Nitrous FAQ
 

I noticed that this site does not have very much information in the way of nitrous. Most of the members are primarily interested in turbochargers so I wanted to write a quick FAQ of what I know about nitrous since I am pursuing this as my route of forced introduction. I still do not have any real first hand experience with this it is just all I have learned through researching so hopefully some of the members who actually have used it can help full in the blanks. (I know at least 2 or 3 members who have been running nitrous)

1. What is nitrous oxide and how is it used to make an engine faster?
Nitrous oxide is normally a gas made of of 2 nitrogen molecules and 1 oxygen molecule. When it is inside the bottle it is in liquid form but once it is injected into the engine it is heated to several hundred degrees which in turn makes it a gas and breaks it down into the nitrogen and oxygen molecules so it is then able to react with the enrichment fuel to make power. It is used as extra oxygen to allow more fuel to be burnt and it also lowers the intake temperate resulting in more power. Nitrous has gotten a bad rap because of new tuners trying it without knowing much about it and blowing their engines but if used correctly then it can be just as reliable as any other form of forced introduction. I would also like to point out that nitrous is commonly miscalled NOS, NOS is a company that makes nitrous kits. You shouldn't refer to nitrous as NOS unless your talking about the company or their kits.

2. What are they ways are getting nitrous into the engine?
It is injected into the engine via either the intake tube or the intake manifold. There are three different types of systems. Dry, Wet, and Direct Port.
-Dry kits only inject nitrous into the intake, a hole is drilled into the intake tube (The short ram intake, cold air intake, or stock air box tube) and then the nozzle is inserted into the tube and faced toward the intake manifold. It has to be placed before the MAF sensor so the stock ecu "senses" that the incoming air is colder and therefor adds more fuel to compensate. These are the least precise and controversially dangerous. They work best on cars with intake manifolds that have weird angles in them that if you use a wet kit the fuel will not stay atomized well enough and might cause detonation.
-Wet kits inject both nitrous and fuel into the engine at the same place as the dry kit (into the intake tube) It works the same way except the engine does not add more fuel by itself because the nozzle already adds the fuel.
-Direct port kits. These are the most precise (and expensive) kits. They also allow the most power to be gained. For civics it is 200hp, but you need a build engine to run anything higher than 75hp. (more on that later in the writeup. For 4 cylinders these kits have 4 nozzles, one for each intake runner of the intake manifold. These are also considered wet kits.

The major company's who make nitrous kits would be Nitrous Oxide Systems (NOS, first company to make nitrous kits but now has a different owner, theywere bought byHolly), Nitrous Express, ZEX, Venom, Elderbrock, and Nitrous Works.

3. What is a "Shot"?
A shot is simply how much hp you get from the nitrous at a time. Shots range from 35hp to over 300hp depending on application. On our civics it is safe to run a 35-55 shot on a stock engine. If the engine is strong and you are brave then you might be able to push it to a 75 shot on a stock engine. From about a 75 shot and more you might need to get a stronger clutch to handle the extra torque. 100 shots will require stronger connecting rods, pistons, and fuel pump. If you are going to do this then you will benefit from high compression pistons as opposed to turbocharges cars that benefit from lower compression pistons. You might also need to get something to control your nitrous so that it does notspray in first gear because with that much power you will just be spinning your tires without actually moving very far or you could get a two stage nitrous system.

4. What is recommended to be done before using nitrous oxide?
Before you do anything, get a compression tester and make sure your engine is in good shape. Also make sure you are not burning oil. If your engine is burning too much oil then it can lead to detonation and a blown engine. Intake, Header, Exhaust would be best to get the most out of your kit. There are also camshafts designed specifically for nitrous setups which are also an option but they will hurt performance of an n/a engine while you are not using the nitrous, so I would not recommend them unless you only use your car for the track and not as a daily driver.
You will need some way of retarding you timing. How much timing is pulled will depend on how big of a shot you run. Most company's come with instructions on how to install the kit and it will also tell you how much ignition retard you need for each shot. (ex. with zex's direct port kit for a 4cyl EFI, a 50 shot needs a ign retard of 2 degrees, 75 shot needs 4 degrees, and so on)
You need spark plugs that are at least 2 ranges colder than your stock plugs. You could either buy ZEX's turbo/supercharger/nitrous plugs that are pre-gapped or you could take your stock plug to Advance auto parts and tell them you need plugs that are 2 heat ranges colder.
There really are a ton of things you could buy to make your nitrous kit more reliable and to get more power out of it.For gaugesI suggest that you get a nitrous gauge to make sure your bottle pressure is within safe limits (800-1,000psi usually), a fuel pressure gauge, oil pressure gauge, and a wide-band a/f ratio senor gauge. Older cars can benefit from using a MSD ignition system because their stock ignitions are no longer strong enough to keep a good spark to get good power out of the nitrous kit.

Some more good things to have would be a purge kit, bottle heater, fuel pressure safety switch, safety blow down kit (if your bottle is inside the cabin with the passengers, this is required if you are planning to race at an NHRA track). If you don't want to have to get out of the car and go to the trunk to open your bottle then you can get an automatic bottle opener also.

Safely features: MSD makes a window switch which is connected to the nitrous and fuel solenoids and only allows you to use your nitrous while you are above a set rpm and below another. This is useful because it is unsafe to use nitrous below 2,500rpm because the intake air is not moving fast enough to suck the nitrous and fuel into the engine and it can cause an intake backfire. It also can be set to not spray nitrous above your rev limit because the stock rev limiter cuts fuel and that will cause the engine to go lean and might cause the engine to blow up. (throw a rod) If you are going to convert to OBD1 and use a chipped ecu then have your tuner make the rev limiter cut spark instead of fuel to be safe.

Finally, before you start spraying do general maintenance. Replace spark plug wires, spark plugs, fuel filter. Do not assume that your timing is set right. Get a timing light and set it correctly or you might regret it later. If you don't know how to set your timing then either have a mechanic do it or the timing lights come with instructions.

5. BestEngine Management?
Although you do not need any big form of engine management it is always a good idea. If your car was made from 1996 or later then you could get a obd2->OBD1 conversion harness and run an OBD1 chipped ecu then take your car to a tuner. This way the ecu can be made to control timing