The Official Unofficial E85 Ethanol Thread

[Stija]

This is why one needs a gauge readout. Otherwise you’re guessing one, two, three variables and then using the result as unknown variable #1 on next fill.

What did you use to test your e85 at 83%? One of those vials mixing with water?

 

[anotero]

This is why one needs a gauge readout. Otherwise you’re guessing one, two, three variables and then using the result as unknown variable #1 on next fill.

What did you use to test your e85 at 83%? One of those vials mixing with water?

Yes, i used a vial. On three different occasions over the span of a couple of months. I was surprised to see such a high level of purity considering this station is not in the best region of the state.

 

[anotero]

This is why one needs a gauge readout. Otherwise you’re guessing one, two, three variables and then using the result as unknown variable #1 on next fill.

What did you use to test your e85 at 83%? One of those vials mixing with water?

Do you use a gauge from Fuel-It?

 

[jimlloyd40]

Half gallon to the point of it spilling out of the tank?

No after the pump shuts off and I add approximately another 1/2 gallon. I wait a second and then squeeze the pump handle one more time and it clicks off pretty quickly and then I stop. I have to fill up every day and I want it filled consistently the same way to check fuel mileage accurately. It never spills out.

 

[anotero]

No after the pump shuts off and I add approximately another 1/2 gallon. I wait a second and then squeeze the pump handle one more time and it clicks off pretty quickly and then I stop. I have to fill up every day and I want it filled consistently the same way to check fuel mileage accurately. It never spills out.

Got it. I read up on how gas station pumps work and how they know when to shut off. When the pump shuts off, the gasoline is already in the fuel tank tank fill up channel, covering the small hole at the pump tip. Assuming some gasoline foaming and letting it settle after the first click, and then letting the pump run until a second click should fill the tank right about full, as far as i understand.

 

[jimlloyd40]

Got it. I read up on how gas station pumps work and how they know when to shut off. When the pump shuts off, the gasoline is already in the fuel tank tank fill up channel, covering the small hole at the pump tip. Assuming some gasoline foaming and letting it settle after the first click, and then letting the pump run until a second click should fill the tank right about full, as far as i understand.

Pretty close. If you're running the pump at full speed it will bubble up the filler neck and shut off sooner than the middle notch that I use. I just fill mine up consistently the same way so my fuel mileage calculations are the most accurate. Some gas stations pumps fill faster than others at full speed and the faster it fills the sooner it will bubble up and shut off requiring more to fill it the rest of the way.

 

[anotero]

Pretty close. If you're running the pump at full speed it will bubble up the filler neck and shut off sooner than the middle notch that I use. I just fill mine up consistently the same way so my fuel mileage calculations are the most accurate. Some gas stations pumps fill faster than others at full speed and the faster it fills the sooner it will bubble up and shut off requiring more to fill it the rest of the way.

Got it. Thanks.

 

[ChrisMk77]

No after the pump shuts off and I add approximately another 1/2 gallon. I wait a second and then squeeze the pump handle one more time and it clicks off pretty quickly and then I stop. I have to fill up every day and I want it filled consistently the same way to check fuel mileage accurately. It never spills out.

You should not top up a MK7 or you risk filling the EVAP canister.

This is a great tool to calculate E blend, I usually just fill 12.5L E85 27.5L 98E5 when the gauge is under 1/4 tank.

https://adamtuned.myshopify.com/pages/tuning-tools#

 

[NeedSleep]

I tested the E85 from station i fill up at, and it's consistently 83%, so pretty much as pure as it gets. However the question still stands: how full is a mk7 tank when the gas pump stops pumping? Using the dash refuel quantity has a margin of +/- 0.5 gal, i assume.

I've calculated about 12.5 gallons until the first click at most stations I've gone to. As someone said above, it can differ with each station -- one station i used to go to would shut off very early.

I don't use the digital refuel quantity read-out that can be enabled via VCDS/OBDeleven to do my calculations. I use the analog gas gauge since the hash marks allow for more precision than the integers in the digital read-out.

There are 8 main indices in the analog gauge. Like someone above, I say 12.5gal/8 = 1.5625gal of fuel are represented by those big indices. Using that has been pretty accurate with how much total fuel I end up putting in.

Sent from my SM-G930T using Tapatalk

 

[anotero]

I've calculated about 12.5 gallons until the first click at most stations I've gone to. As someone said above, it can differ with each station -- one station i used to go to would shut off very early.

I don't use the digital refuel quantity read-out that can be enabled via VCDS/OBDeleven to do my calculations. I use the analog gas gauge since the hash marks allow for more precision than the integers in the digital read-out.

There are 8 main indices in the analog gauge. Like someone above, I say 12.5gal/8 = 1.5625gal of fuel are represented by those big indices. Using that has been pretty accurate with how much total fuel I end up putting in.

Sent from my SM-G930T using Tapatalk

Yeah, i prefer the gauge too. It has a total of 32 divisions, allows for very precise calculations.

 

[MSH]

For those that have one of the Fuel-it flex fuel kits what's the general consensus on the accuracy? I know they use the Conti sensor, which seems to be used in most of these kits. I think the quoted accuracy is supposed to be +/- 5% of blend you are mixing to.
I just pulled the trigger on one of the Fuel-it kits, since I'm having a HPFP installed next week on my R and then getting an e-tune from EQT for E40. Since I'll be on a lower % blend I suppose the accuracy is less critical than if I was tuning for pure E85, but still curious what the experience has been for those running the Fuel-it kit on accuracy

 

[brobst]

Reads pretty well on pump. Would say +-2%

Sent from my SM-G960U using Tapatalk

 

[Hoon]

I was within 1% of the test tube, so pretty damn accurate.

 

[madelinot]

I have the GM sensor combined with Aeroforce wiring harness. I'm really impressed with the accuracy; I would say it's +/- 1%.

 

[MSH]

Reads pretty well on pump. Would say +-2%

I was within 1% of the test tube, so pretty damn accurate.

I have the GM sensor combined with Aeroforce wiring harness. I'm really impressed with the accuracy; I would say it's +/- 1%.

Thanks for the feedback everyone! Super helpful