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Proof premium fuel is better.

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#21
I'm lucky I guess. 4 miles from costco 93 octane and today it was $2.55 when I filled up the tiny tank. I don't plan to run anything else.

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I said the same thing until I became a cornaholic [burnout]
Disclaimer: E85 not available in all markets 😭
 


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jmrtsus

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#23
FYI,
From Ford Performance (Mountune Docs)

"Premium Fuel Requirement: Customers who purchase power upgrade packs, cold air kits with calibration (MP215), TracKey/Track Cal engine calibrations, or superchargers are required to use 91-octane or higher (“premium”) fuels at all times. Any failures associated with the non-use of premium fuel will be ineligible for warranty repair."
 


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#24
Interestingly, the Eat, Sleep, Drive video appears to show the FiST makes more power on 87 than other models using the same engine when running on 87 (Escape, Fusion, etc.).
 


jmrtsus

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#25
Interestingly, the Eat, Sleep, Drive video appears to show the FiST makes more power on 87 than other models using the same engine when running on 87 (Escape, Fusion, etc.).
More yes, and even more on 91 and most on 93. The ST engine is not the same as those engines, they have only 178 Hp not 197. Apples to Oranges
 


OP
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Ford ST

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Thread Starter #26
More yes, and even more on 91 and most on 93. The ST engine is not the same as those engines, they have only 178 Hp not 197. Apples to Oranges
The engine is the same it's just a different tune.
I promise all you have to do is just break down the engine by part number it's identical.

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danbfree

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#27
My MP215 HATES 87, floor it and it sends you a message......it say "really"? Mountune say 93 if you want the extra power you purchased. I get 32 in town and 37 and better on the interstate on non-ethanol. The article simply confirms what many of use knew already. It also likes non-ethanol better as to MPG, 2 mpg minimum better than corn licker. I did not buy an ST and add the MP215 to run 87! Feels like a 1 second delay in throttle response and a distinct loss of power. Had to buy it once in U.P. Michigan on a trip.Fifi didn't talk to me for a week for feeding her that trash!
Every car will get better mileage in general on non-ethanol, but sometimes running an ethanol tune, like e30, I'll actually see very little difference in non-ethanol vs. e30. At higher freeway speeds, it takes less throttle to create power to push against the wind resistance, seems like I get 30-31mpg at 75-80 whether I have 93 or e30
 


danbfree

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#28
The engine is the same it's just a different tune.
I promise all you have to do is just break down the engine by part number it's identical.
100% true, they make all the engines the same, they just change the tune. If one were to search for an engine for your FiST on car-parts you will see tons of Escape engines listed.
 


jmrtsus

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#29
The engine is the same it's just a different tune.
I promise all you have to do is just break down the engine by part number it's identical.

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My point was the HP is different......the ST "tuned" engine would be expected to make more power so Apples to Oranges.
 


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#30
I've only had my car for a couple of weeks and I've been waffling whether I want to drive the car on 87 vs. 91 for commuting, etc. I think this video made up my mind. We're talking about 8.5-13hp worst case, which is roughly a 5-7.5% difference. I thought I felt a bit of a difference between the two. The fuel cost difference is almost 20% where I live. 93 is even more. With less wheel spin and torque steer, I might end up preferring 87. :)
 


Hypergram

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#31
Curious about this. For a tune, is there really any difference between running a 91 octane tune vs a 93 octane tune. Cobb stage 1 for example.
 


Hypergram

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#32
I've only had my car for a couple of weeks and I've been waffling whether I want to drive the car on 87 vs. 91 for commuting, etc. I think this video made up my mind. We're talking about 8.5-13hp worst case, which is roughly a 5-7.5% difference. I thought I felt a bit of a difference between the two. The fuel cost difference is almost 20% where I live. 93 is even more. With less wheel spin and torque steer, I might end up preferring 87. :)
Before I got my tune, I just used regular 87 and that worked for me.
 


jmrtsus

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#34
Curious about this. For a tune, is there really any difference between running a 91 octane tune vs a 93 octane tune. Cobb stage 1 for example.
Both Ford and Mountune state HP numbers at 93 octane.......should say something about that but maybe somebody has a dyno test, LOL!
 


OP
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Like what? Power and Torque gains?
Yes. Just to get the advertised power the OEM power level requires 93. All the guys in California that are stuck with 91 that don't run E tunes would love to have access to 93.

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danbfree

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#37
I've only had my car for a couple of weeks and I've been waffling whether I want to drive the car on 87 vs. 91 for commuting, etc. I think this video made up my mind. We're talking about 8.5-13hp worst case, which is roughly a 5-7.5% difference. I thought I felt a bit of a difference between the two. The fuel cost difference is almost 20% where I live. 93 is even more. With less wheel spin and torque steer, I might end up preferring 87. :)
Well, I prefer doing less than $300 in mounts/bracing and having almost no torque steer even with an e30 tune! ;)
 


danbfree

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#38
Yes. Just to get the advertised power the OEM power level requires 93. All the guys in California that are stuck with 91 that don't run E tunes would love to have access to 93.

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Even without an e30 tune they can add 1.5 gallons of e85 per tank to to get their octane up to a full 93... I mean, even 91 tunes run like crap on their 91 gas from what I experienced, at least they can max out a stock tune properly this way, but again *if* e85 is available.
 


danbfree

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#39
Like what? Power and Torque gains?
Yes, even Cobb publishes their numbers: https://cobbtuning.atlassian.net/wiki/spaces/PRS/pages/96996737/Ford+Fiesta+Map+Notes

"Generally speaking, 91 octane calibrations have a richer fuel curve, and a less aggressive ignition advance map to help compensate for lower octane fuel blends such as those found in Arizona, California, and Nevada; and/or less than ideal atmospheric conditions. The maps designed for 93 octane are the most aggressive."
 


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