[dAng! E90]

I am about to finish my first tank of 50\50 mix. I just wanna know what you guys are doing to insure that your mixture is 50\50 when you go to fill up. I was thinking that if I add 8 Gallons of E85 and then top off with 93oct, that should be correct. Am I wrong? What do you do when you fill up? Thanks for any help...it is much appreciated!!!

[Stucks]

Originally Posted by dAng! E90

I was thinking that if I add 8 Gallons of E85 and then top off with 93oct

This. You got it right! When I run e85 mixes, I usually do about 7-8 gallons of e85 with the rest 93.

[6MTE92]

You don't have to fill the tank up all the way either. You could do 7&7 or whatever gets you close.

[NoQuarter]

Originally Posted by 6MTE92

You don't have to fill the tank up all the way either. You could do 7&7 or whatever gets you close.

This is what I do.

[BMWsky]

Basic math...7+7, 7.5+7.5, 6+6, etc.

[nafoo]

Should take into consideration the actually percentages. When I fill up with 7 gallons of E85 (70% ethanol) and 8 gallons of 93 (10% ethanol) it gives me about 38% ethanol and about 98 octane.

Theres a good ethanol calculator off google.

[BMWsky]

Originally Posted by nafoo

Should take into consideration the actually percentages. When I fill up with 7 gallons of E85 (70% ethanol) and 8 gallons of 93 (10% ethanol) it gives me about 38% ethanol and about 98 octane.

Theres a good ethanol calculator off google.

Do you know that it's 70% ethanol or are you going by the pump saying that's the minimum content? I ask because unless we test the output of the pump, we don't know exactly the content. I simply measure a 50/50 mix and then watch my logs; so far they've been really consistant. I know that as we get closer to colder weather I'll stop using it completely.


Also, I posted in another thread that even though E85 acts like higher octane fuel, it doesn't measure over 100octane when actually tested; it tests more acurately around 96 or so. That being said, it behaves like higher octane fuel with the anti-knock properties. I got the information from a flex fuel white paper.

[GeorgiaTech335coupe]

The Procede map is for 50% 93 octane/ 50% e85 (47.5% ethanol) which makes it easy. It's not 50% ethanol content.

[dAng! E90]

I guess my worry on filling up is the fuel that is left in the tank because I don't run it dry. I had about 1 1/2 gallons left in the tank when I filled up this morning. I put 8.000 gallons of E85, and 7.460 gallons of 93. I squeezed all I could into the car because when the pump stopped, I had only pumped about 6.8 gallons of 93, so I kept going.

[GeorgiaTech335coupe]

Originally Posted by dAng! E90

I guess my worry on filling up is the fuel that is left in the tank because I don't run it dry. I had about 1 1/2 gallons left in the tank when I filled up this morning. I put 8.000 gallons of E85, and 7.460 gallons of 93. I squeezed all I could into the car because when the pump stopped, I had only pumped about 6.8 gallons of 93, so I kept going.

Honestly, it's not that big of a deal to be perfect. Now that you have the first time down, you just need to put equal parts in every other time you fill up. Just check to see how many gallons you have in the tank when you go (est. 16 total) and make sure that you stay under what it would be to completely fill up. E.g. gas tank reads 1/8, so you est there are 2 gallons. You add 6.5 gal + 6.5 gal.

[dAng! E90]

Thanks guys!!!

[plague]

Originally Posted by dAng! E90

Thanks guys!!!

dont have to be that picky. i dont even measure by the gallon. i fill on 93 till the gauge hits half tank. then i drive home and fill the rest with e85.

[BMWsky]

Like everyone said, it isn't an exact science. Even if you're filling up with 93oct, the person before you may have been using 87oct and there will be a little of that left in the lines.

[nafoo]

Originally Posted by BMWsky

Do you know that it's 70% ethanol or are you going by the pump saying that's the minimum content? I ask because unless we test the output of the pump, we don't know exactly the content. I simply measure a 50/50 mix and then watch my logs; so far they've been really consistant. I know that as we get closer to colder weather I'll stop using it completely.


Also, I posted in another thread that even though E85 acts like higher octane fuel, it doesn't measure over 100octane when actually tested; it tests more acurately around 96 or so. That being said, it behaves like higher octane fuel with the anti-knock properties. I got the information from a flex fuel white paper.

The pump said it's "up to 70% ethanol" just like the 93 pump says "up to 10% ethanol."

[idrift4wd]

how do you guys tell how much fuel/gallons are left in your tank?

[AU335i]

Originally Posted by idrift4wd

how do you guys tell how much fuel/gallons are left in your tank?

i never know this either... because even though the light comes on and the Carputer says I have XXX amount of miles left... even after it goes --- I've been able to drive more than expected...

[idrift4wd]

Originally Posted by AU335i

i never know this either... because even though the light comes on and the Carputer says I have XXX amount of miles left... even after it goes --- I've been able to drive more than expected...

there is a 2 gallon reserve i know that, but i wish there was a sure way to know to get a better ratio (without having to syphon the tank)

[AU335i]

Originally Posted by idrift4wd

there is a 2 gallon reserve i know that, but i wish there was a sure way to know to get a better ratio (without having to syphon the tank)

when does the 2 gallon reserve start to go into use?

[GeorgiaTech335coupe]

Originally Posted by idrift4wd

how do you guys tell how much fuel/gallons are left in your tank?

Pretty sure it's close to 16 gallons. The first time I filled up with e85, I estimated my gallons using 16 to full, filled up what I thought I needed to get to 8, then when I went to put e85 in, it was exactly 8 gallons.

[Dave W.]

OK I have a question for you E85 guys.
Has anyone been using E85 long enough to see a difference from winter blend? (E70) ?

I found this link that shows regional differences in winter blends, interesting stuff;
http://www.e85mustangs.com/regions123.html

[pcmacdr]

Well average 50/50 E85/91

Sometimes a put a gallon extra of E85 and very few time run it dry as I can, then fill up with 10 gal of E85 and 8.5 of 91


I've run this mixture for over 2 years ( 40k + ) here in Cali with NO ISSUES, non whatsoever, so there

So through winter and summer, the only difference I feel is when the weather is colder outside, my car pulls and hauls harder than if its above 90
This is my Dyno Results on my 2008 535i

Info at the time of Dyno:

Jb 4 18 ohms
50/50 of E85 and 91
DCI

** UPDATE:
and now that my car has been updated with JB4 15ohms and the latest FW, with clean valves done by Walnut Blasting just a few days ago and 50/50 mix, this car has NOT been the same since the Dyno runs, about 8 pulls, with Terry taking controls

Seriously it PULLS harder and stronger than EVER before

When I get a chance I will Dyno again with Terry, like last time and post up my results with logs


Hope this helps

Stay safe


E85 For the Win !!

[VNeBLOB42]

here is a good calculator to use..

http://www.intercepteft.com/calc.html

It is interesting because, how do we really know for sure what the Ethanol contents is? The pump I use says, 70% min. and 85% max. That alone can vary. Even pump gas, 10% ethanol, that can even vary. Curious to know if Sacramento Valley (California) will be affected by the Winter Ethanol content??? It really doesn't get that cold.

I just stick to the 20% E85. Gauge how many gallons are left in my tank and take 20% of that. subtract that from 20% on a full tank (approx 3.2 gallons) and the difference will be added as my new E85 fill up. Then top if off with Ca 91. Its close enough to fix my timing corrections on aggressive maps. happy logs = happy car