Help me understand E85

[Angrey]

You could but it would be a hassle. You'd have to run the 93 down to fumes before filling up with E85 and make sure that fuel is through the system before you get on it. The closest station for me always runs between 74 and 77% ethanol. A couple gallons of 93 still in the tank puts me under E70 (between 65-68%) which isn't good enough. If it was E80 or up it would probably be good enough. Flashing a tune doesn't take long at all. Only a couple of minutes and another few minutes of driving for the car to adjust. You could even stay on the flex tune and run whatever fuel you want and go to the E85 tune when you want the extra benefit. No reason to go between 3 different tunes. IMO if you're not racing no reason not to use a flex fuel tune unless you have E85 on every corner. You'd be able to tell a big difference in power on a flex tune and running high E content.

I'm getting the impression that he paid for the race tune but doesn't have the flex tune. So he's wanting to jump straight from 93 to the race tune. Which can be done, just have to drive like an old woman for the first tank of E85.

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[RoGCobraRV]

I'm getting the impression that he paid for the race tune but doesn't have the flex tune. So he's wanting to jump straight from 93 to the race tune. Which can be done, just have to drive like an old woman for the first tank of E85.

Hadn't done any tune yet actually just gathering info. Wasn't sure if you could jump from one tune to the other without a flex in-between since their would be reg gas in lines and some in the tank with the E fill up

 

[Cory S]

Hadn't done any tune yet actually just gathering info. Wasn't sure if you could jump from one tune to the other without a flex in-between since their would be reg gas in lines and some in the tank with the E fill up

It’s not very difficult. People make it way more difficult than it needs to be.

 

[Magnetic Stang]

I'm getting the impression that he paid for the race tune but doesn't have the flex tune. So he's wanting to jump straight from 93 to the race tune. Which can be done, just have to drive like an old woman for the first tank of E85.

Agreed. It can be done for sure. I just think the flex fuel tune makes transitioning between fuels simple for someone new to running E.

 

[Angrey]

Agreed. It can be done for sure. I just think the flex fuel tune makes transitioning between fuels simple for someone new to running E.

You'll get no arguments from me. I just got the impression he either didn't want to run the flex or didn't have it.

 

[MurphGT]

Read through this entire thread and it has a lot of great information. I'm kind of on the fence between running a flex tune, or just a dedicated 93 tune (for simplicity and convenience sake).

My main concerns/questions are:
1) Moisture/water buildup, and the resulting damage it could cause

2) Constantly having to worry about testing fuel or keeping a certain ratio if I was running dedicated e85 (It seems that the flex tune can account for less than ideal flex fuel/e85 fuel, but could this still be detrimental to the engine long term if you're getting E70 fuel or sub-par flex fuel?)

3) I've been reading about problems people have been having trying to switch from dedicated E85 to flex tune to dedicated 93, or visa versa ( issues ranging from idling problems to the car feeling sluggish ; this also seems to be the reason Lund is no longer offering/troubleshooting flex fuel tunes to my understanding?) I don't really want to have to constantly bounce back and forth between tunes based on gas availability, so I'm kind of torn between just going with the flex tune and never changing it (is this a bad idea? I've heard people say it's more of a transitional tune), or just going with a dedicated 93 tune and saving myself the headache

4) How much of a difference in horsepower is there between a dedicated 93 tune, and a flex tune running e85? (obviously the e85 will make more power, I'm just curious if the results are somewhat close, or if there's a drastic difference). Does anyone have any dyno results on this with X mods, or a stock vehicle?


I was originally going to do dedicated E85/flex, but then I looked up different ethanol testers and came across a few excerpts from the Rev x Ethanol tester that were mildly concerning, especially living in Florida with constant heat and humidity:


Link: https://www.amazon.com/REV-X-Super-Tester-Flex-Ethanol/dp/B073HLSVHX

" Ethanol is Corrosive
Ethanol, like all alcohol, is very corrosive and hygroscopic (attracts and absorbs water from the air and its surrounding). High amounts of this highly corrosive mixture of water and ethanol will corrode all fuel system components not designed for it. Besides the corrosive nature, the increase in water will begin to rust out the top of gas tanks, including in warm-weather climates that generally do not have rust issues."

" Ethanol Can Damage Fuel Systems
Ethanol's ability to attract and absorb liquids prevents the natural lubricants in gasoline from doing their job, causing all non-alcohol resistant parts like rubber and plastic to dry out, crack and eventually fail. High oxygen levels in ethanol-blended fuels cause fuel to decay much faster, and if left to sit, that decay leaves deposits such as varnish and sludge. The sediments left by the decaying ethanol-blended fuel will clog fuel filters, fuel injectors, carburetors, and fuel lines. Making your engine hard to start, idle rough, stall, and in extreme circumstances, engine failure. "

" Ethanol Decreases Fuel Life

Ethanol increases the octane level in your fuel. Because of this, the base gasoline used to mix E10, E15, or E20 starts at a lower octane level. The ethanol then increases the octane level. As a result, ethanol-blended fuels will begin to decay in as little as two months due to ethanol evaporating faster than gasoline, leaving behind the much lower octane base stock."



Based on the above, what's everyone's thoughts?

 

[ChitownStang]

Read through this entire thread and it has a lot of great information. I'm kind of on the fence between running a flex tune, or just a dedicated 93 tune (for simplicity and convenience sake).

My main concerns/questions are:
1) Moisture/water buildup, and the resulting damage it could cause

2) Constantly having to worry about testing fuel or keeping a certain ratio if I was running dedicated e85 (It seems that the flex tune can account for less than ideal flex fuel/e85 fuel, but could this still be detrimental to the engine long term if you're getting E70 fuel or sub-par flex fuel?)

3) I've been reading about problems people have been having trying to switch from dedicated E85 to flex tune to dedicated 93, or visa versa ( issues ranging from idling problems to the car feeling sluggish ; this also seems to be the reason Lund is no longer offering/troubleshooting flex fuel tunes to my understanding?) I don't really want to have to constantly bounce back and forth between tunes based on gas availability, so I'm kind of torn between just going with the flex tune and never changing it (is this a bad idea? I've heard people say it's more of a transitional tune), or just going with a dedicated 93 tune and saving myself the headache

4) How much of a difference in horsepower is there between a dedicated 93 tune, and a flex tune running e85? (obviously the e85 will make more power, I'm just curious if the results are somewhat close, or if there's a drastic difference). Does anyone have any dyno results on this with X mods, or a stock vehicle?


I was originally going to do dedicated E85/flex, but then I looked up different ethanol testers and came across a few excerpts from the Rev x Ethanol tester that were mildly concerning, especially living in Florida with constant heat and humidity:


Link: https://www.amazon.com/REV-X-Super-Tester-Flex-Ethanol/dp/B073HLSVHX

" Ethanol is Corrosive
Ethanol, like all alcohol, is very corrosive and hygroscopic (attracts and absorbs water from the air and its surrounding). High amounts of this highly corrosive mixture of water and ethanol will corrode all fuel system components not designed for it. Besides the corrosive nature, the increase in water will begin to rust out the top of gas tanks, including in warm-weather climates that generally do not have rust issues."

" Ethanol Can Damage Fuel Systems
Ethanol's ability to attract and absorb liquids prevents the natural lubricants in gasoline from doing their job, causing all non-alcohol resistant parts like rubber and plastic to dry out, crack and eventually fail. High oxygen levels in ethanol-blended fuels cause fuel to decay much faster, and if left to sit, that decay leaves deposits such as varnish and sludge. The sediments left by the decaying ethanol-blended fuel will clog fuel filters, fuel injectors, carburetors, and fuel lines. Making your engine hard to start, idle rough, stall, and in extreme circumstances, engine failure. "

" Ethanol Decreases Fuel Life

Ethanol increases the octane level in your fuel. Because of this, the base gasoline used to mix E10, E15, or E20 starts at a lower octane level. The ethanol then increases the octane level. As a result, ethanol-blended fuels will begin to decay in as little as two months due to ethanol evaporating faster than gasoline, leaving behind the much lower octane base stock."



Based on the above, what's everyone's thoughts? Again, I'm kind of torn on the best decision for a NA daily driver/weekend fun car. I'm just looking to learn from those with more experience than myself in this area

0 issues with the flex tune transitioning fuels. I ran 93 all winter which is same as dedicated 93, no point not to have the option to run e85 for more fun in the summer. If you’re worried about ethanol ruining fuel system then jus run some 93 in every couple fill ups.

 

[WildHorse]

Ethanol increases the octane level in your fuel. Because of this, the base gasoline used to mix E10, E15, or E20 starts at a lower octane level. The ethanol then increases the octane level. As a result, ethanol-blended fuels will begin to decay in as little as two months due to ethanol evaporating faster than gasoline, leaving behind the much lower octane base stock."

Well leaving my car parked for 5 months with e10 read 91% fuel level. After 5 months, still 91% fuel level, not 81%.

anyways, IMO I don't trust anyone's 'flex' tunes. you know, cause the mustang isn't a flex fuel car.

one of my tunes is a E60 tune. E60-E85 there will be zero difference in power or timing IMO.

 

[JustSomeGuy]

I know exactly nothing about e85… if I were to switch after reading this entire thread…

Is the theory that you run your tank (basically) dry, then drive to the e85 gas station, load the e85 tune, fill up with e85 and then start the car? Or do you have to do something else?

Lots of people talking about testing their e85 content when they fill up. So… what happens when the e85 content is too low (presumably that’s why you’re testing)? You can’t fill up and have to go to a different gas station?

 

[WildHorse]

Lots of people talking about testing their e85 content when they fill up. So… what happens when the e85 content is too low (presumably that’s why you’re testing)? You can’t fill up and have to go to a different gas station?

IMO yer safe all the way down to E60.

Results of mix is 103 Octane
Stoich AFR of mix is 10.48
% Ethanol is 60.63

E85 is 105 octane.

Which tells me some tuners are putting way more timing than what's necessary if they want you to test E85. And for what ? 3 more hp ?

 

[Gfswindle]

The ecu can compensate for a large range. After a full up I keep an eye on my afr's for a little while to see if it changes. That let's me know if the e content has changed any.

 

[MurphGT]

one of my tunes is a E60 tune. E60-E85 there will be zero difference in power or timing IMO.

That's kind of interesting. So you program the computer to eliminate the negatives from getting bad fuel, and at worst, get good fuel?

By similar logic, would it make more sense to go with a 91 pump gas tune on a DD, to eliminate the negatives from getting bad gas on a dedicated 93 tune (which i've read can cause you to get engine knock?)

 

[kz]

@MurphGT - my quick thoughts - stock F150 with essentially same engine has flex fuel ability. So the fuel system is designed from the factory to use Ethanol as I see it.

Also - I don't test anymore. And between 93, Flex and dedicated E85 tune from Lund, the last one is the best by far.

 

[MurphGT]

@MurphGT - my quick thoughts - stock F150 with essentially same engine has flex fuel ability. So the fuel system is designed from the factory to use Ethanol as I see it.

Also - I don't test anymore. And between 93, Flex and dedicated E85 tune from Lund, the last one is the best by far.

appreciate the reply man

 

[Angrey]

appreciate the reply man

Just to be clear, the dedicated E85 race tune assumes the E85 is actually 85% and it doesn't wait for the tune/computer to be comfortable, it COMMANDS the additional timing.

The "flex" tune, will allow the computer and the wideband/knock inputs to eventually get up to (or very close) to the same timing as the race tune, but it doesn't force it. So if you fill up with high quality 85%, the flex tune will take advantage of most of the output. The differences between the power output of a car running the flex tune with 85% ethanol and the car running the dedicated race tune with the same fuel would be very small, especially at WOT. The dedicated race tune does feel "snappier" at partial rpm and throttle because again, it's not waiting for the computer to be comfortable, it's basically saying "trust me, send it."

The problem with the dedicated race tune is that there's huge swings in the quality of E85, from station to station and even from the same station. I filled up 2 weeks ago and got really high quality E85. Filled up Saturday and with only 4.2 gallons, it dropped my fuel content from 78 to 72. Meaning the E85 that I added was approximately 55. (total crap).

Does this have an effect? Yes. With cruising, I normally glance over and watch my knock and spark advance. Even a slight uphill or a little throttle to catch back up or accelerate in 6th gear starts to pull timing. This time around I noticed I was getting the full 6 degrees of knock retard when doing slow acceleration in high gear (and that's rare for me to see the full 6 degrees. Normally it'll start pulling timing but it's 2, 3 or 4 degrees. This time it was maxing out).

I highly recommend running a flex tune if you're not getting ALL your E85 from a can or a barrel. (vs the race tune).

If you're running the race tune or you're tuned for a blower setup (without the true flex fuel feature) I recommend getting an ethanol sensor. It costs about $400 with everything required and I can monitor the content value from an app on my phone, instantly and any time the car is running. No more testing with tubes and water bottles at the pump, which irritates people waiting, is a hassle, presents odor/fume issues with any parts you have to keep in your car, etc.

Now that I have the sensor, I can simply adjust my driving habits accordingly and NOT flog the car when I know it's got lesser quality fuel in the tank. Some days I fill up and my content is very high and those are the days it's better/safer to rip the car or rip it back to back with higher IAT's, etc.

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