View Full Version : Switching to and from E85
devo321
03-28-2025, 10:01 AM
Hey guys, thinking about pulling the trigger on an ethanol sensor for my C7.5. (CREC engine)
Live in Arizona so the E85 where is a somewhat limited so I'm curious about the process of switching back to 91 if need be.
I'm currently running the 034 Stage 1 tune. From my understanding going to E85 is fairly simple and there's tons of calculators to help for this. The 034 tune is for E60-E85 so planning to aim for E70.
My main concern is about returning to 91. Do I need to get the ethanol content all the way to E10, or is there some flexibility? If I fill up with 91, can I just drive carefully until the ethanol content drops, or do I need to drain the tank first? Also, should I switch the tune as soon as I go below E60, or wait until I hit E10?
For those running an E85 setup, how do you handle going back and forth, if you do?
Thanks!
Audisthesia
03-28-2025, 02:30 PM
Do you have a fueling solution that can handle E60 ?
devo321
03-28-2025, 02:50 PM
From what I understand the CREC 3.0T SC has the fueling capacity to handle full E85.
I believe it has MPI from factory.
Audisthesia
03-29-2025, 04:02 AM
Does your 034 tune have the ability to read the E sensor and adjust?
Dannnny
03-29-2025, 05:52 AM
Here is a link to an 034 video where they discuss swapping between gas and E85. Looks like the CREC's stock fueling system is enough for full e85 up to stage 2 based on their tuning page.
https://youtu.be/fGf5IVruS7Y?si=rCExFPlKk4aLe-Sw
Sent from my SM-N981U using Audizine Forum mobile app (https://r.tapatalk.com/byo?rid=87676)
wootwoot
03-29-2025, 04:34 PM
Hey guys, thinking about pulling the trigger on an ethanol sensor for my C7.5. (CREC engine)
Live in Arizona so the E85 where is a somewhat limited so I'm curious about the process of switching back to 91 if need be.
I'm currently running the 034 Stage 1 tune. From my understanding going to E85 is fairly simple and there's tons of calculators to help for this. The 034 tune is for E60-E85 so planning to aim for E70.
My main concern is about returning to 91. Do I need to get the ethanol content all the way to E10, or is there some flexibility? If I fill up with 91, can I just drive carefully until the ethanol content drops, or do I need to drain the tank first? Also, should I switch the tune as soon as I go below E60, or wait until I hit E10?
For those running an E85 setup, how do you handle going back and forth, if you do?
Thanks!
Do it! I'm in AZ too running 034 Stage 2 on a CREC. I haven't added an ethanol sensor but will be curious to see how it works out for you. I've considered E85 also but just haven't pulled the trigger yet. This 034 video shows the process on how to switch from one fuel to another. I'm not sure how low of an ethanol content the fuel needs to get before going back to the 91 tune but that would be a good question for the live chats that 034 does. https://www.youtube.com/watch?v=nYKJi8CSZ7s
Burkeomatic
04-02-2025, 09:49 PM
Thing is, with E85, you never know what you're going to get out of the nozzle at the gas station. They do it by vapor pressure not E concentration now. So where it used to be pretty straight forward and you knew roughly what you were going to get, you don't anymore. Luckily down here, I usually get close to E85, but when I'm mathing it trying to keep it around E60 or so (it's what I'm limited to by my fuel pump at the moment) then I run the car for a few minutes and I've got more pesky 93 in there than I want, it's the worst. Make sure you're GTG.
I think the CREC took care of most of the shortfalls for the 3.0t with the port injection. Now if we can just get someone with the proper E-85 sensor that adjusts the map automatically, that'd be the new hotness I think.
Botbasher
04-03-2025, 05:31 AM
Now if we can just get someone with the proper E-85 sensor that adjusts the map automatically, that'd be the new hotness I think.
What??? Like DS1 does?
Up in Mid-Atlantic area, Sheetz is the common supplier for "E85". The few times I have tried it pure (0 miles on the counter), I got ~70% E content, so I adjusted all my calculators and I'm usually within about 2% mix to sensor.
If you are desperate to know without a sensor, get you one of those little E Bottles and test it one day. They're anywhere from $10-40 on Amazon and work well. I did it for a long time on my A5 before I added a sensor and then actually used it to calibrate the sensor! (Continental vs eBay sensors)
Cheers,
KS
devo321
04-03-2025, 07:06 AM
Thing is, with E85, you never know what you're going to get out of the nozzle at the gas station. They do it by vapor pressure not E concentration now. So where it used to be pretty straight forward and you knew roughly what you were going to get, you don't anymore. Luckily down here, I usually get close to E85, but when I'm mathing it trying to keep it around E60 or so (it's what I'm limited to by my fuel pump at the moment) then I run the car for a few minutes and I've got more pesky 93 in there than I want, it's the worst. Make sure you're GTG.
I think the CREC took care of most of the shortfalls for the 3.0t with the port injection. Now if we can just get someone with the proper E-85 sensor that adjusts the map automatically, that'd be the new hotness I think.
Yeah, I'd essentially be looking at doing the same. Probably something like E70 but the 034 tune asks to be between 60 and 85. More concerned about going the opposite way back to 91. AZ has a min content of 54, so the number of gas stations that actually try to get to E85 are slim. Arizona car scene is pretty good at keeping the E85 info up to date though.
What??? Like DS1 does?
Up in Mid-Atlantic area, Sheetz is the common supplier for "E85". The few times I have tried it pure (0 miles on the counter), I got ~70% E content, so I adjusted all my calculators and I'm usually within about 2% mix to sensor.
If you are desperate to know without a sensor, get you one of those little E Bottles and test it one day. They're anywhere from $10-40 on Amazon and work well. I did it for a long time on my A5 before I added a sensor and then actually used it to calibrate the sensor! (Continental vs eBay sensors)
Cheers,
KS
Going to pick up a tester along with a sensor when I get around to it. Def want to know what I'm putting in the tank.
As far as I know, DS1 doesn't support the 3.0t platform?
Would 100% jump to a tune that adjusts the map automatically if someone decides to support the supercharged platform.
Botbasher
04-03-2025, 08:26 AM
As far as I know, DS1 doesn't support the 3.0t platform?
No, they don't... your profile and header don't mention and since Burke is a 4.0t, I presumed... Sorry!
Cheers,
KS
devo321
04-03-2025, 09:03 AM
Ah my bad. How do I set that info in the header? I couldn't seem to find that.
Burkeomatic
04-03-2025, 03:32 PM
What??? Like DS1 does?
Up in Mid-Atlantic area, Sheetz is the common supplier for "E85". The few times I have tried it pure (0 miles on the counter), I got ~70% E content, so I adjusted all my calculators and I'm usually within about 2% mix to sensor.
If you are desperate to know without a sensor, get you one of those little E Bottles and test it one day. They're anywhere from $10-40 on Amazon and work well. I did it for a long time on my A5 before I added a sensor and then actually used it to calibrate the sensor! (Continental vs eBay sensors)
Cheers,
KS
Yes, that's the missing link to 3.0t awesomeness. I'd have kept mine if that were an option. E85 port injection to cool off that roasting hot supercharger air (since you're spinning it way off the compressor map) and auto map scaling to get it perfect because map switching sucks.
Yeah, I'd essentially be looking at doing the same. Probably something like E70 but the 034 tune asks to be between 60 and 85. More concerned about going the opposite way back to 91. AZ has a min content of 54, so the number of gas stations that actually try to get to E85 are slim. Arizona car scene is pretty good at keeping the E85 info up to date though.
Going to pick up a tester along with a sensor when I get around to it. Def want to know what I'm putting in the tank.
As far as I know, DS1 doesn't support the 3.0t platform?
Would 100% jump to a tune that adjusts the map automatically if someone decides to support the supercharged platform.
No, he just mentioned it because I was talking about how that would be a game changer for the 3.0T world. Who ever introduces it would dominate the market. Unfortunately, the tuners care for the 3.0T is long gone. That's the innovation and break through that has been needed for the 3.0T forever, and port injection for the non-crec cars.
I used to mapswitch on my Miata before I was able to upgrade to a megasquirt 3 to use an E85 sensor (exactly like the DS1 uses) and it was the worst. Back in the day, you'd need to keep a laptop with you.
The big things adjusted for E85 are timing and fuel. More ethanol equals more timing and more fuel, and less ethanol equals less timing and less fuel. I was in a pinch and I didn't have my laptop and I couldn't find E85, so I stuck some 93 in it, and it just ran pig rich, I kept out of the throttle too much, basically limping it to where I knew I could get some. And that's always a possible scenario. If your favorite E85 spot is out, and there's not another for 20-30 miles and you're running on fumes, there's a decision to be made, right? E85 is totally worth it, and really wakes these cars up. I just have an app called "e85 stations" and that does a good job finding them.
Anywho, that was probably the main reason I went 4.0T, well that and my kids have my DNA and my girls are destined to be near 6 feet tall by the time they're 14, so there's that as well. I still miss my A7 some days though, it handled better and I had all of the preventative stuff done to it.