The following are answers to the most commonly
asked questions about NOS Nitrous Oxide Systems, compiled by The NOS Research and
There's really nothing mystical about nitrous oxide and the application for automotive
engines. Very simply NOS made it better and safer for customer use. The following
questions and answers are typical of those fielded by NOS R&D people and we hope that
they will be of help to all of those who seek the winning edge.
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 component 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 cylinder. engines normally allow an extra 40-60 HP, 6 cylinder.
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 H.P. gains?
A: Generally, forged aluminum
pistons are one of the best modifications you can make. Retard ignition timing by 4-8
degrees (1 to 1½ degrees timing retard per 50 H.P. 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
For gains over 250 H.P., 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 rod, 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. For more specific
information about your application, please contact the NOS technical dept.
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: What kind of testing or research is performed on NOS products?
A: NOS maintains a complete
research and development center including computerized dynamometer equipment as well as a
nitrous/fuel flow testing facility. In addition, NOS is actively involved in many aspects
of racing; working close with many top name racers to develop the most powerful, reliable
nitrous systems in the world.
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 effect 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 quitter-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,
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: Does NOS manufacture 50-state legal nitrous systems?
A: Yes, in fact NOS has several
EO numbers for various kits such as the 5.0L Mustang and 305/350 GM V8's, etc. In
addition, there is no need to remove any smog equipment when installing a NOS system. For
more information call the NOS tech line.
Q: Will I have to rejet 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 applications 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: Where can I get my bottle refilled?
A: Every NOS kit contains a
geographical list of refill dealers near you in the U.S. and Canada. Should you need a new
list, simply call NOS.
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
Q: Is it a good idea to use an aftermarket computer chip in conjunction with an NOS
A: Only if the chip had 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 potential
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 3 to 5 hours. NOS instruction
manuals are by far the best in the industry; and include specific installation drawings,
wiring diagrams, and bottle mounting procedures as well as performance tips and a thorough
trouble shooting guide.
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 he 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 200 HP, the single plane manifold is better.
Q: Does nitrous oxide raise cylinder pressures 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 800-900 psi. NOS has a
nitrous pressure gauge that allows you to monitor this. If you live or operate a nitrous
system in colder climates, it may also be a good idea to purchase a bottle heater kit,
part #14161. Generally, ambient temperatures of 70-90 degrees F. will allow for best power
potential of NOS kits.
Q: Are there benefits to using nitrous with turbo or supercharger 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
Q: How complete is an NOS kit?
A: NOS prides itself on offering
the most complete systems on the market today. They include virtually every component that
may be needed for a complete installation; parts such as extra long carburetor studs,
gaskets, pipe tap, fuel hose, brackets, filters, fittings, hardware, wiring, filled 10 lb.
bottle with Hi-Flo valve, complete instruction manual, and all other major components are
standard in every NOS kit.
Q: What is the difference between a standard and a NOS Hi-Flo bottle valve?
A: The orifice of the Hi-Flo
valve is much larger than the standard valve allowing for a larger flow of nitrous. With a
small orifice valve a pressure drop could occur when nitrous flow is high; causing surging
or inadequate nitrous flow. The NOS Hi-Flo valve eliminates this problem. NOS Hi-Flo
valves are standard in all NOS kits.
Q: What effect 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
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. For more specific information talk to one of our technicians.
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 more
exhaust overlap and duration. However, it is best to choose a cam tailored to normal use
(when nitrous is not activated) since 99% of most vehicle operation 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 manufacturer's recommendations for your
Q: Are NOS kits applicable on late model EFI cars?
A: Yes, in fact NOS has by far
the most comprehensive selection of nitrous kits available for these cars. Call for your
specific application if you do not see it listed.
Q: What type of nitrous system is better; a plate injection system or a direct port
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, NOS 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 retaining the advantages 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: Does NOS manufacture kits for motorcycles, water craft, or snowmobiles?
A: Absolutely, call or write NOS
to obtain our special catalog devoted specifically to these applications.
Q: What kind of pressures are components subject to in a typical nitrous kit?
A: Pressures often exceed 1,000
psi. This is why NOS uses only high pressure tested aircraft quality components like
stainless steel braided Teflon lines throughout it's systems.
Q: How do I know how much nitrous is left in the bottle?
A: The most reliable way 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
lb. 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
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.