[BEAR-AvHistory]

Sounds good

[VNeBLOB42]

Originally Posted by n54door

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.

agreed,

but in this case how about a step further?

have two cells, ethanol max and min. Calculated at 70% Ethanol and 85% ethanol.

[AltecBX]

Originally Posted by n54door

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.

Great work

[n54door]

^ Thank you sir!

I made a few revisions thanks to all the good feedback.

- You can now mix 3 fuels into the calculation. (for those who like to mix in a little race gas with their E85)

- You can now edit the pump E85 Ethanol Content percentage mixed into 87 octane fuel. Pumps say min %70, but not all are the same. The Ethanol percentage at the pump will vary the overall octane and Ethanol percentage.

- The E85 octane auto calculates based on the % of Ethanol Content. (pure ethanol is roughly 99oct, mixed with 87 octane)

The spreadsheet is locked to keep you from accidentally breaking the calculations.

If you want to unlock the sheet for editing, the pw is 'fuel'

Enjoy!


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

[NoTempoLimitN54]

I think the E85 AKI calculator is a good idea and I want to add some information I have in hopes it can be improved further.

E85 octane is actually a very complicated subject. I did a bunch of research on E85 because race gas is so costly here in SoCal (up to $10/gal) and I was looking for an alternative way to boost octane.

Calculating the octane value of E85 is very difficult. This is probably the reason why an AKI sticker is not required on E85 pumps.

There are three ASTM Volatility Classes of E85:
1 "Summer blend" min 79% ethanol
2 "transitional blend" min 74% ethanol
3 "Winter blend" min 68% ethanol

What you get depends on where you live and what time of year. But to get an idea, in Southern California we only get the summer blend for four months out of the year. We never get the winter blend.

The "blending octane value" of ethanol is about 112.5 AKI - in other words, when added to gasoline at concentration of between 5.7% and 10% it tends to boost the base gasoline octane as if you were adding 112.5 AKI gasoline.

However, the blending octane value is not fixed and drops when you add more ethanol to the gasoline. So you are dealing with a non-fixed value. This explains why the blending octane value can be almost 113 AKI (at E10 concentration) but E85 is most likely around 94-96 AKI (at E80 concentration). [NOTE: source for this info is a race gas website. I'll post the source when I find it again]

Ethanol has a very high RON octane but in comparison relatively low MON octane value.
It has a huge 33 point spread between RON and MON. The blending octane of ethanol (at a 10% blend with gasoline) is:
129 RON
96 MON
112.5 AKI
(Source: Ethanol as a Transport Fuel Report by Downstream Alternatives Inc. 12-16-2002)

Most gasolines have about a 10 point spread between RON and MON, so for example:
96 RON
86 MON
91 AKI

Ethanol is already being added to gasoline in the U.S., largely to boost octane since MTBE (and before that MMT) are no longer allowed in many states. So 87 AKI regular gasoline already has ethanol in it boosting it's octane. For that reason we must assume that since 70%+ ethanol has so much octane boosting capability, they are going to blend it with the cheapest damned gas they can get at the refinery. I doubt the gasoline being used to blend E85 is more than 85 AKI at best. Remember also that they are putting in the gasoline for cold start volatility, so a lower octane gasoline has lower ignition energy.

Yet another reason the AKI of E85 is not as high as we would expect... they are blending it with sh*t gas.

I hope this info is useful.

BTW... CA Reformulated Gasoline is 5.1 - 6.3% ethanol (5.7% nominal ethanol). So there is room to add ethanol to the mix and still stay within 10% total ethanol.

[n54door]

Originally Posted by NoTempoLimitN54

I think the E85 AKI calculator is a good idea and I want to add some information I have in hopes it can be improved further.

E85 octane is actually a very complicated subject. I did a bunch of research on E85 because race gas is so costly here in SoCal (up to $10/gal) and I was looking for an alternative way to boost octane.

Calculating the octane value of E85 is very difficult. This is probably the reason why an AKI sticker is not required on E85 pumps.

There are three ASTM Volatility Classes of E85:
1 "Summer blend" min 79% ethanol
2 "transitional blend" min 74% ethanol
3 "Winter blend" min 68% ethanol

What you get depends on where you live and what time of year. But to get an idea, in Southern California we only get the summer blend for four months out of the year. We never get the winter blend.

The "blending octane value" of ethanol is about 112.5 AKI - in other words, when added to gasoline at concentration of between 5.7% and 10% it tends to boost the base gasoline octane as if you were adding 112.5 AKI gasoline.

However, the blending octane value is not fixed and drops when you add more ethanol to the gasoline. So you are dealing with a non-fixed value. This explains why the blending octane value can be almost 113 AKI (at E10 concentration) but E85 is most likely around 94-96 AKI (at E80 concentration). [NOTE: source for this info is a race gas website. I'll post the source when I find it again]

Ethanol has a very high RON octane but in comparison relatively low MON octane value.
The blending RON of ethanol can be as high as 120-130 but the MON is somewhere around 95. Most gasolines have about a 10 point spread between RON and MON, so for example:
96 RON
86 MON
91 AKI

Ethanol is already being added to gasoline in the U.S., largely to boost octane since MTBE is no longer allowed in many states. So 87 AKI regular gasoline already has ethanol in it boosting it's octane. For that reason we must assume that since 70%+ ethanol has so much octane boosting capability, they are going to blend it with the cheapest damned gas they can get at the refinery. I doubt the gasoline being used to blend E85 is more than 85 AKI at best. Remember also that they are putting in the gasoline for cold start volatility, so a lower octane gasoline has lower ignition energy.

I hope this info is useful.

With that bold point, /thread, lol!

Good points! Since much of these factors are 'unknowns' (ie. amount of ethanol in the overall blend, and ethonal in the 87 fuel blended into it), we can only work off averages and knowns.

Regarding the AKI for Ethanol, I found 100% ethanol is around 99.15 (wiki). Let me know what source you have that might say/prove otherwise so I can revise the value in the calculator.

Hopefully the calculator will serve as a close approximation at the least, knowing many of these factors can change by season and location/gas station.


Good stuff!

[NoTempoLimitN54]

Originally Posted by n54door

With that bold point, /thread, lol!...

...Hopefully the calculator will serve as a close approximation at the least, knowing many of these factors can change by season and location/gas station.

Good stuff!

Thanks! I'm not dissin' on your calculator. I think we can all work together and come up with something really good. BTW I'd love to see a little app for the iPhone that would do this.

BTW, I edited my post and added some more detailed info about the RON and MON of ethanol.

[n54door]

Originally Posted by NoTempoLimitN54

Thanks! I'm not dissin' on your calculator. I think we can all work together and come up with something really good. BTW I'd love to see a little app for the iPhone that would do this.

BTW, I edited my post and added some more detailed info about the RON and MON of ethanol.

Oh I know, you're good.

It's a lot to take in, hence the need for the calculator. I'd love to see this become an App, that is my long-term goal here, but I don't do software... soo....

Thanks for conrtibuting man, that's what this place is all about... well most of the time, anyway.

Regarding the Ethanol AIK, I found it to be 99.5. Let me know your thoughts.

"Both alcohols have a high octane rating, with ethanol at 109 RON (Research Octane Number), 90 MON (Motor Octane Number), (which equates to 99.5 AKI) and methanol at 109 RON, 89 MON (which equates to 99 AKI)."
http://en.wikipedia.org/wiki/Alcohol_fuel

[Mahhvinn]

This is awesome. Thanks for creating this.

[n54door]

Originally Posted by Mahhvinn

This is awesome. Thanks for creating this.

You're welcome, glad you like it!