As I recall, the Raptor is configured for nothing stronger than E10.
The thing with E85 is that it is both higher octane (something like 108), meaning that it resists detonation very well, and much less energy-dense than gasoline... so it takes more of it (in terms of volume) to make a given amount of power. That's why mileage on E85 sucks, and why there's no performance advantage unless a tune is configured to take advantage of the extra octane.
Tunes configured to use E85 will allow for more boost/timing than would be possible on pump gasoline, but you also must have enough fuel system (fuel pump, injectors) to move the volume of E85 required by the higher horsepower level. Additionally, the fuel lines, etc... must be made out of materials that won't be damaged (dried out) by the use of fuel with high alcohol content.
Likely, the reason that the Raptor isn't compatible with E85 when stock is because it either doesn't have or has a limited range ethanol sensor in the fuel tank.
