What Is Flex Fuel?

Flex fuel refers to the ability of your car to run on a mix of gasoline and ethanol — specifically E85, which is 85% ethanol and 15% gasoline. With the right setup, your vehicle can seamlessly adjust to whatever blend you’re using.

Why E85 Makes More Power

E85 is popular in the performance world because it has a higher octane rating than pump gas — often 105 or higher. This means your engine can handle more boost, more timing, and make more power without knocking. Ethanol also burns cooler, which helps reduce engine temps under load.

What You Need to Run Flex Fuel Safely

• Flex Fuel Sensor – Detects ethanol content in real time

• Upgraded Fuel System – Bigger injectors and fuel pump are usually required

• ECU Tune – Custom tuning is necessary to manage fuel delivery and timing

• Proper Monitoring – Ethanol content and AFR should be logged regularly

Pros and Cons

Pros:

• Big power potential

• High knock resistance

• Lower intake temps

• Cleaner burn

Cons:

• Lower MPG

• Requires fuel system upgrades

• Not available everywhere

Is E85 Right for You?

Flex fuel is a great option for turbocharged builds or high-compression engines looking for safe power gains. But it’s important to upgrade responsibly. If you're unsure what you need, we offer full flex fuel conversion packages with tuning.