So this might be a silly question, but ive been racking in over in my head for a while.
Using a tuner (edge evo for example) For high performance tunes require high octane 91+ fuel because of the timing bump. Would one be able to substitute E85 instead? I believe E85 in around 105 octane, so that would work. But is there something else im missing here?

 

If the truck is not a flex fuel and tune is not for E85 you can't do it. While E85 does have much higher octane rating while burning cooler you have to burn about 30% more of it. So you have to have injectors capable of that as well as a variable speed fuel pump. All of which would be controlled by the pcm.

Also since E85 burns cooler you have offset that with some additional spark advance. So the timing curves in an E85 tune are quite different from the timing curve of gasoline. some parts of the timing curve run a lot more spark, while in other areas you only add a little bit.

 

My truck is an 08, so it has the factory E85 tune. My question is, bear with me I've had a few brews, is that tune so much different that a high octane tune? What exactly does the factory PCM do when it recognizes E85? As simple as it sound I want to know if when my edge evo requires 91+ octane for high performance tune (level 3). If I can run E85 instead of premium fuel in place of it?

 

KPF is the 8th digit in your VIN a "V" ? The E85 fuel will give you slightly higher horsepower output at a trade off of 25% worse gas mileage. So if you're going quarter mile racing in your truck buy the E85, otherwise it's not worth it.


-Mike


VIN decoder sheet for 2008 Ford trucks: http://www.fleet.ford.com/ngtemplate...ce/VIN2008.pdf

 

Hamfisted, my 2008, 5.4 motor is flex fuel.

 

If your truck is stock, or just a few bolt-ons it's not worth it..... 91/93 will support 500-600 hp.

 

The best answer for this is to call or email the folks at Edge. I would think it would be covered in the instruction manual. I've read conflicting info all over the place about this. So I would go to the source to find out for sure.

The answer should be simple. Either they turn off the logic in their tune which allows your PCM to identify E85 and use a different map or they do not.