of your current system. The fuel supply comes from a similar jetting system.

There you have it — a basic understanding of the components of a NOS kit, its layout, and how a NOS system works. With all that behind us, we can move on to our next section in which we'll look in more detail at NOS installation ...