Nitrous Q&A (Sticky for future reference.) - Hemi Truck Club
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Old 03-05-2007, 02:20 PM   #1
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Another reference for future questions. This is a great article!!! Don't know who the author was.

Jim C.

Here are some Q's and A's for you. Enjoy!

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. Nitrous 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. Most Nitrous 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. Most 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 .5 to 3 full seconds and 5 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 3,000 RPM under full throttle conditions.

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 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! Most sell 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 program in conjunction with an ntrous System?
A: Only if the program has been designed specifically for use with nitrous oxide. Most aftermarket programs 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 program before using it.

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 900-1050 psi.

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: 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. Nitrous 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 nitrous 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: 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.

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Old 03-05-2007, 02:23 PM   #2
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More good info -

Jim C.

Wet vs. Dry
These questions will come up alot, so I'll try to address them now. The main difference between the 2 is the Wet kit injects fuel AND nitrous into the intake tract, whereas the Dry kit will only inject nitrous. They both have their advantages and drawbacks. If you're new to nitrous, Dry is probably for you. Its very simple to install, mostly plug and play and gives the most hit. Wet kits are generally a smoother hit comparatively and require more installation. Dry kits do not inject more fuel into the intake directly, but if nothing else was done, your engine would lean WAY out, and thats never good. What the dry kit does is fool the fuel pressure regulator into thinking its not adding enough fuel. It opens it up (or closes it, however the LS1 works)[LSx platform uses the MAF to tell pcm to add fuel thru injectors, and LTx uses reg to spike fuel pressure with aux fuel pump. Robert56] and adds more fuel that way. The problem with this is its very easy to lean out. If the vaccuum line pops off or something goes wrong with the FPR, you can lose fuel and this can damage your engine in no time if the nitrous isnt turned off. Also, you'll probably get people telling you that you cant run big shots on dry. This is not true. USA Motorsports used to competitively race using a 2 stage dry kit 175-300.
Wet on the other hand is the most tuneable of the 2 (not including foggers or direct port, I'll go over that later). It adds additional fuel through a seperate solenoid and atomizes it with the nitrous in the intake tract. This is safer in the sense that you dont rely on the FPR to add more fuel, but the downside is if you shut down too early and do not stop spraying early enough, the fuel/nitrous mixture can puddle up inside the intake and cause a nitrous backfire. If you have never seen one, I hope you never do. They are not pretty. I had one in my old racecar. It was a 250 shot and it blew halfway down the track. The hood was toast, the intake was split in 3 pieces, TB cracked in half and the MAF was blown away somewhere and couldnt be found. Not fun. While this isnt a common occurance, it IS possable.

What is a Purge Valve?
This comes up alot, especially with the newer nitrous junkies. Purge is probably the most un-necessary part of a nitrous system. Its more useful in a Wet application so the fuel and nitrous get to the nozzle at the same time, but its still not mandatory unless youre running a large shot or need that extra .01 sec. All a Purge does is clear the air between the bottle and the solenoids. That being said, its best to put the Purge solenoid as close to the nitrous solenoid as possable to get rid of as much air as you can. But at 1200psi, the nitrous isnt moving that slow, so its not going to take long to clear that air on it's own anyway. If you havent purchased one, dont yet. Add this last to your kit and get something more useful now like a warmer or a window switch. If you already have one or nobody can talk you out of it, dont overuse it. Nothing will make you look like a ricer faster then someone who purges whenever they pull up somewhere. Thats like taking a gallon of your gas and pouring it on the ground. At ~$2.00/lb, nitrous isnt cheap. Why waste it? The ONLY time you should need to purge is right before staging at the strip. A couple short bursts is all it takes. Once you see the white gas come out, thats enough. Purging more then that is the equivalent to doing a John Force burnout on BFGs. And PLEASE PLEASE DONT buy the bottle and a purge valve only. I was flipping through 5.0 Mustang mag this week and saw an advertisment for a kit (NX I believe) that was just a bottle and a purge valve...

How will nitrous work on a high milage motor?
It all depends on how it's maintained. On my first 5.0, I had over 200k on the clock and was spraying a 100 dry shot at the track. I didnt have much blowby, so it was safe. My motor did die, but not because of the nitrous. My oil pump shaft broke. But as long as the motor isnt beat to hell, nitrous should be ok on it.

Why nitrous?
Forced induction guys will always give us hell because we have to turn ours on, but thats the beauty. Nitrous is GREAT for a daily driver. You can drive a 350hp car around every day making 27mpg and go to work/school/mall/ect and have fun. Go to the track, flip a switch, BAM, 150 more horses. Now youre racing with ~500hp on a car that can be driven daily with confidence. Also, you can run higher compression. Nitrous loves high compression motors. Nitrous motors generally make the best street cars because of this. With turbos or blowers, sure you can turn down the boost or pulley down, but even then, you still have a hot air charge (even with an intercooler, the air is hot enough to cook an egg) and most blown motors have low compression. Low boost on a low compression motor=no fun

What do I need with the kit?
This depends on what you get. Most people will get a simple Wet or Dry kit. If youre getting a fogger or direct port, I hope you dont have to read FAQ. You can custom build your own kit, but if this is your first, I suggest buying a pre-packaged one. TNT is good, so are NOS and NX. There is also Zex. Some love it, some hate it. I'll stay away from it and tune my nitrous myself. A prepackaged kit should come with a Bottle, Nitrous feed line, proper solenoids (type depending on the kit wet/dry), power relay for the solenoids, jet(s), AN fittings, nitrous injection line, nozzle, and a bottle bracket. This is the bare minimum. It will work, but not as well as a nicely modified kit. First, before you can even think about running, you have to find out what your track rules are. If they have NHRA rules, you will need a blowdown tube for your bottle. This evacuates the nitrous out of the car in the even the valve on the bottle fails. If you have a convertable, you wont need it since the bottle is not in the passenger compartment, but its still recomended. Next is a bottle warmer. If you want the most out of your kit, this is what you need. This will keep your bottle at a fixed pressure so you have consistent results. Without a warmer, nitrous is near impossable to tune because when you first fill the bottle, you might have 900psi, but after a couple runs you might be down to 750psi. A warmer will SAFELY warm the bottle to raise the pressure to 900psi again. A warmer kit will come with a relay. USE IT! This will help keep it from overheating. Seperately from nitrous components, you will need colder plugs with a smaller gap. 1 or 2 ranges colder is usually acceptable for a shot on a stock motor.

What can I add to it?
There are so many things you can add to a nitrous kit. A few are a window switch, timing knob, activation switches, purge, opener, etc.
A window switch will only allow the system to engage inside a certain RPM window. You NEVER want to spray in the low RPM, this is very bad for the motor. Generally wait until at least 2000rpm. The window switch is useful for keeping the timing of the injection in check. If you miss a shift and nail the gas, the nitrous will re-engage and damage the motor. if you have it pilled from 2000-6500, the nitrous will shut off when the motor reaches 6500rpm. A timing knob is used to retard the timing without getting out of the car. It is used in conjunction with an ignition box and will allow you to adjust the timing easily. If you are running N/A, you can have the timing advanced. But if you go to the track and are going to spray, just twist the knob back to take some timing out of it and youre good to go. There are various activation switches used with a nitrous kit. First is the arming switch. Without this on, nothing will happen (unless you suck at wiring). But to actually fire the nitrous system, you can use a WOT (Wide open throttle) switch or a push botton. These are the 2 most common used. A WOT switch only fires when the pedal is on the floor. That way if the nitrous is armed, with or without a window switch, nothing will happen until the pedal gets to the floor. A push button is just that. When you push it, the nitrous fires. A remote opener is ideal for the street. Its not very useful at the track since you usually have prep time, but on the street you dont. Im not endorsing street racing, but if you do, a remote opener is for you. It allows you to keep the actual valve of the bottle open without keeping pressure on the solenoids. If you pull up next to someone who wants to race, just flip a switch to open up the bottle and youre ready to go.

Here are some general DOs and DON'Ts with N2O
-DO keep the bottle pressure constant when in use
-DON'T use anything less then Premium Unleaded
-DO run a fuel pressure safety switch on a Dry nitrous kit
-DON'T always go by the jetting listed on websites
-DO learn to read the plug's heat range and tune it yourself
-DON'T open the bottle and leave it for long periods of time, the pressure is bad for the solenoids
-DO always purge off the excess N2O after shutting off the bottle for the day
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Old 03-05-2007, 03:04 PM   #3
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Great info BG - thanks for sharing
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Old 03-05-2007, 05:00 PM   #4
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Alot of reading there, but some great information!
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Old 03-05-2007, 06:33 PM   #5
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I believe thats what I read on the NX website. Good find!
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Old 03-06-2007, 04:35 AM   #6
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Wizard of Nos is a good resource too.
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Old 03-06-2007, 04:49 AM   #7
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Old 03-06-2007, 09:49 AM   #8
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Old 03-06-2007, 03:05 PM   #9
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Old 03-12-2007, 11:35 AM   #10
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Great info... I'm new to the nitrous scene and this info REALLY helps! Thanks!
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