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Old 09-01-2010, 07:39 PM   #31 (permalink)
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NIssan Titan pickup 2008 flex fuel
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Looks like about 75% on E85 versus Gas. Works out fairly close to the actual energy content percentages, if you consider E100 instead of E85. Maybe slightly less due to larger throttle opening using E85 for slightly higher BSFC.

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Old 09-01-2010, 08:22 PM   #32 (permalink)
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Originally Posted by redpoint5 View Post
My comments on ethanol contain no myth, only facts. The fact is that ethanol contains 2/3 of the energy per volume as gasoline.

Please do not spread any myth that is contrary to science and logic. Should you disagree with the facts I have presented, the burden lies on you to debunk them with evidence.
I agree with you ceasing to spreading myths, energy density does not directly relate to fuel economy.
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Old 09-02-2010, 06:57 AM   #33 (permalink)
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I agree with you ceasing to spreading myths, energy density does not directly relate to fuel economy.


Then what does?

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Old 09-02-2010, 06:46 PM   #34 (permalink)
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Originally Posted by Old Mechanic View Post
Then what does?

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Nothing by itself, you can have an inefficient motor running on an energy dense fuel compared to an efficient motor running on a low density fuel and have the answer end up moot or even in favor of the lense dense fuel. You can even run the same motor on different fuels and due to complex engine management and odd behaviors of the fuel mix itself end up with the same fuel economy or better than expected comparitively.

There were peer reviewed papers on this subject of how ethanol blends commonly get better than expected fuel economy due to vapor pressure phantoms AKA the mix did not have the expected volitility.

There are also situations like comparing my fathers 1985 Yugo to my 010 cobalt. My cobalt is over 1000's heavier, has double the motor runs on e10 and get 15mpg better than the Yugo did on the real gas available in the late 80's and early 90's.

I would also estimate if his yugo was on the road (its in the garage with a frozen brake and rotten hoses) it would get this 20% worse economy on e10, yet my cobalt gets better on 89 octane e10 than it does on 87 octane e5ish.

All antidotal in this case but a million monkeys can't all be wrong.
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Old 09-04-2010, 02:55 PM   #35 (permalink)
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I think a factor that may be throwing our figuring and pondering into the unknown is the flux of the actual mix of e85.

Quote:
"E85 is an alcohol fuel mixture that typically contains a mixture of up to 85% denatured fuel ethanol and gasoline or other hydrocarbon (HC) by volume. On an undenatured basis, the ethanol component ranges from 70% to 83%."
WIthout a static ratio of dino fuel to corn fuel, it is difficult to nail down any figures concerning the stuff. My only suggestion is to use the price of the e85 compared to the normal 87 octane to determine what the target mpg would be to get the same miles per dollar or better with the mix. In my case I used a bit of algebra to determine that, for the price, if I got 17 mpg or better on the e85 compared to the price at the same station of 87 octane, i would come out ahead on my cost per mile, which I did in a non e85 vehicle AKA the 97 mercury villager with fuel injection.

I don't claim to know much as it concerns e85 vs 87 octane, only personal experience. But there seems to be more mpg available per unit of energy in e85 than in 87 octane.
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I think you missed the point I was trying to make, which is that it's not rational to do either speed or fuel economy mods for economic reasons. You do it as a form of recreation, for the fun and for the challenge.

Last edited by ShadeTreeMech; 09-04-2010 at 03:28 PM..
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Old 09-16-2010, 11:52 AM   #36 (permalink)
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Quote:
Originally Posted by rmay635703 View Post
Nothing by itself, you can have an inefficient motor running on an energy dense fuel compared to an efficient motor running on a low density fuel and have the answer end up moot or even in favor of the lense dense fuel. You can even run the same motor on different fuels and due to complex engine management and odd behaviors of the fuel mix itself end up with the same fuel economy or better than expected comparitively.

There were peer reviewed papers on this subject of how ethanol blends commonly get better than expected fuel economy due to vapor pressure phantoms AKA the mix did not have the expected volitility.

There are also situations like comparing my fathers 1985 Yugo to my 010 cobalt. My cobalt is over 1000's heavier, has double the motor runs on e10 and get 15mpg better than the Yugo did on the real gas available in the late 80's and early 90's.

I would also estimate if his yugo was on the road (its in the garage with a frozen brake and rotten hoses) it would get this 20% worse economy on e10, yet my cobalt gets better on 89 octane e10 than it does on 87 octane e5ish.

All antidotal in this case but a million monkeys can't all be wrong.
You bring up a good point. The biggest problem with Gasohol in the 70's was that cars were not tuned or built to run on it at the time. I doubt they will keep dictating the gasoline blend based on 20+ year old cars but it does leave a lot of people, like me too, with problems if we own a car that is not up-to-date.

While I realize some people are seeing huge(more than 3.5%) MPG drops with E10 I think it is a problem that can be fixed not some base problem with Ethanol. The best efficiencies in regards to MPG per unit of energy have been with 50/50. And not just on custom jobs like on the Ricardo flexfuel engine. I've even heard from some people(some on Ecomodder) that 50/50 is better. But it is not a commonly accepted finding. The more I read about Ethanol the better I feel about it's properties. But Popular opinion on the internets is that ethanol is bad. It was Ethanol blends that were capable of operating on a variable geometry(bleh) turbo charger with 19:1 Static Compression ratio not Unleaded Gasoline.

10% Ethanol is for the Federal oxygenate requirement and that is the maximum, I've heard it might be closer to 5-7% due to available and the minimum but I'm not 100%. Most states don't have laws that require the pumps to state if they may contain Ethanol, Kentucky is one of them. I've seen pumps that state they contain E10 like Shell stations as a rule while others say nothing and some like the BP station I saw in Clarksville, TN that stated that all grades contained up to 10% Ethanol. I've seen a Shell station with E85 too as crazy as that sounds. it wasn't under the canopy like Kerosene but it was on the property.
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Old 09-17-2010, 11:47 AM   #37 (permalink)
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my curiosity is how the throttle needing to be open further for a lower energy density fuel come into play? I suspect there would be a lower hp rating from such an engine, and possible more useful energy from a lower energy fuel in an engine designed for a higher density fueL Or does this make sense only to me?

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Originally Posted by jamesqf View Post
I think you missed the point I was trying to make, which is that it's not rational to do either speed or fuel economy mods for economic reasons. You do it as a form of recreation, for the fun and for the challenge.
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