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Alcohol in gas affects mixture

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79wagonator
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Re: Alcohol in gas affects mixture

Postby 79wagonator on Sat Jun 22, 2013 8:25 pm

jrm81bu wrote:
Chris Van wrote:Well my car ran worse with a mixture of 93 and E85. I have no scientific formula for coming to this conclusion but what I do have are the time slips to prove it.


What did you do to your set up to take advantage of the change? If you're not pushing detonation with you're set-up there isn't a lot to gain.

Bonnewagon wrote:OK well I'm no genius nor an engineer nor a chemist. I'm just a guy who likes to play with Q-jets. So someone tell me why a bone stock motor with a stock 1980 TA 301 Q-jet set up to a much richer 1979 TA 301 specs detonated all the time and then richening up the jets by 3 more numbers cured it. No other changes were made to anything and there were no vacuum leaks. I was tempted to fool with the vacuum advance first, but to prove a point to myself, I didn't. And how stock is this 33 year old carb? It still has rivets on the choke housing. I'm pretty sure I didn't accidentally "fix" something else during the rebuild.


I have every bit of faith that you know what your doing. I have no reason why anything you did fixed anything you had a problem with, but i'm guessing you are inlcined to believe you think your need for running pig rich is because of a tiny % of thermal output? Your comparison of the alcohol(methanol) drag racers needing to double up has nothing to do with the alcohol(ethanol) in your pump gas. They are two very different creatures.

79wagonator wrote:Well.. being the gas alcohol mixture has less thermal energy even by just a small amount
Being jetted the same as for running pure gas it would run slightly lean thereby causing more heat
which in turn = Detonation!
Makes perfect sense to me..
Good call Bonnewagon..
Everybody knows your gas mileage sucks with E10 as compared to straight gas..
Not a problem with newer injected motors as fuel, air and timing is automatically adjusted to compensate.
Sucks for older cars like ours..
E10 is even worse for boats with constant loads on motor and fuel sitting for longer periods evaporating and absorbing moisture from the air with vented fuel systems. :?
Now there pushing for e15 in some states... F&*k That!!
Is it really helping in any way? I don't think so..


You need to do more research. On e10 not changing your jetting would have almost no effect on you mixture let alone enough to go lean enough to cause a pinging issue. Your mileage shouldn't see any more of change than any other naturally occurring events would make it vary(wind, other drivers, your mood). Why would the "newer injected motors" not see a drop in mileage? They are programmed to target a certain mixture ratio, and if by your reasoning it would take more gas with ethanol in it to make that same ratio then they would lose the same mileage that any other vehicle would. Why would it be worse for an engine that sees constant loads? Yes ethanol absorbs moisture, it also hols it in suspension. The only time that causes a problem is when it gets more moisture than it can hold then it drops out. However the more alcohol, the more moisture it can actually hold, so a higher level is actually better in that respect.
And yes if it's handled correctly it can definitely help, however there is way too much politics involved in that for discussion here.

I guess I wrote it wrong, newer motors see a drop in mpg also is what I've heard from people in areas where pure gas and e10 is available
On LI only e10 is available.
As far as the high performance boating community, nobody likes the e10 which in my area is whats sold at the docks also.
And being able to absorb more moisture cant be a good thing..
I'm no scientist but Last I checked, water doesn't burn
I drain the fuel tank in the boat at the end of every season and burn it in my truck.
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CWPottenger
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Re: Alcohol in gas affects mixture

Postby CWPottenger on Sat Jun 22, 2013 8:44 pm

jrm81bu wrote:And yes if it's handled correctly it can definitely help, however there is way too much politics involved in that for discussion here.


Totally agree with that statement.

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Clone TIE Pilot
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Re: Alcohol in gas affects mixture

Postby Clone TIE Pilot on Sun Jun 23, 2013 12:26 am

It's pretty simple, a motor set up to burn gas won't have enough compression to properly burn ethanol. If it did, it would spark knock badly running on just gas. Cliff who is one of the top Qjet guys around says ethanol leans out the fuel mixture on older engines because they are not set up to burn it. It's just 10% inert filler to a gasoline engine, so you must enrich your mixture to make up for it. Ethanol has an -OH group in its chemical formula. That OH group is IN THE FUEL, you can not get rid of this -OH group. The only way to do so is to run straight gasoline. This extra oxygen IN THE FUEL, combined with the oxygen in the air (approximatley 21% O2, 78% N2) leans out your engine if you have a carbed motor. So basically you have extra oxygen in your fuel which changes the chemical equation from stoich and causes a lean burn, which results in higher flame temps. By having this leaner mixture, your jetting would need to be a size or two richer to compensate. A perfectly running engine uses 14 parts air to 1 part fuel. If that one part fuel is 100% fuel then your ratio is a perfect 14:1 When you introduce ethanol it uses up a percentage of the 1 part fuel. For example if you are running 15% ethanol then your new ratio is leaned out to 14:0.85. Ethanol burns at a different air/fuel ratio. It takes more ethanol for the same amount of air. An E10 combo is going to take slightly more fuel than straight gas for the same amount of air.
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Re: Alcohol in gas affects mixture

Postby Bonnewagon on Sun Jun 23, 2013 9:41 am

Now THAT is what I was thinking. ^^^^^^^^ Thank's Clone TIE Pilot for putting it in technical terms that make sense.
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Re: Alcohol in gas affects mixture

Postby jrm81bu on Sun Jun 23, 2013 5:30 pm

79wagonator wrote:And being able to absorb more moisture cant be a good thing..
I'm no scientist but Last I checked, water doesn't burn


Yes and no. Water in gas is a bad thing because they won't mix. The gas will float on the water and all you get out of the pickup is water. However since the alcohol in e10 will absorb the water it does get burnt because it gets all mixed together. Water is nothing more than hydrogen and oxygen, both of those elements burn when separated.
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79wagonator
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Re: Alcohol in gas affects mixture

Postby 79wagonator on Sun Jun 23, 2013 5:35 pm

So water has no effect on the fuel you burn in your car?
OK.
Refer to what Clone TIE Pilot wrote above..
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jrm81bu
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Re: Alcohol in gas affects mixture

Postby jrm81bu on Sun Jun 23, 2013 5:46 pm

Clone TIE Pilot wrote:It's pretty simple, a motor set up to burn gas won't have enough compression to properly burn ethanol. If it did, it would spark knock badly running on just gas. Cliff who is one of the top Qjet guys around says ethanol leans out the fuel mixture on older engines because they are not set up to burn it. It's just 10% inert filler to a gasoline engine, so you must enrich your mixture to make up for it. Ethanol has an -OH group in its chemical formula. That OH group is IN THE FUEL, you can not get rid of this -OH group. The only way to do so is to run straight gasoline. This extra oxygen IN THE FUEL, combined with the oxygen in the air (approximatley 21% O2, 78% N2) leans out your engine if you have a carbed motor. So basically you have extra oxygen in your fuel which changes the chemical equation from stoich and causes a lean burn, which results in higher flame temps. By having this leaner mixture, your jetting would need to be a size or two richer to compensate. A perfectly running engine uses 14 parts air to 1 part fuel. If that one part fuel is 100% fuel then your ratio is a perfect 14:1 When you introduce ethanol it uses up a percentage of the 1 part fuel. For example if you are running 15% ethanol then your new ratio is leaned out to 14:0.85. Ethanol burns at a different air/fuel ratio. It takes more ethanol for the same amount of air. An E10 combo is going to take slightly more fuel than straight gas for the same amount of air.


How is ethanol inert? You don't have to have massive compression to use it. By you first two sentences alone you, you are saying that having a flex fuel vehicle is impossible. I agree that to take advantage of the extra oxygen content you would want to add fuel. Thats exactly what running nitrous does. But 10% ethanol is no where near that. I honestly don't think that if you were using a wideband o2 that you would see any difference. Even if it did run slightly leaner the ethanol burns at a slower rate and that would negate any chance of detonation. All your math for your ratios is wrong, your are concluding that ethanol is not a fuel at all and therefore isn't a part of the ratio. I'm sorry but it is a fuel and is still a part of the ratio. Also 14.7:1 is stioch but you won't see any vehicles runnig that ratio when they are accelerating anyway. I do agree with your last sentence though, you will need more e10 to make the same power but that has nothing to do with causing detonation.
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Re: Alcohol in gas affects mixture

Postby jrm81bu on Sun Jun 23, 2013 5:49 pm

79wagonator wrote:So water has no effect on the fuel you burn in your car?
OK.
Refer to what Clone TIE Pilot wrote above..


Read again. Since the alcohol absorbs the water, it is no longer is water just laying in the tank.
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Re: Alcohol in gas affects mixture

Postby 1bad79 on Sun Jun 23, 2013 5:50 pm

clone has it exactly right, ethanol leans your fuel mixture out

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Re: Alcohol in gas affects mixture

Postby jrm81bu on Sun Jun 23, 2013 5:53 pm

1bad79 wrote:clone has it exactly right, ethanol leans your fuel mixture out


Then explain how.
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