Nitrous Chemistry

The Properties contained in Nitrous Oxide


Two atoms of nitrogen and one atom of oxygen make up one nitrous oxide molecule. The weight is 36% oxygen; but it should be remembered that air is 23.6% oxygen. For nitrous oxide to maintain its liquid state its vapour pressure must be 760 pounds per square inch at a temperature of 70 degrees F.  When and if the temperature reaches 97.7 degrees F the liquid form of the nitrous oxide can no longer be attained.  As soon as this temperature is reached nitrous oxide will be at 1069 pounds per square inch and will become gaseous and develop into a detonation risk.  If the temperature rises still further then the pressure will increase yet the gaseous form will be maintained.  Anybody intending to siphon liquid nitrous oxide must remember that it is essential to keep the temperature below 97.7 degrees in the interest of safety.  Upon release its pressure will soon drop to the pressure of the atmosphere which is 14.7 pounds per square inch from its 760 psi working pressure. Once discharged into the atmosphere then the nitrous oxide will expand and start to boil although the drop in pressure will instigate a rapid fall in temperature.


The Reason for Combustion in Nitrous Oxide


The process that enables nitrous oxide to produce more power begins with a method that enables more fuel to be burned just by providing more oxygen.  This is due to the make up of nitrous oxide molecules that are fused together.  As the temperature reaches 565degrees F, this fusing begins to break down thus enabling the oxygen to break free.  As the combustion process continues the temperature exceeds 565 degrees and the whole action is made easier.  The volume of oxygen increases as nitrous oxide is introduced into an engine and this limits the other gases that are not required to enhance the combustion process.  Controversially this action requires less timing advance due to the fact that the burn rate has quickly increased. Although in some quarters this has been hard to comprehend, it has been repeatedly proven beyond doubt that more power can be produced with less timing.  By using nitrous oxide it is very easy to achieve too much ignition advance and this will have an adverse effect on the power required so it is important that peak cylinder pressure happens at around 20 degrees ATDC. It should also be remembered that the risk of detonation will be higher if the peak cylinder pressure occurs too soon.


Why Detonation Occurs


When using nitrous oxide in your engine, the heat that it generates must be kept under control.  Failure to do this will increase the risk of detonation and the time and money spent on your engine will be wasted if it is destroyed as a result of careless actions. Simply by adding water this can reduce the risk of detonation and a finely tuned water injection system can be an asset and enable you to have more control over the engines fuel nitrous oxide ratio therefore controlling its temperature. Water injection will eliminate the risk of detonation brought about by the extra fuel that is required when the application of rich jetting is undertaken which the nitrous oxide uses to achieve a safe starting point.  This action will enable you to run your engine more efficiently as well as taking the safety aspect into account.  It is advisable to run a slightly richer mixture to maintain more control. Raising the detonation limit will force more nitrous oxide to be used and increase the power to compensate for the reduction in intensity that water injection and running richer will initiate.


Using the Correct Ratios of the Chemical to Fuel


For the sake of your engine you must never run lean; there should always be enough fuel for the nitrous oxide to blend with. Lack of fuel could see temperatures rise alarmingly and oxidisation will take place if there is not an adequate supply of fuel for the oxygen to react with and this could prompt overheating.  To ensure correct performance, the ratio of nitrous oxide to gasoline is 9.649:1


The Role of the Plate Systems


The most widely used system for injecting nitrous oxide into your engine is the spray bar type. This involves sandwiching a plate between the manifold and the carburettor each plate has two spray bars one being fuel and the other nitrous oxide. Because the upper spray is nitrous oxide a better mixture can be achieved. The installation of these plates is a reasonably easy process and favourable results can be achieved, however this is not the most efficient system. The longer nitrous oxide takes to get to the engines cylinders the more it expands and because it has to pass through the inlet manifold it could expand at the expense of the naturally aspirated mixture that the engine requires. As a result of this the closer to the cylinders the point of injection is, the more power can be achieved. Further problems have been experienced when using spray bars with larger kits in the region of 300 hp. Engines have been known to pause when nitrous oxide is introduced which can initiate wheel spin but once the system is running no problems have been experienced.


Nozzle Systems and how they operate


Much more power can be achieved by making use of the nozzle system. This involves more work but the advantage is in the results. It involves drilling and tapping the cylinder head by each inlet runner and adds one nozzle for each cylinder.  However, with experience it is possible to add more than one nozzle per cylinder but if you are just starting out one is good enough.  The extra work will result in a better mixture because the fuel and the nitrous oxide will be allowed to mix before injection.  There is hardly any expansion because the injection is so close to the cylinder and dependent on the positioning of the nozzles, airflow could increase. These are just some of the many advantages of installing a nozzle system.


Cooling and the Overall Effects


Cooling has a great effect on engine power and an extra 1-1.5 % more power can be achieved by dropping the intake air by 10 degrees.  This boost in power is caused by more fuel being burned as intake air is reduced in temperature.  As much as 30 hp can be obtained with a 400 hp engine from the cooling effect which is quite a significant amount.


The Results of Average Power


It has been proven that a nitrous oxide engine will always achieve better results than a traditionally aspirated engine. A nitrous oxide injected engine will reach a higher average horsepower at a lower rpm. Nitrous oxide is able to fill the cylinders at lower speeds.  This, in turn, will allow more nitrous oxide into the cylinders when the rpms are low and as the revs increase the engine will start to run on more naturally aspirated power.


Is Concentrated Oxygen an Option?


Adding pure oxygen has been tried but this process proved that by adding just a minimal amount, the control of the heat became a problem.  Also the oxygen proved to take up too much room and this was at the expense of naturally aspirated power. Nitrous oxide contains 64% nitrogen and 36% oxygen and the reason that engines gain heat rapidly when injected with nitrous oxide is the more that is injected the less nitrogen there is to absorb the heat.  By making use of nitrous oxide in your engine you are allowing more nitrogen and oxygen into it and as well as generating a lot more power you are able to gain control of the overall heat factor.