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      03-10-2013, 08:20 PM   #1
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Fuel & Octane calculator

The websites I found were a little over the top, and I couldn't find one to download anywhere. So, I decided to make a simple calculator using Excel and though I'd share it.

I run e85, so this is a nice tool to help determine the fuel percentages and combine ocatate rating based on how much of each fuel you put in the tank.

It's easy to use, enjoy. Just alter the values in RED, everything else calculates.

[Revised]

https://docs.google.com/file/d/0B66v...it?usp=sharing


Last edited by n54door; 03-18-2013 at 10:43 PM.
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      03-10-2013, 11:29 PM   #2
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Cool, looks good.. Thanks.
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      03-10-2013, 11:33 PM   #3
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thanks, i think most of us will find this very useful!

I don't have E85 where i live, but i replaced the values with 91 and 104oct which is what i use.
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      03-11-2013, 08:29 AM   #4
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can you please make a LITERS version?
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      03-11-2013, 08:44 AM   #5
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You're welcome guys!


^ for liters, just enter in the liters as opposed to gallons. It should work the same way since there are no equations specific to the value of a 'gallon'.

You can also rename anything that says 'gallon', its just a label.
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      03-13-2013, 09:07 AM   #6
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What is the highest E85 percentage some of you guys are running without a flash?

So far I'm getting away with 35%. I'm going to try 40% this weekend.
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      03-16-2013, 10:13 PM   #7
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you guys do realize e85 is not equal to 105 octane
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      03-17-2013, 11:05 AM   #8
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Quote:
Originally Posted by John Dempsey View Post
you guys do realize e85 is not equal to 105 octane
105
It has been said that it can be close to 105 either way, the calculator allows you to key in the octane value for each fuel.

EDIT: To settle the debate, http://www.ethanol.org/index.php?id=50

"Because ethanol has an octane rating of 113, adding 10% ethanol to gasoline raises the finished fuel's octane rating by 2 or 3 points, improving the fuel's performance."

"E85 is the highest performance fuel you can purchase at the retail level with its octane rating of at least 105."

Last edited by n54door; 03-17-2013 at 02:02 PM.
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      03-17-2013, 12:58 PM   #9
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This is an awesome tool. I made something but wasn't anywhere near as simple.
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      03-17-2013, 02:03 PM   #10
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^ Glad you like it!
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      03-17-2013, 04:23 PM   #11
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Quote:
Originally Posted by John Dempsey View Post
you guys do realize e85 is not equal to 105 octane
What is it equal too? The tool looks real good so what are the numbers to use for E85?
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      03-17-2013, 05:21 PM   #12
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Quote:
Originally Posted by BEAR-AvHistory View Post
What is it equal too? The tool looks real good so what are the numbers to use for E85?
It is considered to be 105, granted each Pump might be a bit off from that.

Dempsey is the first person I have read that says it's not, so I'm interested to see what information supports that claim.

In the meantime, http://www.ethanol.org/index.php?id=50

It says ethanol is 113 oct. So if my math is correct, to make e85 (70% min Ethanol Content) you take 70% of 113 oct corn ethanol, and mix it with 30% of 87 oct fuel to blend the e85 gas. This ratio would have an effective octane of 105. You can use the calculator to determine this as well.

Dempsey?

Last edited by n54door; 03-17-2013 at 05:29 PM.
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      03-17-2013, 05:43 PM   #13
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Is the base always 87 octane? Right now I am putting a bit over 3 gallons into a full tank of 93. I would like to go a bit further but still stay under 40% E85 because I don't want to be bothered worth a backend flash.

That being said I also have access to 100 octane so am trying to figure out the best way to go. 93+100 -- 93+E85 -- 93+100+E85
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      03-17-2013, 06:46 PM   #14
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Quote:
Originally Posted by BEAR-AvHistory View Post
Is the base always 87 octane? Right now I am putting a bit over 3 gallons into a full tank of 93. I would like to go a bit further but still stay under 40% E85 because I don't want to be bothered worth a backend flash.

That being said I also have access to 100 octane so am trying to figure out the best way to go. 93+100 -- 93+E85 -- 93+100+E85
From what I know, yes, the base fuel they mix the ethanol with is 87 oct.

For me the ultimate question becomes, what octane do I run? And with that, what is the most convenient and cheapest fuel I can get to accomplish my target. I run about 35% E85.

I don't want to both with the map right now either. I'm going to see if I can get away with 40%. It seems to differ from car to car.
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      03-17-2013, 07:13 PM   #15
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Quote:
Originally Posted by n54door View Post
105
It has been said that it can be close to 105 either way, the calculator allows you to key in the octane value for each fuel.

EDIT: To settle the debate, http://www.ethanol.org/index.php?id=50

"Because ethanol has an octane rating of 113, adding 10% ethanol to gasoline raises the finished fuel's octane rating by 2 or 3 points, improving the fuel's performance."

"E85 is the highest performance fuel you can purchase at the retail level with its octane rating of at least 105."
Not to chime in late, but my resource, wiki says 105 RON octane. Thus you are not apples to apples when matching with USA Octane. Europe guys yes, but not USA octane. USA octane is R+M / 2 = AKI (USA OCTANE). RON plus MON divided by 2 equals anti knock index. thus it's more like E85 is 96 AKI USA octane blended with 91 or 93 AKI USA octane.

So to correctly calculate octane you must have your octane ratings correct.
http://en.wikipedia.org/wiki/Octane_rating

And yes, E85 is blended with 87 AKI Octane, at least here on the west coast.

I use this calculator,

http://e85prices.com/milesperdollar.htm

Use bottom calculator.
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Last edited by VNeBLOB42; 03-17-2013 at 07:20 PM.
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      03-18-2013, 09:44 AM   #16
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Quote:
Originally Posted by VNeBLOB42 View Post
Not to chime in late, but my resource, wiki says 105 RON octane. Thus you are not apples to apples when matching with USA Octane. Europe guys yes, but not USA octane. USA octane is R+M / 2 = AKI (USA OCTANE). RON plus MON divided by 2 equals anti knock index. thus it's more like E85 is 96 AKI USA octane blended with 91 or 93 AKI USA octane.

So to correctly calculate octane you must have your octane ratings correct.
http://en.wikipedia.org/wiki/Octane_rating

And yes, E85 is blended with 87 AKI Octane, at least here on the west coast.

I use this calculator,

http://e85prices.com/milesperdollar.htm

Use bottom calculator.
Great post! I learn something everday, very useful info!

Found this to back it up as well.

"Octane: A minimum octane for E85 is not specified. FFVís
can tolerate the lower octane of gasoline i.e. 87 (R+M)/2.
There is no requirement to post octane on an E85 dispenser.
If a retailer chooses to post octane, they should be aware that
the often cited 105 octane is incorrect.
This number was
derived by using ethanolís blending octane value in gasoline.
This is not the proper way to calculate the octane of E85.
Ethanolís true octane value should be used to calculate E85ís
octane value. This results in an octane range of 94-96 (R+M)/
2. These calculations have been confirmed by actual octane
engine tests."

http://www.ethanolrfa.org/page/-/rfa...pdatedLogo.pdf
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      03-18-2013, 09:49 AM   #17
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Quote:
Originally Posted by n54door View Post
Great post! I learn something everday, very useful info!

Found this to back it up as well.

"Octane: A minimum octane for E85 is not specified. FFVís
can tolerate the lower octane of gasoline i.e. 87 (R+M)/2.
There is no requirement to post octane on an E85 dispenser.
If a retailer chooses to post octane, they should be aware that
the often cited 105 octane is incorrect.
This number was
derived by using ethanolís blending octane value in gasoline.
This is not the proper way to calculate the octane of E85.
Ethanolís true octane value should be used to calculate E85ís
octane value. This results in an octane range of 94-96 (R+M)/
2. These calculations have been confirmed by actual octane
engine tests."

http://www.ethanolrfa.org/page/-/rfa...pdatedLogo.pdf
Cool stuff bro. Next time you fill up take a look at the pump, you'll see the R+M/2 under the octane rating.
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      03-18-2013, 10:10 AM   #18
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Quote:
Originally Posted by VNeBLOB42 View Post
Cool stuff bro. Next time you fill up take a look at the pump, you'll see the R+M/2 under the octane rating.
Yup, makes sense now!

I love me some e85!
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      03-18-2013, 12:41 PM   #19
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Quote:
Originally Posted by n54door View Post
Yup, makes sense now!

I love me some e85!


Also to make clear, is your calculator percent of E85 Pump or percent of Ethanol?

for instance, I run E50 (on my pro tune), which is 50% Ethanol. So I put in 8.5 gallons of E85 pump and 7.5 gallons of 91 octane (based upon 91 having 10% ethanol). Which is E50. But is 53% of E85 pump. You may want to add another cell in there which tells you the percent of total Ethanol. That way we could take advantage of knowing how many gallons of E85 to put in as well as knowing the amount of total Ethanol.
based upon USA octane being E10 and E85 @ 85% Ethanol

thanks,

Vince
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      03-18-2013, 01:47 PM   #20
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Quote:
Originally Posted by VNeBLOB42 View Post


Also to make clear, is your calculator percent of E85 Pump or percent of Ethanol?

for instance, I run E50 (on my pro tune), which is 50% Ethanol. So I put in 8.5 gallons of E85 pump and 7.5 gallons of 91 octane (based upon 91 having 10% ethanol). Which is E50. But is 53% of E85 pump. You may want to add another cell in there which tells you the percent of total Ethanol. That way we could take advantage of knowing how many gallons of E85 to put in as well as knowing the amount of total Ethanol.
based upon USA octane being E10 and E85 @ 85% Ethanol

thanks,

Vince
It's a percentage of two fuels with respect to their octane of quantity ratio.

In the screenshot example, one fuel is 93 (premium), the other is 105 octane (E85, but should be 96 oct at this point).

So to answer your question, E85 pump. With the understanding there is a min. of 70% ethanol content, thus the octane value can be off a bit depending on the true E85 mix at the actual pump.
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      03-18-2013, 02:46 PM   #21
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Was more worried about the total ethanol percentage of the fuel. I think our JB4 systems without the back end COBB flash are limited to 40% ethanol or less. You have ethanol the 93 & in the E85 so its more then just a 50/50 mix of the gas divided by 2 to get octane level. You also need to calculate the actual ethanol level as a separate item.
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      03-18-2013, 04:20 PM   #22
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Quote:
Originally Posted by BEAR-AvHistory View Post
Was more worried about the total ethanol percentage of the fuel. I think our JB4 systems without the back end COBB flash are limited to 40% ethanol or less. You have ethanol the 93 & in the E85 so its more then just a 50/50 mix of the gas divided by 2 to get octane level. You also need to calculate the actual ethanol level as a separate item.
Correct, but the value of ethanol content would be an arbitrary value at best unless you knew the exact mix the gas station you visit uses. Each station will say a min of 70, and a max of 85 (hence e85), but they never know the exact amount. I'm sure it can vary by each bulk delivery of fuel for the gas station.

I see the importance, so I also thought about breaking it down separately, but again, it would only be a guess unless you actually sampled and tested the e85.

So, for this reason I'll stick with 70% Ethanol and factor the octane from that value since that is the minimum.

My original purpose was to determine how much e85 is in my tank, not ethanol, as the ethenal content will not be the same at every pump.
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