shore

I've not figured this out yet but something changed. Could be the combination of both or just one. I tried two things at the same time and noticed a welcomed difference in engine response.
I put 35 Toyo MT's on my truck and of course suffered the effects of the weight. Yesterday, I filled up with premium just to try it out and I also turned off Advance Trac just for the heck of it.

1..no sport mode but advance trac off. I don't care for sport mode. The delayed shifting and held shifts where annoying for just DD duties. Just hold down the dash button for several seconds and it will turn off.

2. I put 3/4 tank of 93 in with the leftover 87.

The pedal response and overall feel was much improved by one of these or maybe the combination. The truck felt like stock tires again. I was kind caught off guard by it. Full tank and towing my trailer, I got the same mpg as I did with the stock 18's. That right there confirmed something got happy.

Try these things and come back with your opinions.

BOSSMAN2888

Similar here but more so with E-85. The below article is a few years old, showing the '11 F150 as 360 hp vs the '15 385, but I have witnessed stock 5.0 Mustang dyno gains from E-85 (100-105 0ctane). Same principle as Premium super sensitive anti-knock sensors are not retarding timing and power gains are had with premium 93.

2slow05

Really I didn't know the e85 would make more power. I figured e85 would make the truck more sluggish and get worse fuel mileage. I might should try a tank of e85 and see what it does in the real world

On my 2004-5.4 f150 if I ran with 87 octane fuel the truck had a slight ping to it. The ford dealer told me to always run 93 in it and it ran better and had little better performance. I drove that truck to 327,000 miles with no major problems really

Toovey2v

My next fill will be premium now, I have 35s also, test this out, I also notice that there is a ton of torque management in 4 auto vs 2wd, sport mode or regular.

Toovey2v

I want to see a write up like that on the new engines, what would the new 5.0 make for power just by switching from regular to premium or e85?

OkaloosaFX4

Placebo. Unless your timing is advanced there is no scientific/physical reason to use 93 octane in the 5.0L N/A V8... 100% total and complete waste of money... Unless your tuned, it makes no sense to run higher octane fuel. There is absolutely zero benefit.

nd5.4f150

There are dyno graphs somewhere out there of f150 5.0 on 87 and on 93 and it did make a tish more throughout. not a lot around 6-7 if remember correctly. But it was enough to convince me to run only 91. Lol. I believe it was 5 star il try to find it

nd5.4f150

lol wrong.

Toovey2v

Do you have a source to back this up?

This is kind of common sense, if it make u to 15 more hp on e85, then you can bet that 6-7 sounds about right with what nd5 is saying.

With e85 it would most likely advance the timing which is where you would get your gains from, so why would it not do the same with 91 or 93 octane over 87?

Maybe that's not the case and maybe it's just the sensors aren't sensing any ping in our motors now which is allowing it to make the intended power, which we weren't making on crappy regular fuel. I noticed significant better fuel mileage in my 05 with premium, something like 100kms extra per tank over using regular, it also had better throttle response and passing power. Now this 2015 is a different world all together, but if there is actual software perameters to sense the difference between regular and e85 to cause those power gains as stated, then you can bet that there is definetly some gain in using premium in the 5.0.

nd5.4f150

Not quite as good as I earlier thought but a definite 10+ gain from 5k to 6k and a peak gain of about 8. 287 to 296. I would say if you don't play hard with your pickup yes of course 87 is fine but for those of us that like to know we got a little more than most people under the hood theirs nothing wrong with runnin a little 91 or 93, the gains are there. I realize this graph is a 2011 but it shouldn't really matter the gains should be similar. Il try to find the 5 star one I believe they actually had the results on a 15 and they were real similar to this mpt graph