Nitrous Oxide or (NOS) as its commonly known to enthusiasts is something that isn’t new to combustion engines by any stretch of the imagination. It’s adding one component to an equation to create more power and greater output from your engine, but many people have questions about the safety of using nitrous and for good reason.
Everyone has a “friend of a friend” who blew up their motor when spraying nitrous, but in reality is it as dangerous as many people think? Not at all.
We’ve recompiled this writeup from 2001, when we fielded these questions with the NOS R&D people who hoped to arm customers with knowledge and help them better understand what nitrous is, and how safe it can be.
Q: Will Nitrous affect engine reliability?
A: The key is choosing the correct HP 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 applications.
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 2500 RPM under full throttle conditions.
Q: Is Nitrous a 50-state legal power adder?
A: Yes. In fact, NOS and many other manufacturers 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 an nitrous system.
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: Genreally, forged aluminum pistons are one of the best modifications you can make. Retard igntion 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 .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 requirements 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: 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 quarter-mile passes may be expected. If nitrous is only used in 2nd and 3rd gears, the number of runs will be more.
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 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 recommend and sells only the automotive grade, called Ny-trous Plus. Ny-trous Plug contains a minimal amount of sulfur dioxide (100 ppm) as a deterrent to substance abuse. The additive does not affect performance.
Q: How long does it generally take to install an NOS kit?
A: The majority of NOS kits be installed using common hand tools in approximately 4 to 6 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 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: Are there any benefits to chilling the nitrous bottle?
A: No. Chilling the bottle lowers the pressure dramatically and will also lower the flow reate 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: 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, 10 lb. bottle with Hi-Flo valve, comprehensive 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 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 oxide 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 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 vehicles 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: Are NOS kits applicable to 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 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 ot mount a nitrous bottle?
A: NOS bottle come with siphon tubes and, in order to maintain proper nitrous pick-up, 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 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: Does NOS manufacture kits for motorcycles, water craft, or snowmobiles?
A: Absolutely. Call or e-mail 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 its system.
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. Overfilling and/or to much heat can cause excessive bottle pressures forcing the safety seal to blow and releasing all 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.
- Pro Street Staff