pure ethanol and hp,mpg..etc

[jaxtell671]

i'm so confused about all this ethanol information that everyone is putting out. it lowers pollution, it decreases hp and mpg. i looked through all the info that my brain could handle and i still have some questions . if you run on just ethanol and the engine was designed to run on ethanol alone couldn't you build an engine with higher compression to make up for the lower energy content? does e85 increase the octane of the fuel when compared to regular? any help would be appreciated

[534BC]

Hi, welcome to auto-forums. Here's my take on it.

It will give same hp and a slight decrease in mpg and slight decrease in pollution in an average car/truck when mixed at 10% like at normal pumps.

If you were to purpose build an engine with high comp like you say the mpg and hp would come right up to where the original engine was. I say you have the right idea.

Ethanol must be about 108-110 octane or so and does increase the octane of the mixture, however 87 gas with ethanol is still 87 octane because it starts with a lower number 84 octane gas with ethanol 10% = 87 octane.

I almost forgot, there's got to be a reson they are making e-85 and keeping the 15% gas. Maybe has to do with cold start-up or something.

[UncleBob]

that is correct 534, cold start is an issue with ethanol.

You can make a very serious engine to run on just ethonal. I was playing with the idea of making a street/drag bike on E85, but unfortunately, my plan was ruined when I discovered you can't get E85 in WA state...yet. Bummer.

300HP with 1.0L engine on "pump" gas sounded like a lot of fun.

[Dakota_Don]

i tried the e85, decressed MPG a lot, car ran like crap to.. unless you have your car set up for it or its a newer car that will run on it, dont use it, its not worth the poor MPG, oh



watch out for rippedstang he is sending junk mail in your PM boxes..

[534BC]

There was a fella that campaigned a race car (drag) on ethanol. I think He was from Canton , Ohio. Never saw the car run, saw it in magazines though. I am sure it had high compression. Nice for a turbo job, kinda like running methanol probably.

[drew300]

From what I read, E85 has the 15% gas to keep the vapour pressure in the gas tank too rich to explode.
My brother told me of Offenhauser race engines that ran 100% ethanol, and ran into trouble with engine reliability with 80 psi boost! So a high performance engine can be built.

[KiwiBacon]

Originally Posted by drew300

From what I read, E85 has the 15% gas to keep the vapour pressure in the gas tank too rich to explode.
My brother told me of Offenhauser race engines that ran 100% ethanol, and ran into trouble with engine reliability with 80 psi boost! So a high performance engine can be built.

I heard the 15% petrol is to stop people drinking it.

Since petrol vapour can explode, I doubt preventing explosion is the reason.

[534BC]

I think you are both slightly mistaken. Pure Ethanol has "up to 5 %" gasoline in it supposedly to "keep people from drinking it" I have heard that as well.

The E-85 blend for cunsumer use in Flex fuel autos uses 15 % for some other reason, maybe for cold starting or cold weather operation? Regardless of the mixture of gas and ethanol (up to 100% of either produst) the vapors in the tank will be too rich to burn.

[kachok25]

OK yall here is the real breakdown of alcohol vs gas. Yes gas has a higher BTU rating than alcohol so in the same eingine gas is more efficent, but that is not the whole story ethanol can run a much higher compression ratio almost the perfect 17:1 where the internal combustion engine makes its peak torque, so if you compared the 10:1 gas engine vs the 15:1-16:1 ethanol engine I honestly don't know which one would burn less fuel given the same load. Here is the kicker for me, alcohol is 1/3 liquid oxygen the same oxygen content of Nitros Oxide this means that it is capable of making about 33% more power than a gas engine even at the same compression ratio! Think your 300hp 350Z is fast, convert it into an alcohol car and it is pushing 400hp with no other modifacation, now increase your CR and you are about 460-480 with no boost and a completly street cam. OR keep the same CR, beef up your internals, and boost it to 19psi and you are making 800+hp. It is the resistence to detonation the makes alcohol a better fuel than gas. From what I understand the reason they are making E85 is because pure alcohol will dry out and crack the rubber gaskets in most gas powerd cars. If alcohol catches on don't be supprised if you see E100 cars in the next ten years.

[SaabJohan]

Ethanol increases some emissions while it decreases others. With the current production, the net emissions of CO2 are only 10-20% lower with E85 than for gasoline while it is very costly to produce.

Pure ethanol has an energy content of 26 MJ/kg, gasoline is at 42-44 MJ/kg, but ethanol is slightly more dense. In any case, the result is that the engine will consume more E85 than it consumes gasoline, even if we increase the compression ratio.

E85 should only be used in cars capable to run on E85 fuel, there are several good reasons for this.

Ethanol is mixed with gasoline due to several reasons, most of them has already been mentioned here:
1. To increase vapor pressure, mainly to aid cold starting.
2. To make it impossible to drink (although some have tried to destillate it for the ethanol)
3. To make its flame more visible, increases safety

To prevent tank fires, cars designed for E85 may be fitted with flame arrestors and shielded tank electronics. At temperatures below 10 degC there is a combustable mixture in the tank, that can be compared with the below -10 degC of gasoline.

The oxygen already in the fuel will not support combustion as in nitromethane.

For example Saabs 2.0t BioPower makes 150 hp on gasoline but 180 hp on E85. That increase is mainly due to the increase in boost pressure when the engine runs on E85. But the engine can also run closer to lambda 1 at high loads due to the higher octane of the E85 and that saves a bit of fuel.
To withstand the fuel, many parts in the fuel system is replaced with ethanol resistant parts. The intake valves and valve seats are also replaced in order to withstand the fuel.

[kachok25]

Originally Posted by SaabJohan

Ethanol increases some emissions while it decreases others. With the current production, the net emissions of CO2 are only 10-20% lower with E85 than for gasoline while it is very costly to produce.

Pure ethanol has an energy content of 26 MJ/kg, gasoline is at 42-44 MJ/kg, but ethanol is slightly more dense. In any case, the result is that the engine will consume more E85 than it consumes gasoline, even if we increase the compression ratio.

E85 should only be used in cars capable to run on E85 fuel, there are several good reasons for this.

Ethanol is mixed with gasoline due to several reasons, most of them has already been mentioned here:
1. To increase vapor pressure, mainly to aid cold starting.
2. To make it impossible to drink (although some have tried to destillate it for the ethanol)
3. To make its flame more visible, increases safety

To prevent tank fires, cars designed for E85 may be fitted with flame arrestors and shielded tank electronics. At temperatures below 10 degC there is a combustable mixture in the tank, that can be compared with the below -10 degC of gasoline.

The oxygen already in the fuel will not support combustion as in nitromethane.

For example Saabs 2.0t BioPower makes 150 hp on gasoline but 180 hp on E85. That increase is mainly due to the increase in boost pressure when the engine runs on E85. But the engine can also run closer to lambda 1 at high loads due to the higher octane of the E85 and that saves a bit of fuel.
To withstand the fuel, many parts in the fuel system is replaced with ethanol resistant parts. The intake valves and valve seats are also replaced in order to withstand the fuel.

All of the downfalls with pure alcohol that you listed can be easly fixed, such as denaturing the alcohol or mixing a small amount of wood alcohol into it. Correct me if I am wrong but I think only Methanol is invisable when burning, I have seen a moonshine Malatov cocktail and it's flame is very visable. I don't know how you figured your numbers but alcohol has over 2/3 of the BTU of gas. 125,000 BTU per US gal vs 84,400 BTU per US gal that is 67.5% not 61% Then again that might be due to the very small difference in density between the two like you mentiond. But one more thing to consider is that if you raise the octaine of gasoline to ethonals 108 equ then you loose BTUs considerably because octaine boosting fuels have less energy. And they simpley don't, make a real gasoline that approches methonals 126 octaine equ, though there are exotic aromatic mixtures that approch that rating they can hardly be considerd gasoline anymore.

[curtis73]

Originally Posted by kachok25

I don't know how you figured your numbers but alcohol has over 2/3 of the BTU of gas. 125,000 BTU per US gal vs 84,400 BTU per US gal that is 67.5% not 61% .

Uhh... 67% IS two-thirds. I'd call that close enough.

[SaabJohan]

Originally Posted by kachok25

All of the downfalls with pure alcohol that you listed can be easly fixed, such as denaturing the alcohol or mixing a small amount of wood alcohol into it. Correct me if I am wrong but I think only Methanol is invisable when burning, I have seen a moonshine Malatov cocktail and it's flame is very visable. I don't know how you figured your numbers but alcohol has over 2/3 of the BTU of gas. 125,000 BTU per US gal vs 84,400 BTU per US gal that is 67.5% not 61% Then again that might be due to the very small difference in density between the two like you mentiond. But one more thing to consider is that if you raise the octaine of gasoline to ethonals 108 equ then you loose BTUs considerably because octaine boosting fuels have less energy. And they simpley don't, make a real gasoline that approches methonals 126 octaine equ, though there are exotic aromatic mixtures that approch that rating they can hardly be considerd gasoline anymore.

Typically you don't denature ethanol with just methanol as that mix would still seem drinkable, the denaturing additives used usually give the ethanol a bad taste or smell so that it can't be mistaken for pure alcohol. Usually color is added too. Around here E85 fuel is colored red.
In the case of engine fuel, methanol is typically not used as a denaturing additive.

There are several fuels that burn with an invisible or close to invisible flame. That's related to the fuel chemistry, carbon and high carbon fuels burn with a yellow sooty flame while hydrogen and fuels containing more hydrogen tend to be a clean blueish or invisible flame. Ethanol tend to be a bit blueish, and compared to gasoline it can be harder to detect. Add a few percent gasoline and the flame becomes more yellowish.

Ethanol has a net energy content of 26.7 MJ/kg, gasoline is at 42-44 MJ/kg. Actual numbers may vary a bit depending on what reference is used. In any case, note that energy content is related to mass, not volume. The density of gasoline is a bit lower than the density of ethanol, 0.72-0.74 vs. 0.79 grams per cubic centimeter. Also, in most ethanol fuels gasoline is added, so for E85 we end up with a net energy content of 31 MJ/kg or so compared to the 42-44 MJ/kg of gasoline. This also affects the stoichiometric air fuel ratio of the fuel, 9 for ethanol, 10 for E85 and 14.7 for gasoline. Methanol is even lower at 6.5, but it's energy content is slightly below 20 MJ/kg, less than half that of gasoline.

There is no relation between energy content and octane rating. The actual octane rating of alcohol fuels differs a bit depending on the source, alcohol fuels are quite sensitive. In any case, there are several hydrocarbons commonly found in gasoline that have an octane rating that is higher than for ethanol and methanol. But you don't make fuels in that way. If we increase the octane rating of the fuel, the engine will consume more fuel, but the refinery that makes the fuel will consume more oil in relation to the fuel produced if we increase the octane rating as that would require additional processes. So gasoline is normally made to produce the lowest overall energy consumption, and you will find that low point at about RON 95.

Many of the problems with ethanol can not be overcome so easy. For example, there are no fuel additives that can reduce the corrosive properties of ethanol to the level of gasoline. You also can't increase the vapor pressure to the level of gasoline unless you blend it with some other fuel, like gasoline.

Ethanol can decrease certain emissions, such as aromatics while others increase, such as aldehydes. Current production of ethanol is in general very ineffective. For example ethanol production from corn as common in the US require an energy input of approx. 80%. That means if you want to create 100 MJ ethanol, you must add 80 MJ of energy, typically from a fossil source. Production from for example sugarcane in Brazil is more efficient though.

[kachok25]

No mixture with methanol in it is drinkable that stuff is bad news if injested, it turns into formaldehyde in the human body making it very toxic! In the prision that I worked in there was an inmate that stole some and brought it back to the housing area,and made a block party out of it, three died and the rest of them went blind! There is a connection between octaine and BTUs namly the energy content of the aromatic additives used.

[crtravis55]

Here is an example of real world economics of e85. I've been tracking the milage of my 03 Explorer 4.0 and over the last several months I was averaging city/hwy 14.29 mpg on regular gas. switching to E-85 over the last 6 weeks my average has dropped to 12.3 mpg - a 13.9% decrase in mileage. The average price I've paid for E85 over the last 6 weeks was $3.09/g while the average for regular gas at the same station was $3.63/g or 14.8% less. (my last fill up was $3.29 E85/ $3.99 gas).

In reality my cost per mile has been at most a penny less than gas and on average the same cost ($.2512 E85 vs. $.2542 gas). As long as the E85 cost is less than gas by equal or greater than the percent decrease in mileage then it is a slight advantage. But some stations only charge $.10/ gal less so it will cost you money to switch. Even the Ford manual says that you may see up to a 30% decrease in mileage on E85.

My drawback has been hard starting when the engine is cold in the morning (April/May in SE Michigan). It will start then stall at least 1 -3 times until it warms up before I get moving . The rest of the day there is no issue. For that reason alone I'm going to go back to gas because I can't justify the meager if any savings I'm getting. And part of me is bothered by the fact that it takes the energy equivilant of 4 gal of gas to make one gal of E85 and that diverting all that corn to fuel has created cost increases for the enitire food chain.

When I ask people at the pump how much their mileage has dropped they either tell me they don't know, " but its cheaper", or they feel like they have more power because the octane is higher. Obvioulsly the media has never done a good job on educating the public or maybe the corn lobby has done a good job of covering it up. Maybe the government shold give mileage ratings with E85 in addition to gas.