How Much HP Does E85 Add? Understanding the Power of Ethanol Fuel

Are you wondering how much horsepower E85 can add to your engine? Ethanol fuel, also known as E85, is a popular choice for car enthusiasts looking to increase their engine's performance. With its higher octane rating and ability to support more boost through latent heat of evaporation, E85 can provide significant power gains over traditional gasoline. In this article, we'll explore how much HP E85 can add, its benefits and drawbacks, and how to make the most of its potential.

How Much HP Does E85 Add?

The exact amount of horsepower that E85 can add to your engine depends on several factors, including the engine's design, fuel system, and tuning. However, it's not uncommon for engines to see power gains of 5% to 15% when running E85. This means that an engine producing 400 horsepower on gasoline could potentially see an increase of up to 60 horsepower on E85.

How Does E85 Affect Engine Performance?

E85 is a fuel blend containing 85% ethanol and 15% gasoline.  BOOSTane’s E85 will comprise this ratio with its 15% gasoline being made up of a higher octane (~100) equivalent.  Whereas “E85 or FlexFuel” at the pump can legally be between 51% and 83% ethanol, with the remainder made up of gasoline, usually being somewhere closer to an 87 octane. It is obvious to see why it's important to understand the kind of E85 you are tuning with and using regularly

Compared to traditional gasoline, E85 has a higher octane rating, which means it can withstand more compression before detonating. This makes it an ideal choice for high-performance engines, as it allows for more boost and increased power output.

What Are the Benefits of Using E85?

Apart from the potential horsepower gains, there are several other benefits to using E85 fuel:

  • Lower cost: E85 is often cheaper than gasoline, which can result in significant cost savings over time.
  • Better for the environment: Ethanol is a renewable resource, and its use reduces greenhouse gas emissions and dependence on fossil fuels.
  • Safer to handle: Ethanol is less volatile than gasoline, making it safer to store and transport.

 What Are the Drawbacks of Using E85?

  • Reduced fuel economy: Because ethanol has less energy content than gasoline, you may experience reduced fuel economy when running E85.
  • Availability: E85 is not as widely available as gasoline, which can make it challenging to find a gas station that offers it.
  • Compatibility issues: Not all engines are compatible with E85 fuel, and you may need to upgrade your fuel system to handle it.
  • Ethanol is hygroscopic: E85 it phase separates over time by drawing water into the fuel.  This can cause harm to the engine’s internals through corrosion and drop in fuel quality.

Be very careful to maintain your E85 and not leave it in your tank or gas can for extended periods of time, without testing its quality.

How to Maximize the Potential of E85 Fuel

To make the most of the potential horsepower gains from E85 fuel, you'll need to ensure that your engine is properly tuned and that your fuel system can handle the increased demands. This may involve upgrading your fuel injectors, fuel pump, and tuning software to take full advantage of E85's benefits.


Can I run E85 in any car?

No, not all cars are compatible with E85 fuel. You should check your vehicle's owner's manual to see if it's safe to use E85 before switching to it.  

If you are wanting to use E85 as a power-adder and tune to it, consult your tuner/engine builder as AFR/Lambda, timing, boost, injectors, etc. will need to be addressed to optimize for your setup.

Does E85 require any special maintenance?

YES.  E85, while fantastic for making power, requires a lot of attention so as not to cause any issues down the road.

  • If you are getting E85 at the pump, test it to make sure it truly is E85, unless you have a flex fuel sensor.
  • Test the fuel if its been allowed to sit for any extended periods of time.
  • Monitor fuel lines and injectors to be sure they are up to spec to handle the high alcohol/high flow requirements.

Is it safe to mix E85 with gasoline?

Yes, E85 by definition is ethanol mixed with gasoline.  While it's not necessary to blend with gasoline outside of that unless you are trying to achieve a particular percentage, we do have customers that will augment their blend with BOOSTane PRO additive to increase the effective octane of poor quality octane E85 at the pump.


Ethanol and specifically E85 is an incredible fuel for the high performance enthusiast.  A fairly affordable, sometimes very available, and highly tunable fuel, E85 can bring a lot of opportunity to the grassroots and even professional racer.  

However, be sure to understand the drawbacks with using E85, as it is far from a “drop-in” fuel for anyone to use without consideration. If misused, E85 and any ethanol fuel (even E10) can cause issues through corrosion, inconsistent blends, and phase separation.  

E85 is a use with caution fuel that can either deliver big results  or bite you under the right circumstances.

For further context, check out our in-depth article on Engine Labs.

E85 Race Fuel

Our E85 Race Fuel contains a premium blend of race-grade components and high-quality ethanol. A tried and tested race fuel for high-boosted applications.