Switching between pump 93 and e85

[ZuMBLe]

I understand that this has something that's been discussed before, and maybe it's a wash, but is there any clear advantage to using full e85 as opposed to a e60 blend in these cars?

The most clear advantage is not switching pumps and mixing.

 

[billbadass]

I understand that this has something that's been discussed before, and maybe it's a wash, but is there any clear advantage to using full e85 as opposed to a e60 blend in these cars?

lots of "E85" out of the pump is actually closer to E60 anyway, but regardless there are charts of the effective octane of various ethanol mixes that you can find online and the incremental octane benefit above E50 gets fairly small, and E50 is really easy to mix and you still get decent MPG, so i went and tuned my car on E48 originally, and then in the last round of mods I had it tuned at E55 but didn't gain much power (for a lot of reasons). In short when I looked into this I thought E50 seemed like the sweet spot. Plus a stock mk7 GTI fuel system will do ~400whp on E50 pretty easily, which imo is the sweet spot for these mk7 cars anyway.

 

[El_bigote_AJ]

The most clear advantage is not switching pumps and mixing.

This.

And yeah as said above most pumps for me are lower anyways....

I’m
Tuned for e50 right now and I’ve got a couple stations that are low content that I’m only adding 3 gallons of 91 on a full tank to be at 50

 

[Reggie Enchilada]

Here's hoping that we'll eventually have someone other than UM with flex fueling capability

 

[Wastegate13]

Do you guys see a consistent e percentage buying from the same station? I’m ready to install my mpi setup and have identified 2 stations that are either on the way to work or on the way home so I can make one my default and only station. Basically wanna tune for e85 and switch back to my eqt 93 tune if I was ever in the situation where I couldn’t get e85. I commute in the car but if we were to go anywhere far we would just take the wife’s Tiguan.

 

[JerseyDrew77]

Do you guys see a consistent e percentage buying from the same station? I’m ready to install my mpi setup and have identified 2 stations that are either on the way to work or on the way home so I can make one my default and only station. Basically wanna tune for e85 and switch back to my eqt 93 tune if I was ever in the situation where I couldn’t get e85. I commute in the car but if we were to go anywhere far we would just take the wife’s Tiguan.

Nope. My E pump is constantly fluctuating between 72 - 83.

 

[El_bigote_AJ]

Yeah we have a station in town that lists as the pump it’s min will only be e75 (the one most hot roders go to) there is also another company in town that has 3-4 stations that carry it so it’s easier to get it - but they list the ratings can be 51-85, and it’s always in the 50-65 range regardless of the year.

The Ethanol process will always cause it’s self to have fluctuating contents just some stations have higher standards for their suppliers, you’ll just have to find the better ones it town.

 

[JerseyDrew77]

Yeah we have a station in town that lists as the pump it’s min will only be e75 (the one most hot roders go to) there is also another company in town that has 3-4 stations that carry it so it’s easier to get it - but they list the ratings can be 51-85, and it’s always in the 50-65 range regardless of the year.

The Ethanol process will always cause it’s self to have fluctuating contents just some stations have higher standards for their suppliers, you’ll just have to find the better ones it town.

There's only 2 in my area and the other one has been down for over 3 months.

 

[Wastegate13]

Is there a problem with the variation in e content or does the tune accommodate for it? Guess that’s probably a question for the tuner but any insight is helpful.

 

[JerseyDrew77]

Is there a problem with the variation in e content or does the tune accommodate for it? Guess that’s probably a question for the tuner but any insight is helpful.

I can feel a difference between the lower and higher content.

 

[ZuMBLe]

Is there a problem with the variation in e content or does the tune accommodate for it? Guess that’s probably a question for the tuner but any insight is helpful.

if you're setup for flex fuel, your tune should accommodate for it. With that said, it would accommodate by applying less timing. You will feel that. If your tune is not a flex tune, and you're just "adding 4 gallons", then the variation in E content will change the octane of your fuel. The result could be knock and pulled timing, which you will likely feel also.

 

[Wastegate13]

if you're setup for flex fuel, your tune should accommodate for it. With that said, it would accommodate by applying less timing. You will feel that. If your tune is not a flex tune, and you're just "adding 4 gallons", then the variation in E content will change the octane of your fuel. The result could be knock and pulled timing, which you will likely feel also.

I’m on an access port and Cobb doesn’t support native flex fueling yet. I’ll talk to my tuner about it. Thanks guys.