when installed properly, it is no more harmful than a properly installed turbocharger or supercharger application. The problem is that a "proper setup" is typically very expensive.

the reason that nitrous oxide has such a bad rep is that it is far easier to 'throw together', and its cheaper than a decent turbo or blower setup. so what happens is that kids who want to go faster without alot of money buy themselves a nitrous kit for 600 or so bucks, and that kit can provide about 100hp. that basic kit can still be done "safely", but some cars (such as my stratus) just dont take to nitrous. when you hear about someone adding nitrous and blowing the engine 10 minutes later, they are typically cheap and lazy. they buy a basic kit which only includes a bottle, the lines, and a swtich/solenoid to activate the system. they put a switch on the steering wheel or something, and push the button like the guys on the fast and the furious...

When the basic kit is hooked up correctly (and "Safely") it will typically be a wet kit. the difference between a wet kit and dry kit is that on a wet kit, there is a nozzle that introduces the nitrous oxide into the system, but there is also a nozzle that adds addition gasoline, thus preventing the car from running lean, or at least lessening the concern of running lean. ideal internal combustion occurs at 14.7 to 1 air to fuel. so for every 1 part of fuel, you have 14.7 parts of gasoline. it is far more complicated than just that, but for this discussion, that amount of information will suffice. some cars, such as something like an SRT4, will have an air to fuel ratio of around 12 to 1...the lower the first number is, the "richer" your engine is...the higher that first number is, the leaner it is. too rich will cause the engine to produce less power, too lean will cause the engine to create tremendous amounts of heat, thus doing things like breaking pistons, rods, etc. adding the additional fuel with a wet kit allows you to run more nitrous without a fuel system controller/piggyback, thus preventing the engine from going too lean, but it only does so much as it is a VERY small amount of gasoline.

all types of forced induction, be it nitrous, turbo, or a supercharger, builds excess heat, hence intercoolers on a turbo or blower setup. the problem is that when nitrous is thrown on a car, it is a far more violent form of adding horsepower. with a supercharger, say that you run 14 pounds of boost which in a perfectly efficient engine (which none are) will roughly double your horsepower. the internal speed of the supercharger increases with engine rpm, so the added power is progressive, and not all at once. a turbo works the same way, but it is even more progressive, since the turbocharger internal speed is fully dependant on the flow of the exhaust gas, and not a belt.

say that youre running the proper amount of boost with a turbo or supercharger to add 100 horsepower to an engine which makes 200 stock hp. with a turbo, at idle, you are receiving very little, if any, gains since the turbo has not spooled up to the proper internal rpm range. a supercharger will have the same effect...as you begin to accelerate with either setup, and your engine rpms increase so does the boost, so the power is added gently, over the power curve, so you may not actually make 100 more horsepower until something like 2500-3000 rpm (just a random number for the example, actual numbers vary greatly) a thrown together nitrous setup is the opposite. as soon as you activate the system and the nitrous is injected into the system, it is adding the amount of nitrous needed to provide 100hp, all at once, so with the flick of a switch you go from 200 to 300hp...that is much harder on the engine than just adding the amount of boost to add 100hp.

the most correct way to run nitrous, and the way that some people successfully and safely run HEAVY nitrous for a long time is to run an progres