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Author Topic: BTU's are 35% less for Ethanol but we are not heating water... Back to Topics
JonnyEnergyE85

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Message Posted: Apr 11, 2012 9:28:07 AM

The minimal difference in mileage is not a matter of BTU. A British Thermal Unit is a measurement of how long it takes a particular fuel to heat one pound of water one degree. It is a heat measurement, and if we were all concerned about only BTU for our engines we would be running them on candle wax, dynamite or any other number of high BTU content fuels. The problems with running candle wax or dynamite should be obvious. Lets say that there are other more important issues with a liquid fuel than just the very simple and blunt BTU, shall we? I see BTU content as more of a red herring, something to bitch about and a chip to use with less than knowledgeable people who dont understand the inner workings of engines and the relationship they have with differing fuels.

If all we wanted to do was heat water, then sure gasoline is better than ethanol. The thing is we want to do work, in an internal combustion engine, that has to suck its air in, squeeze it pretty hard, ignite it, then expel the burned gasses. The fact of the matter is, ethanol does that work more efficiently than does gasoline. Outlaw was being overly generous with gasoline engines and thermal efficiency, they are usually around 20%, and rarely if ever above 25%, because the vast majority of the BTUs in gasoline go to waste heat, that needs to be shed through the radiator to the air, or it will cause all the parts in the engine to expand, break down the oil film protecting the surfaces, and destroy the engine due to friction.

So we want to do work, you know, twist the crankshaft which turns the transmission, which turns the diveshaft and then the wheels. Work, moving something that would be otherwise stationary. Work over time is horsepower, a simple measurement of work is Torque, or twisting force measured in ftlbs or Nm.We want torque, its what moves things. Engines with pistons, connecting rods, and crankshafts all respond similarly to increases in compression and airflow as to how much work they can do. It affects the engines capability because it changes the amount of torque the engine produces. Cam timing can move the torque range around a bit, but it is still based on air and fuel going in, then exploding thus shoving the piston back down the cylinder to move the crankshaft.

Higher compression results in higher torque for a given displacement. Just raising the static compression ratio (SCR) will have an effect on the torque produced even if nothing else in the engine is changed. An engine with an 8:1 scr will produce less torque than a same sized engine with 14:1, quite a bit less actually. Timing also has an effect on the torque output, and preignition and other problems can arise with gasoline that simply arent there with ethanol. To a certain extent advancing the timting from top dead center will increase power, retarding it from TDC will reduce power, generally speaking

(Thanks Thumpin)
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Banjoe
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Message Posted: Apr 12, 2014 8:17:39 AM

Being classified as somewhat of an Einstein gives me a vague understanding of relativity and the relationship between energy content and available power.

Your question does provide its own answer.

My diesel does produce much more power per unit of fuel than does our gasoline engines. Conversely, burning ethanol mixtures does result in less mileage (you can read that as available work) than more energy dense fuels.

I think you're starting to catch the glimmer of what is really going on when various energy sources are converted to useful work.

Now excuse me while I get back to this string theory I've been working on.
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SilverStreaker
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Message Posted: Apr 11, 2014 10:54:28 AM

Banjoe says "Ethanol has less energy content than gasoline"
If you are talking about the BTU value, consider how that is measured. Diesel fuel has a much higher BTU value than gasoline, but will you get more MPG using it in a gasoline engine compared to gasoline or ethanol?
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SoylentGrain
All-Star Author Illinois

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Message Posted: Apr 11, 2014 9:52:24 AM

"More energy in equals more energy out unless there's some serious fractures to thermodynamics going on."

Bingo, Einstein. One of the only things with an ounce of validity you have ever posted on this site. A gasoline engine is highly inefficient. Only a small portion of the heat energy going into the system is converted to work. While ethanol contains less energy per gallon, it does burn more efficiently. So, a higher percentage of it's btu content is transferred to work.

The fact remains, the energy developed by a fuel is more dependent on how much combustion product is produced per pound and the temperature that volume of gaseous material can be heated to. The reality is methane, methanol, ethanol, gasoline, nitromethane all produce a similar amount of hourse power per pound of fuel. It's just that some of these fuels can be delivered at a higher rate than gasoline and, therefore, produce more horsepower.

BTU content per gallon is, for the most part, meaningless.
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Banjoe
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Message Posted: Apr 11, 2014 8:46:57 AM

I'm not sure where this hot air engine keeps coming back from but it certainly has legs. And I do appreciate and respect the enthusiasm to explore and explain the concepts.

Ethanol has less energy content than gasoline and, in spite of the volumetric power society beliefs, that's what provides power for our engines.

To get the same power out requires the same energy in (all things being equal) and the air/fuel mixtures need to be set to allow proper combustion with each fuel.

The thin linkage to hot air engines is valid to the point that hot air is needed. What is being missed is that we are dealing with hot air. That heat comes from the input energy contained in the selected fuel laid on top of the incoming air stream. More energy in equals more energy out unless there's some serious fractures to thermodynamics going on.
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SoylentGrain
All-Star Author Illinois

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Message Posted: Apr 11, 2014 8:26:05 AM

"The lower ethanol ratio means more more fuel is needed to burn correctly. You must match the stoichiometric air fuel ratio to burn all the fuel with the available air in the engine cylinder."

Doesn't work that way. The air fuel ratio simply means less air is required to OPTIMALLY burn a pound of fuel. A pound of ethanol and a pound of gasoline produce about the same amount of work. That's because a pound of gasoline and a pound of ethanol produce a similar volume of combustion product.

PV=nrt is the gas law that your engine follows. There aint no BTU per gallon in that equation. While t refers to temperature, btu per gallon has no relationship, in this case. Temperature is controlled by amount of oxygen present and pressure. In your engine, those parameters are controlled by the throttle, timing, and octane of the fuel. All of those affect absolute compression.

Yes, more fuel can be used with ethanol. But, that is by turning the engine faster to generate more horsepower. Both fuels generating the same hp will be consumed at a similar rate, assuming the fuels are burned optimally.
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CrazyComputers
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Message Posted: Apr 1, 2014 11:37:13 PM

The forum doesn't seem to allow for URL's in the post.
I tried to edit the URL's but it didn't work.

sorry about that.

I only got one edit so I posted this note.

Just copy and Google the partial URL to get the whole thing.

[Edited by: CrazyComputers at 4/1/2014 11:38:14 PM EST]
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CrazyComputers
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Message Posted: Apr 1, 2014 11:27:37 PM

There is more than the 35% less energy of the ethanol fuel that affects the mileage.

The stoichiometric air fuel ratio also is necessary to see what the fuel usage will be.

The stoichiometric air fuel ratio for gasoline is 14.7:1

The stoichiometric air fuel ratio for ethanol is 9:1

en. /wiki/Stoichiometry (Grab your math books, folks)
www. /machine-design/15235-the-stoichiometric-air-fuel-ratio/

The lower ethanol ratio means more more fuel is needed to burn correctly. You must match the stoichiometric air fuel ratio to burn all the fuel with the available air in the engine cylinder.

Automobile racers use this fact to get a lot of horsepower out. (Think Indy cars.)

By raising the compression ratio to 14:1 and dumping in lots of fuel and the engine just screams. Not good for fuel mileage though.

E85 fuel needs the air fuel percentage changed to do the same thing in the engine. The ECU is programmed to do this when switched for flex fuel, and dumps in more fuel into the engine. You might get more horsepower out, but it will burn more fuel doing it too.

Read this about Indy Car rules, it's interesting.
www. /en/News/2013/02/2-12-Fuel-options-for-teams


[Edited by: CrazyComputers at 4/1/2014 11:32:57 PM EST]
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Chazzer
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Message Posted: Mar 30, 2014 2:01:33 PM

You've got that right!
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Banjoe
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Message Posted: Feb 15, 2014 8:05:27 AM

Now things are getting interesting again.

Bring on some science about oxygenation so we can all learn something new.
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krzysiek_ck
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Message Posted: Feb 14, 2014 9:48:57 PM

GrumpyCat wrote: "Thats what oxygenation is/was all about, the richer mixture burns cleaner."

Wrong. Oxygenated fuel will cause the lean mixture not rich. Also, complete burn requires air. Rich mixture lacks the necessary air to fully burn fuel.
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Banjoe
Champion Author Winnipeg

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Message Posted: Feb 14, 2014 6:23:37 PM

Thanks GrumpyCat.
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GrumpyCat
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Message Posted: Feb 14, 2014 4:09:31 PM

""EPA forces manufacturers to run engines rich for less emissions. Thats what oxygenation with ethanol is all about, fooling the O2 sensor into running richer, which in the early 1980's the EPA found burned cleaner."

That's nonsense."

Its fact. Thats what oxygenation is/was all about, the richer mixture burns cleaner.

All research quoted by EPA to support reformulation and oxygenation used early 1980's vehicles and is still quoted as current fact.

Fact: big American engines suddenly started getting spectacular MPG in the 1990's. Fact: The EPA had a fit when they found software was being used to bypass the O2 sensor during relatively clean periods in the EPA test cycle where the manufacturer tuned for MPG. Manufactures were meeting the specified emissions while bypassing the EPA's editing by reformulating fuels. In early O2 sensor engines the O2 sensor was directly connected to the carburetor or injector. In later generations the O2 sensor was connected to the ECU.
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krzysiek_ck
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Message Posted: Feb 14, 2014 3:20:14 PM

CiVX wrote: "It would be better to compare net BTU's of the two fuels and cost, performance and maintenance."

Not so fast. Assumptions like this is a reason why OP created this post in the first place.
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nighthawk91
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Message Posted: Feb 14, 2014 12:28:28 AM

You need to look at things as mile per $. Not miles per gallon.

If it cost less, it cost less. It doesn't make a difference how my BTU's it has.
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CiVX
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Message Posted: Feb 13, 2014 9:30:43 PM

I don't know why they compare them that way because gasoline is just more energy dense per unit volume. It would be better to compare net BTU's of the two fuels and cost, performance and maintenance.
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SilverStreaker
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Message Posted: Feb 13, 2014 9:52:51 AM

I've used ethanol blends in two non-FFVs and haven't seen any significant change in mileage at any blend. The only substantial difference that I have seen is between summer and winter. I haven't determined if that's because of the different fuels or the outside temperature difference.
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HotRod10
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Message Posted: Dec 18, 2013 12:44:09 AM

"SilverStreaker - thanks for the study link. I'm reading that as resulting in lower mileage with ethanol blends right across the board."

That's what I got from it too - significantly lower mileage using E85. That's after they optimized the programming of the ECM for E85, which the vast majority of people would have to pay someone to do; then you'd probably get worse mileage if you went back to E10 than you were before the reprogramming.
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Banjoe
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Message Posted: Dec 14, 2013 8:22:34 AM

SilverStreaker - thanks for the study link. I'm reading that as resulting in lower mileage with ethanol blends right across the board.

Of course, this little report does present equivalent gasoline gallons but doesn't provide the calculations for these so I don't buy what I can't see.
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bikemannc
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Message Posted: Dec 11, 2013 2:32:00 PM

Thankfully this is a better discussed topic than most of the rest of this forum area!
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namzza6310
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Message Posted: Dec 11, 2013 9:28:18 AM

love it
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SoylentGrain
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Message Posted: Dec 11, 2013 9:15:18 AM

"Lame "study", SilverStreaker. Lets tune pure gasoline engines for maximum MPG without respect for emissions and we'll get the same improvements."

First, there's no such thing as "pure gasoline." bpBut, if you were doing you thing with regular unleaded gasoline and 105 octane E85, you might be disappointed.

"EPA forces manufacturers to run engines rich for less emissions. Thats what oxygenation with ethanol is all about, fooling the O2 sensor into running richer, which in the early 1980's the EPA found burned cleaner."

That's nonsense.
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GrumpyCat
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Message Posted: Dec 11, 2013 2:05:46 AM

Lame "study", SilverStreaker. Lets tune pure gasoline engines for maximum MPG without respect for emissions and we'll get the same improvements.

EPA forces manufacturers to run engines rich for less emissions. Thats what oxygenation with ethanol is all about, fooling the O2 sensor into running richer, which in the early 1980's the EPA found burned cleaner.
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SilverStreaker
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Message Posted: Dec 9, 2013 10:37:33 AM

HotRod10 asks "Can you provide a link to the actual study where they proved that?"
I think it is this study
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HotRod10
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Message Posted: Oct 2, 2013 9:52:10 AM

""FACT: Ethanol-blended fuel keeps your fuel system clean for optimal performance because it does not leave gummy deposits"

If you read the rest of the statement, modern unleaded gasoline doesn't leave gummy deposits either. They were comparing to leaded gasoline. If you want unbiased information, you have to go to unbiased sources instead of the ethanol shills.

"Mileage Gains Using Ethanol Seen 20% Higher Than EPA Says"

Can you provide a link to the actual study where they proved that? All I could find from that story was the undocumented assertion. Well, they did say they'd "seen" it, not that they could prove it.

"When oxidized, ethanol simply converts to co2 and water"

Uh oh! Don't let the global warming believers hear that!

[Edited by: HotRod10 at 10/2/2013 9:58:22 AM EST]
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SilverStreaker
Champion Author Twin Cities

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Message Posted: Sep 7, 2013 11:57:08 AM

Mileage Gains Using Ethanol Seen 20% Higher Than EPA Says
"A tweak to an automobile’s engine software can improve by as much as 20 percent the estimated fuel efficiency when using gasoline with ethanol or methanol"
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SilverStreaker
Champion Author Twin Cities

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Message Posted: Aug 10, 2013 5:01:52 PM

Ethanol Facts: Engine Performance
"FACT: Ethanol-blended fuel keeps your fuel system clean for optimal performance because it does not leave gummy deposits"
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SoylentGrain
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Message Posted: Jun 11, 2013 8:03:58 AM

"goldseeker Would you kindly point us to a valid source that shows that ethanol added to gasoline prevents gunk in the engine. Because, gasohol still includes gasoline. "

I can provide a source: Morrison and Boyd, Organic Chemistry, 1972. Gasoline is composed of hundreds of aliphatic hydrocarbons. They are nonpolar molecules. Therefore, only nonpolar solutes will dissolve in gasoline.

Ethanol is a bipolar molecule. Ethanol will dissolve both water soluble and oil soluble compounds. In borsht terms, that means more "gunk" will be removed from the fuel system.

Also, by the nature of the simple ethanol molecule, it burns cleaner. When oxidized, ethanol simply converts to co2 and water. Gasoline, on the other hand, forms hundreds of intermediate nasty compounds that get expelled into the exhaust and, to a small extent, the crankcase.
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Banjoe
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Message Posted: Jun 9, 2013 8:16:06 AM

borsht - dead on again. I love this topic for exactly the point you're making. The voodoo science that shows up under this topic keeps me laughing in the face of rising gas prices.

Then again, there are some exceptionally brilliant folk here that really try to pass on their wisdom and I've learned a lot from their efforts. They consistently get mocked by the flat earth luddites only proving the pearl before swine reality. Unfortunately as you've just pointed out the truth, you will be likely be tossed into the 'bad' side of this discussion.

Keep your humor, wit, and common sense, and try not to go screaming into the night when it's being suggested that heat content of a fuel source doesn't make any difference in engine performance "because we're not heating water".

Oh man, my ribs are still hurting over that one.
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borsht
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Message Posted: Jun 8, 2013 11:42:18 AM

goldseeker said “Actually it is gasoline that gunks up your engine. Ethanol will prevent this from happening.”

Gunk is what builds up in the oil system.
Gunk, engine sludge, is the stuff that can build up in the oil system, pan, valve covers, valves, around bearings etc.

goldseeker Would you kindly point us to a valid source that shows that ethanol added to gasoline prevents gunk in the engine. Because, gasohol still includes gasoline.
This looks like another Bovine Scatological statement. Drama but not fact.
Like the headline post that states, mileage ,” The minimal difference in mileage is not a matter of BTU. A British Thermal Unit is a measurement of how long it takes a particular fuel to heat one pound of water one degree”.
A BTU does NOT include time, it is merely the amount of heat required to raise the temperature of 1 pound of water at STP 1 degree F.
This Johnny Energy85 statement has already been thoroughly debunked.
But as someone suggested, this board is not for serious inquiries, it’s for laughs.


[Edited by: borsht at 6/8/2013 11:44:27 AM EST]
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Banjoe
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Message Posted: Jun 8, 2013 7:59:34 AM

Actually it's the gunk that gunks up engines. The fuel just loosens it up and gets it moving about.
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goldseeker
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Message Posted: Jun 8, 2013 2:01:27 AM

"It gunks up the engine" LOL!

Actually it is gasoline that gunks up your engine. Ethanol will prevent this from happening.
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krzysiek_ck
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Message Posted: Jun 7, 2013 12:44:20 PM

GrumpyCat wrote: "The cited E35 will run in his 13:1 engine but not have as much HP as real race gas."

I mentioned E35 and WE0H mentioned 13:1 egnine. Two different cars. I use E35 in a turbo car as a replacement for 100 octane racing fuel. If also generates same is not better HP. Ethanol cooling properties, one of few, help accomplish this task.

[Edited by: krzysiek_ck at 6/7/2013 12:48:19 PM EST]
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GrumpyCat
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Message Posted: Jun 7, 2013 12:22:01 PM

"I know a few folks in my area that special orders racing fuel and the last I heard was $7.00 per gallon."

Octane *rating* is only a measure of knock resistance, not of energy content or HP output. Real race gas has real energy increases. The cited E35 will run in his 13:1 engine but not have as much HP as real race gas.

VP C12 is apparently $9/gallon at the race track pump, or $80 for a 5 gallon can:
Race Fuel Prices at US-131 Motorsports Park
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renegaudet
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Message Posted: Jun 7, 2013 11:51:38 AM

It gunks up the engine.
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krzysiek_ck
Champion Author Illinois

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Message Posted: Jun 7, 2013 9:37:32 AM

borsht wrote: "What a cop out krzysiek_ck.
NO ONE buys 100 Octane to maximize the miles/ dollar. Absolutely no one!!!!"

Spoken like a true armchair expert you are.
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WE0H
Champion Author Twin Cities

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Message Posted: Jun 6, 2013 7:22:13 PM

Guess that's why my 13:1 motor loves running on 105 octane :-)
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goldseeker
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Message Posted: Jun 6, 2013 5:56:22 PM

"I blend to achieve E35 in place of 100 octane racing gas. My miles per dollar while using E35 is cents on a dollar comparing to the price of 100 octane racing fuel."

I know a few folks in my area that special orders racing fuel and the last I heard was $7.00 per gallon.

So, yes that would be a true statement.
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borsht
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Message Posted: Jun 6, 2013 5:07:52 PM

krzysiek_ck said:

"I blend to achieve E35 in place of 100 octane racing gas. My miles per dollar while using E35 is cents on a dollar comparing to the price of 100 octane racing fuel."

What a cop out krzysiek_ck.
NO ONE buys 100 Octane to maximize the miles/ dollar. Absolutely no one!!!!
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Shockjock1961
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Message Posted: Jun 6, 2013 4:37:27 PM

"Obviously not, or you would realize that different fuels obtain different thermal efficiencies depending upon the engine design."

The major influence on an engines efficiency is it's design. If you wre using two different engines one with high compresssion using ethanol and one with a lower compression using gasoline, then you might find the mileage were equivalent. However, in a flex fueled vehicle you are using the same engine to burn both fuels, so the fuel with the lower energy content is going to give you ower mileage....
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krzysiek_ck
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Message Posted: Jun 6, 2013 1:38:51 PM

borsht wrote: "Your get more miles per dollar with gasoline than you do with E85."

Wrong assumption from the armchair expert.

I blend to achieve E35 in place of 100 octane racing gas. My miles per dollar while using E35 is cents on a dollar comparing to the price of 100 octane racing fuel.

[Edited by: krzysiek_ck at 6/6/2013 1:45:26 PM EST]
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borsht
Champion Author Oakland

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Message Posted: Jun 6, 2013 12:07:59 PM

Efficiency is one thing,(Shaft work out/energy in) the cost per mile is the bottom line.
Your get more miles per dollar with gasoline than you do with E85.
By the way how much does this ebdi engine cost?
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SilverStreaker
Champion Author Twin Cities

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Message Posted: Jun 6, 2013 11:16:01 AM

Shockjock1961 claims "IU fully understand the concept of thermal efficiency SS."
Obviously not, or you would realize that different fuels obtain different thermal efficiencies depending upon the engine design. This is obvious when you consider that higher compression engines are more efficient with ethanol than lower compression engines.

Case in point, the EBDI Engine
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Banjoe
Champion Author Winnipeg

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Message Posted: Jun 6, 2013 8:59:55 AM

And at this point someone is supposed to point out that we aren't heating water so heat content of the fuel isn't an issue to power or mileage.

I lost track of whose turn it is to make this claim but please make your move.
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SoylentGrain
All-Star Author Illinois

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Message Posted: Jun 5, 2013 3:24:38 PM

" The problem is you are using ethanol in the exact same engine that you use gasoline. "

And since ethanol has different combustion properties than gasoline, that "exact same engine" burns the two fuels differently. Ethanol has a higher latent heat of vaporization, higher octane rating, and requires less O2 to burn. Those are all positives. Although energy content per gallon is less than gasoline, it does burn more efficiently, even in the "exact same engine".

Nice try.
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Shockjock1961
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Message Posted: Jun 5, 2013 1:22:14 PM

IU fully understand the concept of thermal efficiency SS. The problem is you are using ethanol in the exact same engine that you use gasoline. That being so there is no increase in thermal efficency and therefore, ethanol with the lower heat content will produce less work. Less work = lower mpg...
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krzysiek_ck
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Message Posted: Jun 5, 2013 8:53:48 AM

oilpan4 wrote: "So you are saying they don't know what they are doing and just made up a bunch of numbers?"

Straight from DOE website.

However, since ethanol contains less energy per volume than gasoline, FFVs typically get about 25-30% fewer miles per gallon when fueled with E85.

and

FFVs operating on E85 usually experience a 25–30% drop in miles per gallon due to ethanol’s lower energy content.

Yes, DOE is making a huge assumption based on a single piece of information.
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oilpan4
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Message Posted: Jun 4, 2013 7:59:25 PM

"Department of Energy did not do actual tests".

So you are saying they don't know what they are doing and just made up a bunch of numbers?

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SilverStreaker
Champion Author Twin Cities

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Message Posted: Jun 4, 2013 4:48:30 PM

Interesting that an alleged physics professor can't understand the concept of thermal efficiency
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Shockjock1961
Champion Author Illinois

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Message Posted: Jun 4, 2013 4:19:31 PM

"Whats wrong with all these vehicles then?"

Nothing.... That's what you get when you use a fuel that has 2/3rds the heat content of gasoline...
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krzysiek_ck
Champion Author Illinois

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Message Posted: Jun 4, 2013 3:40:00 PM

oilpan4 wrote: "Why do you name call like a 7 year old?"

Learn to properly type other members names first and drop the sarcastic tone in your posts. Maybe next time you will not get the response you got.

oilpan4 wrote: "For 2012 it looks like every car manufacturer that makes E85 vehicles is reporting 20% to 25% lower fuel economy.
Whats wrong with all these vehicles then?"

As previously stated as well, U.S. Department of Energy did not do actual tests.

Once more, what tests?

[Edited by: krzysiek_ck at 6/4/2013 3:40:33 PM EST]
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