Nitro Fuel

Now that we've looked at a basic overview of a typical nitro RC engine, we need to touch upon the special RC nitro fuel required by these engines.  Nitro fuel It is NOT gasoline!  Never try to feed a nitro engine gasoline, because it will cause all sorts of problems.  Besides, it won't work anyway!  RC nitro fuel is made up of a custom blend of 3 primary components. 

1) NITROMETHANE.  Also commonly referred to as NITRO for short.  Nitromethane is derived from propane.  In itself, nitro is not even extremely flammable as one might think.  The real power producing potential of nitromethane is that it carries additional oxygen with it into the combustion process.  It does act as a fuel too, but the extra oxygen contained in the nitromethane molecule helps increase performance.  In a way, nitromethane is sort of like a chemical "supercharger" for an engine.  It helps get more oxygen into the engine to help burn more fuel and therefore produce more power.  For most nitro engines used in RC trucks, a 20% nitro blend is probably a good balance.  Most nitro engines in cars and trucks could probably tolerate fuels with up to 30% nitro, but it's probably best to avoid going much over that in a typical nitro engine.  A 20% nitro fuel is probably one of the most common blends for RC truck nitro engines.  This would probably be a safe choice for most people.  If you follow the recommendations of your engine manufacturer, then you should be safe.

2) METHANOL.  Methanol is sometimes referred to as "wood alcohol", because it was originally derived from distilled wood products.  However, methanol can be made from more than one source, and today it is very commonly derived from natural gas.  Methanol is the primary fuel component of nitro fuels and is usually also the most dominant ingredient in a nitro fuel mixture.  Methanol is also a common fuel used in full size motorsports and racing.  The methanol has a natural intercooling effect that helps to cool the air going into an engine which means cooler, denser (more oxygen) and more power potential.  Also, the evaporative cooling effect of methanol can help keep engine temps running cooler than other fuels.  The methanol provides the primary energy content in nitro fuels.         

3) OIL.  The oil portion of the nitro fuel blend is very interesting.  Over the years, there has been much debate and changing recommendations.  First there was castor oil.  Then there were synthetics.  Some fuels have been blended with all castor oil and some with all synthetic oils.  Today, most nitro fuels contain a combination of both synthetic and castor oil.  Castor oil is a naturally occurring oil that is derived from a plant.  It is a natural lubricant that has some very unique properties.  When subjected to higher temperatures, castor oils will actually begin to break down.  Normally, this would be a bad thing for a lubricant in an internal combustion engine.  However, in the case of castor oil, this "breaking down" is one of it's greatest strengths!  When castor oil breaks down at high temperatures, it's properties change and it's high temperature lubricating properties actually increase!  As engine temperatures go up further, the castor oil continues to break down and forms a lubricating film that actually protects the engine better.  In the process, this film or residue (like varnish) can also gum up the engine and cause other problems.  On the other hand, synthetic oils are typically much cleaner and normally do not leave residues behind.  Synthetic oils can help lubricating metal surfaces at higher RPM's when temperatures are lower.  However, when temperatures rise, synthetic oils can break down and actually burn off leaving little protection for the engine.  So, there are strengths and weaknesses of both castor and synthetic oils.  Thankfully, most modern RC trucks run on nitro fuel blends that utilize the strengths of each type of oil, and contains a blend of both castor and synthetic oils to help offer maximum protection for the nitro engine under many different conditions.  

In addition to these 3 primary components to nitro fuel, there are often other additives added in small quantities which help alter some of the characteristics of the nitro fuel.  Among others, these additional RC nitro fuel additives might include anti-foaming agents and substances to help prevent corrosion inside the engine.  As you can see, these nitro fuels are more complex and more interesting than many people realize.