Types of Nitrous Oxide Systems
These are three basic types of nitrous systems: dry, wet, and direct port. The most misunderstood is the “dry” type of system. A “dry” nitrous system simply means that the fuel required to make additional power with nitrous will be introduced through the fuel injectors (remember, fuel makes power, nitrous simply lets you burn more of it). This keeps the upper intake dry of fuel. We accomplish this by two methods. First, is to increase the pressure to the injectors by applying nitrous pressure from the solenoid assembly when the system is activated. This causes an increase in fuel flow just like turning up the pressure on your garden hose from 1/2 to full. The second way we can add the required fuel is to increase the time the fuel injector stays on. This is accomplished by changing what the computer sees, basically tricking the computer into adding the required fuel. In either case, once the fuel has been added, the nitrous can be introduced to burn the supplemental fuel and generate additional power
The second type of nitrous kit is the “wet” style of kit. These kits include carburetor plate systems and add nitrous and fuel at the same time and place (normally 3-4" ahead of the throttle body for fuel injected applications or just under the carb as with plate systems). This type of system will make the upper intake wet with fuel. These systems are best used with intakes designed for wet flow and turbo/supercharged applications.
The last type of system is the direct port system. Just as it’s name implies, it introduces the nitrous and fuel directly into each intake port on an engine. These systems will normally add the nitrous and fuel together through a fogger nozzle or a NOSzle™. The fogger nozzle mixes and meters the nitrous and fuel delivered to each cylinder. This is the most powerful and one of the most accurate type of systems. This is due to the placement of the nozzle in each runner, as well as the ability to use more and higher capacity solenoid valves. A direct port system will have a distribution block and solenoid assembly which delivers the nitrous and fuel to the nozzles by way of connecting tubes. Because each cylinder has a specific nozzle and jetting (both nitrous and fuel), it is possible to control the nitrous/fuel ratio for one cylinder without changing that of the other cylinders. These systems are also one of the more complicated systems when installation is considered, as the intake must be drilled, tapped, and the “plumbing” made to clear any existing obstructions. Because of this and the high output of these systems, they are most often used on racing vehicles built for the strain of such high horsepower levels.
"AN" Thread Sizes AN sizes, originally developed for use by the U.S. Armed forces ("A" for army and "N" for navy), describe the outside diameter (O.D.) of tubing in 1/16-inch increments. For example, an AN 2 fitting will fit a tube with an O.D. of 2/16", or 1/8", while an AN 8 fitting will fit a tube with an O.D. of 8/16", or 1/2". Because the actual thickness of tube walls can vary from brand to brand, the inside diameter of a tube is not used as a reference. You will also find the dash (-) symbol or the word “dash” itself used in conjunction with AN sizes. A “dash six” fitting translates to AN-6. Each AN fitting has an established thread sizing. The following chart shows the relationship between AN size, tube O.D., and SAE thread size: "NPT" Thread Sizes NPT sizes (National Pipe Taper) are the most commonly used fitting sizes for general plumbing, piping, and tubing use; not quite as popular as AN for automotive use, but still very common. While AN fittings depend on the outside diameter of a tube for sizing, NPT fittings depend on the interior diameter (I.D.) of the fitting itself. The following chart shows the each size’s thread-per-inch count, the I.D. of the fitting, and the AN fitting size with the closest-matching I.D.(inside dimension).