Are you a car owner who is unsure if using E85 fuel in your engine is a good idea? You’re not alone. The debate on if E85 fuel is bad for your engine has been ongoing for years, and many car owners are uncertain of its impact on their engine performance.

If you're running—or planning—a performance build, E85 changes more than just what you put in the tank. It affects injector sizing, fuel system design, and overall engine strategy. We’ll break that down so you can decide if it actually makes sense for your setup.

Many drivers are apprehensive about the potential effects that this alternative fuel source could have on their vehicles. To help dispel any uncertainty and give you sound advice, we’ve done the research to uncover the facts behind E85 fuel and what it means for your engine. We will provide the facts about E85 fuel so that you can decide if this alternative is the right choice for powering up your vehicle. 

Discover the answers to you pressing questions like:

• How much ethanol is present in a standard tank of gas?
• What type of engines require regular maintenance when using E85
• Which experts think this gasoline option provides better fuel efficiency than traditional gasoline. 

Get informed and get the detailed knowledge necessary to make an informed decision about bringing home some tanks filled with E85.

What is E85? 

E85 is a fuel made up of 85% ethanol and 15% gasoline. It is used in Flexible Fuel Vehicles (FFVs) that can run on any combination of ethanol and gasoline, up to 85% ethanol. The ethanol in E85 is made from corn, which is a renewable resource. FFVs have been available in the United States since the late 1990s.

The use of E85 has been growing in recent years. There are now over 9,000 fueling stations that sell E85 across the country. The number of FFVs has also grown, with over 16 million now on the road.

The primary purpose of developing E85 fuel was to reduce the amount of harmful emissions released into the atmosphere. The government believed that using a renewable resource as a fuel source would be beneficial for the environment and help to lower our dependence on foreign oil.

What are the economic benefits of using E85?

E85 also offers several economic benefits:

• Lower fuel costs due to lower taxes: E85 can cost up to 30% less than regular gasoline.
• Reduced maintenance costs: Since E85 is a cleaner burning fuel, it reduces the amount of carbon buildup on engines, resulting in fewer maintenance issues.
• Increased economic activity from local agriculture and biofuel production.
• Reduced dependence on foreign oil sources.
• It can be used in many existing vehicles without any modifications.
• Supports U.S. economy: Because ethanol is produced in the United States, using E85 helps to support the domestic economy.

Now that you know the basics of E85, let’s take a closer look at whether or not it is bad for your engine. 

Why Performance Builds Use E85

In performance applications, E85 isn’t used for fuel savings—it’s used for power and safety under load.

Benefits we see in the shop:

• Higher effective octane (knock resistance)
• Cooler combustion temperatures
• Ability to run more timing and boost safely

This is why turbo and high-horsepower LS builds frequently move to E85—but it only works when the fuel system is built correctly.

Is E85 bad for your engine?

The short answer is no. E85 has been tested and certified by the Environmental Protection Agency (EPA) for use in FFVs, which means that it is approved for safe use in these vehicles. In fact, many experts believe that using E85 can actually provide better performance than regular gasoline in certain models of FFVs.

It is important to note that E85 can require more regular maintenance than traditional gasoline. This is due to the higher level of ethanol in the fuel, which can cause corrosion and other issues over time. In addition, vehicles using E85 should be tuned up regularly for optimal performance and fuel efficiency. Regularly changing oil and spark plugs are essential to keeping your engine running in top shape. FFVs powered by E85 require no extra maintenance than those running on gasoline. 

As mentioned earlier, E85 allows for higher performance potential due to its octane rating and cooling effect—but it requires significantly more fuel volume than gasoline.

Most experts agree that, despite the advantages of E85, certain engines may not be able to handle its corrosive properties. Engines with higher compression ratios and materials that are sensitive to corrosion may experience increased wear and tear if operated on E85 exclusively. Mechanical parts such as fuel pumps, fuel injectors and pistons may be at risk of damage from the higher water content of E85.

For drivers who want to use a blend of both traditional gasoline and E85 in their vehicles, a "flex-fuel" system can be installed. This allows car owners to switch between fuels depending on what is more cost-effective or readily available. Contact our experienced professionals for more information on converting to a "flex-fuel" system.

Drawbacks to using E85

The use of E85 in your vehicle is not without its drawbacks. These include:

• Reduced power in certain FFV models: Some FFV models experience a decrease in power when running on E85. This is due to the lower energy density of ethanol compared to gasoline, which requires more fuel for the same amount of energy produced.
• Higher water content: Ethanol has a higher water content than gasoline, which can lead to corrosion or other damage in certain vehicles. To prevent this, it is important to make sure your vehicle is properly sealed and you are regularly monitoring the fuel tank for water buildup.
• Incompatible engines: E85 can only be used in FFVs and other cars designed specifically to run on a blend of ethanol and gasoline. Regular gasoline engines cannot use E85 without modification.
• More frequent maintenance: Your engine may require more frequent maintenance when using this fuel than with gasoline.
• E85 may not be as readily available in certain areas: E85 is not as widely available as regular gasoline, so you may have to travel farther distances to find a fueling station.
• Not as efficient as gasoline: This means that you need to use more of it to get the same amount of power. In fact, your car's fuel economy can drop by up to 30% when you switch to E85.
• E85 can damage your car's engine: Ethanol is a corrosive substance that can wear down your engine's components over time. Ethanol can also cause problems with your car's fuel system and ignition system.

Despite the drawbacks, many car owners believe that the benefits of using E85 outweigh the negatives. The lower fuel costs and reduced emissions can be very attractive for those looking to save money or be more environmentally friendly. Additionally, since E85 is a renewable resource, it helps to reduce our dependence on foreign oil sources and stimulates economic activity from domestic agriculture. 

 

What Most People Miss About E85

The biggest issue we see isn’t E85 itself—it’s running E85 on a fuel system that wasn’t designed for it.

E85 requires roughly 30–40% more fuel volume than gasoline.

That means:

• Larger injectors
• Higher capacity fuel pumps
• Proper line sizing

This is where most builds run into trouble—not because of E85, but because the system can’t support it.

Injector Sizing for E85 (Where Builds Go Wrong)

One of the most common mistakes is running injectors that were sized for pump gas.

On E85, that same setup will run out of injector much sooner, leading to lean conditions under load.

If you're unsure what injector size your setup actually needs, we break it down here:

What Injectors Do I Need? (Sizing Guide)

For E85 builds, we typically step into higher-capacity Bosch-based injectors with verified data, paired with a fuel system that can maintain pressure under load.

• Browse Injector Options for E85 Builds
• Fuel Pumps for High Horsepower
•  Fuel System Components

What vehicles can't use E85?

E85 is not suitable for use in all vehicles. Most notably, engines manufactured before 2001, and especially before 1990, may not be able to handle the unique properties of E85. This includes classic cars and some other older models that have been restored or modified. If you love older cars, be sure you know what to look for or consult a good mechanic before filling up with ethanol-based fuels.

Injector Maintenance Matters (Especially on E85)

Because E85 can attract moisture and carry contaminants, injector maintenance becomes more important over time—especially on vehicles that sit or aren’t driven regularly.

We offer professional injector cleaning and flow testing services to:

• Restore proper spray pattern
• Verify flow consistency
• Prevent drivability issues

This is often overlooked—but it makes a significant difference in long-term reliability.

Injector Cleaning Service

How to decide if E85 is the right choice for you

When it comes to ethanol fuel, there are a lot of choices available on the market. E10, E15, E85. What’s the difference? And more importantly, which one is right for you?

• E10 is the most common ethanol fuel blend and is made up of 10% ethanol and 90% gasoline. It’s approved for use in all cars built since 2001 and is available at most gas stations.
• E15 is an ethanol fuel blend that contains 15% ethanol and 85% gasoline. It’s approved for use in all cars built since 2007 and is becoming more widely available.
• E85 is a fuel blend that contains 85% ethanol and 15% gasoline. It’s only approved for use in flex-fuel vehicles, which are designed to run on either unleaded gasoline or E85.

So which one should you choose? Well, that depends on a few things, including:

• The type of car you drive: If you have a flex-fuel vehicle, then E85 may be the best choice for you. However, if your car is not designed to run on E85, then it’s best to stick with E10 or E15.
• Your budget: Generally speaking, ethanol fuel blends are cheaper than regular gasoline, so if you’re looking to save some money on fuel costs, then E85 may be the way to go.
• Your environmental goals: Ethanol fuel blends produce fewer emissions than regular gasoline, so if you’re looking to reduce your carbon footprint, then E85 may be the best choice for you.

Ultimately, the choice is yours. No matter which ethanol fuel blend you choose, there are benefits that come along with it. So take some time to research your options and make an informed decision that’s right for you and your car. If you have any questions, you can always reach out to our amazing team at Snake Eater Performance. We can guide you through selecting new spark plugs or our performance throttle bodies to maximize your vehicle's output.

If you’ve made it this far, you already understand that E85 isn’t “good” or “bad”—it’s a tool.

When the fuel system and injector setup are correct, it can significantly improve performance and reliability under load.

When they’re not, it creates problems quickly.

The key is building the system around the fuel—not the other way around.