While most people aren’t too concerned with what fuel they put in their vehicles, the same cannot be said for car enthusiasts and racers. Fuel and air are key components in an internal combustion engine and whether you have a high-performance street car or a full-tilt race machine, having the right fuel can ultimately make a big difference. We talked to Brad Horton, regional sales manager for VP Racing Fuels, to get a basic understanding of performance fuels, the terminology involved, and what some of the options are for a number of different applications.
Using the optimum fuel for your vehicle is another way to get the most horsepower and torque out of any internal combustion engine, whether it is your classic muscle car, a UTV, a motorcycle, a race car, or whatever. Horton told us that he often finds customers are confused about all of the different blends that VP Racing Fuels has to offer, and so it’s best to begin by asking the customer questions.
“We get a lot of questions and people often say, ‘You have so many different fuels, I don’t know what to choose.’ The reason we have so many is the reason we are successful—we have a fuel for every type of racing,” Horton said. “In a lot of applications, the consumer will get the choice wrong. They will get one that will work, but it might not make the best power, so one of the first things I do is ask them to tell me about what they’re doing. Is this a late-model car with O2s and catalytic converters, or is it an old muscle car with none of that stuff. Is it turbocharged, blown, or naturally aspirated? What sort of compression ratio does the engine have? What are you doing with it? A road course has different needs than a drag car.”
Horton explained that people should get use to the idea that racing fuel is a performance part.
“It’s no different than a camshaft or a set of pistons,” said the 29-year veteran of VP Racing Fuels. “I can’t tell you how many times people have called and just ask for the highest octane fuel. More than likely, the highest octane is not what they need. They often relate octane numbers with the performance of the fuel, but that’s not necessarily the case, and most of the time it’s wrong. Octane is just a number assigned to a fuel to show how well the fuel resists detonation on an octane machine.”
According to Horton, picking a fuel is far more involved.
“You have things involved like burning speed that need to be considered. A high-rpm motorcycle engine benefits more from a faster burning fuel versus a lower rpm, big-cube engine that benefits from a slower burning fuel.”
Likely the first decision to be made depends on whether or not the vehicle employs catalytic converters and oxygen sensors. Leaded fuels can damage both of these items, which can cause a myriad of issues. These days, oxygen sensors are used to control the engine calibration in late-model cars and some aftermarket applications, and if the sensor reads poorly or not at all, your engine is not going to run optimally. Damaged catalytic converters can result in costly repairs, which could have simply been avoided by putting the correct fuel in your vehicle from the start.
Unfortunately, there are customers that throw caution to the wind and run leaded fuel in emissions-equipped vehicles, but there’s no reason to take chances like that when companies like VP Racing Fuels offer products that give you the increased performance you’re looking for without the harmful consequences.
A lead-free fuel commonly used in higher-performing street cars these days is E85, which is often available right from the pump at the local gas station. E85 has become the hot ticket for street cars due to its high octane rating—and thus resistance to detonation—and relatively inexpensive cost, but the version you get at the local pump station can be inconsistent, with the government allowing for over a 20 percent swing in the mixture. While some engine management systems can compensate for the changes, having inconsistent fuel means having inconsistent performance.
“They go to wherever they find it and oftentimes it’s a 60-percent blend,” Horton said. “They should consider our X85 when they are going to take their street car on the race course, which is always 85 percent, that way it’s always the same.” The X85 also has racing fuel for the 15 percent part instead of pump gas. VP also carries 100 and 101 octane street-legal fuel, which is perfect for your car when driving public roads.
Going in the other direction, it’s been a common thought that old-school muscle cars needed leaded fuels due to older products used in the engines, as well as to stave off detonation in the higher compression engines. According to Horton, they see fewer and fewer issues with using unleaded fuels in these engines, as many of them have been rebuilt with hardened valve seats and newer components that work well with unleaded fuels.
“It used to be that you needed leaded fuel for classic muscle cars. They had lots of compression and normal pump gas can’t necessarily stop the detonation. The flame front gets out of control in their inefficient combustion chambers with high compression, then they detonate and tear the motor up.
Another thing Horton pointed out was that classic muscle cars or show cars often don’t see a lot of use, and having an ethanol-free fuel in the tank like their unleaded C9 or leaded 110 lasts much longer and will save you a lot of trouble.
“Ethanol and methanol are hydroscopic and will absorb water from the air through the tank vents and trap minute particles of water,” Horton explained. “Pump gas is manufactured to be consumed, not to sit for long periods. We built a whole business around how terrible pump gas is. This line of fuels is called SEF, which stands for Small Engine Fuels, and are designed for mowers, generators, weed eaters or any small equipment that will go bad if you let pump gas sit in them for any length of time.”
Getting into the more serious racing side of the spectrum, competition engines may require something even further specialized, and this is where things like oxygen-bearing compounds come in.
“Many people don’t know or don’t understand what oxygen-bearing compounds are,” Horton told us. “They are compounds that we put in some fuels to make a little more power. Q16 is an example of that. There are a number of different chemicals we use that are considered oxygen-bearing—they have oxygen in their chemical makeup. If you look at a naturally aspirated engine, it can only get so much air in the combustion chamber. An oxygenated fuel will drag more oxygen into the combustion chamber via this chemical, which will lean the motor out, so you have to richen the mixture, which in turn increases power by creating more energy through the combustion process. These oxygen-bearing fuels are optimal for NA (normally aspirated) classes—on a 1,000hp motor, you might get another 10-15 horsepower, and in some applications up to 25 hp.”
As Horton explained, though, oxygenated fuels aren’t just for naturally aspirated engine combinations, as certain rules may limit boost pressure either electrically with a boost management system or mechanically by the physical size of the power adders.
“We often recommend Q16 or C16 for blower and turbo applications. Q16 is highly oxygenated, and they might be pushing the turbo boost to the max, and want more power via the added oxygen content.”
Aviation Fuel—It’s for the Planes
Aviation fuel or AvGas has been a popular fuel for enthusiasts, but aside from the higher octane rating and having lead in its chemical makeup, the fuel design parameters are far off of what you would look for in an automotive application.
“One of the biggest problems we run into is people using aviation fuel,” Horton said. “It is good fuel for airplanes, and it’s mandated by the government to meet a very stringent set of tests. They hold 100-octane, low-lead fuel at extremely tight tolerances. It is designed for a horizontally opposed, air-cooled, big-cylinder, slow rpm engine that sits at a certain rpm range and does not change for hours. You might be 2,700 rpm at take off and when you get up to cruise, you back it off to 2,400-2,500 rpm—it’s blended in the wrong proportions for higher-rpm applications. The burning speed of the fuel is way too slow. It has less lead per gallon than most leaded racing fuels and is designed for an application that likely only has an 8:1 compression ratio as most aviation engines have.
If you look at fuel as a performance part like Horton says to, then using a product designed for a very different application probably isn’t your best bet.
“It’ll burn in your car engine, but is it the most efficient? No.”
For a starting point to the conversation of which fuel to use, we asked Horton to give us some ballpark recommendations for several applications. It should go without saying that these are rough estimates for general applications and that you’ll want to talk with a VP representative to ensure you’re choosing the optimal fuel for your specific application.
For late-model street cars, use VP’s street-legal 101 or 100 for on-road performance, and for competition or off-road uses, Motorsport 109 is a popular choice that is a highly oxygenated, unleaded fuel. According to Horton, X85 might be an option depending on boost pressure.
Often the backbone of racetracks and races everywhere, naturally aspirated bracket cars can surely benefit from a race fuel, with Horton looking to non-oxygenated fuels such as VP110, C12, X14, or X16. Oxygenated options include VP113 or Q16.
Taking a look at high-rpm, naturally aspirated engines, C14 and C25 are non-oxygenated fuels originally developed for NHRA Pro Stock, but are still capable in today’s applications. If you want to go the ethanol route, X85 and X98 are ethanol blends that could work in this situation.
Similarly, C16, C23, X16 as well as C25, are recommended for use with nitrous oxide applications.
“One thing to consider about nitrous applications is that the nitrous oxide will kill an engine in a second if not used properly, so it’s important to consider the characteristics of the fuel you’ll be using,” Horton said.
Opposite of nitrous is the high heat generated by boosted applications. Increased manifold pressure results in higher intake temperatures, so choosing the right gasoline or methanol fuel can make a big difference.
“C16 works really well in a high-heat situation and can withstand temperature really well,” Horton said. “Turbos and blowers create heat!”
While this information is enough to get your brain thinking, you’ll want to reach out to VP Racing Fuels, which has a staff waiting to talk with enthusiasts and racers to help them choose the right fuel.
VP Racing Fuels
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