Higher ethanol fuel

[DonG]

The Bronco Sport owner's manual states that you can use fuel that has up to 15% ethanol in it. What would be the downside to using this fuel as it's approximately $.30 a gallon cheaper?

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[thekingprawn]

The Bronco Sport owner's manual states that you can use fuel that has up to 15% ethanol in it. What would be the downside to using this fuel as it's approximately $.30 a gallon cheaper?

Reduced fuel economy because of the lower energy density.

 

[Mlarv]

The Bronco Sport owner's manual states that you can use fuel that has up to 15% ethanol in it. What would be the downside to using this fuel as it's approximately $.30 a gallon cheaper?

When I ran Flex fuel in an F150 made for it my MPG went down. So I would always fill at half a tank once with flex the next with normal. Seemed to keep my MPGs better

 

[Warpious]

Okay so I'm just starting to work my way down this rabbit hole...ethanol has lower energy density, but I was reading its added to boost octane? Which wouldnt that make it higher energy density...chemistry, not my best subject.

 

[jrsj70]

if you can find it in your area try a tank of E88, .30 cheaper and still 27-30 mpg

 

[jofer]

Okay so I'm just starting to work my way down this rabbit hole...ethanol has lower energy density, but I was reading its added to boost octane? Which wouldnt that make it higher energy density...chemistry, not my best subject.

I'm very much not a chemist here, but octane rating doesn't have anything to do with energy density directly. Instead, it's a rating of resistance to causing knocking under high compression. (That's why many turbocharged engines recommend premium - to prevent knocking, as the turbo means things operate under higher compression.)

E.g. https://www.fueleconomy.gov/feg/octane.shtml

Ethanol happens to reduce knocking under high compression for reasons I don't remember. As a result, ethanol blends can have very high octane ratings. Premium fuel adds additional additives to reduce knocking, but still, the ethanol itself raises the octane rating.

 

[Osco]

Tech babble:
Ethanol has a slower flame propagation. Try and google that one.
The really scientific approach is get a small gas can of ethanol gas and set it next to a can of NON ethanol.
Smell each, careful now, just a little sniff.
If your old enough you will remember the smell of true gasoline.
It’ll almost knock you back.
Ethanol (E85) has 88,258 BTU’s per gallon.
NON Ethanol, what I like to call real gas has 112,114 BTU’s per gallon.
BTU= British Thermal Unit
one BTU is equal to one candle flame.

 

[Mark S.]

Okay so I'm just starting to work my way down this rabbit hole...ethanol has lower energy density, but I was reading its added to boost octane? Which wouldnt that make it higher energy density...chemistry, not my best subject.

The two major benefits to ethanol are that it burns cleaner and increases octane. Cleaner burning means it's (purportedly) better for the environment. The higher octane means the engine is less prone to detonation (engine knock).

Octane is a measure of a fuel's resistance to ignition at higher temperature/pressure. Most modern engines operate with a higher compression ratio and or turbocharging, both of which add heat to the fuel/air mixture, and so benefit from higher octane fuel.

 

[Jess1]

At worse mileage. "Octane" seems to have become a buzzword for "power"...

 

[Mark S.]

At worse mileage. "Octane" seems to have become a buzzword for "power"...

If your engine's PCM is programmed to take advantage of it—like those used in Ford's EcoBoost engines—higher octane can indeed mean more power.

 

[Fordson04]

I've been running e15 88 octane for a few months now and I'm still getting between 26 to 29 mpg average.

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