Nitrous Basics - Team Integra Forums - Team Integra
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Nitrous Basics

Posted 05-28-2002 at 12:00 AM by ski_rebel_3

Ahhh nitrous, the infamous black art of drag racing. Compared to the other forms of forced induction, nitrous has always been the one considered the most dangerous, but is it really that dangerous or just misunderstood? This article is not meant to persuade anyone to use or not use nitrous nor is it meant to be overly technical, its purpose is to give you a basic understanding of the fundamentals of nitrous injection so that you can make a more educated decision when it comes time to decide to walk the path of nitrous or another form of performance modification.

[yellow]What is nitrous and how does it work?[/yellow]

In its most basic form nitrous is just an oxygen molecule combined with two nitrous molecules. It has no color or smell and will not harm the atmosphere in any way. Nitrous is stored under very high pressure in a liquid form in a tank much like a SCUBA tank. When nitrous is introduced to the normal air and pressure that we breathe it turns into a gas.

Contrary to popular belief nitrous by itself will not make any power for an engine. All the nitrous does is give the engine more oxygen to burn fuel with. When the nitrous hits the engine the additional oxygen helps to burn the fuel at a much faster rate, which in turn provides more power to drive a piston down faster in the piston chamber and thus creates more power. The key to the whole equation is fuel and how much power can be harnessed by the consumption of fuel. If this combination is not correct then it will lead to an uncontrolled bust of energy otherwise known as detonation inside the engine. When this happens one can expect to experience burnt pistons, blown rings, and thrown rods. Yes, not good at all!! This is where the problem lies with the bad reputation that nitrous has in the performance community.

Now let me make this point very clear. It is not nitrous that destroys engines but the lack of fuel (running lean) and the components of the engine itself that determine when damage will occur. That is why it is vitally important to make sure you have done the proper research and performance modifications to your car prior to injecting nitrous into your engine. We will get into recommended modifications a little later in the article but now on to the various types of nitrous injection.

[yellow]Types of nitrous injection[/yellow]

For the purpose of this article I will cover the four main types of nitrous injection, which are dry, wet, direct port, and plate injection.

By far the easiest to understand and use of all four types is the dry injection system so we will cover it first. Probably when you think of a street-car running nitrous you are thinking of this form of injection. Companies such as Zex and NOS have made dry systems extremely popular recently. Usually these systems are activated at wide-open throttle (WOT) and are almost as easy to use as just flooring the accelerator. A dry manifold injection system works by simply spraying only nitrous into the intake manifold. At this point, the cars fuel injectors must supply enough fuel to burn the additional oxygen.

Now, remembering what we learned earlier about fuel being the key to nitrous injection, we can see the biggest disadvantage to having a dry system. Because the cars fuel injectors are supplying the additional fuel the amount of power you can gain from a dry system is going to be limited. As a general rule of thumb you can only get a maximum of a 75 hp shot out of a dry system. Another common problem with dry kits is that they suffer from distribution problems, meaning that there is always the possibility that the cylinders will get an uneven amount of nitrous sprayed into them. This uneven distribution can cause the injection to be less potent. However, dry kits have some good advantages as well. As I mentioned above, dry kits are very easy to install and use so that means they are perfect for the nitrous beginner. Also if you opt for a Zex kit you get the benefit of a “computer controlled safety module.” Just be careful and do not let the “safety features” lure you into thinking that you are 100% safe from mishaps.

The next type of system that we will cover is the wet system. In the wet system both fuel and nitrous are mixed together before they are injected. The most common Honda/Acura wet system that you will encounter is the “single fogger” set-up but there are also plate kits, direct port injections, and multi-stage injections as well. There are several manufactures of wet nitrous systems, but the main ones are NOS and Nitrous Express. In a typical wet set-up both fuel and nitrous are delivered and separated from each other by solenoids. Once the system is activated both the fuel and nitrous are pumped into jets/nozzles that will mix the fuel and nitrous together before allowing it to flow into the engine. These systems can be either set-up to inject at WOT or at the push of a button that the driver controls.

Now although wet nitrous injection does have some special problems (especially the single fogger), it is the best way to experience true nitrous power. Because the mixing of fuel and nitrous is done by the solenoids and jets, you get a more accurate shot and you do not have the limitations on a “safe” shot size like you have in a dry system. Wet systems will allow you to use any size shot of nitrous that you want, just be sure you have taken the necessary precautions with your engine. Another advantage of wet kits over dry is the multiple application methods of which we will discuss a little later. Some of the disadvantages that you can expect to see with wet kits are increased install time and costs, extra engine build up and support modifications cost, and more monitoring and maintenance of your engine.

The best thing about the wet systems in my opinion is the ability to lay down some serious power for the good old drag strip! Two of the most common ways to do this is with either a NOS Plate Kit for the Acura GSR and Honda Prelude or Direct Port systems. In terms of monster nitrous power the plate kit that NOS makes for the Acura GSR is the best bang for your buck. People who have installed the plate kit correctly can easily rival a turbocharged car any day of the week. The reason the plate kit is only available for the GSR is due to the installation requirements. Basically what happens is that a plate is installed between the two-piece intake manifold found on GSR’s or Honda Preludes. This allows the nitrous and fuel to be directly injected into the intake as opposed to jets spraying nitrous into the intake. The end result will absolutely amaze you, please trust me on this one!! In terms of shot size the plate kit ranges anywhere between 75-200 hp so there is great flexibility to be found with it. Unfortunately, all that power can cause some problems if your engine is not somewhat built or supported with the proper support modifications. We will get into what exactly is needed/recommended for each application in a little while but for now on to the last type of injection that we will discuss. The final nitrous application is direct port injection. Essentially, you will hardly ever see direct port injection on the street because it is usually a race only application. For our purposes lets keep if fairly simple and just lightly touch on it because it can get very complicated very quickly. Direct port injection works by directly spraying nitrous and fuel into each intake port on the engine independently. This makes direct port the best system to have if you need to adjust the amount of nitrous for each cylinder independently of each other. It is a very complicated injection method and is extremely challenging to install, therefore it is usually best to leave this type to the pros!

[yellow]Dry vs. Wet. Which is better?[/yellow]

This question always comes up with every nitrous discussion. The bottom line is what is your ultimate goal? If you are just looking for a small performance increase, working with a small budget, or new to nitrous then the dry system is the best way to go. On the other hand, if you are looking for big nitrous power, building a drag car, or you feel comfortable with nitrous injection and have the money to spend to get the proper support modifications then a wet system is probably for you. If you have any doubts about nitrous at all then the best policy is to wait and decide if it is really what you want to do. If you are unsure about your decision then research some more or ride in a nitrous powered car until you feel sure about your decision. Better safe than sorry if you ask me!

[yellow]Equipment Needed[/yellow]

In this next section we will cover the recommended equipment needed for each shot size. There has been and will always be a debate about exactly what kind of support modifications are needed for each shot. My point here is to make a list of things that will keep your engine as safe as possible. Your local performance shop or friends might tell you to add or subtract things from this list but if you follow the guidelines I am about set, you will be as safe as possible. Also, remember as with any other form of forced induction, sometimes bad things happen and even the best precautions cannot stop them but that is the risk we all run when we enter the realm of performance modifications.

[yellow]The basics[/yellow]

In order to be as safe as possible I would recommend “the basics” for anyone running nitrous. I am also going to assume that you already have an intake, header, and exhaust installed. The basics set-up will be the same for both dry and wet applications with the exception of a 255 lph fuel pump that is recommended for a wet set-up due to the increased fuel requirements.

1. Aftermarket ignition, wires, cap, rotor, and coil. MSD is the most popular brand. If you are on a budget then the MSD 6AL will work fine but if you have some extra cash to spend then the MSD Digital 6 is very nice to have. The great thing about the Digital 6 ignition is that it will automatically retard your timing when you activate the nitrous system and it has a dual stage rev limiter all built in! **Unless you are planning on getting a Jacobs Nitrous Mastermind, then the Digital 6 is my recommended ignition.**

2. Colder spark plugs. NGK bkr7e usually work fine. Make sure to always use copper plugs and avoid platinum and make double sure to gap them correctly.

3. Fuel pressure regulator. B&M is an excellent brand to get.

4. Timing change. The rule of thumb is 2 degrees for every 50 shot of nitrous. This is always under debate but to be absolutely safe use the rule of thumb.

5. A performance clutch because the stock clutch will probably not last long.

• 60 shot or less
“The basics” should be just fine. As noted above there is a constant debate over what exactly is needed. Some people will run a 50 shot with stock everything and be just fine while others will buy some extra parts to be safe. The bottom line is use your best judgment here.

• 60-70 shot
“The basics” and make absolutely sure to adjust your timing by one or two degrees.

• 75 shot
“The basics” and make sure to have you timing kicked back at least 3 degrees. This is also the maximum shot you want to use with a dry kit so unless you just want to blow your motor keep it here for all you dry kit guys. At this level you are probably most likely to see lean conditions and detonation therefore it might be a good idea to pick up an Apexi or Fields vtec/fuel computer so that you can control your fuel flow a little more.

• 75-100 shot
At this level you have officially entered wet kit territory so “The basics” and a 255 lph fuel pump are required. Some other goodies that you might want to seriously consider would be a Jacobs Nitrous Mastermind, an Apexi or Fields vtec controller, performance brakes, and motor mount inserts. Also since at this point you are spraying quite a bit of nitrous into the engine, building up the bottom end is an excellent idea. Some things to consider here would be forged pistons, rods, and crankshaft, and a port and polished head.

• 100+ shot
Once you reach this level you must be seriously racing. Everything that is listed for the 75-100 shot is required and an engine build-up and larger fuel injectors are a must now too. You will also want to look into getting a limited slip differential kit so that you can get traction. Once you reach this level you are going to have to be very familiar and comfortable with nitrous or an accident is just waiting to happen.

[yellow]Goodies to get for the nitrous kit[/yellow]

1. Bottle heater – a must for every nitrous user. This will allow you to keep your bottle pressure at the optimal level. NOS says 900-950psi is optimal but other brands may vary so be sure to check with the manufacturer to be safe.

2. Bottle blanket - to keep your bottle nice and warm so that you can maintain proper pressure.

3. Purge kit – so that you can remove any air that is in your nitrous lines to ensure a good shot. Also it looks really cool to purge at the line right before you pull up to the staging lights at the track! There is no better way to get a good reaction from the crowd then a nice purge before staging! Word of caution though, it looks cool but it is also a fantastic waste of nitrous so don't make it a habit of purging all the time.

4. Pressure gauge – so that you know your pressure is correct to ensure a good shot.

5. Remote bottle opener – very useful in my opinion. A remote bottle opener will allow you to open and close the bottle with a flick of a switch instead of getting out and manually turning the nitrous bottle on and off.

Well that concludes the basics lesson. Again I hope that everyone finds this article useful in some way. Now that you have a basic understanding of nitrous and how it works go out and have fun!
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