What Octane Fuel?

[Spartan]

that 1% hit is why i use 93, even though that's pretty dumb

Dont' quote me on that but that was what was written by a few people in the long MPG threads we had debated about months ago...but I believe it is close to accurate within a few %...even if you went down to 400 hp I'm sure that's enough for most people.

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[opensesame]

I use non-ethanol 93.

Better performance, better fuel economy, and healthier for the engine from what I understand.

And if you want to find non-ethanol gas in your area, download the app "Pure Gas". (Its better to call the location first to verify as i've learned it's not always the most accurate)

If I could, I use use 93 non-ethanol, but all we have here in Ontario Canada is 91 non-ethanol and that is what I'll be using.

 

[jmhtang]

87 is fine for all 3 engines (V6, EB, GT).

The EPA tested the MPG using 87 octane.

Using 87:
The V6 takes no HP hit.
The EB takes about a 29-30'ish HP hit (something like 13% loss of HP).
The GT takes about a 1% HP hit

You're fine running 87 in all of them, the EB is just the one that suffers the biggest HP hit because the turbo relies on that premium fuel (it's why on the Ford Mustang page there is an * next to the EB HP/TQ figures). If you run 87 in the EB and really just want the car for your DD and once in a while fun, then honestly 87 is fine for it. You'll save lots of money. Now if you plan on doing more fun things with it then you should be running 93 in it.

All cars built in America supposedly are required to run on 87 octane.

Thanks. Great information. Interesting about the octane requirement for American cars.
You see, I'm trading in my 328i BMW. It has an inline 6 engine with 230 HP. I've always used 93 octane fuel, as recommended and, BTW, full synthetic motor oil.

So it's a little hard for me to wrap my head around using 87 octane fuel and half synthetic oil in an engine with almost 2x the horsepower. Also, the BMW called for 15,000 mi. oil changes, although neither I nor most other owners did that. We tended to change it at about 7500 mi. So again, it'll take some getting used to a 10,000 mi change, although I probably won't wait that long. Have done extensive search on this forum about oil and have not made up my mind about which I'll use. Hell, maybe I'll use the BMW oil! LOL.

Also, I tracked the Bimmer and intend to do the same with the Mustang (come to Lime Rock and we'll rock the place!).

So thank you all for you answers and your time.
Cheers,
Jeff

 

[phil1336]

V6 with 87 Octane Fuel = 300 HP. For a daily driver, I need more?

 

[Asharus]

Dont' quote me on that but that was what was written by a few people in the long MPG threads we had debated about months ago...but I believe it is close to accurate within a few %...even if you went down to 400 hp I'm sure that's enough for most people.

yeah, i dont doubt the difference is very minor in the 5.0. your post was not the first ive seen claiming 1%.

 

[Alloye]

California-tastic 91.

 

[Hack]

Horsepower and torque

MPG also improves slightly with higher octane fuel...all things equal

Not necessarily true on either point.

If the car detonates on 87 it will pull timing. SO - if it's a hot day yes I would expect that the power will be improved with higher octane. If the outside temperature is cool enough that there is no detonation, the computer won't pull timing and the power will be the same with 87 octane.

Regarding fuel economy - it depends on the fuel mix and the ambient temperature and your driving conditions. If the higher octane fuel has extra ethanol to get to make the higher octane number I expect your fuel economy will decrease. Ethanol has lower energy content, so more fuel is needed. Fuel economy with E85 could be expected to be 20-25% lower than economy with gasoline.

http://www.edmunds.com/fuel-economy/e85-vs-gasoline-comparison-test.html

If the relative proportions of ethanol and gasoline are identical between the 87 and 91 octane, you may still get identical fuel economy. At this point it would depend on whether the engine is making adjustments to timing to prevent detonation. If the ambient temperature and your driving conditions are such that no timing adjustment is needed, you will get the same mileage with either fuel.

 

[DivineStrike]

On road trips I'm using 87...I will probably continue to use it. I feel no difference in drivabilty really. I will for sure still use 93 from time to time

 

[Spartan]

Not necessarily true on either point.

If the car detonates on 87 it will pull timing. SO - if it's a hot day yes I would expect that the power will be improved with higher octane. If the outside temperature is cool enough that there is no detonation, the computer won't pull timing and the power will be the same with 87 octane.

Regarding fuel economy - it depends on the fuel mix and the ambient temperature and your driving conditions. If the higher octane fuel has extra ethanol to get to make the higher octane number I expect your fuel economy will decrease. Ethanol has lower energy content, so more fuel is needed. Fuel economy with E85 could be expected to be 20-25% lower than economy with gasoline.

http://www.edmunds.com/fuel-economy/e85-vs-gasoline-comparison-test.html

If the relative proportions of ethanol and gasoline are identical between the 87 and 91 octane, you may still get identical fuel economy. At this point it would depend on whether the engine is making adjustments to timing to prevent detonation. If the ambient temperature and your driving conditions are such that no timing adjustment is needed, you will get the same mileage with either fuel.

SCIENCE!

 

[phil1336]

Science is fine but if you smash your foot unto the accelerator on a regular basis, your fuel economy is gone regardless if your burning 87, 91, or higher octane.

 

[15Pony]

Would I gain hp or mpg using 93 in the V6?

 

[Phlyguy]

...100 Proof pure West-By-GOD-Virginia corn squeezin's here...

 

[phil1336]

Would I gain hp or mpg using 93 in the V6?

Probably not enough to justify the extra cost per gallon of Fuel for the upgrade.

 

[15Pony]

What about using pure gas instead of 10% ethanol, what would I gain? I looked up pure gas in my area and most are un-branded and sold thru little mom and pop outlets so I'm worried about quality.

 

[monksey7]

in the UK 95 is the lowest you'll find in most petrol stations

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