Why does ethanol get worse mileage but still increases performance ?

Question

Hello,

When used in “regular” cars, ethanol (E85) tends to decrease the mileage compared to gazoline. This increased consumption suggests a lower energy density.

If that’s the case, why is ethanol used on tuned cars to increase their performance?

Thanks !

In: 2

Answer 1

To increase performance an ethanol based engine can run a very high compression ratio whereas gasoline cannot run at similar ratios without a high risk of preignition or knocking (which would destroy the engine)

It isn’t as simple as changing the fuel – the engine itself has to be purpose built for alcohol in order to maximize performance.