It seems everyone has a story about a racing friend who had a racing friend that somehow got away with hiding a nitrous bottle or an extra fuel container with nitromethane-laced fuel that helped them win races they wouldn't have otherwise. You've maybe even heard a few yourself. Odds are that many of these old stories are fabrications like the old "alligators in the New York sewers" urban legend, but more than a few are also likely true.

There are lots of other popular cheating stories that follow various themes in racing, but the illegal fuel stories are among the most popular because it actually is one of the easiest ways to squeeze more power out of your engine.

Of course, there are also lots of situations where your choice of racing fuel doesn't have to be shrouded in secrecy because it isn't prohibited by the rules. In fact, your fuel choice can be critical to the success of your racing program. We've already done research in Circle Track proving that a quality race gas can provide quite a bit better performance over standard pump gas even in low-compression engines because the companies that blend the pump gas are more concerned with protecting OEM vehicle's exhaust sensors, limiting hydrocarbons and cutting costs than they are the power potential of the fuel. Plus, pump gasoline blends will vary quite a bit from summer to winter, making tuning your carburetor that much more tricky.

But not all race fuels are created equally, either. In fact, because manufacturers of racing fuels do not have to take the "one size fits all" mentality, they can blend fuels specifically for certain engines or racing classes. One of the subcategories when it comes to different types of racing fuel is what's known as an oxygenated fuel. Oxygenated fuels can be either leaded or unleaded, have a wide variety of octane levels, and have many other characteristics. But almost all oxygenated fuels have some type of additives in the gasoline that have the right mix of ingredients in the chemical compound to create oxygen molecules when that compound is broken down.

This is the key to making extra power: The extra oxygen in the combustion chamber means you can add even more fuel, and when the two are burned the result should be additional energy pushing down on the piston. When done correctly, the extra oxygen molecules also help burn the existing fuel more completely. For years a compound known as MTBE was a common additive oxygenated fuels, but MTBE has been proven to be quite dangerous to both the environment and ourselves so it's rarely found in fuels anymore. Since the demise of MTBE, ethanol and a chemical called propylene oxide have become two of the more popular attitudes to create oxygenated fuels. But since there is no requirement to print an ingredients label on the side of your fuel can like you would find on a pack of Twinkies, it can be difficult to learn precisely what is in the fuel you are burning. Understandably, fuel manufacturers like to keep the exact recipe for the blends used in their racing fuels private.

Regardless, most of us are more interested in improving our results on the racetrack than we are retaking that high school chemistry class we slept through anyway. The truth of the matter is that in the right situations, and oxygenated race fuel can help a race engine produced significantly more power than the same engine own standard race gas.

Everett Bradham is the shop foreman for Willy's Carburetor and Dyno Shop in Mt. Carmel, Illinois. Willy's is one of the top carb tuners in stock car racing and is constantly improving its carburetors through rigorous research and development. Willy's offers its customers carburetors tuned specifically for racing with oxygenated fuel, so we asked Bradham about the benefits of racing with the stuff.

"We've tested with oxygenated fuels several times," he says. "And just recently we did a test with some of VP's fuels. We tested the VP113, which is an oxygenated fuel, against the VP-110, which is a very high quality standard race fuel. The VP113 is considered a 5-percent oxygenated gas, and we were running it on what you might consider a standard Street Stock motor with a two-barrel carburetor. We had to go up two jet sizes with the VP113 compared to the standard fuel and we saw a gain of around 10 horsepower.

"Then we tested VP's CHP race fuel, which is a 10 percent oxygenated fuel. We ran it on the same engine as the VP-110 and the VP113 and had to go up another two jet sizes, but we also saw a gain of around another 10 horsepower. So the stuff really does work. You won't see gains that good in a better engine with more efficient cylinder heads, but for that application with the Street Stock level engine that's pretty good power to be made."

VP's Freddy Turza explains that oxygenated fuels are most effective in stock-style or low compression engines because the oxygenated fuel blend helps the engine work more efficiently. "A lot of times when people hear 'oxygenated fuel' they think about cheating with nitromethane in the fuel. And that's not the case. There is a power-enhancing chemical blend that goes into the fuel but the purpose of it is to achieve better vaporization to equalize all of the runners in the intake manifold.

"Whenever you have to work with an inefficient combustion chamber, that's where this fuel is typically going to be the most helpful," he continues. "Like the CHP fuel we designed specifically for applications racing crate engines like the Chevrolet 602 or 604 engines. Those are typically lower compression engines and its efficiency is low because of restrictions in the carburetor, intake manifold, or the intake runners themselves. By increasing the efficiency of the fuel, you are able to help these types of engines generate more power."

The key with oxygenated fuels is that the performance gain isn't necessarily with the peak power numbers. Hendren Racing Engines in Rutherfordton, North Carolina, is a certified crate engine rebuilder for several series. Steve Hendren says that one of the biggest benefits of oxygenated fuels when it comes to crate racing is lower in the rpm range. "We've done extensive testing on oxygenated fuels versus standard race gas," he says. "On average, depending on the engine and the weather, you are looking at a gain of 7 to 10 horsepower versus standard race gas. And that's a big deal with a 602 or a 604 crate because they are all the same, so even a seven horsepower advantage is going to be significant on the racetrack.

"But the gains you can make with a fuel like this isn't simply a peak power number. Really, the main difference you will see is the low-end torque and the horsepower through the midrange. And that's pretty much where you want it anyway, because you don't pass too many guys going into the corner. Most of your passing is coming out of the corner, and that's where that extra low end torque is going to come into play."

One issue with oxygenated fuels is that you can't simply pour it into your fuel cell and expect an instant bump in both horsepower and torque. As Bradham mentioned, on the dyno the oxygenated fuel required bigger jets. The reason is simple: to make more power you have to burn more fuel. Simply increasing the jet size may work on the dyno, but we're racing cars, not engine dynamometers.