FAQ MUST READ... Lots of technical ?'s answered! [Archive]

Carb0n

February 17th, 2006, 08:28 AM

Nitrous

heres some of my basic knowledge of nitrous compiled from reading and what not

Let's start with chemisty: Nitrous Oxide(N2O) is two parts nitrogen a one part oxygen.
Now if you recall, combustion requires a fuel source and an oxidizer(oh and a source of ignition). As you may be aware, more air causes a fire to burn higher and hotter. Why? Because the chemical process of combustion is receiving more oxidation from the oxygen present in air. Now in regular Naturally aspiriated internal combustion engines. The fuel source is gasoline, and the oxiderizer is atmospheric air being drawn through the intake tract. More air(oxidizer) forced into the combustion chamber means a hotter more powerful combustion which in turn means higher cylnder pressure which = more power.
The oxygen present in the N20 is an oxidizer just the same as the oxygen in air is. When the N20 is introduced into the intake charge and combusted, the oxygen goes to work at making that process that much more powerful. Now since the O of the N2O is being burned, what do we have left? thats right kids N2 or good old fashioned nitrogen! Now you may be thinking what good is nitrogen to the internal combustion process since it is not an oxidizer?(well at least some of you "may" have been thinking that) Well I'll tell you. Besides acting as a buffer for the combustion of the oxygen(pure oxygen would actually burn quite erractically and unevenly) it also serves to lower the combustion chamber by about 70 degrees on average. This is the reason nitrous is sometimes described as being self intercooling.

How it makes power:
Now based on the chemical processes described above, you shold now be aware of the function of N2O to the combustion process. All this extra oygen is now making your combustion process that much more powerful. The N20 is basically performing chemically, what Superchargers and turbochargers do mecanically, Force more oxygen into the combustion process. This is why you may have heard the term blower in a bottle. Because the bottle in which the N2O is stored is basically doing the same the as the SC or TC. Now having more oxygen involved is great, but we must not forget that other part of the equation- the fuel. An internal combustion motor requires a precise ration of Air to Fuel. This optimal ratio is called the stoichometric ratio. IT states that the combustion process should be metered at 14.7:1. Meaning 14.7 parts air to every part fuel. Adding all this extra oxygen by way of N2O requires and equal addition of fuel to keep the ratio from going to lean ( too much air/oygen) , which can cause engine damaged. A a properly designed nitrous kit includes fuel compensation to keep this ratio in check aswell as adding more fuel to the combustion which also adds to the power produced. Now remeber that cold remaining Nitrogen. It also helps make power by lowering combustion chamber temps and keeping things from breaking due to heat or detonation.

Types of Kits available:
There are several types of nitrous kits marketed these days for EFI use and many ask which to use. A typical Nitrous kit comtains the following. A 10-15 lb bottle to store the N2O, a braided SS line for going from the tank to the motor, Solenoids for N2O and or fuel, Spray nozzels for injection of N2O and or fuel, and activation electronics(relays, arming and activation switches) A brief run down of the styles available is as follows:
Dry Kit: A dry kit is a kit which only indtroduces N2O ALONE into the intake manifold. This is typically accomplished through a single nozzle placed into the intake tract 10-16 inches from the Throttle body. When the kit is activated Nitrous is injected into the intake tract and pulled through the upper plenum. As it reaches the lower plenum and intake ports, this is where additional fuel is added. The injectors handle the duty of adding extra fuel. How? well at the same time as the nitrous solenoid opened to release the N20, a regulator or solenoid as closed off the injector fuel rail return line to increase pressure in the fuel rail. This extra pressure increases the amount of fuel being given by the injectors. The term dry therefore stems from the fact that only "dry" gaseous N2O is going throught the intake tract. The benefits of these kits are relatively easy installation, cheaper cost and realtive safety as these are not usually high hp kits(35-100max usually)

Wet kit: Now that you know what a dry kit is, you should understand a wet kit alittle better. A wet kit is essentially the same in terms of N2O delivery, but the difference is that a second "fuel" solenoid is used to delived fuel through the intake tract aswell. The injector nozzel placed before the throttle body is now handling the duty of adding addition fuel aswell. The nozzel is now injecting gaseous N2O and "wet" Liquid atomized fuel through the entire intake tract down onto the combustion chamber. So a "wet kit" gets it's name from the fact that both N2O and Fuel are injected through the nozzel. Wet kits are generally safer and allow for more N2O to be used because they can compensate the fuel delivery with much more volume then the factory injectors of most vehicles can. They can also generate more power because you can use more nitrous then you could with a dry kit given equal engines with a given hp potential

Direct port kits:
Direct port kits are essentially wet kits with one difference. Instead of a single nozzel place in front of the Throttle body, the intake manifold is tapped and one nozzel per cylider is installed. This allows equal distribution and a high volume of fuel and N2O to be injected directly into the combustion chamber. These kits can generate extreme HP greater then 500 hp in some applications, but require careful tunning and engines built to withstand the imediate dose of extreme hp to not be destroyed instanly. Also they are substantially more dificult to install as the intake manifold needs to be machined and tapped for the nozzel installation at every port and two individual lines run to each nozzel

What is right for you? Well that depends on many factors. Your HP and performance goals, then engine hp capability, The complexity of installation involed. In the case of the tibs I would never suggest anybody use a dry kit greater then a 50 hp shot on an I4 and 75 hp shot max on the V6(though I would even be comfortable with that and would stick to 50) for stock bottom ended motors. Wet kits could possibly be used upto 75 hp shots in either case relatively safely, not withstanding engines predisposed to premature grenading.....cough...<delta>....cough.

In summary if you want an easy to install kit with good performance gains a dry kit like the Zex universal could be for you.
If your performance goals are alittle higher,or you want a higher margin of safety,and don't mind alittle more complex install and alittle higher price, Then a wet kit might be for you.
***Under no circumstances should anybody unfamiliar with N2O try to install and use a direct port kit on a stock motor***

Misc info:
Cost-
Dry kits $400+
Wet kits $600+
Nitrous Refills $3-$5 per lb

How long will a bottle of nitrous last?
That depends on the level of power being produced. The formula for calculating your nitrous usage is: 0.8 lbs N2O X 10 seconds = 100 horsepower. I.E. If your system is jetted for 100 horsepower it will use 0.8 lbs of nitrous for every 10 seconds of usage.

Will it destroy my engine?
That is a popular myth usually told by people who know nothing about N2O. Nitrous when used correctly and in moderation is no more dangerous then a TC or SC. In fact it is probably better for a motor since it is an instant on power adder. An SC or TC are always running therefore always increasing stress and heat on the motor. A properly designed N2O kit does so only when the performance boost is actually needed in about 5% of situations.

In summary I hpe this info helps clear the air about the function and use of N2O. Nitrous can be one of the best things to do to your car if you go about it the right way and understand what it can and can't do for you