Quote:
Originally Posted by 2gnt2wrx
There is a huge misunderstanding on here as to why a "stock" brz/frs can't use E85.
It can't be used on a stock tune or the settings in the cars engine computer from the factory. These settings can be adjusted by a "tuner... think... visconti here". The tuner will have to re-scale your injectors back 30% in order for the engine to run properly. What this will do is adjust your afr or air fuel ratios back to where they need to be, in order to idle/accelerate properly.
The other benefit of e85 is the higher octane rating. This will allow the tuner to advance the engines ignition timing which will result in more power.
Hope this helps
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He has to increase the injector duty cycle, no decrease it. Ethanol caries a lot of oxygen with it so you need more of it to hit the proper air/fuel ratio (Stochiometric). Normal fuel requires around 14 lbs of air for every lb of fuel. E85 requires only 9 lbs of air for every lb of fuel. Since the amount of air that can pass through the intake (Volumetric Efficiency) doesn't change, you have to add more fuel.
OP: Ethanol is actually the same alcohol you drink. Essentially you'd be running your car on moonshine. The big difference (and why you don't want to drink E85) is because it's only 85% Ethanol and 15% Gasoline.
A tune is needed for a non-flex fuel car to use E85 because of what I outlined above.
Another interesting thing is that E85 isn't always E85. The mix varies depending on region and expected monthly temperatures. Ethanol doesn't mix with air as readily as gas at lower temperatures. So in the colder month the mix can get as low as E70. That's why, while E85 can have an Octane rating between 105 and 110, most tunes for it tend to plan around an Octane rating of only 100 or so to handle variances in mix. (Flex Fuel cars have a sensor that can determine the Ethanol/Gasoline mix and adjust fueling accordingly).
But it's the high octane rating and the air-cooling properties of alcohol for less money than gasoline that makes E85 so attractive to forced induction applications. The extra ignition stability and the way alcohol takes heat out of the incoming air helps prevent pre-ignition (knock). That's why the turbo kits you see for these cars can only hit about 10psi on gasoline, but then you have Don running around on 20psi using E85.
Now why isn't E85 used everywhere if it's so good? Lots of logistical, political, and ecological reasons. Suffice it to say, we'd have to rebuild and/or double our infrastructure for moving liquid fuels around, politicians would have to stop demanding we use corn to make Ethanol, and at present it costs more energy to get a gallon of Corn Ethanol in your tank than Gasoline and the best source (cane sugar) won't grow reliably in the US.
At present E85 is a failed non-diesel Bio-Fuel for the masses. But it is a great race fuel and as long as it looks good on paper it will be available in cities near rail lines for a while to come.