Tuning Basics
E85 & Flex Fuel Tuning Explained
· 1 min read · PTEB Tuning
Many of the biggest results in modern tuning — including PTEB's world-record Tiguan R — run on E85. Here's why ethanol is such a powerful tuning tool.
Why E85 makes more power
E85 is a blend of up to 85% ethanol. It has much higher knock resistance than 98 RON petrol and a strong cooling effect as it evaporates. That lets the calibration safely run more ignition timing and boost.
What flex fuel means
A flex fuel system uses an ethanol content sensor so the ECU knows exactly what blend is in the tank. The calibration blends between petrol and E85 maps in real time, so you can fill up with either.
Hardware you'll need
- Ethanol content sensor
- Higher-flow injectors
- Upgraded fuel pump(s)
- A custom calibration
Fill up anywhere
E85 isn't available at every service station. Flex fuel solves that by letting you run petrol whenever you need to — the car adapts automatically.