Peak whp will be the same. Dedicated though ramps up timing faster so a dedicated tune will have a stronger lower end.
Are we talking single digit torque differences, or noticeable torque numbers? Improving that initial grunt is always a plus with the 5.0.
The power just comes on earlier because timing is earlier. If you look at the curve you will see a bit more linear on flex vs steeper on dedicated. I still run flex full time myself for convenience due to availability in Phoenix and much of it only being e54 as a bit of earlier timing doesn't outweigh the convenience factor of not swapping between tunes when changing fuels personally. If i fill up on tested e90 on a strip day that could be the exception making it worth swapping tunes.
The flex tune allows the computer and the wideband to gradually find the timing that's happy with the knock sensors. The dedicated race tune assumes you have high quality E85 in the tank and doesn't ask, it forces the timing down it's throat. As he said, peak for peak it's usually within the typical error/confidence of a dyno, but on the lower end, the race tune will seem a little more sporty/responsive. You can always flash back to the flex tune, but you shouldn't flash the dedicated race tune unless you've verified it's high content E85. It's no longer asking the knock sensors, it's telling the computer what it knows to be safe timing.
If you're going direct from gasoline to E85 race tune, you're going to have to ensure you're not diluting the E85 with remnant 93. You can either idle the car all the way until it dies which is a pain in the ass. You can buy the module from VMP that you connect at your fuel rail and it pumps the fuel out. In either of those cases, I'd still take it very gingerly on that first tank of E85 as there's still quite a bit of fuel in the bottom of both saddles. You could remove the fuel hats and siphon out from the top openings (it's a good time to wipe out the tank and get any debris or residue out).
The flex is meant to avoid switching back and forth. If wanting to go dedicated, run the tank near as empty as possible, closest to 0 miles left the better. Test the e to confirm it's high enough quality, fill up and allow a before going wot.
You could but it would be a hassle. You'd have to run the 93 down to fumes before filling up with E85 and make sure that fuel is through the system before you get on it. The closest station for me always runs between 74 and 77% ethanol. A couple gallons of 93 still in the tank puts me under E70 (between 65-68%) which isn't good enough. If it was E80 or up it would probably be good enough. Flashing a tune doesn't take long at all. Only a couple of minutes and another few minutes of driving for the car to adjust. You could even stay on the flex tune and run whatever fuel you want and go to the E85 tune when you want the extra benefit. No reason to go between 3 different tunes. IMO if you're not racing no reason not to use a flex fuel tune unless you have E85 on every corner. You'd be able to tell a big difference in power on a flex tune and running high E content.
At least it definitely should be tested at the the pump before consumption yes. If I'm testing it over 70%, it dinner time. On my dedicated "E85" calibration, my trims are only removing 6% fueling @ 70%. I've tried as low as around a 67% blend, and indicators in the logs were still well within the operating windows. I'm also testing and logging 90% of the time the car is running.
Right, but if running a flex tune you only have to fuel up and go.