Gasoline or E85 ethanol-blended fuel?

David Freiburger and Steve Dulcich at Engine Masters wanted to find out which makes more power and by how much. So they grabbed a 489-cubic-inch, 13.5:1 compression big block Chevy, teamed up with our partners at Summit Racing for a couple of key parts, and started playing.

To ensure a level playing field, they used Rockett Brand’s 114-octane race gas and 112-octane E85 racing fuel. Unlike pump fuel whose octane ratings can vary, these fuels are consistent from batch to batch.

Freiburger and Dulcich also used Holley Ultra XP carburetors tuned for gasoline and for E85.

The guys also dive into some tuning differences between the two fuel types (E85 tends to be more forgiving of tuning errors) and cover the pros and cons of using each, especially on the street.

Find out what our Engine Masters friends learned in this video (Episode 30) and then head over to the Motor Trend YouTube channel for more great Engine Masters tech.

Parts List

  • HLY-0-80805HBX Holley Ultra XP Carburetor, 950 cfm, gasoline, gray finish
  • HLY-0-80845HBX Holley Ultra XP Carburetor, 950 cfm, E85, gray finish
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