I have a 2015 5.0 truck. Getting ready to do a bunch of towing. I'm wondering if E85 is worth the mileage penalty and extra cost per mile. I have the 23 gallon gas tank, so it would need to make a noticeable improvement in performance to justify the more frequent fuel stops.

 

I'm sure it make some extra power but whether that would be noticeable? It will certainly keep timing maximized and help cool air charge.

 

I'm sure it make some extra power but whether that would be noticeable? It will certainly keep timing maximized and help keep combustion chamber cooler.

 

You will not notice any types of gains until you run through at a minumum of 1 tank of fuel of E85, and more so if you do not have a tune on the truck for E85. The Engine Management System must recognize the efficeincies of E85 and it takes many cycles for it to begin constructing those efficiencies. If you plan to just fill it with e85 and go, then you will be losing fuel mileage, at the cost of nothing. You must also be able to consistently find E85 if you need to refill, much more troublesome rather than finding a higher octane. If it were me, and I did not have an E85 tune, I would stick to a higher octane level of fuel, and go with that. E85 is generally a waste unless you have a specific tune.

 

Must be a 5.0 thing? My ecoboost responds to a few gallons of e85 within a short drive which is easily seen through the addition of timing.

 

Must be a 5.0 thing? My ecoboost responds to a few gallons of e85 within a short drive which is easily seen through the addition of timing and much lower knock levels.

 

i find it doubtful that extra torque would be worth the ~30% loss of fuel economy. I doubt an E85 towing tune would be as aggressive as an E85 performance tune anyway. I googled a couple of quick graphs and looks like in the lower rpm range its 20-30ft lbs, not exactly earth shaking.

A better description of what you're going to tow and where might help but again, Im doubtful unless E85 is just super cheap around you and don't forget the cost of the tune and device if you dont already have one

 

turbo engines are not applicable for E85.

 

I used 5 tankfuls of E85 and truck ran fine. nearest station is 36 miles away. I use regular till I can get it near home. trips might be an adventure finding it.

 

Here is more in-depth info from testing and tracking data.
And difference between your lower compression ratio and my 12 to 1 in a 2018 5L.
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It has been found by Dyno testing that Ethanol percentages above about 35% in an >untuned< 5L is of little value for performance increases that amount to about 4%.
We can't do much about the jump from E 10/15 to E 85 except to mix the ratio in the fuel tank between E10/15 and E 85 to get the % down.
In addition, re-fueling to a tank partially filled with E 10 or E 15 depends on that tank level above or below the half point for how the PCM handles the refueling to shift the Long Term Fuel Tables, at that time. It uses the fill gauge to decide which way to go.
Once the Ox Sensor reports a >>stable A/F<<, the Tables are shifted for that result and fuel is 'assumed' to be fully mixed.
This info is described in the Ford Doc in OBDII overview on fueling for years 2004 to the present. The engines do not use a fuel sensor otherwise.
There will be a difference in results on lower compression generation engines due to the lower efficiency of lower CR.
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On re-filling, from one Eth value to another requires some drive time and milage to stabilize the fuel Tables that will be shifted using E 85 to about plus +20% if looked at with a Scanner. The shift will be normal and come down with use of E10 or E 15, after stabilization occurs in the opposite direction for the same reasons as described above for increasing E %.
As for feel from the seat, expect somewhat sharper throttle response in the default shift mode, Tow mode and Sport modes if you have a 10 speed.
ECO and Wet/Snow shift modes in the 10 speed, the PCM softens the Throttle response by intent and skip sifting occurs in an attempt to improve fuel mileage with a soft foot.
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Just offering that there is more to changing Gas Eth levels and Octane than just changing fuel grades and the time interval required for how the PCM handles it.
Good luck.