Used Premium Fuel for the First Time

[PSUTE]

Been putting 87 in my 2.7. One thing I have noticed is while I normally run Exxon or Sunoco, times I had to buy convenience store gas, mileage and performance suffered enough for it to be noticeable...

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[DrewBronc21]

I haven’t put 87 in any of my vehicles probably since 1987, especially anything turbocharged.

 

[RHeinz]

Sort of a related question:
What is the simple answer as to why would a city of 100+ population in west Texas not have ANY fueling stations with 93 octane? 91 octane is the highest available.
I’ve used 91 since day one in my 2.7
Thanks

At higher altitudes the air is thinner and therefore the dynamic compression ratio of your engine is actually lower. There are less pounds of air getting into the cylinder on each cycle. At higher altitudes the gasoline octane rating can be less because of this.

At sea level we have 87 and 93. For normally aspirated vehicles, those octanes are not needed at “higher altitudes”. Unfortunately, the turbo has the capability of restoring the design dynamic compression ratio and could probably benefit from the higher octane.

 

[Paul Gagnon]

https://en.m.wikipedia.org/wiki/Octane_rating

 

[Lcubed]

Because the in tank fuel pump is cooled by being immersed in fuel, when the tank is very low there is little to no cooling available for the in tank fuel pump.

is that why the fuel pumps were failing on the 2.7's off-road?

 

[Bird Dog Off Road]

...and I could tell a real difference in the way the Bronco drove.
I'm not one to accelerate aggressively so that's not what I noticed, rather an overall smother drive. Sometimes in the past I would find just a bit of sputter when using 87 octane, nothing major but not an entirely smooth experience. After using 91 octane the drive is smoother, especially prior to the vehicle fully reaching temperature.

2022 BD
2.7 Auto, non-Sas

I tried using 93 octane while I was in Tennessee this past summer and didn’t notice a difference.

 

[zyglyrox]

I noticed that, with the two tanks of 93 I used at 70mph the engine was happy to sit at 5-7psi of boost under load instead of downshifting.

on 87 it won’t go as high, maybe 3-5psi or it’ll drop to 9th.

honestly I don’t like that it’s sitting under load like that while cruising, especially as 6-7psi is half of the avg pressure it’ll pull. usually you stay out of boost for MPG reasons.

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