E85 on stock car

[JD S4]

Doing my first E85 mix today.
Stock 3.0T (intake/exhaust, no tune).
At elevation (6,000 ft base, will be up to 12,000ft this weekend)
Will report back on findings

I'm scared. Hold me.

[redline380]

Doing my first E85 mix today.
Stock 3.0T (intake/exhaust, no tune).
At elevation (6,000 ft base, will be up to 12,000ft this weekend)
Will report back on findings

I'm scared. Hold me.

You are running E85 without an E85 tune? May God have mercy on your engine.

[Silverbullet S4]

What's your mix and what are you hoping to gain?

[DGVR6]

Lol

[doug97gxe]

You are running E85 without an E85 tune? May God have mercy on your engine.

he is doing a mix.. if he does 3 gallons it won't be that bad of an impact

[mintytoo]

he is doing a mix.. if he does 3 gallons it won't be that bad of an impact

I'm guessing cel while on e85/mix then normalizes once reg gas is used?

[doug97gxe]

I'm guessing cel while on e85/mix then normalizes once reg gas is used?

depends.. if he does more than 4 gallons he might see a CEL .. 3 gals of E85 and 93 should be good

but yeah if you switch back to full 93 no more codes

[jimrobbington]

You are running E85 without an E85 tune? May God have mercy on your engine.

I hope you are being ridiculous on purpose... If not, please educate yourself on both E85 and modern technology. Lol.

I run E85 in Colorado in my stock S4 as often as possible. 3 gallons in a full tank does the trick. Feels better in the heat, pulls a little longer, power is more consistent. I messed with multiple ratio mixes, 3 gallons makes me happy. I did get a lean code once when I was trying a 3.5 gallon mix. Tony at EPL himself has stated that this type of lean code is completely software based, as the ecu can't keep up fuel supply within the parameters of the stock tune. There actual limits of the hardware are higher.

I've driven with this mix up to above 8k feet without issue. I don't think you'd have an issue at higher elevation, as the car is actually more starved for air, so I would think fuel demand would be lower if anything? Just an uneducated guess really..

[jimrobbington]

depends.. if he does more than 4 gallons he might see a CEL .. 3 gals of E85 and 93 should be good

but yeah if you switch back to full 93 no more codes

He'd be damn lucky to find 93 in CO. 91 is typically the best available.

[JD S4]

3 gallons of E85 vs. fill on 91.

As mentioned - no 93 octane in CO (almost anywhere).

Will be running no more than 3. Same car/mods/location as Jim ^^

[JD S4]

What's your mix and what are you hoping to gain?

Empty tank, 3 gallons of E85.

More consistency. it's been incredibly hot and I'm heading to elevation. No real "goals" - just consistent feedback across forums that it pulls stronger, even on a stock tune.

[jimrobbington]

Empty tank, 3 gallons of E85.

More consistency. it's been incredibly hot and I'm heading to elevation. No real "goals" - just consistent feedback across forums that it pulls stronger, even on a stock tune.

It doesn't blow your mind or anything, but it's noticeable. Definitely worth it in the summer. I go back to normal 91 through winter. It also brings more instant power from the gas pedal during shifting imo.

[BAHNSTORMER]

My fill ups are typically 10 gal 93 octane E10 and 2 gal E85. The mix gives me a bit over 95 octane & E22. No issues so far.

[4RCFED]

It doesn't blow your mind or anything, but it's noticeable. Definitely worth it in the summer. I go back to normal 91 through winter. It also brings more instant power from the gas pedal during shifting imo.

Yessir, been doing this for well over a year, hell all the Colorado Audiziners (including Jim ☝️) got together and made a list of stations with E85. Drove it home to Telluride and higher with no problems.

[jimrobbington]

My fill ups are typically 10 gal 93 octane E10 and 2 gal E85. The mix gives me a bit over 95 octane & E22. No issues so far.

So you don't fill the tank?

I calculate based on claimed tank size 16.9

I like my 3 gallon mix.

3/16.9 = 17.75% e85

After monitoring and calculating mpg for a while with this mix, I can typically get 19 mpg in my normal city driving.

When it's time to fuel up, I divide miles traveled on the last tank by 19, then multiply that number by .1775 and this gives you the amount of E85 to pump. I pump the e85 and then top with 91 until it clicks off.

[BlownOne]

I've went as high as 3.5 gallons of e85 in a tank of 91 untuned and I'm currently running 5 gallons of e85 with about 10 gallons of 91 on my stage 3 file. Jim is right the higher in elevation you go, the less air you have to mix with fuel so your system would have less of a demand to reach the target afr. E blends and check engine lights seem to vary car to car...I started out with 2 gallons, then 2.25, 2.5, 2.75, 3, 3.5, 4 and finally 4.5. I ran that mix for stage1 and 2, but eventually said fuck it and put 5 gallons in. I don't know if this gave my ecu time to slowly adapt, but I've never had a check engine light. Anything above 2-3 gallons and you need to log.

Will

[redline380]

Tony at EPL himself has stated that this type of lean code is completely software based, as the ecu can't keep up fuel supply within the parameters of the stock tune. There actual limits of the hardware are higher.

Of course the ECU can't keep up with supply since it takes more fuel on e85! Also, all codes are software based since it is the software triggering the code. The software is telling you "Hey, I'm leaning out. This isn't safe." But you are all "I know more than you. Shut up with your stupid lean code."

I mean do as you guys wish, but I wouldn't without a re-tune. However, it may not make a huge deal depending on which gas you are using and how much alcohol you put in. What is fed requirement, cars must be able to run on 15% ethanol? If you start with straight gas and go 20% ethanol, this probably wouldn't cause a massive concern but still probably too lean for the engine to like it. Here in MN, ethanol is required to be added to gas. So, by adding another 20% ethanol to gas that is already diluted could cause cauastrprohic failure without a retune for additional fuel. If you guys in Colorado are diluting straight gas with ethanol, it won't matter since the car can handle 15%. But in other states, adding ethanol to gas that already has ethanol in it could be bad. Hence, my concern.

[onlyaudis]

been running 3 to 4 gallons e85 with a fill up on my EPL stage 1 car for nearly a year, no cels, no issues at all. even at 4 gallons of E85 (which is usually less than 85-more like 70) you are still less than E20 overall if you do the math, and these cars can deal with that no problem. I get maybe 2 MPG less, but E85 is cheaper so it almost even's out. My car pulls noticeably harder and is more responsive --its not a subtle difference and was even more noticeble going backwards when I had to put a tank in without the E85 once. CA 91 gas is not great for high HP forced induction cars

[onlyaudis]

Of course the ECU can't keep up with supply since it takes more fuel on e85! Also, all codes are software based since it is the software triggering the code. The software is telling you "Hey, I'm leaning out. This isn't safe." But you are all "I know more than you. Shut up with your stupid lean code."

I mean do as you guys wish, but I wouldn't without a re-tune. However, it may not make a huge deal depending on which gas you are using and how much alcohol you put in. What is fed requirement, cars must be able to run on 15% ethanol? If you start with straight gas and go 20% ethanol, this probably wouldn't cause a massive concern but still probably too lean for the engine to like it. Here in MN, ethanol is required to be added to gas. So, by adding another 20% ethanol to gas that is already diluted could cause cauastrprohic failure without a retune for additional fuel. If you guys in Colorado are diluting straight gas with ethanol, it won't matter since the car can handle 15%. But in other states, adding ethanol to gas that already has ethanol in it could be bad. Hence, my concern.

adding 4 gallons of E85 will not be adding another 20% ethanol. more like 10-15 % most blends are really like E70 or even lower. Our tank takes 16 gallons, so only if the stuff was E100 would it be close to 20%. Could always do 3 gallons if you are concerned about how much is already in the fuel, which will be only adding another 10%. The engine management in these cars is superb (its why people can run those add on box Chipwerke tuners and not destroy their engines) It can easily cope with 15 to 20 % total ethanol. Been doing it for nearly a year with no issues at all.

[BAHNSTORMER]

So you don't fill the tank?

I calculate based on claimed tank size 16.9

I like my 3 gallon mix.

3/16.9 = 17.75% e85

After monitoring and calculating mpg for a while with this mix, I can typically get 19 mpg in my normal city driving.

When it's time to fuel up, I divide miles traveled on the last tank by 19, then multiply that number by .1775 and this gives you the amount of E85 to pump. I pump the e85 and then top with 91 until it clicks off.

Yeah, I fill the tank. I drive the about the same number of miles every week so the gallons are pretty consistent.

[redline380]

adding 4 gallons of E85 will not be adding another 20% ethanol. more like 10-15 % most blends are really like E70 or even lower. Our tank takes 16 gallons, so only if the stuff was E100 would it be close to 20%. Could always do 3 gallons if you are concerned about how much is already in the fuel, which will be only adding another 10%. The engine management in these cars is superb (its why people can run those add on box Chipwerke tuners and not destroy their engines) It can easily cope with 15 to 20 % total ethanol. Been doing it for nearly a year with no issues at all.

Of course it can handle 15%, EPA says it has to. I'm saying going over that is a problem. If you are adding more ethanol to gas that already is 15% ethanol, you are going to reach the limit sooner or later. I'm not going to do the math on how much e85 to add to 100% gas since it seems like you guys have that handled. But there are seven states that require ethanol to be blended into gas. Saying you are fine running X gallons of e85 is not exactly accurate if you take into account E15 fuel.

[jimrobbington]

Of course it can handle 15%, EPA says it has to. I'm saying going over that is a problem. If you are adding more ethanol to gas that already is 15% ethanol, you are going to reach the limit sooner or later. I'm not going to do the math on how much e85 to add to 100% gas since it seems like you guys have that handled. But there are seven states that require ethanol to be blended into gas. Saying you are fine running X gallons of e85 is not exactly accurate if you take into account E15 fuel.

We do have e10 in our 91 here, still hasn't been a problem with a 3 gallon mix, for me.

[redline380]

We do have e10 in our 91 here, still hasn't been a problem with a 3 gallon mix, for me.

Again, do as you wish but you wouldnt catch me experimenting like that on a car that new. Well, unless I had realtime logs of AFR's and EGT's while doing it. But still probably not...

[sirsycott]

engine is smart enough to compensate where it can, unfortunately (or thankfully) no one has locked up their engine or blown up their motor mixing e85 or running full e85 on stock software to forum knowledge

we have guys running around with full e85 tanks and dedicated full e85 tunes, only thing that changes hardware wise was the fuelpump and a sensor for the APR beta guy who was running it, epl is running their own variation of that

but it tells you that the motor when told to run full e85 is just technically a remap (yes I'm oversimplifying it) , which means the car can handle it

stock software with the code, would mean if the ecu detected something out of parameter it would try whatever it can do to keep it running safely in which ever way it can

[JD S4]

When E85 came out and people started using it 5-10 years ago in boosted applications - I remember people talking about an E85 "conversion".. If I recall - the discussion was always around fuel lines and pumps needing to be changed out.. Strange to see that has gone away - at least in the 3.0T over the years.

I have zero worries. Will toss 3 gallons in and roll.

[jygesq]

Doing my first E85 mix today.
Stock 3.0T (intake/exhaust, no tune).
At elevation (6,000 ft base, will be up to 12,000ft this weekend)
Will report back on findings

I'm scared. Hold me.

what do expect to gain? We in CT. are lucky I get 93 Shell for $2.89 gall. Was $2.79 for long time. Get 19.5 MPG city/

[JD S4]

what do expect to gain? We in CT. are lucky I get 93 Shell for $2.89 gall. Was $2.79 for long time. Get 19.5 MPG city/

Common consensus is that E85 mix gives the ECU enough net octane to hit that extra timing map, run a little stronger, pull a bit stronger into the rev range, etc. Especially in heat (and elevation). Dyno proven on tuned cars - not sure if anyone has dyno'd a stock tuned car with E85 blend but common consensus is butt dyno approves. We don't get 93 here due to the elevation so I'm just fiddling around to see what we can do.

[Silverbullet S4]

I guess I don't see the point in running a mix on a stock car. That said, I'm currently stage 2 on a 91 map and have been running 3-4 gallons mixed with 91 and haven't throw any CELs. Good enough results that I'm about to get the 93 map instead of the 91 and run a blend from here on out targeting ~94 octane with the blend.

[jimrobbington]

I guess I don't see the point in running a mix on a stock car. That said, I'm currently stage 2 on a 91 map and have been running 3-4 gallons mixed with 91 and haven't throw any CELs. Good enough results that I'm about to get the 93 map instead of the 91 and run a blend from here on out targeting ~94 octane with the blend.

Well, since our cars are engineered for 93 octane, but many of us are only able to run 91 Oct, there is the immediate benefit of increasing octane and getting the full potential out of the oem software without having 93 to use.

[Silverbullet S4]

Well, since our cars are engineered for 93 octane, but many of us are only able to run 91 Oct, there is the immediate benefit of increasing octane and getting the full potential out of the oem software without having 93 to use.

That's sound logic right there and I hadn't even taken that into account. Good call!

[jimrobbington]

That's sound logic right there and I hadn't even taken that into account. Good call!

[redline380]

That's sound logic right there and I hadn't even taken that into account. Good call!

But you have to keep in mind it takes more alcohol to reach stoich than gas! Sure, you can add alcohol to get to your 93 oct, but you'll have to inject more fuel overall to run safe AFR's. Which is of course why E85 vehicles get worse mileage. It has way more power potential, but takes more fuel to reach it safely.

[Silverbullet S4]

But you have to keep in mind it takes more alcohol to reach stoich than gas! Sure, you can add alcohol to get to your 93 oct, but you'll have to inject more fuel overall to run safe AFR's. Which is of course why E85 vehicles get worse mileage. It has way more power potential, but takes more fuel to reach it safely.

True but, I can't imagine most folks in S4s are that worried about losing a couple MPGs. Especially if it results in (as Clarkson would say) "mooore powerrrrrr"! ;-)

[JD S4]

But you have to keep in mind it takes more alcohol to reach stoich than gas! Sure, you can add alcohol to get to your 93 oct, but you'll have to inject more fuel overall to run safe AFR's. Which is of course why E85 vehicles get worse mileage. It has way more power potential, but takes more fuel to reach it safely.

Happy to make that trade off.

E85 is 75% the price here which also offsets a portion of the mileage decrease. Wrong car to own if you're solely focused on MPG anyways as we all know. Performance is a tradeoff I'm willing to make.

Cliff notes: most of us are rich as fuck and dont care about MPG.

[redline380]

True but, I can't imagine most folks in S4s are that worried about losing a couple MPGs. Especially if it results in (as Clarkson would say) "mooore powerrrrrr"! ;-)

MPG's are the last concern. The reason behind lower MPG's is the biggest concern. When comparing to gas, it takes more alcohol to fuel an engine hence the lower MPG's. But if you are running the same amount of alcohol as you did gas, AFR's and EGT's go up and shit starts getting hot. As we already went over, the stock ECU has to be able to compensate for up to 15% alochol per EPA regs. Anything over that and you are running into uncharted territory and the ECU cannot compensate to run enough alcohol to properly fuel and prevent high combustion temps. Running lean is a bitch.

Admittedly, I know next to nothing about recent model cars. Perhaps the B8 S4 ECU is smart enough to compensate for running alcohol above 15%. But I am willing to bet it isn't and I certainly wouldn't be the one who wants to try it. I want to emphasize nobody here gives a cat's ass about MPG's, it is the reason MPG's are lowered that matters, and that is because it takes more fuel when running alcohol to avoid lean conditions.

[BAHNSTORMER]

Adding 2-3 gallons of E85 per tank didn't affect my calculated mpg at all.

[redline380]

Adding 2-3 gallons of E85 per tank didn't affect my calculated mpg at all.

It probably wouldn't, although driving and weather conditions do matter greatly. However, going to full E85 would have a very negative effect on MPG's. However, because of the lower price, it could all equal out in the end, or close to it.

[4RCFED]

Well, since our cars are engineered for 93 octane, but many of us are only able to run 91 Oct, there is the immediate benefit of increasing octane and getting the full potential out of the oem software without having 93 to use.

FTW! We use it to boost octane, IIRC E85 is like 105-110 octane.

[BAHNSTORMER]

FTW! We use it to boost octane, IIRC E85 is like 105-110 octane.

Yup. 3 gal of E85 + 13.9 gal of 91 octane = 93.5 octane E23

[redline380]

FTW! We use it to boost octane, IIRC E85 is like 105-110 octane.

Might as well just use straight e85 for 105oct then 😔