Project Fiesta ST Sees What a Difference 100 Octane Makes
It was deflating to find out that the 2015 Ford Mustang EcoBoost loses around 35 horsepower and 20 lb-ft of torque when being filled with 87 octane fuel. This begs the question: does a vehicle become more powerful when operating on higher-quality fuel.
With “Project Fiesta ST,” the folks at TheSmokingTire put this theory to the test, bringing a stock Ford Fiesta ST to COBB Tuning SoCal to see how it runs with 100 octane fuel.
When dyno tested, a Fiesta ST operating with 100 octane fuel was rated at 240 horsepower and 318 lb-ft of torque. For comparison: the 2015 Ford Fiesta ST is stock rated at 197 horsepower (using 93 octane fuel) and 202 lb-ft of torque. The stock Fiesta ST tested in the video gets 191 horsepower and 236 lb-ft of torque; running on 91 octane Stage 3 OTS, the Fiesta ST tests at 217 horsepower and 287 lb-ft of torque.
This means that the Fiesta ST, when using 100 octane fuel, is 23-horsepower and 31 lb-ft of torque better than when tested with 91 octane and 43-horsepower and 116 lb-ft of torque better than Ford’s tested figures using 93 octane.
Then, just to really drive the point home, Matt Farah takes it out for a drive through the back roads, and good lord.
Translation: use 100 octane for our performance cars. You owe it to yourself.