MISS1LE

Now that you mention it, there is a station not far from my house that sells 100 octane. I think I may go that route as well.

Steven Tomassetti

So guys, just to reiterate... my best bet after the CAI and Dual FlowMasters AND bigger tires is to start putting in a couple tanks of 89 or higher Octane (not sure about the Octane rating in all the areas I drive) then use my new SCT tuner to upload a pre-loaded tune and this will boost my HP and increase MPG?? Let me know how much of this statement is wrong. I am a 'newbie' in the high performance world and need all the help in this matter, thanks all.
My truck: 2018 Ford F-150 2.7l eco.

w00t692

Put the highest octane you can in. Whether that is 91 or 93, put the highest you can.

bad packet

That's not good enough. If you have a tank full of 87 and you fill up with 91... you'll have lower than 91 octane in the tank. Then you load your 93 tune up and you got big problems. Even if you have a 91 tune in there, I'd consider it pretty risky. We can be scientific about it. A normal "empty" on a 36gal tank leaves ~6 gallons of 87 octane in the tank. Adding 5 gallons of 100 octane to that brings the total octane level up to 93. Then you fill the rest of the 25 gallons tank with 93 pump gas and you now have 36 gallons of 93 octane. Load up your 93 tune and let r rip.

If your 93 octane pumping part is substantially less than 25 gallons, that means you had more than 6 gallons in the tank to start and you are likely a bit under 93 octane. Proceed with caution.

Steven, just remember you never want to be running a lower octane than your tune is programmed for. Doing so could lead to pre-ignition detonation and bad things like melted pistons or rods hanging out of the side of your engine. Octane is a measurement of a fuels resistance to ignition from heat. As you compress the air/fuel, you don't want the fuel to ignite until the spark plug lights it off. If the compression and heat ignites the fuel before the spark plug fires... the piston will be moving upwards trying to compress the air and fuel. The fuel burns, expands into gas with the valves closed, pushes against the piston, and you basically create a bomb.

w00t692

Well that's just not true. Any tune from a competent tuner is going to have the ability to pull timing out for fuel octane that isn't up to snuff. If you have a 93 tune and you fill up with 93 from 5 gallons of 87 in your 36 gallon tank, you end up at 92.2 octane anyways.

I don't put any tunes out on 93 that NEED 93 to run. All my 93 tunes will work on anything from 89 to 93 based on the maximum air load and a variety of other things. The only thing i wouldn't say to run on a 93 tune is a full tank of 87. 91? it's fine. 89 in a pinch is fine.

bad packet

OK...true any good safe tune will leave the knock timing retard system intact... but do you want to be hammering on that? A 93 performance tune is pushing timing and boost way past what Ford sets. Depending on where you live you may get away with it in the winter with super cold IAT's, but when they say 93 tune... I'm thinking they have the thing on kill mode set to run at 93 octane. Not 92 octane.

w00t692

93 octane isn't enough octane to put it on "kill"

i'd never do that and the difference wouldn't really be worth the result.

2017bluetruck

Over the summer I run a custom 93 octane tune. Several trip made to areas without 93 octane so used 91, OAR never went over -.60. Tossed in some STP fuel treatment and it went back to -.89+. 1000 miles that way and no troubles at all. Back to regular 93 octane and it -.96 on my GTX display.
MISS1LE, I'd just switch to 93 and quit worrying about it. KM