Originally Posted By: horse123
Why don't FF vehicles adjust timing automatically to provide more power on E85? It's basic enough knowledge that E85 is higher octane (100+) and therefore it seems like it's just some simple software engineering to be able to advertise a 20% increase in horsepower when you use E85. I couldn't ever see using E85 unless it became ridiculously cheap, OR the vehicle took advantage of the power potential.
My 2008 Ram 1500 (4.7FF) does adjust timing on E85, there's quite a bit more overall power and (especially, since its lacking on that engine)noticeably more low-end torque.
But there are limits to how much extra power you can extract by advancing the timing- even if you had infinite octane, there comes a point where advancing the timing starts to DECREASE output very quickly. Especially with an engine that already has dual plugs and rapid combustion anyway- its not long before you get more of the combustion happening before TDC than after it, and that's not beneficial. If the engine was boosted, then the computer could increase the boost and get quite a bit more power out on E85, but its not. Are there any turbo or supercharged flex-fuel engines out there? Ecoboost Fords maybe?
FWIW, the difference in cost between E85 and E10 has to be 30 cents/gallon just to break even due to the difference in mileage on my Ram. Often that's the case and so I do occasionally use E85. But when the cost is 25 cents/gal less for E85, its a money-losing choice and I don't do it.