• Aug 1, 2006

Nitrous oxide is known by several names - "nitrous", "spray", "the bottle" , "giggle juice", "laughing gas", "N-O-S" (just please dignify yourself and don't refer to it as "nawz") - but yet it's also perhaps the least understood piece of technology that is available to a modern hot rodder. Considering that it's one of the most economical ways to add 50% or more power to an internal combustion engine, this seems like a topic ripe for a technical discussion.

The Germans discovered the effects of nitrous oxide on internal combustion engines and applied it to their Luftwaffe fighters and bombers in the form of the GM-1 high-altitude performance system. Like so much of hot rodding's early days, nitrous resulted from the post-war "peace dividend", and savvy mechanics started using it for improved performance at the drag strip and during top-speed attempts on dry lake beds and salt flats. Its popularity has continued to rise since then, driven by a combination of its cost effectiveness, its compatibility with modern engines and engine controls, and of course, its mythology. Along the way, the technology has become ever easier to use, thanks to some dedicated vendors and a growing knowledge base in the high-performance world.

So, what is nitrous oxide? Simply stated, it's a compound consisting of two parts nitrogen and one part oxygen. At room temperature and atmospheric pressure, it's a gas, but it can be condensed to a liquid at 75 degrees F by applying approximately 780 PSI. When heated to approximately 570 degrees F, it will break down and release the oxygen, giving the resultant gas mixture an oxygen concentration of approximately 35 for atmospheric air. This gas is also denser than air, so the oxygen content by volume is more than twice that of the air we (and our engines) breathe. More oxygen equals more power - if it can be controlled. Since the potential for substance abuse is substantial, the stuff that's purchased at the local speed shop includes a small amount of noxious sulfur dioxide. This has no effect on an engine, but will quickly deter any deadheads who are looking for a cheap buzz.

Not only does nitrous oxide bring along extra oxygen, but the evaporative cooling effects of the liquid-gas conversion (nitrous boils at -128 degrees F) also drops the temperature and thus increases the density of any atmospheric air in the engine's induction path. This often referred to as "chemical intercooling", and while the nomenclature may not be all that accurate, the effect itself makes nitrous oxide a great companion for high-compression naturally-aspirated engines, forced-induction powerplants, and diesels. The combination of these two effects can bring an theoretical power increase of over 100%, although this is rarely achieved in practice for a variety of reasons.

In our next post, we'll take more of an in-depth look at the hardware and control strategies that are required to safely and effectively implement nitrous oxide in a typical gasoline internal combustion engine application.



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  • 13 Comments
      • 8 Years Ago
      TC - That is a good point as to why turbo would the best compromise between On/Off nitrous and Always-On supercharging... nothing to think about... the car behaves appropriately depending on how you're driving it.
      • 8 Years Ago
      Pardon the grammatical error in my second sentence; changed the wording and forgot to turn 'neglecting' into 'neglect'.
      • 8 Years Ago
      As a percentage of the general population, more people die in their sleep than streetracing. Everyone can die in their sleep, and only a small percentage of the population street races, so I think the relative numbers might be a lot different. This also ignores wrecks where no one dies.

      Take it to the track where it belongs. Endanger yourself if you like but don't take others with you. This from a guy who drives a 600 hp daily driver but never drives more than 10 - 15 mph over the speed limit on the street.
      • 8 Years Ago
      I just like saying "Nozz," like Paul Walker did.
      • 8 Years Ago
      I thought that nitros oxide was made of 1 part Paul walker and 1 part VIn Diesel...
      • 8 Years Ago
      Well...no offense Shawn but nobody really wants to hear anything about how bad street racing is and all that. Anyone who is really stupid on the roads is going to get theirs anyway, so you don't need to make it your problem. And, since this is the internet, you can't really tell who the "real racers" are anyway.
      I think nos is a great way to add power and some customization to your car. I also believe 1.) That people who install nos on their cars don't need to run around thinking they are the best in their fastnfurious cars, and 2.) The "real" racers shouldn't be so harsh on people who just like to make some cheap, fun mods on their daily. That's about it. No disrespect meant to anyone whom I contradicted
      far jr
      • 8 Years Ago
      Good article... how about one on water, propane, or methanol injection in diesels!
      • 8 Years Ago
      Actually Riker, if you drive sedately in most turbocharged cars, fuel consumption is significantly lower due than when racing due to less spooling of the turbo at lower revs - it's not 'always on' so to speak. But props to PBCrunch for using NOS to spool the turbo! Forced Turbo spooling (like the prodrive P2) is a blast and it makes great noises!
      • 8 Years Ago
      In regards to the fire retardent suit comment.

      Nitrous Oxide is NON FLAMMABLE.
      i.e. Don't believe what you see in Fast and The Furious.

      As the article states it takes high temperatures to release the Oxygen, even then that doesn't mean it will 'explode'. Fire requires two things, fuel and oxygen. Nitrous Oxide only gives it one.

      The biggest risk is that the bottle itself will explode.. well if you've hit something hard enough that makes a properly mounted bottle explode you're probably already dead.
      • 8 Years Ago
      Shawn, why don't you go back to the D.A.R.E. blog where you came from? More people die of accidental strangulation in their sleep (by a factor of 10) than die from "street racing". Should we outlaw sleeping?
      • 8 Years Ago
      To argue the counter point, forced induction only consumes extra fuel when you use it. It's "always on" was a bad statement on my part. I should have said "always ready to go".
      I agree that street racing is stupid. I'm guessing you drive a prius? If not, I think you took too big of a bite. Just because you drive a corvette doesn't mean you're out to kill people.
      BTW, I have upgraded my brakes. Stop is definitely more important than go. The mechanic's log: http:mechlogs.com/maverik (You can get one too.)
      I agree about the NOS bottle being under pressure and slightly dangerous. Not flamable, but dangerous. The pressure in those things is enormous (relatively speaking to your passenger compartment). Plus, if it springs a leak, the escaping gas is going to be colder than dry ice.
      I won't argue that it should be illegal for street use, turbo + NOS (or actually the other way around) is a worthwhile investment. But buy the turbo first. You'll probably find it's what you want.
      • 8 Years Ago
      Great article, look fwd to the next one. Do you mind if i use this article on my local forum- Lexistreets.com. I think the members there would find it very informative.
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