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At a common gas pump, there are four, maybe five, different options presented to the buyer. Drivers can choose from regular unleaded with 87 octane, midgrade with 89 octane, premium with 91-93 octane, diesel, and possibly E85 flex fuel with ethanol. At certain gas stations, however, there is another option: racing fuel.

Regular gasoline and racing fuel cannot be used and discussed interchangeably because they have entirely different makeups. Not even every type of racing uses the same type of fuel, as each series and sport has vastly varied demands and requirements. And pro tip: Do not put this in your regular car, that Toyota Camry XLE is not part-for-part identical to the one you see on NASCAR tracks.

To better understand why certain cars require special types of fuel and how those fuels are formulated, Car Bibles’ editors need to get a bit scientific and break down their components. Fire up the coffee pot and warm up those biscuits, it’s time to talk gas.

What Is Racing Fuel?

In its simplest definition, racing fuel is a general classification for the type of fuel used in and by racecars, race motorcycles, and other powersports vehicles in various professional and amateur racing series and events. Though, technically anybody could use it given the right set of circumstances and engine modifications. 

Dozens of types of racing fuels exist and primarily use formulas that include conventional gasoline, ethanol, methanol, nitromethane, or nitrous. Leaded fuel, which was heavily used in the past, can no longer be purchased for on-road use, but it is still available in some places for racecars.

Why Do Different Racecars Use Different Racing Fuel?

In short, because the racecars use different styles and types of powertrains, those powertrains have different advantages and limitations to exploit and work within, the races are different, and the goals of those races are different. 

Certain race series have specific levels of power required or allowed. And to work within all of these parameters, it’s up to the engineers to figure out the perfect mixture of air, fuel, spark, and timing to accomplish perfect combustion. Weight, gravity, octane, temperature, air flow, oxygen levels, energy potential, burn rate, fuel state, and various other aspects all matter. 

The pit crew puts new tires and fuel into an Indycar.
Indycars use giant hoses to refuel during pit stops. (Photo: Chevrolet)

Racing Fuel Properties To Consider

Get the flashcards ready, these terms will help you understand racing fuel and gas in general.

Octane

Octane, which has a chemical formula of C8H18, is a hydrocarbon that comes from processing petroleum. An octane rating, the number attached to the gas at the gas pump, is a measurement of a fuel’s ability to resist engine pinging. In general, a higher octane rating means the fuel is more stable, and various products like lead are added to fuel to increase its octane rating. Racing fuels typically have high octane ratings. 

Specific Gravity

In general, specific gravity is a substance’s density compared to a standard, which in the case of fuels is water. Thus, as stated by Sunoco, specific gravity can be determined by dividing the fuel’s density by the density of water. For example, Sunoco Supreme weighs 5.95 pounds per gallon, so 5.95 divided by 8.325 equals 0.715. The specific gravity of Sunoco Supreme is 0.715. This can make a difference in how quickly the fuel burns and could affect certain vehicle fuel settings.

Burning Rate

Burning rate is a measurement of how quickly a fuel releases its energy. This is important to know for fuel and combustion timing.

Latent Heat of Vaporization/Cooling Effect

Latent heat is the energy a fuel absorbs or releases while it’s changing states. The latent heat of vaporization is the energy when something is vaporized or vapor is condensed. Fuel with high latent heat can help its cooling effect.

Energy Value

The energy value of a fuel represents its potential energy. It is measured in British Thermal Units (BTU) per pound.

Jimmie Johnson's Lowe's NASCAR stops in the pits.
Sunoco provides the official gas of NASCAR. (Photo: Chevrolet)

Common Components of Racing Fuel

The ingredients list of your racing fuel will most likely show one or more of these substances: 

Gasoline: Yes, spec gas is still used to varying degrees in racecars.

Tetraethyl Lead (C8H20Pb): Though restricted from on-road use today, lead can still be used in racecars as an effective octane booster that can aid in allowing increased compression.

Ethanol (C2H5OH): Ethanol, or ethyl alcohol, is made from biomass like corn or sugar cane. It has a higher octane rating but has less energy than gas and is often used in gasoline blends.

Methanol (CH3OH): Methanol, or methyl alcohol, is a biofuel that is used like ethanol, in that it can be burned alone or in a fuel mixture. It is commonly used in supercharged dragsters. 

Nitromethane (CH3NO2): Nitromethane is a product of combining propane and nitric acid. It has lower energy value than regular gas, but it can operate without much atmospheric oxygen. With combustion, it produces extremely high levels of energy and performance, but it is equally as hard on the engines, which is why they have to be rebuilt so frequently.

Nitrous Oxide (N2O): NOS, or nitrous, is added to an engine at the same time as the primary fuel. When it’s heated up, the nitrogen and oxygen particles break apart and instantly introduce more oxygen to the engine. That extra oxygen helps burn the fuel, which creates more boom and more power.

What Fuels Do Common Racing Series Use?

Here are a few of the types of fuels used in top-spec racing.

NASCAR: Sunoco Green E15 (up to 15 percent ethanol)

INDYCAR: Speedway E85 fuel (up to 85 percent ethanol)

NHRA Top Fuel: Nitromethane

NHRA Top Alcohol: Methanol

Formula 1: F1 has requirements, “intended to ensure the use of fuels that are composed of compounds normally found in commercial fuels and to prohibit the use of specific power-boosting chemical compounds.” Those specifications and requirements can be found starting in article 19.1 in the FIA’s technical rules and regulations booklet.

What Is Racing Fuel and How Is it Formulated?
VP Racing Fuels and Sunoco are two of the most popular racing fuel brands. (Photos: Sunoco and VP Racing Fuels) Nikhil Dhanani

The Racing Fuel Questionnaire

Car Bibles answers all of your burning questions.

Q: Can you put racing fuel in a regular car?

A: Do not put racing fuel in your regular car. It is not designed to run on racing fuel, so the result could be damaged car parts.

Q: What is racing fuel called?

A: There is no one specific name or brand for all racing fuel. Two of the most well-known brands, however, are Sunoco and VP Racing Fuels.

Q: Does higher octane mean more power?

A: Not necessarily, it depends on the car, the engine, the tune, and the equipment.

Q: Does high octane fuel last longer?

A: No, the octane rating does not determine how long your fuel will last.

Q: Where can I buy racing fuel?

A: Racing fuel is not readily available at every single gas station, so you’ll have to do an online search to find nearby locations where it’s sold. Sunoco and VP Racing Fuels would be good places to start.

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