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Nitrous Oxide Master FAQ List

Old 05-01-2009, 12:02 PM
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Default Nitrous Oxide Master FAQ List

By section-8:

This info is from the Holley NOS site and other sources as I add them. I will be listing the sources and links accordingly.

An informative listing of the history of Nitrous:

This chart is intended to graphically show what is required in the way of engine preparation and tuning to obtain best results with each particular NOS system:

Overview of NOS systems and components and links to information on each system:


Types of NOS Systems; An Overview Of Wet, Dry And Direct Port Systems

These are three basic types of nitrous systems: dry, wet, and direct port. The most misunderstood is the "dry" type of system. A "dry" nitrous system simply means that the fuel required to make additional power with nitrous will be introduced through the fuel injectors (remember, fuel makes power, nitrous simply lets you burn more of it). This keeps the upper intake dry of fuel. We accomplish this by two methods. First, is to increase the pressure to the injectors by applying nitrous pressure from the solenoid assembly when the system is activated. This causes an increase in fuel flow just like turning up the pressure on your garden hose from 1/2 to full. The second way we can add the required fuel is to increase the time the fuel injector stays on. This is accomplished by changing what the computer sees, basically tricking the computer into adding the required fuel. In either case, once the fuel has been added, the nitrous can be introduced to burn the supplemental fuel and generate additional power.

The second type of nitrous kit is the "wet" style of kit. These kits include carburetor plate systems and add nitrous and fuel at the same time and place (normally 3-4" ahead of the throttle body for fuel injected applications or just under the carb as with plate systems). This type of system will make the upper intake wet with fuel. These systems are best used with intakes designed for wet flow and turbo/supercharged applications. The reason for this is the fact that fuel flows differently than air or nitrous. This difference in flow characteristics can lead to distribution problems and, in some cases, intake backfires. Intakes designed for wet flow (such as with carburetors) cause much less separation of the nitrous/air, and fuel. Because modern fuel injection intakes are designed to flow air only, they have tighter turns and a more compact design as a result. Thus, they generally do not make good candidates for wet flow nitrous systems.

The last type of system is the direct port system. Just as it's name implies, it introduces the nitrous and fuel directly into each intake port on an engine. These systems will normally add the nitrous and fuel together through a fogger nozzle or a NOSzleTM. The fogger nozzle mixes and meters the nitrous and fuel delivered to each cylinder. This is the most powerful and one of the most accurate type of systems. This is due to the placement of the nozzle in each runner, as well as the ability to use more and higher capacity solenoid valves. A direct port system will have a distribution block and solenoid assembly which delivers the nitrous and fuel to the nozzles by way of connecting tubes. Because each cylinder has a specific nozzle and jetting (both nitrous and fuel), it is possible to control the nitrous/fuel ratio for one cylinder without changing that of the other cylinders. These systems are also one of the more complicated systems when installation is considered, as the intake must be drilled, tapped, and the "plumbing" made to clear any existing obstructions. Because of this and the high output of these systems, they are most often used on racing vehicles built for the strain of such high horsepower levels.

System Overview & Technical Information: This is informative if you can look past the fact that they use a carbureted engine as an example...regardless, nitrous works the same in any combustion chamber, no matter which method of fuel delvery is employed.


Tuning Technical Information

Nitrous System Theory, Selection, and Tuning
As modern engines become more difficult to modify, the use of nitrous oxide to obtain phenomenal performance gains is on the rise.and for good reason. We firmly believe that our nitrous systems and related products are the highest quality, performance, and value available anywhere in the world. We can make this claim because we've been manufacturing nitrous systems and components since 1978. The value of this to you is the vast experience we have accumulated throughout the history of our company. (once again, this is from teh NOS website, so I'm not trying to plug their product)
How to Make Horsepower:
An engine operates by burning fuel, which then expands and pushes the pistons down. Want to make more horsepower? Burn more fuel so it will push the pistons down with more force. Sounds pretty simple. But, it's not quite so easy. While there are any number of factors that make increasing power a complex engineering problem, we will deal with three of the most basic ones here.

First, all fuels require oxygen in order to burn. If you want to burn more fuel, you need to also put in more oxygen. Virtually all engine performance products increase power by increasing the flow of fuel and oxygen. Camshafts, larger carburetors or valves, porting, intake manifolds, exhaust headers, superchargers, turbochargers, and nitrous oxide are clear examples of how improved engine breathing (putting in more oxygen in order to burn more fuel) will give you an increase in horsepower. Nitrous oxide injection systems are probably the most efficient way to increase the flow of oxygen and fuel. That's the basic reason why nitrous systems produce such large horsepower increases.

Another basic power factor is vaporization of the fuel. Gasoline, as with other racing fuels, will not burn in a liquid state. The gasoline must be turned into a vapor for it to burn. This process of turning gasoline into a vapor is simple evaporation. It is basically no different from setting a glass of water outside and waiting for it to dry up. In the engine, of course, evaporation happens very quickly. Engine heat and fuel atomization are the keys to accelerating the evaporation process enough to turn raw gasoline into a vapor at 8000 RPM. The process of atomization turns raw fuel flow into tiny droplets which then evaporate faster due to the larger amount of surface area presented for evaporation. The size of the fuel droplets is very important. Take a large droplet of gasoline, break it up into 10 smaller droplets, and you've increased the surface area for more efficient evaporation. The result is more fuel available to be burned and do work during combustion. A well-designed nitrous system will produce very small droplet sizes in the supplemental fuel that flows into the engine with nitrous. This is one of the reasons that NOS nitrous systems can make more horsepower than some other systems.

The third basic power factor we will look at is air/fuel mixture density. Ever try to jog on top of a 10,000 foot pass in the Rockies? Leaves you gasping for breath, doesn't it? That's because the air is thinner, less dense, higher up in the atmosphere than it is at sea level. It is also why you would run slower on a track in Denver than you would near sea level in New Jersey. Density is affected by atmospheric pressure (the weight of the atmosphere above you), heat, and humidity. We can't change the pressure of the atmosphere; but we can regulate the heat of our intake charge to some extent. Cool cams and intercoolers make extra power by cooling the fuel and air/fuel mixture to make it denser. And, the denser the mixture is, the more the cylinder is packed with fuel and air to burn and make power. When nitrous oxide is injected, it turns from a liquid to a gas instantly and becomes very cold. This cold nitrous vapor drops the temperature of the whole intake charge in the manifold by as much as 65 degrees F. The denser mixture that results helps an engine produce even more extra horsepower with a nitrous system.

What Nitrous Oxide Is and What Nitrous Oxide Isn't
To your engine, nitrous oxide is a more convenient form of normal air. Since we are only interested in the oxygen the air contains, nitrous oxide provides a simple tool for manipulating how much oxygen will be present when you add additional fuel in an attempt to release more power. The power always comes from the fuel source. Nitrous oxide is not a fuel. Nitrous oxide is a convenient way to add the additional oxygen required to burn more fuel. If you add only nitrous oxide and do not add additional fuel, you would just speed up the rate at which your engine is burning the fuel that it normally uses.

This, more often than not, leads to destructive detonation. The energy comes from the fuel, not the nitrous. Nitrous oxide simply allows you to burn a greater quantity of fuel in the same time period; thus, the overall effect is a tremendous increase in the total amount of energy, or power, released from the fuel and available for accelerating your vehicle.

There is no voodoo involved in nitrous oxide. In effect, using nitrous is no different from using a bigger carburetor, a better manifold, a supercharger, or a turbocharger. Understand that the air you and your engine breathe is made up, at sea level, of 78% nitrogen, 21% oxygen, and just 1% other gases. Nitrous oxide (N2O) is made by simply taking the 2 major components of earth's atmosphere (in this case 2 molecules of nitrogen and 1 molecule of oxygen) and attaching them together with a chemical bond. When the nitrous oxide goes into your engine the heat of combustion breaks the chemical bond to provide your engine more oxygen with which to burn fuel. As you've read, all race engines operate under the same principles: more air (better breathing, supercharging, turbocharging, or nitrous) plus more fuel in a denser vapor equals more power.

Nitrous Oxide vs. Other Performance Products
Dollar for dollar, nitrous oxide offers the most performance a consumer can buy. You could spend thousands of dollars on carburetion, a manifold, valve train components, exhaust, pistons, porting, supercharging, or turbocharging to get the same amount of extra horsepower that a nitrous system would provide for just a few hundred dollars. But this doesn't mean you won't benefit if you also install other performance parts. Once you have installed a nitrous system, all those other performance parts just increase the nitrous power. If you just have a few dollars and want lots of extra power, the best choice is a nitrous system.

Only nitrous is a part time power increaser. All of the standard performance parts put additional stress on the engine and burn more fuel all the time; not to mention what a pain it is to ride around town with a lumpy idle from a camshaft that is barely streetable. Power on demand is one of the great things about a nitrous system; it only works when the driver wants it. All the rest of the time, the engine operates normally; no extra stress, no extra fuel use, and no driveline problems.

Nitrous Oxide and Emissions
Use of nitrous oxide (N2O) doesn't necessarily increase the oxides of nitrogen (NOx) that pollute the air. Of course, there are "race only" systems that are not legal for use on pollution controlled engines. However, many systems have received certification for 50-state emissions legal use in the United States.

Types of Nitrous Oxide Systems
The two most popular types of nitrous oxide systems are spray bar plate systems, such as the Powershot, Cheater, and Big Shot automotive systems (which use a spacer plate between the carburetor and manifold) and direct port. The plate adds nitrous and supplemental fuel to the intake air stream through built-in spray bars. Plate systems are used on automotive engines on the street and in many racing classes.

Direct port systems use specially designed injectors, FoggerTM nozzles, to add the nitrous and supplemental fuel to each individual intake runner. These systems can flow huge amounts of nitrous and fuel while distributing it evenly to every cylinder. Multiple stage direct port systems have produced much more than 500 extra horsepower on some pro racing engines. All NOS Direct Port systems feature changeable nitrous and fuel jets for horsepower adjustments and system tuning. Direct port systems are used in both street and racing applications on virtually every kind of engine. Some nitrous systems for fuel injection are a variation of Direct Port technology.

Tuning Your NOS System:
A Few Important Points to Remember

Always start conservative. Follow the recommended jet combinations and start with the lowest level if you have an adjustable system. It only takes a few moments to change the jets so don't take unnecessary risks by starting at the highest level.

Be realistic about how much power your engine will handle. Don't get carried away here. Only you know exactly which components are in your engine. If you don't know what's inside your engine, then you are most safe by assuming that the components are factory stock and choose the correct system for that application.

The power comes from fuel. The additional power is set by the amount of additional fuel your system supplies while the nitrous system is in operation. If the fuel isn't there, the power won't be either and no amount of nitrous or anything else can bring it back.

There are two controls typically available to manipulate the amount of fuel available during system use; the fuel jet size and the fuel pressure. The correct fuel pressure is read while the system is flowing fuel. Some fuel pressure regulators give false readings because the pressure reading will creep up when the system is not activated. When this happens, the actual flowing fuel pressure will be much lower than expected and can cause problems.

When problems with misfire or detonation are encountered, ALWAYS reduce the size of the nitrous jet first! Remember that the power comes from the fuel, not the nitrous, so trying to cool things down by adding fuel simply adds more power and complicates the problem. Carburetors jetted over-rich run cooler and release less power. Nitrous systems jetted over-rich will possibly just release more power, so if you run into problems, reduce the size of the nitrous jet(s) first.

When you check your spark plugs for signs of how your system is operating, CHECK EVERY SPARK PLUG, not just the easiest plug to get to. No two cylinders ever run exactly alike. Nitrous has the unique characteristic of cleaning the spark plugs very well and leave them looking like you just installed them. If there are any signs of detonation such as tiny silver or black specks deposited on the porcelain, reduce the nitrous jet size. If the ground strap of the spark plug exhibits a bluish-rainbow coloring, reduce the nitrous jet size. If the ground straps shows signs of melting, reduce the nitrous jet size and change to a spark plug with a shorter and thicker ground strap.

If you system suddenly begins to experience problems even though you haven't changed anything, the culprit is most often a clogged nitrous or fuel filter. The instructions that come with your system contain information about where the nitrous and fuel filter screens are located. Check them periodically.

Spark Plugs and Nitrous Oxide:
Some of this has been covered by my previous post in the Maintenance and Help forum, but if you're still with me, you may as well read it here...or if you have read and enjoyed my previous post, fell free to skip over the plug section.

What Works, What Doesn't, and Why
Over the years there seems to have been a great amount of technical material written about the simple operation of a spark plug and what they can do in relation to the way an engine runs. There are a few basic characteristics about spark plugs that you need to know to make an intelligent choice about the correct spark plug for your application.

First, and most important; a spark plug must be of the correct design to operate within the environment of your engine, not the other way around. This means that the spark plug has virtually no influence on how the engine burns fuel or runs in general. The correct spark plug will simply survive the conditions present in your engine. A spark plug must maintain a certain temperature to keep itself clean. The wrong heat range can cause an overheated plug or a fouled plug. The heat range refers to the temperature of the ceramic material surrounding the center electrode.

Lean air/fuel ratios are more difficult to light because there are less fuel molecules in the area of the plug gap when the plug is scheduled to fire; thus, projected nose plugs were designed for late-model lean-burn engines. Modern high-energy ignition also allowed larger plug gaps. All the while this was happening, something else happened. Something that no one seems to have really noticed as the real culprit when the issue of factory type plugs being used with nitrous comes up.

Quite often, a factory type, wide-gap projected plug will produce a misfire condition after only a few seconds of nitrous use. The misfire is not due to the heat range. The misfire occurs because the ground strap of the spark plug becomes a glowing ember because it is too long to dissipate the extra heat produced by a nitrous-accelerated burn condition. The correct fix for this phenomenon is to replace the plugs with one that has a shorter ground strap. By doing this, you will shorten the path for the heat being absorbed by the ground strap. You can use the same heat range, you just have to find a non-projected nose plus with a shorter and preferably thicker ground strap.

If you only change the heat range of the spark plug to a colder heat range, you may very well still have the misfire problem. Since the length of the ground strap is the cause of the misfire, a colder spark plug may have the same length of ground strap as the hotter plug you replaced it with.

Spark plug gaps should generally be .030" to .035". Never try to gap a plug designed for an .060" gap down to .035". Find the correct non-projected nose plug designed for an .035" gap.

These are some base-line tuning combinations for different engine sizes and sytem sombinations.

A Word On Fuel Pressure
Fuel pressure regulators should be set to a flowing fuel pressure or false readings may be obtained. To set flowing fuel pressure on the vehicle, use a test jet flowing fuel into a container to find what size test jet should be used when flowing multi-nozzle systems. Use the following formula:

Jet size2 x number of nozzles (per fuel solenoid).
Then take the square root of this number.
This is the Test Jet in thousands of an inch.

Eight #32 Fuel Jets are equal to one 91 Jet
32 x 32 = 1024 x 8 Jets = 8192
The square root of this number is 90.509...

This procedure cannot guarantee a steady fuel pressure during a run. As G-forces and cell placement will affect the fuel pump's load. Which cannot be easily duplicated in the pits.

NOTE: NOS Systems using multiple stages and/or H.P. levels over 400 H.P. will benefit from a super Hi-Flo bottle valve (PT.# 16139) and/or a large bottle (15 or 20lb.) Due to a lower pressure drop during a run. This valve also allows pressure readings with a closed bottle valve; via one of the valve's built-in direct reading ports, one 1/8 NPT and one 1/4 NPT.
* A 15 pound bottle equipped with a super Hi-Flo valve works great on maximum effort systems (with a minimum effect on weight).


Q: Will Nitrous affect engine reliability?
A: The key is choosing the correct H.P. for a given application. A kit that uses the correct factory calibration does not usually cause increased wear. As the energy released in the cylinder increases so do the loads on the various components that must handle them. If the load increases exceed the ability of the components to handle them, added wear takes place. NOS kits are designed for use on demand and only at wide open throttle. Nitrous can be extremely advantageous in that it is only used when you want it, not all the time. All NOS kits are designed for maximum power with reliability for a given application.

Q: Can I simply bolt a nitrous kit onto my stock engine?
A: Yes. NOS manufactures systems for virtually any stock engine application. The key is to choose the correct kit for a given application; i.e., 4 cyl. engines normally allow an extra 40-60 HP, 6 cyl. engines usually work great between 75-100 extra HP, small block V8's (302/350/400cid) can typically accept up to 140 extra HP, and big block V8's (427-454) might accept from 125-200 extra HP. These suggested ranges provide maximum reliability from most stock engines using cast pistons and cast crank with few or no engine modifications.

Q: What are some of the general rules for even higher HP gains?
A: Generally, forged aluminum pistons are one of best modifications you can make. Retard ignition timing by 4-8 degrees (1 to 1-1/2 degrees timing retard per 50 HP gain). In many cases a higher flowing fuel pump may be necessary. Higher octane (100+) racing type fuel may be required as well as spark plugs 1 to 2 heat ranges colder than normal with gaps closed to .025"-.030". For gains over 250 HP, other important modifications could be necessary in addition to those mentioned above. These special modifications may include a forged crankshaft, a high quality race type connecting rods, a high output fuel pump dedicated to feeding the additional fuel demands of the nitrous system, and a racing fuel with high specific gravity and an octane rating of 110 or more.

Q: How does nitrous work?
A: Nitrous oxide is made up of 2 parts nitrogen and one part oxygen (36% oxygen by weight). During the combustion process in an engine, at about 572 degrees F, nitrous breaks down and releases oxygen. This extra oxygen creates additional power by allowing more fuel to be burned. Nitrogen acts to buffer, or dampen the increased cylinder pressures helping to control the combustion process. Nitrous also has a tremendous "intercooling" effect by reducing intake charge temperatures by 60 to 75 degrees F.

Q: How much performance improvement can I expect with a nitrous system?
A: For many applications an improvement from 1 to 3 full seconds and 10 to 15 MPH in the quarter mile can be expected. Factors such as engine size, tires, jetting, gearing, etc. will affect the final results.

Q: How long will the bottle last?
A: This largely depends on the type of nitrous kit and jetting used. For example, a 125 HP Power Shot kit with a standard 10 lb. capacity bottle will usually offer up to 7 to 10 full quarter-mile passes. For power levels of 250 HP, 3 to 5 full quarter-mile passes may be expected. If nitrous is only used in 2nd and 3rd gears, the number of runs will be more.

Q: How long can I hold the nitrous button down?
A: It is possible to hold the button down until the bottle is empty. However 15 continuous seconds at a time, or less, is recommended.

Q: When is the best time to use nitrous?
A: At wide open throttle only (unless a progressive controller is used). Due to the tremendous amount of increased torque, you will generally find best results, traction permitting, at early activation. Nitrous can be safely applied above 2,500 RPM under full throttle conditions.

Q: Will I have to re-jet my carburetor on my car when adding nitrous?
A: No! The NOS system is independent of your carburetor and injects its own mixture of fuel and nitrous.

Q: Is nitrous oxide flammable?
A: No. Nitrous Oxide by itself is non-flammable. However, the oxygen present in nitrous oxide causes combustion of fuel to take place more rapidly.

Q: Will nitrous oxide cause detonation?
A: Not directly. Detonation is the result of too little fuel present during combustion (lean) or too low of an octane of fuel. Too much ignition advance also causes detonation. In general, most of our kits engineered for stock type engines will work well with premium type fuels and minimal decreases of ignition timing. In racing application where higher compression ratios are used, resulting in higher cylinder pressures, a higher fuel octane must be used as well as more ignition retard.

Q: Is there any performance increase in using medical grade nitrous oxide?
A: None! NOS recommends and sells only the automotive grade, called Ny-trous Plus. Ny-trous Plus contains a minimal amount of sulfur dioxide (100 ppm) as a deterrent to substance abuse. The additive does not affect performance.

Q: Is it a good idea to use an aftermarket computer chip in conjunction with an NOS System?
A: Only if the chip has been designed specifically for use with nitrous oxide. Most aftermarket chips use more aggressive timing advance curves to create more power. This can lead to possible detonation. You may wish to check with the manufacturer of the chip before using it. The top manufacturers, such as Hypertech do make special chips for use with nitrous.

Q: How long does it generally take to install an NOS kit?
A: The majority of NOS kits can be installed using common hand tools in approximately 4 to 6 hours.

Q: Which type of manifold is better suited for a plate injector type of nitrous system, single or dual plane manifold?
A: As long as the manifold doesn't interfere with the spray pattern of the bars, either will work fine in most cases. The distribution is better with a single plane at high RPM. If your goal is to increase power by more than 150 HP, the single plane manifold is better.

Q: Does nitrous oxide raise cylinder pressure and temperatures?
A: Yes. Due to the ability to burn more fuel, this is exactly why nitrous makes so much power.

Q: Are there any benefits to chilling the nitrous bottle?
A: No. Chilling the bottle lowers the pressure dramatically and will also lower the flow rate of the nitrous causing a fuel rich condition and reducing power. On cold evenings you might run on the rich side. For optimal running conditions, keep bottle pressure at approximately 900-950 psi. NOS has a nitrous pressure gauge that allows you to monitor this. If you live or operate a nitrous system in colder temperatures, it may also be a good idea to purchase a bottle heater kit, part #14164. Generally, ambient temperatures of 80-90 degrees F will allow for best power potential of NOS kits.

Q: Are there benefits to using nitrous with turbo or super-charger applications?
A: Absolutely! In turbo applications, turbo lag is completely eliminated with the addition of a nitrous system. In addition, both turbo and superchargers compress the incoming air, thus heating it. With the injection of nitrous, a tremendous intercooling effect reduces intake charge temperatures by 75 degrees or more. Boost is usually increased as well, adding to even more power.

Q: What affect does nitrous have on an engine with considerable miles on it?
A: This depends largely on the actual condition of the engine components. Any performance modification to an engine that is worn out or poorly tuned will have detrimental effects. However, an engine in good condition, with good ring and head gasket sealing, should be able to use nitrous without any abnormal wear.

Q: Will the use of nitrous oxide affect the catalytic converter?
A: No. The increase in oxygen present in the exhaust may actually increase the efficiency of the converter. Since the use of nitrous is normally limited to 10-20 seconds of continuous use, there usually are no appreciable effects. Temperatures are typically well within acceptable standards.

Q: Will the percentage of performance increase be the same in a highly modified engine compared to a stock engine when using the same NOS kit and jetting?
A: Not really. In most cases the percentage of increase is greater from a stock engine because it is not as efficient as the modified engine in a normal non-nitrous mode. However, since the effects of nitrous oxide magnify the output of any engine, the total power output will be much higher in the modified engine.

Q: Can high compression engines utilize nitrous oxide?
A: Absolutely. High or low compression ratios can work quite suitably with nitrous oxide provided the proper balance of nitrous and fuel enrichment is maintained. NOS kits are used in applications from relatively low compression stock type motors to Pro-Modifieds, which often exceed 15 to 1. Generally, the higher the compression ratio, the more ignition retard, as well as higher octane fuel, is required.

Q: Can service station fuel be used for street/strip nitrous oxide applications?
A: Yes. Use of a premium type leaded or unleaded fuel of 92, or greater, octane is recommended for most applications. Many NOS systems are designed for use with service station pump gas. However, when higher compression or higher horsepower levels are used, a racing fuel of 100 octane, or more, must be used.

Q: What type of cam is best suited for use with nitrous oxide?
A: Generally, cams that have less exhaust overlap and more exhaust duration. However, it is best to choose a cam tailored to normal use (when nitrous is not activated) since 99% of most vehicle operations is not at full throttle. There are special cam grinds available for nitrous competition which have more aggressive exhaust profile ramping, etc. Since cam selection depends largely on vehicle weight, gearing, etc., it is best to stick to cam manufacturers' recommendations for your particular goal.

Q: What type of nitrous system is better; a plate injection system or a direct port injection system?
A: The advantages of a plate system are ease of installation and removal, ability to transfer easily to another vehicle, ability to change jetting combinations quickly, and in most cases, provide you with all the extra HP you will ever need (75 to 350 more HP). In some cases, such as in-line type engines with long runners, a direct port type system is advisable for maximizing distribution. Also, where more than 350 HP is needed, our direct port Fogger systems will provide the ultimate in distribution and power (up to 500+ HP). Direct port injection is also desirable when the system is hidden under the manifold.

Q: Should I modify my fuel system to use nitrous oxide?
A: Most stock fuel pumps will work adequately for smaller nitrous applications. It is important to check to see if your pump can flow enough fuel to your existing fuel system (whether carburetor or fuel injected), as well as being able to supply the additional fuel required by the nitrous kit under full throttle conditions. It may be a good idea to dedicate a separate fuel pump to the nitrous kit.

Q: Which is the best position to mount a nitrous bottle?
A: NOS bottles come with siphon tubes and, in order to maintain proper nitrous pickup, it is important to mount the bottle correctly. We recommend mounting the bottle at a 15 degree angle with the valve end higher than the bottom of the bottle. The valve end of the bottle should point to the front of the vehicle and the valve knob and label should face straight up.

Q: How important is it to use nitrous and fuel filters in a kit?
A: Some of the most important components of any nitrous system are nitrous and fuel filters. To keep contaminants from attacking the solenoid or plugging up a jet, nitrous filters feature a special stainless steel mesh element from the aerospace industry.

Q: What are the advantages of using nitrous compared to other performance options?
A: The cost of many other performance options can put you in the poorhouse. Dollar for dollar, you can't buy more performance with less money than nitrous. With a nitrous system, performance and reliability can be had for a much more reasonable price while still retaining the advantage of a stock engine during normal driving. And, Nitrous offers tremendous gains in torque without having to rev the engine to excessive rpm's. These factors help your engine last longer than many other methods of boosting horsepower.

Q: What kind of pressures are components subject to in a typical nitrous kit?
A: Pressures often exceed 1,000 psi.

Q: How do I know how much nitrous is left in the bottle?
A: The most reliable method was is to weigh the bottle to determine how many pounds remain. When a bottle is near empty (about 20% or less nitrous remaining) a surging effect is normally felt.

Q: What is the function of the blow-off safety valve on the bottle?
A: It is very important not to overfill a bottle; i.e., a 10 lb. capacity bottle should not be filled with more than 10 lbs. of nitrous oxide by weight. Over-filling and/or too much heat can cause excessive bottle pressures forcing the safety seal to blow and releasing all the contents out of the bottle.

Q: Will I have to change my ignition system?
A: Most late model ignition systems are well suited for nitrous applications. In some higher HP cases, it may be advisable to look into a high quality high output ignition system.

Hopefully, this info will help some of you on your quest for more power. Good luck.

Any questions that are asked about nitrous which have the answer contained above will be linked to this topic.
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Old 05-01-2009, 07:24 PM
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Good info here, however the wet nozzle information was strictly about carburetor based engines, not fuel injected engines. They make Wet kits which atomize air and fuel just like the direct ports. I run one.
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Old 05-07-2009, 08:16 PM
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QUOTE(DTN @ May 2 2009, 01:24 AM)
Good info here, however the wet nozzle information was strictly about carburetor based engines, not fuel injected engines. They make Wet kits which atomize air and fuel just like the direct ports. I run one.

Wet kits aren't "just like" direct ports in one important way: equal distribution of fuel and air in each cylinder.

"Back in the day", intake manifolds were the distribution method from your carb to the individual cylinders. These manifolds were meant to flow both atmospheric oxygen (in gaseous form) and gasoline (in liquid form.) Thus, adding more fuel and oxygen in the form of a wet nitrous kit was ultimately no different to the manifold than the job it performed every other day of the week.

But modern MPFI intake manifolds are meant to flow gasses only, not liquids. The fuel distribution is handled by individual injectors placed strategically at the edge of the intake ports on the cylinder head. And since gasoline is heavier than the gasses that make up our atmosphere, it will (given all else is equal) fall out of suspension in the plenum chamber due to nothing more than gravity. This means that the fuel will tend to gravitate to the cylinders nearest the injection point, or in the case of our motors, cylinders 4, 3, 2, and then 1 in that order.

As such, in a "wet" nitrous injection scheme, cylinder 1 will run the leanest of the bunch. Perhaps not to a drastic degree with something "small" like a <=50hp shot, but the bigger you get, the more danger you're in of running too lean on the cylinders furthest from the throttle body. Further, as modern intake manifolds aren't meant to flow liquids, they are not built in a way that prohibits liquid puddles in the plenum chamber. This can result in fuel puddles, which (in a worst case) can cause nasty intake-manifold-backfire issues that can be incredibly harmful to engine components.

Direct port ensures that your expected fuel and nitrous distribution reaches each cylinder equally, and drastically reduces the possibility of fuel pooling.

In the end, it's not a "huge deal" so long as you're not going crazy with the spray. But, for my own car, I'd personally stop the wet shot after 75hp at the absolute most.
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