Lessons in Nitrous Oxide


Because Your Vette May Enjoy A Little Laughing Gas
by Jason Giacchino

Contrary to what movies like The Fast and the Furious will have you believe, nitrous oxide (?NOS? if you want additional street cred) isn’t quite the mysterious, highly explosive, limitless power-source they portray it to be.  In fact, nitrous oxide isn’t even flammable at room temperature (which is probably a good thing, considering smoking in public used to be allowed; yes, even at the dentist’s office).

Nitrous oxide requires a great deal of heating before its explosive properties become realized ? to the tune of nearly 570 degrees Fahrenheit!  Even at this high temperature, contrary to common misconception, the gas is not a combustible so much as it is an oxidizer.  What this means is that in the fiery instant where fuel and spark meet, nitrous can provide much more oxygen to the process than air can alone (a little over 35% more to be specific).

Since, as the name implies, nitrous oxide consists of both nitrogen atoms (2 of them) and oxygen (1), what actually happens within the engine’s combustion chamber is that the nitrogen atoms split apart, freeing the oxygen to do what it does best in the situation: oxygenize the fuel molecules.  More oxygen enriched fuel burns more efficiently, and you feel this in the form of a power boost throughout the duration of the nitrous oxide’s injection.

There’s an added power boost often overlooked as well in that the nitrous stored in that little can is in liquid state and under a great deal of pressure (1000+ psi isn’t uncommon).  Once exposed to the atmosphere, the liquid instantly vaporizes (the process of liquid turning into gas).  As this happens, heat in the surrounding area becomes absorbed as well. Hence, the vapor benefits from an instantaneous drop in temperature.  In plain terms this means that intake charge itself is cooler and thus denser than if you were drawing in ambient air.  A denser charge packs even more oxygen, which, of course, only further compliments the power boost you feel.

Since nitrous allows for a much denser charge into the cylinder it simultaneously dramatically increases cylinder pressures. The increased pressure results in heat, so ironically a colder intake charge results in a surge of heat. The most common problems resulting from prolonged cylinder heat include piston deformation, valve damage or warping or cracking of the head or predetonation (pinging).

Nitrous oxide injection systems, come in either ?dry? or ?wet? configurations.  The difference is simple and really quite logical: A dry kit relies only upon the gaseous form of the nitrous oxide for an increased boost while a wet kit combines the nitrous oxide with pressurized fuel (gasoline) to accomplish the same task. 

Generally speaking, a dry kit is cheaper as it requires fewer parts, less complexity, and there are some kits that require no engine modification whatsoever by instead injecting the N2O into the air box to be ?inhaled? by the motor rather than into the cylinder directly.

As the following jump demonstrates, the amount of boost you seek can typically be altered using the included hardware:

no2.jpgAll this Nitrous talk begs the question: to NOS, or not to NOS? Click here to voice your opinion!