Fuel is fuel, right? After all, regardless of the brand you choose it's all leaded race gas, right? Wrong! Fuel is not just fuel. Fuel is the food for your engine. As silly as that might sound it couldn't be more true. And just like the food we eat, the gas you put into your race car can affect the engine in ways both good and bad. Consider this, how many times have you eaten a monster, fat-laden meal only to feel pretty bad afterward, almost like you need a nap? Garbage in, garbage out-and the same holds true for your race car. Put in substandard fuel or the wrong fuel and you'll have problems . . . guaranteed.
So How Do You Go About Choosing the Right Fuel?
First off unless you run a series that requires a specific fuel be used by all teams such as ARCA, NASCAR, or Pro Cup, your fuel choice is yours and yours alone. There are some sanctions that have a fuel sponsor for their series and require teams to buy a specific amount, say 5 gallons, per race. In cases like these, teams that do not want to run the sponsor's fuel will sometimes buy that set amount for a friend's team, thereby fulfilling their obligation to the series while leaving themselves free to run their chosen fuel. But in the end what you put in your tank is up to you.
Between the two largest racing fuel suppliers in the U.S. there are more than 30 different fuel blends just for oval track racing applications. More than 20 of those belong to Texas based VP Racing Fuels.
Chart A: This chart shows...
Chart A: This chart shows the fractional distillation of crude oil. At the bottom is where you'll find greases and heavy lubricants. Near the top (Light Straight Naphtha) is where you'll find the origins of gasoline. -Courtesy Carnegie Mellon University
Why so many different fuel blends? "Why do you have so many camshafts?" quipped VP's founder Steve Burns when asked that question. "Seriously, it suits the application. Because of growing up in an environment where 2 horsepower means something, I got to develop fuels with some of the best engine guys in the world. It taught me that one or two fuels don't fit every application. And that has become our philosophy."
Obviously to find out the type of fuel that is best for your car or application you need to consult both your engine builder and your chosen fuel manufacturer. VP has a nifty color coded icon system on its website that identifies the different fuels based on your racing application (off-road, drag, circle track, and so on). Beyond that, specific decisions such as octane rating can be handled by talking with your engine builder as well as VP's Technical Support Department. But before you do there is some information that you'll want in your back pocket.
Motor Octane Versus Research Octane
There are actually two different ways to rate the octane of fuel; Motor Octane rating and Research Octane rating. Simply put, the Motor Octane rating of a fuel is arrived at through a test that involves putting an engine (and the fuel) through a heavy load test that simulates "severe" driving conditions such as hard acceleration. On the other hand, the Research Octane test simulates cruising conditions with lighter loads and less stress. The Research Octane rating will always be higher since the test conditions are generally milder. Think of it this way, easier test . . . better grades.
The most economical way to...
The most economical way to purchase your race fuel is a 55 gallon drum, just be sure you have a good pump to get it into your containers. -Rob Fisher
Because the Motor Octane rating test simulates heavy load conditions that is the rating we, as racers, want to pay closest attention to; highway cruising is just something we don't do unless of course we're heading to the track. VP has even modified its in-house motor octane test rig to more closely simulate race conditions rather than just relying on standard heavy load testing. Bottom line: Always look at the Motor Octane rating.