Fuel Question

[Ardfarkl]

I have a 2019 GT I have been running a non ethanol 90 octane gas Would the motor rather have 93 octane with ethanol? Going to get a tune soon and not going E-85 yet
Thanks!

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[Cory S]

Engine could care less. The amount of Ethanol in todays pump fuel is usually less than 8%, with most being closer to 5-6% (or LESS). It's has zero effect with todays ECU mapping.

With that said, 93 octane with a titch of Ethanol would be a hands down winner.

 

[illtal]

Not going to hurt it. More octane is better.

 

[Andy13186]

The more ethanol the better. 93 will be better than non ethanol 90. Will run slightly cooler and is higher octane, so more power and knock resistance. Over 10% may require a tune.

 

[Angrey]

The concerns around ethanol content are old/dated (up to a point) because ethanol is more chemically active in attacking fuel system polymers (hoses, plastic vessels, etc).

Most modern cars are now equipped with more more resistant components to run higher ethanol content without risk of degradation.

Additionally, ethanol has less potential chemical energy than longer hydrocarbons contained in gasoline. This means your vehicles wideband tuning will have to adjust and increase the amount of fuel in order to keep the appropriate air/fuel mixture for desired tuning.

From what we've seen, the modern coyote tune and wideband can accommodate ethanol content upward of about 30% before it becomes problematic and requiring a tune adjustment. (that doesn't mean you should run E30 without a tune, but the computer has adjustment).

In additional to being more chemically active, ethanol is also much more hydrophilic. In purest form, it's impossible to get ethanol purer than about 95% (the other 5% being water) through physical means (evaporative fractioning) because small portions of water evaporate over with the ethanol (in using a simple still or a double effect evaporator, etc). You can chemically process it and get it purer, but it's expensive and much more effort.

What does that mean? Ethanol likes water. When left exposed to air with water vapor, it pulls the moisture out of the air.

In a typical modern fuel system, the tank has an evap system which will allow it to purge when the pressure in the tank becomes too high (to keep the tank or other components from bursting). Additionally, it can purge and equalize if the pressure becomes too negative (to keep the tank from collapsing). This venting obviously presents a widespread pollution point/source so the EPA and manufacturers go to great lengths to reduce the constant suck/blow of fuel tank valving to equalize pressure.

For us, it means anyone running higher content ethanol should be wary that long periods of storage where the temperature swings widely each day, the tank will continue to suck and blow and bring in fresh new ambient air (which has moisture in it) and the fuel will desiccate the air and draw in most of it's moisture. The result is that over time the fuel will continue to increase in water content.

Long story endless, not optimal to leave high ethanol fuels for long periods of time without operation and/or refresh.

The good news however is that not only is ethanol much higher octane rating/resistant to knock and preignition than typical gasoline hydrocarbons, it burns cooler as well.

In the end, as long as the E content isn't excessive, you should run as much of it as possible and just refresh the tank normally (no long storage) and enjoy the higher octane rating/knock resistance.

 

[Cory S]

From what we've seen, the modern coyote tune and wideband can accommodate ethanol content upward of about 30% before it becomes problematic and requiring a tune adjustment.



Long story endless, not optimal to leave high ethanol fuels for long periods of time without operation and/or refresh.

More great truthful info there^.

The issue with "long periods" is that there is a LOT of large varying personal experiences with this. Paranoia has made shelf life labeled as super short, which clearly isn't truth. From my research and others long term experiences, a "LONG" period would be around 12 months in a sealed out of sunlight environment.

 

[glockholiday]

Ford's website lists the 460hp being made (on 93 octane)

 

[Angrey]

More great truthful info there^.

The issue with "long periods" is that there is a LOT of large varying personal experiences with this. Paranoia has made shelf life labeled as super short, which clearly isn't truth. From my research and others long term experiences, a "LONG" period would be around 12 months in a sealed out of sunlight environment.

Truly, it mostly depends on the ambient humidity in your area and the daily temp swings. And of course like anything, what's a "long time" to one person vs another?

Point is, it doesn't store as long as well as lower content blends or ethanol free fuel (which is part of the reason why it's best to use ethanol free fuel in small engines).

Over long periods of time even gasoline will laminate and varnish.

 

[EFI]

I have been running a non ethanol 90 octane gas Would the motor rather have 93 octane with ethanol?

110% yes. More octane and more ethanol is always better for performance. It might suffer 2-3% worse fuel economy and cost a bit more, but that's the only downside.

 

[Ardfarkl]

Thank you all I come from the vintage dirt bike world where ethanol is not very good (carbs). Very educational!

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