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Holley Frequently Asked Questions

QUESTION Will Nitrous affect engine reliability?
ANSWER 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. There's a video on Holley TV that shows what's happening in your engine once nitrous and fuel are introduced. Click Here To View.
QUESTION Can I simply bolt a nitrous kit onto my stock engine?
ANSWER 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. There's additional information on our Holley TV that shows the different types of systems that are available. Click Here To View.
QUESTION What are some of the general rules for even higher HP gains?
ANSWER 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. For more specific information about your application, please contact the NOS technical dept.
QUESTION How does nitrous work?
ANSWER Nitrous oxide is made up of 2 parts nitrogen and 1 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. Watch our video on Holley TV that shows what's happening in your engine once nitrous and fuel are introduced. Click Here To View.
QUESTION How much performance improvement can I expect with a nitrous system?
ANSWER 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. There's a video on Holley TV that shows how nitrous oxide works to make more power. Click Here To View.
QUESTION How long can I hold the nitrous button down?
ANSWER It is possible to hold the button down until the bottle is empty. However 15 continuous seconds at a time, or less, is recommended.
QUESTION When is the best time to use nitrous?
ANSWER 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.
QUESTION What kind of testing or research is performed on NOS products?
ANSWER 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 closely with many top name racers to develop the most powerful and reliable nitrous systems in the world.
QUESTION How long will the bottle last?
ANSWER 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.
QUESTION Will I have to re-jet my carburetor on my car when adding nitrous?
ANSWER No! The NOS system is independent of your carburetor and injects its own mixture of fuel and nitrous.
QUESTION Is nitrous oxide flammable?
ANSWER Nitrous Oxide by itself is non-flammable. However, the oxygen present in nitrous oxide causes combustion of fuel to take place more rapidly. There's a video on Holley TV that shows what's happening in your engine once nitrous and fuel are introduced. Click Here To View.
QUESTION Will nitrous oxide cause detonation?
ANSWER 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.
QUESTION Where can I get my bottle refilled?
ANSWER Simply call 1-800-997-3345 for the location of the nearest NOS dealer with refilling capabilities.
QUESTION Is there any performance increase in using medical grade nitrous oxide?
ANSWER 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.
QUESTION Is it a good idea to use an aftermarket computer chip in conjunction with an NOS System?
ANSWER 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. Watch our video on Holley TV that shows the basic overview of a typical dry system that would be used on a computer controlled engine. Click Here To View.
QUESTION How long does it generally take to install an NOS kit?
ANSWER The majority of NOS kits can 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. We have a couple of helpful videos on Holley TV that can give you additional information. Dry Kit Installation Click Here To View. Plate Kit Installation: Click Here To View.
QUESTION Which type of manifold is better suited for a plate injector type of nitrous system, single or dual plane manifold?
ANSWER 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. Our video on Holley TV may also be helpful. It shows how to install a typical NOS plate system. Click Here To View.
QUESTION Does nitrous oxide raise cylinder pressure and temperatures?
ANSWER Yes. Due to the ability to burn more fuel, this is exactly why nitrous makes so much power. There's a video on Holley TV that shows what's happening in your engine once nitrous and fuel are introduced. Click Here To View.
QUESTION Are there any benefits to chilling the nitrous bottle?
ANSWER 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 guage 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 Fahrenheit will allow for best power potential of NOS kits. Our video on nitrous bottle mounting tips may also be helpful. Click Here To View.
QUESTION Are there benefits to using nitrous with turbo or super-charger applications?
ANSWER 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.
QUESTION How complete is an NOS kit?
ANSWER 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. There's a video on Holley TV that showcases what's included in a typical NOS kit. Click Here To View.
QUESTION What is the difference between a standard and an NOS Hi-Flo bottle valve?
ANSWER 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.
QUESTION What affect does nitrous have on an engine with considerable miles on it?
ANSWER 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.
QUESTION Will the use of nitrous oxide affect the catalytic converter?
ANSWER 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.
QUESTION How important is it to use nitrous and fuel filters in a kit?
ANSWER 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.
QUESTION 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?
ANSWER 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.
QUESTION Can high compression engines utilize nitrous oxide?
ANSWER 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.
QUESTION Can service station fuel be used for street/strip nitrous oxide applications?
ANSWER 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.
QUESTION What type of cam is best suited for use with nitrous oxide?
ANSWER 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.
QUESTION What type of nitrous system is better; a plate injection system or a direct port injection system?
ANSWER 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. We have a couple of videos on Holley TV that you may also find helpful to watch. NOS Direct Port Systems: Click Here To View. NOS Plate Systems: Click Here To View.
QUESTION Should I modify my fuel system to use nitrous oxide?
ANSWER 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.
QUESTION Which is the best position to mount a nitrous bottle?
ANSWER 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. Watch our video on Holley TV that offers additional tips on mounting a NOS bottle. Click Here To View.
QUESTION What are the advantages of using nitrous compared to other performance options?
ANSWER 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. 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. Watch our video on NOS to get a better understanding on what nitrous oxide does to improve the power in your engine. Click Here To View.
QUESTION Does NOS manufacture kits for motorcycles, water craft, or snowmobiles?
ANSWER Absolutely. Call or write NOS to obtain our special catalog devoted specifically to these applications.
QUESTION What kind of pressures are components subject to in a typical nitrous kit?
ANSWER 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.
QUESTION What is the function of the blow-off safety valve on the bottle?
ANSWER 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. Our video on NOS bottle mounting may provide some additional tips. Click Here To View.
QUESTION Will I have to change my ignition system?
ANSWER 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 with a built in spark retard.
QUESTION How do I know how much nitrous is left in the bottle?
ANSWER The most reliable method 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.

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