How it Works?
You have seen it in the movies. Hit a button and in an instant the engine produces 50, 100, 150 or more additional horsepower.
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 B16 in your Civic, 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
A bottle, high-pressure lines, solenoids, jets and nozzles are included in all nitrous-oxide systems. The nitrous-oxide bottle usually holds 10 lb of nitrous oxide and the trunk is the most popular mounting location. A high-pressure line will carry the nitrous oxide forward to the solenoid. The solenoid is an electronically controlled valve. When a signal of 12 volts is sent to the solenoid, it opens and nitrous oxide is then sent to the nozzle and into the engine. At 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 700 to 1200 psi.
"Dry" and "Computer Controlled" Systems
The 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.
The Good, The Bad, The Ugly
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 40-hp shot is all that you can do on a stock D16, believe them.
Better Safe, Than Sorry
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.
Coming Soon
In the next installment of Horsepower 101, we'll take a look at boost. That's right, the power of the turbo and the supercharger. Knowledge is power, we'll catch you next month.