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      05-14-2012, 04:42 PM   #1

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E85 concentration calculator

Well, I would have just uploaded the bloody spreadsheet, but the software doesn't like the Excel extension.

Here is how to make a simple spreadsheet for calculating the % E85. I think it works, but caveat emptor.

I put it on my android phone ala quickoffice. The iPhone will also let you ingest an excel spreadsheet.

It will only work if you fill up the tank...feel free to make an unlazy version.

You can do something similar to calculate octane concentration by using the same formula, which is VoCo + VaCa - VdCd = VfCf

V = volume
C = concentration

o = original
a = add
d = drain
f = final

So make columns for:

size of tank (Vt)

initial concentration % (Co)

amount E85 added (Va)

final concentration % : the formula is =1- (1 - ((Vt*Co) + (Va)) / Vt)

Last edited by Slidewayz; 05-14-2012 at 04:50 PM.
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      05-14-2012, 05:21 PM   #2

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Originally Posted by kdiggz View Post
My head hurts. Just tell me how many gallons to put in please
I just did !

Get the mods to let me post the spreadsheet and you're good.

Alternatively, just put that stuff into a spreadsheet and you're good to go.
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      05-14-2012, 06:09 PM   #3

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Here's how I do mine:

For the first time, meaning zero E85, I wait until 1/4 tank which equals to ~4.05 gallons. I fill it with 3 gallons of E85 then 6 gallons of pump gas. So now you have 3 gallons of E85 and 10 gallons of pump, which is about 30%. Adjust as necessary.

For the consecutive fills with E85, figure out how many gallons of pump you are going to pump. Let's say 10 gallons. Then just multiply that by 0.3 which gets you 3 gallons for a total of 13 gallons.

If you only want to pump 8 gallons, 8 * 0.3 = 2.4 E85 = 10.4 total mix.
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      05-14-2012, 06:12 PM   #4
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