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Fuel & Octane calculator
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03-18-2013, 05:54 PM | #23 |
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03-18-2013, 06:00 PM | #24 | |
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but in this case how about a step further? have two cells, ethanol max and min. Calculated at 70% Ethanol and 85% ethanol.
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03-18-2013, 08:25 PM | #25 | |
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03-18-2013, 09:15 PM | #26 |
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^ 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 Last edited by n54door; 03-18-2013 at 11:43 PM.. |
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03-19-2013, 11:08 AM | #27 |
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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.
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03-19-2013, 11:33 AM | #28 | |
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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! Last edited by n54door; 03-19-2013 at 12:05 PM.. |
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03-19-2013, 04:39 PM | #29 | |
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BTW, I edited my post and added some more detailed info about the RON and MON of ethanol.
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03-19-2013, 04:48 PM | #30 | |
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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 Last edited by n54door; 03-19-2013 at 05:33 PM.. |
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03-19-2013, 05:23 PM | #31 |
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This is awesome. Thanks for creating this.
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