Sunoco E85-R 99 Octane Race Fuel

Sunoco E85-R 99 Octane Race Fuel

Consistent 85% Ethanol Unleaded Racing Fuel for E85-Compatible Fuel Systems

Sunoco E85-R is an unleaded racing fuel blended to consistently contain 85% ethanol by volume. The remaining fuel is made from highly refined racing hydrocarbons to provide greater consistency and stability than variable conventional E85 blends.

E85-R is highly oxygenated, containing approximately 29% oxygen by weight, and requires significantly greater fuel flow than conventional non-oxygenated gasoline. Its stoichiometric air/fuel ratio is approximately 9.8:1, so engines must be equipped with an E85-compatible fuel system and calibrated specifically for high-ethanol fuel.

Sunoco lists E85-R at an estimated 99 Anti-Knock Index (R+M)/2. Because of the fuel's high oxygen content, conventional ASTM octane test methods cannot measure it in the same way as traditional gasoline racing fuels.

Key Features

• Consistent 85% ethanol by volume
• Estimated 99 (R+M)/2 Anti-Knock Index
• Unleaded racing fuel
• 29% oxygen by weight
• 9.8:1 stoichiometric air/fuel ratio
• Highly refined racing hydrocarbons in the non-ethanol portion
• Pale green color
• Does not contain metallic additives
• Compatible with oxygen sensors
• Designed for fuel systems specifically built for E85 blends
• Shelf life exceeds one year when properly stored
• Intended for off-road and racing applications

Consistent 85% Ethanol Content

One of the primary advantages of Sunoco E85-R is fuel consistency.

Conventional E85 composition can vary depending on the fuel source, season, and location. Sunoco E85-R is blended to consistently contain 85% ethanol, helping racers and tuners maintain a more repeatable fuel calibration from one container to the next.

The non-ethanol portion is made from highly refined race-fuel hydrocarbons selected for stability and consistency.

Estimated 99 Octane Rating

Sunoco lists E85-R with an estimated 99 Anti-Knock Index (R+M)/2.

The value is identified as an estimate because the conventional ASTM laboratory methods used to determine gasoline octane cannot accommodate the unusually high oxygen content of E85-R.

For engine setup and tuning, use the published fuel properties together with recommendations from the engine builder, tuner, or fuel-system manufacturer rather than treating E85-R exactly like a conventional 99-octane gasoline.

E85-R Requires Increased Fuel Flow

E85-R is not a drop-in replacement for conventional gasoline race fuel.

Its high ethanol and oxygen content means the engine requires substantially more fuel volume. Sunoco E85-R has a stoichiometric air/fuel ratio of approximately 9.8:1.

Fuel-system components must be sized and calibrated accordingly, including:

• Fuel injectors
• Fuel pumps
• Fuel rails
• Fuel-pressure regulators
• Carburetors
• Fuel lines
• Seals and O-rings
• Fuel cells and tanks

Consult your fuel-injection system supplier, carburetor manufacturer, tuner, or engine builder before changing fuels.

Racing Applications

Sunoco currently identifies E85-R for racing applications including:

• Drag racing
• Asphalt oval
• Dirt oval
• Rally
• Road course
• Turbocharged engines
• Supercharged engines
• Nitrous applications
• Truck and tractor pulling
• Other off-road racing applications where E85 is permitted

The engine and complete fuel system must be compatible with high-ethanol fuel.

Fuel-System Compatibility

E85-R should only be used in fuel systems specifically designed for E85 blends.

Ethanol can interact differently with elastomers, plastics, coatings, metals, and fuel-system components than conventional gasoline. Before use, verify compatibility with the manufacturers of the fuel pump, injectors, lines, seals, fuel cell, carburetor, and storage container.

Oxygen Sensors and Metallic Additives

Sunoco E85-R does not contain metallic additives and is identified as compatible with oxygen sensors.

This makes it suitable for many modern race-engine management systems that rely on oxygen-sensor feedback, provided the entire fuel system and calibration are compatible with E85.

Storage and Shelf Life

Ethanol fuels can absorb moisture from the atmosphere, so proper storage is important.

Store Sunoco E85-R:

• In a dark or opaque container
• In a tightly sealed container
• At a stable temperature
• Away from prolonged exposure to air
• In a container specifically compatible with E85 and high-ethanol fuel

When stored under these conditions, Sunoco lists a shelf life of more than one year.

Current Technical Properties

Typical properties are provided for reference. Sunoco identifies the 99 (R+M)/2 octane value as estimated because conventional ASTM octane test methods cannot accommodate the high oxygen content of E85-R.

Racing Use

Sunoco E85-R is intended for off-road and racing applications only. In California, it is legal only for racing vehicles used in sanctioned racing events.

Frequently Asked Questions

What is Sunoco E85-R?
Sunoco E85-R is an unleaded racing fuel blended to consistently contain 85% ethanol. It is designed for race engines and fuel systems specifically configured for E85.

Is Sunoco E85-R really 85% ethanol?
Yes. Sunoco blends E85-R to consistently contain 85% ethanol by volume.

What octane is Sunoco E85-R?
Sunoco lists E85-R at an estimated 99 Anti-Knock Index (R+M)/2.

Why is the 99 octane rating estimated?
E85-R contains so much oxygen that conventional ASTM gasoline octane tests cannot measure it in the same way as traditional gasoline fuels. Sunoco therefore identifies the 99 AKI rating as an estimate.

What is the stoichiometric air/fuel ratio of E85-R?
The published stoichiometric air/fuel ratio is approximately 9.8:1.

Does Sunoco E85-R require different tuning?
Yes. E85-R requires significantly more fuel flow than conventional non-oxygenated gasoline. Injector size, fuel-pump capacity, fuel pressure, carburetor calibration, and engine-management tuning may need to be changed.

What is the difference between Sunoco E85-R and pump E85?
Sunoco E85-R is blended to consistently contain 85% ethanol and uses highly refined racing hydrocarbons in the non-ethanol portion. Conventional E85 composition can vary, which can make precise racing calibration less repeatable.

Is Sunoco E85-R unleaded?
Yes. Sunoco E85-R is an unleaded racing fuel.

Does Sunoco E85-R contain metallic additives?
No. Sunoco states that E85-R does not contain metallic additives.

Is Sunoco E85-R safe for oxygen sensors?
Yes. Sunoco identifies E85-R as compatible with oxygen sensors when the fuel system and engine calibration are appropriate for E85.

Can E85-R be used in a gasoline fuel system?
Only if the entire fuel system is specifically compatible with E85. Pumps, injectors, hoses, seals, regulators, carburetors, fuel cells, and storage containers should all be verified before use.

How much oxygen does Sunoco E85-R contain?
The current 2026 technical data sheet lists approximately 29% oxygen by weight.

What color is Sunoco E85-R?
Sunoco E85-R is pale green.

How long does Sunoco E85-R last in storage?
Sunoco lists a shelf life of more than one year when the fuel is stored in a dark, tightly sealed, compatible container at a stable temperature.

Does E85-R absorb moisture?
Ethanol-based fuels can absorb moisture from the air. Keep E85-R tightly sealed and minimize prolonged exposure to atmospheric humidity.

Is Sunoco E85-R street legal?
No. Sunoco E85-R is intended for off-road and racing applications. In California, it is legal only for racing vehicles used in sanctioned racing events.