Other than “not gasoline,” most hobbyists who are new to nitro power don’t understand what’s in nitro fuel, or more importantly, how those ingredients effect power, performance, and engine life. Any fuel you purchase that’s labeled “for RC cars” will work just fine, but if you want to choose the best fuel for your type of vehicle and your driving style, this article will be a big help. Ready to add some know-power to your go-power? Let’s take a closer look at the genie inside that fuel bottle.
WHAT’S IN IT?
Every container of nitro car fuel you’ll see at your hobby shop has the same base set of components. The proportions of each compound varies from manufacturer to manufacturer and within a company’s products lines depending on application, but you can always count on these three essential ingredients:
Methanol, the largest component of nitro fuel, is that part of the fuel that burns. It’s a simple compound made of carbon, oxygen, and hydrogen atoms. Methanol can burn in air, even without the other components in nitro fuel. An important thing to remember about methanol is that it is hygroscopic, meaning that it absorbs moisture from the air. This is the reason that it is so important to keep fuel containers tightly sealed. If you don’t, moisture in the air will be drawn into the fuel, causing it to spoil.
Nitromethane is a simple compound, consisting of carbon, hydrogen, oxygen, and nitrogen atoms. That’s right — the “nitro” is from nitrogen, which is what air is mostly made of (not oxygen, as commonly believed). Nitromethane is flammable on its own, even without oxygen, but it has a very high burning point—well over 4,000 degrees Fahrenheit. When mixed with methanol, nitromethane acts as a catalyst, increasing the burn rate of the fuel blend to produce more power. The more nitromethane that is used in the fuel blend, the faster the fuel can burn, letting the engine run at higher rpm. The big percentage number you see on a bottle of fuel is its nitro content, which generally ranges from 10-40%. For all-around use, 20% nitro is the most popular choice. Nitrometane and methanol are sourced by fuel makers rather than manufactured, so different brands don’t lay claim to unique or better nitrometane and metanol. However, the conditions in which these materials are stored and mixed greatly affects fuel quality. Byron Originals fuel blending facilities were designed and built solely for the production of model engine fuel and use processes engineered to assure high quality is maintained throughout the manufacturing process.
Lubricants are an integral part of nitro fuel recipes, since our 2-stroke engines don’t have oil-filled crankcases and instead rely on lubricants mixed into the fuel to keep the internals running smoothly. Since early days of fuel-powered models in the mid-20th century, oil from the castor bean has been used as a lubricant in nitro fuel. It is resistant to breaking down at high temperatures, a desired quality in a 2-stroke fuel. However, it can leave a gummy residue. Byron Fuels developed a castor oil that provides superior lubrication yet does not leave the negative byproducts of standard castor oils. Byron Fuels use a blend of natural castor and synthetic oils in their fuels, although there are a few pure synthetic blends available. Byron Synthetic is a proprietary lubricant package with fortifications in both corrosion protection and high pressure lubrication (load carrying capacity). Only Byron Fuels contain this superior synthetic formulation. The percentage of lubricant in the blend depends on the purpose of the fuel; premium race fuels have less lubricant, typically in the 8-12% range, than fuels designed for engine longevity, which can consist of upwards of 20% lubricant. The reason for this is that with less lubricant in the blend, there can be more methanol, which makes for a more powerful combustion process, but with increased engine wear. Racers will gladly sacrifice piston and sleeve life for greater performance, but if you want your engine to last longer between rebuilds, choose a blend with a higher percentage of lubricant.
WHAT MAKES ONE BLEND DIFFERENT FROM ANOTHER?
Lots of companies offer nitro fuels for cars, and every fuel company has a variety of blends and different quality of components in their product lines. While the ingredients are pretty basic, the differences lie in the lubricant component. Although the amount of lubricant in a blend is usually stated right up front, every manufacturer has its own recipe for the chemical components used to make the lubricant. While most still depend on some castor oil, especially for its premium fuels, the synthetic portion of the mix is proprietary and the lubricant requirements for a race fuel are different than for a general-running fuel. A race fuel should burn cleanly and expel thoroughly so that more fresh fuel can come in for the next combustion cycle. The fuel you choose for fun-running should have sufficient protective lubrication to minimize engine wear. That doesn’t mean that you can’t run a 40% nitro blend with 9% lubricants in your backyard — you’ll just be replacing the engine’s piston and sleeve more often.
SO, WHAT SHOULD I BUY?
The first guideline for your fuel selection should be what your engine manufacturer recommends. Usually, the guidelines are for engine longevity, not for performance. Next, see what fuels are most popular at your local hobby shop. The fuels that sell the most are going to be replenished most often, so you’re more likely to get fresh fuel. Popular brands like Byrons are restocked because drivers use the fuel and come back for more–that’s the best endorsement of quality. Next, check with the other racers at your track running similar vehicles and engines to yours, and use their experience as a guide in selecting the blend that works best.