Nitrous oxide, also known as N2O, NOS, laughing gas, bottle feeding, spray, juice...and many others I am forgetting. Nitrous oxide is made up of 2 nitrogen atoms bonded with 1 oxygen atom.
Is it magic? Not really. The explanation is rather simple, but before understanding how a nitrous-oxide system allows an engine to generate a rush of additional horsepower, it's best to understand a little on how the engine itself makes power.
Internal combustion engines, like that VQ30DEK in your Maxima, are designed to convert one form of energy to another. The engine takes the energy in the fuel and then, through combustion, the fuel's energy is turned into heat and pressure to produce horsepower at the flywheel. Even if you can't remember this, all that you need to remember is that the more fuel that you can combust, the more power that you can make. Bottom line, to make more power we need to be able to combust more fuel.
This brings us to combustion. What do we need to be able to burn more fuel? The answer is simple, as just two things are needed. First, we need a way of adding additional fuel. Second, we need something that will supply an additional amount of oxygen to let the fuel burn.
Regardless of who manufacturers the nitrous-oxide system, every nitrous-oxide system accomplishes both of the above. In some way, either through the factory injectors or by adding additional fuel nozzles, the nitrous oxide system puts more fuel into the engine. The additional amount of oxygen needed to burn this fuel is also supplied by the nitrous-oxide system. The additional oxygen is supplied by injecting gaseous nitrous oxide into the engine. When the nitrous oxide gets inside the engine, it supplies almost twice the amount of oxygen for combustion. The air that we breathe is about 21-percent oxygen. On the other hand, nitrous oxide contains 36-percent oxygen by weight.
The Basic System The basic system is exactly like it sounds. For a bare bones nitrous system you need a bottle, nitrous lines, solenoid valve, various jets, a nozzle assembly and 2 switches. The bottle obviously supplies the nitrous which when full, is injected at anywhere from 900-1200 psi. The nitrous line carry’s the N2O from the bottle to the solenoid valve. The solenoid valve is opened when triggered by a switch. There are 2 switches used for obvious reasons. One switch is to “ARM” the system. The other switch is most commonly placed on the throttle body assembly. When the throttle goes wide open (WOT) it is activated. The “WOT” switch receives it’s power source from the “ARM’ switch, so both have to be energized before the solenoid can be opened. Once activated they send a 12v signal opening the solenoid. “CAUTION” It should be noted here that you don’t want to inject Nitrous unless you are under WOT conditions and usually not below 3000RPM. If not in “WOT” you’ll run extremely lean and detonate leading to serious internal damage. Under 3000rpm the motor will be shocked by the immediate addition of torque and most likely bend or snap a rod. When opened the solenoid valve sends the nitrous to the nozzle assembly which houses the nitrous jet itself. The size jet you select to put inside the nozzle will determine the amount of nitrous that is injected into the motor. This type of kit is referred to as a “dry” system because you aren’t adding fuel only nitrous. When using a “dry” system you usually don’t want to exceed a 50HP shot. Exceeding that will require timing adjustment and fuel enrichment. It should also be noted that when using a “dry” kit, you’re depending on your stock fuel system to provide the extra fuel required to mix with the nitrous. So having your system up to spec is a must. To much nitrous without the addition of fuel will cause a serious lean condition, again resulting in internal damage.
"Wet" SystemAt the same time that nitrous oxide is injected into the engine, the nitrous-oxide system will by some means add additional fuel into the engine. The original and most simplified method of injecting the fuel is by using a solenoid and nozzle setup. This setup is often referred to as a "wet" system and is nearly identical to the configuration for the nitrous except that the fuel is injected at anywhere from 6 to 60 psi, while the nitrous oxide is injected at 900 to 1200 psi
"Dry" and "Computer Controlled" SystemsThe term "dry" nitrous-oxide system refers to nitrous-oxide systems that use the factory injectors to supply the additional fuel into the engine. The original dry systems designed by Nitrous Oxide Systems send a pressure signal to the factory fuel pressure regulator to increase the fuel pressure. This increase in fuel pressure allows the injectors to supply more fuel for the added nitrous oxide. Taking a bit of a different approach, Venom's VC-2000 system uses a computer control module to increase the amount of time that the injectors are open to put more fuel into the engine. Additionally, the Venom system uses the signal from the vehicle's oxygen sensor to ensure that a safe air-fuel ratio is maintained. If the sensor detects an excess of nitrous without enough fuel, the Venom system shuts off the delivery of nitrous oxide, saving the engine from harm.
Other useful info…The good news is that dollar for dollar, the horsepower increase from a properly installed nitrous-oxide system is hard to beat. Most starter systems come ready to generate an additional 40 to 120 hp. Above this power level, a more sophisticated system is required and previous experience with nitrous oxide is highly suggested.The bad news is that an improperly installed nitrous-oxide system can cause severe engine damage. If nitrous oxide is injected into the engine without supplying an adequate amount of fuel or no fuel at all, then you've got trouble. The temperatures in the combustion chamber will skyrocket, and the engine may detonate and parts will be broken and melted.There are some ugly facts that you'll have to face when it comes to using a nitrous-oxide system. First, bottles are only so big. The more frequently you use the juice, the more times you will be refilling the bottle. Second, the less you learn about nitrous, the more likely you are to have a bad experience. Third, and most important, it is not the use of nitrous oxide that causes engine damage. It is the misuse of nitrous oxide by the tuner and driver. Every engine has its limit. A stock engine doesn't have the toughness of a racing engine. Chances are that there's a tuner out there with your same engine and they have experience with using nitrous oxide on your engine. If they tell you that a 75-hp shot is all that you can do on a stock VQ30DEK, believe them.
If you want to have a good nitrous-oxide system experience there are some considerations you can make to increase the chances of coming away with a smile. Since a nitrous-oxide system relies on the fuel system, it is always best to be sure that your fuel system is at its peak efficiency. Factory fuel filters begin to degrade in performance as early as 10,000 miles. When installing a new nitrous-oxide system, it is recommended that you replace your factory fuel filter and be sure that the injectors are clean. The other area that you need to address is the vehicle's ignition system. A factory ignition system is designed to operate at near factory horsepower levels. A nitrous-oxide system can easily overcome the capabilities of a stock ignition system. Be sure that the spark plugs are new and that the ignition cables are in good condition. The cap and rotor should also be inspected on non-direct-ignition-system (non-DIS) cars. An ignition amplifier, high-performance ignition wires and spark plugs that are one heat range cooler (for applications over 50 hp). In the absence of an ignition amplifier, it's a good idea to tighten your spark plug gap by .010 to .005 in. This will make it easier for your ignition to generate a spark even in the high-horsepower range, and less of a chance for the spark to be “blown out”.
Q: How does nitrous work? A: Nitrous oxide is a gas that contains two parts nitrogen and one part oxygen. When the combustion process heats this gas, the oxygen is released. This extra oxygen then supports the combustion of the enrichment fuel the nitrous system adds when it is engaged. The additional fuel that is burned, creates greater cylinder pressure, which makes the extra horsepower you feel.
Q. How does a nitrous system operate on a fuel-injected vehicle? A. The nitrous system is a complete stand-alone air/fuel delivery system that augments the standard factory EFI unit. It provides additional fuel and oxygen to the cylinders via the nozzle mounted in the intake tract to provide additional horsepower.
Q. How does a nitrous system operate on a carbureted vehicle? A. The most common method of boosting power on carbureted applications is the use of a "plate" sandwiched between the carb and the intake manifold. This plate contains tubes that deliver the nitrous/fuel mixture in precise ratios.
Q. How easy is it to install a basic wet nitrous system? A. The systems are very straightforward. It requires no engine disassembly, no fuel system modifications or timing retards. Simply install the nozzle in the intake tract approximately 2-6 inches in front of the throttle body and connect the fuel solenoid to the high-pressure side of the injection rail and your ready to go.
Q. Purge valves look cool, should I get one for my nitrous vehicle? A. A purge valve is a valuable tool for increased nitrous performance. It allows the user to "Purge" all gaseous nitrous from the bottle supply line prior to using the system. This allows for a harder "Hit" from the system thus increasing performance.
Q. What safety features come with a nitrous system? A. There are several safety related devises that can be used with a modern nitrous system. The first, and most important is the WOT (wide-open throttle) switch. This prevents the user from accidentally engaging the system. A special high flow nitrous filter is recommended. All hoses should be aircraft quality stainless steel braided, Teflon.
Q. How does the solenoid know when to open and release the nitrous oxide? A. A signal is sent from the Wide Open Throttle switch. This switch signals the solenoids to open when the motor reaches wide-open throttle.
Q. What are the differences between a dry nozzle and a wet nozzle? A. The "dry" system uses the factory fuel injection to enrich the nitrous introduced into the engine. The flaw with this technology is that no matter how much nitrous arrives at a certain intake port it always gets the same preset amount of fuel, or if a fuel injector becomes clogged engine damage will result. The "Wet" technology introduces a precise amount of fuel and nitrous through a high tech mixing nozzle that atomizes the fuel to microscopic proportions. This allows every cylinder to receive a precise, homogenous mixture of fuel and nitrous, thus insuring a safe, powerful increase.
Q. What is nitrous backfire? A. Nitrous backfires can be caused by two situations. 1. A nitrous system that is two rich or a system that atomizes the fuel poorly, thus causing pooling or puddling of fuel in the intake manifold. 2. A system that is operated too lean.
Q. Should I use an aftermarket ignition with nitrous? A. Most systems are designed to operate with stock ignition; however any upgrade in the stock ignition is a definite plus.
Q. Should I change my ignition system in any way (timing, plugs, etc.)? A. Most systems are designed to operate with no timing retard. Spark plugs should be changed to non-platinum style, 1 to 2 steps colder than stock.
Q. Will a bigger bottle give you more horsepower? A. No; however a larger capacity bottle will provide a more stable bottle pressure resulting in a lower E.T. and a higher M.P.H.
Q. What is the difference between a 1 stage and a 2 stage system? A. A single stage system refers to one single nitrous system; a 2 stage or dual stage incorporates two nitrous systems on one application. This allows a car to launch with the maximum horsepower possible, with the traction available, then add more power down track as the car can handle it.
Q. Why does my engine need more fuel while on the bottle? A. The fuel, or gasoline, is the source of the additional horsepower. The nitrous' job is to provide the oxygen to allow the fuel to be burned.
Q. How can my engine get more fuel while on the bottle? A. Most systems add additional fuel during nitrous usage by injecting it directly with the nitrous through the nozzle. This method assures 100% atomization of the fuel and accurate air/fuel ratios.
Q. What is the safest way to configure nitrous activation? A. The only safe way is to use a wide open throttle switch, however you may configure any number of ways to "trip" the system but all must be used in conjunction with some type of wide open throttle switch.
Q. Is a bottle heater good? A. A quality bottle heater is essential to proper nitrous system performance.
Q. How much pressure should be in my bottle? A. Most systems are designed to operate between 900-1200 PSI.
Q. Are there any dangers or things to stay away from while using nitrous? A. Standard recommendation is that no more than an additional 15 horsepower per cylinder be used on a stock engine, with a stock fuel pump. Always be sure you are using clean, uncontaminated nitrous. Also, be sure you have the highest octane fuel available, I.E. 93 octane premium for, stock compression, street cars and the highest motor octane fuel available for competition type vehicles.
Q. Is there a trade off for engine reliability and power produced with nitrous? A. When used according to factory recommendations, shortened engine life should not be a concern.
Q. Can you feed an engine too much nitrous even if you keep the air/fuel ratio the same? A. Yes, if the mechanical limits of the engine are exceeded catastrophic engine failure will result.
Q. Can I hide my nitrous system from a novice tuner? A. Yes, it is quite easy to hide a nitrous system from the casual observer.
Q. Can I use a nitrous kit on an automatic? A. Yes, the preferred application, for nitrous, is an automatic transmission equipped vehicle.
Q. Can you powerbrake an automatic with nitrous without it blowing up? A. The answer is a qualified, yes. If your brakes can hold your engine, at full throttle, with the nitrous on, the answer is yes, but it is doubtful this would be possible.
Q. Can a nitrous system be set up to shut down once the brake is depressed? A. Yes, if the user wires his system with a double throw-double pole relay placed between the arming switch and the wide open throttle switch that is activated when the brakes are applied.
Q. Can nitrous systems be used with aftermarket chips or ECU's? A. Yes, however close attention must be paid to excessive timing advance that could cause detonation.
Q. Are drag racing launch techniques any different with nitrous for AT or MT's? A. Depending on the traction available the launch techniques are the same, however with the increased torque and horsepower generated by nitrous usage, sometimes is necessary to delay the nitrous onset for a brief period.
Q. How high must the RPM's before activating nitrous? A. The RPM level is not as important as is the motors ability to rev freely when the nitrous is engaged, I.E. If the vehicle is in low gear, nitrous can be engaged at any time, but if the vehicle is in a higher gear moving at a slow speed when the nitrous is engaged the engine will detonate and damage will occur.
Q. Does nitrous increase cylinder temperatures and combustion chamber pressure? A. No, cylinder temperatures should stay the same when the correct nitrous air/fuel ratio is used. Yes, increased cylinder pressure equals increased horsepower.
Q. Can I use nitrous on my high compression engine? A. Yes, but the proper octane fuel must be used to prevent detonation.
Q. Can I use nitrous on my turbo or supercharged vehicle? A. Yes, however you need a specific application for turbo or supercharged vehicles.
Q. What are some general rules for creating the most horsepower without damaging anything? A. Generally speaking the amount of power that can be created with nitrous is almost limitless. To avoid a catastrophe, the internal components of the engine must match the amount of power that is going to be generated. The use of proper air/fuel ratios is essential and the quality of the nitrous system is paramount.
Q. Is there any harm that can be done to my engine if I use nitrous while the bottle pressure is too high? A. Yes, the nitrous system will run "lean" if the nitrous pressure is high beyond specification. This could cause severe engine damage.
Q. Where should I run the main nitrous feed line? A. The feed line can be run either under the car or through the passenger compartment. Care should be taken to route the line away from any voltage points or moving suspension parts.
Q. Where should I install my bottle? A. The ideal place to mount the bottle is in the trunk; however if your car is a hatchback it is permissible to mount it in the passenger compartment if an external pressure relief vent is properly installed on the bottle.
Q. Why does nitrous have such a scary reputation? A. There has been some very shoddy nitrous "kits" sold to unsuspecting customers over the last 20 years; this along with the abuse nitrous has suffered from "idiots" who damage their own engines.
This article is a compilation of many useful points found while researching.