running 15% ethanol and 91 octane

[Longhorn]

i went to a pump and mixed using an e85 calculator to get e15 2gals e54 and 15 gals of good old 91 octane just to see how it would affect my vehicle! so far so good, hopefully once i get a cobb accessport i can run e54 by itself!

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[alex lobos]

i went to a pump and mixed using an e85 calculator to get e15 2gals e54 and 15 gals of good old 91 octane just to see how it would affect my vehicle! so far so good, hopefully once i get a cobb accessport i can run e54 by itself!

So can we off the bat use e10 and e15?
Does it perform any differently? (Pre tune)

 

[Busa789]

You can run E15 with a stock vehicle. I've never seen E54. We have E10, E15, E40 and E85. I wouldn't expect E54 to be any more consistent than E85, which is known to vary a lot. If a person is serious, they get an ethanol test tube and adjust based on the actual ethanol content.

 

[denis4x4]

On my second tank of non ethanol in a '26 Lariat hybrid. Mileage above 40 MPG so far.

 

[psuarmy]

What is the purpose of mixing? I have not heard of this. Is it just for people who tune?

It is an honest question on what it does. Please don't think I am being mean or cynical. I really want to learn something.

 

[notfast]

i went to a pump and mixed using an e85 calculator to get e15 2gals e54 and 15 gals of good old 91 octane just to see how it would affect my vehicle!

Congratulations, unless you tested the fuel ahead of time, you might have anywhere from E20 to E30 or so.

Ethanol ratings are less stringent than octane ratings. They can have "up to" the E number but don't have to be exactly that. Just can't exceed it. For example, E85 can legally be anywhere from E51 to E83 and be sold as E85.

What is the purpose of mixing? I have not heard of this. Is it just for people who tune?

It is an honest question on what it does. Please don't think I am being mean or cynical. I really want to learn something.

Ethanol has more octane than gasoline, so you can run advanced timing without risking engine knocking. It also burns slightly cooler than gasoline.

On the street, you won't notice a difference on the butt dyno. The main advantage to running E15-E85 is to reduce fuel costs, assuming that the loss of fuel economy is offset enough by the lower price.

 

[MaverickDragon]

The fuel system components in FFVs (flex fuel vehicles) are different as well as the engine settings for vehicles that can run the E-85 fuel on a regular basis.

The vehicle can run on it, but as ethanol is corrosive in high concentrations, and is prone to phase separation that can be bad news if it's left in the tank for long periods, it's more like a recipe for problems than a viable long term solution.

High percentage ethanol fuels also reduce MPGs because the fuel has less BTU's per unit volume.
It takes more fuel for the same power output.

Adding ethanol to fuel for a vehicle designed for gasoline isn't a good thing.
It's just getting more expensive to avoid it.

P.S. Ethanol does not have more octane than gasoline, it has zero octane, but it does increase the octane rating of the fuel.

 

[tiktokbrainrot]

The fuel system components in FFVs (flex fuel vehicles) are different as well as the engine settings for vehicles that can run the E-85 fuel on a regular basis.

The vehicle can run on it, but as ethanol is corrosive in high concentrations, and is prone to phase separation that can be bad news if it's left in the tank for long periods, it's more like a recipe for problems than a viable long term solution.

High percentage ethanol fuels also reduce MPGs because the fuel has less BTU's per unit volume.
It takes more fuel for the same power output.

Adding ethanol to fuel for a vehicle designed for gasoline isn't a good thing.
It's just getting more expensive to avoid it.

P.S. Ethanol does not have more octane than gasoline, it has zero octane, but it does increase the octane rating of the fuel.

"

• Anti-Knock Index (AKI): The rating displayed on U.S. fuel pumps (calculated as the average of RON and MON) for pure ethanol is generally around 100 to 109, though some sources cite it as high as 112–113 based on blending octane values (BOV).
• E85 Comparison: In contrast, the common E85 blend (85% ethanol) typically has an AKI of 100–105, while straight gasoline usually ranges from 87–93 AKI.
• Performance Impact: The high octane rating of ethanol allows engines to run higher compression ratios and boost levels without knocking, often resulting in increased power output despite ethanol's lower energy density compared to gasoline.

"

How are you raising the octane rating of gasoline by adding something with no octane rating itself? That makes no sense.

 

[MaverickDragon]

How are you raising the octane rating of gasoline by adding something with no octane rating itself? That makes no sense.

Alcohol increases the octane "rating" of the fuel it's added to, but alcohol does not contain octane.
Octane is one of many components of gasoline, and ethanol is a completely different molecule.

Ethanol increases the AKI of the fuel it's added to, just like octane would if it was increased in the fuel mixture. In both cases, the result is a decrease in premature ignition which is what knock is.

An octane rating, actually it's the AKI which have become somewhat interchangeable terms, is what the fuel "acts like" in an engine rather than what it contains.

 

[BigOil]

Alcohol increases the octane "rating" of the fuel it's added to, but alcohol does not contain octane.
Octane is one of many components of gasoline, and ethanol is a completely different molecule.

Ethanol increases the AKI of the fuel it's added to, just like octane would if it was increased in the fuel mixture. In both cases, the result is a decrease in premature ignition which is what knock is.

An octane rating, actually it's the AKI which have become somewhat interchangeable terms, is what the fuel "acts like" in an engine rather than what it contains.

THIS. Octane is a molecule. Source - Retired ChemE for one of world largest oil companies...me.

Ramble_ON
Almost all the hydrocarbon interface and bottom's garbage that is combustible in a gasoline terminal goes into the RUL FYI. Dilution is the solution ! Did not even affect the octane rating. Typically we came out of refinery at about say 87.2 R+M/2 ... IIRC

The raw gasoline is fungible. MUST meet pipeline specs. The additive and the ethanol is added at the terminal. Yes we tested at Refinery and Terminal. There was always a little bit of diesel in the gasoline because that's how you separated the slugs coming up the pipeline. Low tech or was....There was a clear side pipe you could see and Operator spin the valve to separate the grades ...JET/AVGas/Distillate(Diesel-Fuel oil)/RUL-PUL (we blended midgrades typically)

ETHANOL is a PITA due to water absorption. As an Engineer ethanol is not needed for pollution. Virtually all cars burn Stoichiometrically now. EtOH was for carburetors. Over oxygent to fully burn fuel for less HC pollutions. Then argument was about energy independence. EtOH was always VERY political. I have no idea if EtOH is a "net win" some say it is or it isn't. Meh

 

[rlhdweman]

I have done this myself, using 13 gallons of no ethanol 91 & adding 2 gallons of E85, so I get a tank of about 93, the ecoboost really noticed the difference. I am planning to try this at the track to see what the actual difference is from 91.

 

[Longhorn]

So can we off the bat use e10 and e15?
Does it perform any differently? (Pre tune)

it doesn’t preform any differently other than saving 6$ off just buying 91

 

[MaverickDragon]

If you really want to see a difference at the track, add a nitrous injection system...
Powertrain warranty OTOH is risky.

 

[Mldavis]

Google it!
Ethanol typically has an octane rating of 113, which is higher than standard gasoline.

 

[alex lobos]

it doesn’t preform any differently other than saving 6$ off just buying 91

I’m just wondering if you would get the same performance out of E 15 gas as premium. Because it’s like a dollar cheaper by me.

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