This E85-specific carburetor from Quick Fuel is one example of how chemical differences between gasoline and E85 fuel require certain parts upgrades in order for ethanol to perform at its best, and to prevent damage to parts designed for gas engines. (Image/Holley)

Q: I want to run E85 in my car. What should I know before changing fuels?

A: Many of us have seen the cars making huge power on E85 and naturally want to know more.

First, you can’t just switch fuels from gasoline to E85. Your performance will suffer, and you can damage parts by doing it.

Does E85 make more power than gasoline?

It can—just ask the folks at Steeda.

E85 contains less energy per gallon than gasoline.

But, an engine designed specifically for E85 can make more power. The trade-off is that it requires more fuel.

More fuel volume and the chemical makeup of E85 keep the air/fuel mix cooler. E85 also has a higher octane rating than gasoline, which increases:

  • Ignition timing advance
  • Compression
  • Boost

How can E85 damage parts?

E85 has a different chemical makeup than gasoline, and some of those differences can damage rubber parts.

Also, hot spots in the combustion chamber can cause pre-ignition.

The Basics of Switching to Ethanol​​​​​​​

The fuel system must be designed to deliver more fuel for E85 to be effective.

Every part of the system needs to be alcohol compatible. Parts to consider include:

E85-ready carburetors are available. Some are coated to prevent corrosion. They have updated floats and larger jets. The internal passages are also enlarged to handle more fuel. E85 conversion kits are available for some carbs.

E85-ready fuel injection kits are also available. The ECUs are programmed to work with E85. They have the right seals and O-rings. More good news—they also work with gasoline. If you upgrade to fuel injection and you might ever run E85, just buy a compatible kit from the start.


  • Some fuel injection kits can be ‘tricked’ into providing enough extra fuel to work with E85. This must be researched on a case-by-case basis.
  • Fuel injection kit max horsepower ratings are based on gasoline. The horsepower capacity of the kit will drop 30 percent when used with E85.

This is another in a series of weekly Q&A Mailbag sessions with Summit Racings tech department, in which there are hundreds more. Click here to see them all.