About 27 different basic blends of gasoline are created for specific regions of the country. The various blends are based on climate, environmental and political requirements in those particular regions. The blends might contain anti-icing agents for the northern states in the winter or anti-condensation or anti-algae growth agents in fuels sold in the south during the hot summer months. Yes, things can grow in your fuel if it sits around in the heat long enough.
Fuel can also lose its potency over long periods of time if it is not stored properly. How many of you have shoved the lawn mower into the back of the garage or shed after the last lawn cutting in the fall and then drug it out the next spring only to become frustrated when it wouldn't start? You open the gas tank and get that funky smell of stale gas that has been left in the mower since the previous fall. All of those regionally blended fuels with their special additives can gum up (varnish) the jets in your mower as the fuel evaporates over the winter. Want to keep that from happening in the future? Just fill the tank with racing fuel the last time you use the mower in the fall and it will fire right up in the spring. Why? Because racing fuels do not have all of those special additives that many of the passenger car fuels do. Racing fuels are formulated to make horsepower and nothing else.
So how do you make horsepower with racing fuel? Remember the "O" words -- octane and oxygenates. Basically the more fuel and air mixture you can push through an internal combustion engine, along with higher RPM's and a higher compression ratio, then the more horsepower you can generate with it. Boost the octane rating (better living through chemistry) and raise the oxygen level in the fuel and you will get more horsepower per gallon. Sounds easy enough doesn't it. It actually is almost that simple except for the 800-pound gorilla named NASCAR that is looking over your shoulder if you are a Nextel Cup racer. NASCAR has this concept that they should control what type of fuel blend will be run each weekend and who, if anybody, adds anything to it. In fact, they are extremely adamant that nobody should mess with the fuel supplied to the tracks each week by Sunoco. It is one of NASCAR's major "No-No" areas in the Nextel Cup rule book.
So we've established that NASCAR, through Sunoco, controls the blend of racing gasoline allowed to be used in Nextel Cup and we all know that racers would never cheat so that's the end of this article -- right? Wrong Nitrobenzene breath!
Let's do some Racing Fuels 101. Gasoline is a form of liquid hydrocarbon (why don't they just say oil?) that has been refined or "cracked" through a process whereby complex organic molecules such as heavy hydrocarbons are broken down or distilled into simpler molecules to create lighter hydrocarbons. The rate of cracking and the end product are strongly dependent upon the temperatures and the catalysts that are applied during the cracking process.
NASCAR officials, being the stuffed shirts that they are, specify in their rule book that their fuel must be "automotive gasoline" and "limited to liquid hydrocarbons only". That eliminates our using exotic words such as ethanol, methanol, ether and a whole myriad of other "oxygenates" ending with "oxide" in our description of NASCAR fuels because they are forbidden as are octane boosters and other methods possibly available to the teams to raise the potency levels of the fuels.
Sunoco's 260 GTX Racing Gasoline is the official fuel of NASCAR. Sunoco 260 GTX is an unleaded racing fuel that contains no oxygenates and no metal additives (lead). It also does not contain any ethers or alcohols such as ethanol or methanol or any other oxygenates. It is a disgustingly boring fuel as fuels go. No propylene oxide, no acetone, no nitro propene no nitrobenzene, no tetraethyl (whatever that is -- maybe the fossil of an extinct flying dinosaur? Actually it is a form of lead.), no ethanol, no methanol, no ether, no alcohols, etc. There is a whole list of "chemicals" and "chemical compounds" that could make 260 GTX a lot more sexy and exciting -- I'm getting a headache just trying to read and pronounce most of them -- but NASCAR wants its fuel to be pure and chaste. I asked the engineers at Sunoco to give me a breakdown on 260 GTX but they graciously declined to provide any comments concerning NASCAR fuels for this article. So I will endeavor to enlighten you with my own researched definitions below.
What is octane? It is the fuel's measured resistance to burn. The higher the octane the easier the fuel can withstand higher temperatures and compressions without igniting which could cause pre-ignition or spark knock. The octane number is the numerical rating indicating the anti-knock properties of a particular fuel blend. Many experts say that octane has nothing to do with horsepower or torque because octane is a "method of measurement" or "rating" and not a "thing." I understand that gasoline is a blending of hydrocarbons and selected chemicals that make specific grades for which one method of measuring them is the "octane rating." But if someone can educate me on how a longer burn time during the ignition cycle does not create a more sustained thrust (thus producing more power) when it drives the piston downward for a longer period of time then please explain that to me. I will be in my room at the asylum.
Nextel Cup engines have a 12-to-1 compression ratio and burn unleaded fuel. Although past compression ratios and octane ratings have been higher, the current octane rating is 99 from what I can determine. That is one reason you might see flames coming from the engine's exhausts at night when the drivers let off going into the corners. Special note here: if the flames coming out of the exhaust have a bluish hue in color versus an orange/red/yellow hue then it ain't pure 260 GTX being burned in that particular race car. If I know that then you can rest assured that NASCAR knows that so whoever produces a blue flame during the race will probably feel even bluer when the race is over and the inspection process begins.
What is a compression ratio? It indicates the amount that a volume of a fuel and air mixture can be compressed. For example, a 12-to-1 compression ratio means that a particular volume of fuel and air mixture will be compressed to one-twelfth of its original volume.
Oxygenates? Any fuel additive that increases the amount of oxygen contained within the fuel. You get more "kick" when you mix gasoline with a purer form of oxygen than you do when you mix gasoline with regular air so if you can introduce oxygen (in some chemical form that releases it during the burn cycle) then you can boost the amount of oxygen in the fuel-air mixture without significantly increasing its overall volume. That allows you to feed more fuel into the fuel-air mixture and gain horsepower in the process. More fuel without more oxygen can be a negative but more of both is a positive. That is one reason why NASCAR forbids oxygenates in their fuels.
Nextel Cup teams are using unleaded fuel for the first time this season. Lead helps to lubricate the engine which allows it to run cooler. Some teams have adapted more quickly to the new unleaded blend while others, such as Dale Earnhardt, Inc., have had their problems with blown engines. I hate to burst the bubbles of the conspiracy theorists who believe that the evil step-mother has been sabotaging Dale Junior's engines but it is more likely that the DEI engine builders have not solved the problems that switching from leaded gasoline to unleaded gasoline presented to them.
Over the years competitors have tried just about every trick in the book to boost the octane rating and oxygen content of the fuel. NASCAR has managed to catch all of them in some way or other so it has become very difficult for a team to gain an advantage in a race. Some have found ways to gain an edge in qualifying, which has become more important because track position has become so critical.
They have even tried to pack the fuel lines and carburetor in ice to cool the fuel and make it more dense which would allow more fuel to flow into the engine. However, NASCAR has pretty much caught up with most of the ways teams were gaining an advantage in qualifying as well. Michael Waltrip learned that painful lesson in February at Daytona. Nitrous oxide would provide an advantage in qualifying because of the short duration the car is on the track. However, it would not be an advantage in a race unless the driver could activate it in some way to have a short burst of power to pass another competitor. That has been done in the past but I seriously doubt that it would get past NASCAR with today's tight inspection process. Add the fact that particular engine configurations will perform best on compatible gasoline blends and you may or may not gain an advantage by messing with the dictated blend that is to be used in the race.
That leaves the teams with the option of trying to get as much air to the carburetor as possible to mix with as much fuel as possible. That is no easy task because they expend a considerable amount of time making the cars as aerodynamically slick as possible, which causes the air to flow over the car and past the carburetor intake area. It can be a catch 22 for the engineers. I guess that is why they get paid the big bucks.
Well, now you know more than you may have ever wanted to know about racing fuels. The next time you go to a race you can drag your lawn mower along with you and sneak it into line when the teams are filling up their fuel cans at the Sunoco pumps before the race. That way, even if your favorite driver doesn't win, you will at least keep from being frustrated next spring when you prepare to mow the back 40. One pull and that old mower will fire up just like a Nextel Cup car.