Effect of Ethanol on HP and Mileage

[War Eagle]

The local gas station I have been using has recently gone to a 10% ethanol mix in their gas. Does this have any effect on HP and mileage?


Steve

[Chevyrocker]

E85 ethanol has a higer octane level so it does increase horsepower and decrease fuel economy.

[kylepo]

10%= no noticeable change. E85 gives you more HP more Ft LBs and less MPG

[CamaroSpike23]

i dont believe he's talking about switching to e85. he's talking about how his gas station now has conventional gas with up to 10% ethanol added in..... like nearly every other gas station out there. its getting hard to find "pure" gas stations anymore. as for the effects, up to 10% i dont think would be noticable on either hp or mpg

[MerF]

I truly believe the 10% thing is a gimmick...however it is DEFINITELY not good for engines not run regularly. Talk to a local outboard mechanic for proof...my dad's engine needed new seals and floats throughout due to the ethanol.

Daily driven cars are no issue, but if it's allowed to sit it does something to the engine...dunno what, but it's a real issue.

[RonC]

Originally Posted by PoleCat2SSRS2010

Ethanol requires more fuel consumption always! Its attractiveness comes from the cost per gallon and higher octane (from running cooler). Racing ethanol by comparison to racing gas requires ~33% more consumption and a butt load of maintenance b/c it draws in water from the air. There is an additive but you still have to flush the system when you are done for the day.
As for E85 in comparison to pump gas, you will use more and in the end there is no real savings.
Also, ethanol in general will dry out the rubber seals in the pumps and hoses and cause break down. Not sure what has been engineered into the system and not sure if anyone is talking.

PoleCat is right about ethanol efficiency. It has about a third less BTU's per gallon than gasoline but is higher in octane. BTU's are the units of energy being released (power) and its higher octane rating helps reduce spark knock. 10% ethanol mix would have about 3% less BTU's than a gallon of gasoline, so in theory it would lose 3% in fuel mileage. If you got 23 mpg on gasoline you would get about 22.3 mpg on 10% ethanol mix. In my testing it on my 1500HD truck it averages about .5 mpg less than straight gasoline. For it to be an equal value the price would need to be 3% less and for people using E85, the price would need to be 33% less. I hope this helps you understand it better.

[DGthe3]

Originally Posted by PoleCat2SSRS2010

Ethanol requires more fuel consumption always!

Not quite. Its been shown that midrange blends (20-30%) seem to have hit a sweet spot where they can provide better fuel economy than regular gasoline.

[CamaroSpike23]

Originally Posted by DGthe3

Not quite. Its been shown that midrange blends (20-30%) seem to have hit a sweet spot where they can provide better fuel economy than regular gasoline.

thats what the OP is asking about. how gas stations have converted to a "up to 10% ethanol" in their gasoline and its effects compared to "100% gasoline"

[kylepo]

Originally Posted by DGthe3

Not quite. Its been shown that midrange blends (20-30%) seem to have hit a sweet spot where they can provide better fuel economy than regular gasoline.

source? Now can that mid range be put in a regular GAS er?

[Mr. Wyndham]

I've been using 10% ever since I bought my car...and I did go for pure gasoline for a month...to test some theories....

The 10% actually gives me better mileage...and the stations who sell it (Sunoco) are always ~10c lower than everyone around them. It's a no-brainer for me.

[CamaroSpike23]

Originally Posted by Dragoneye

I've been using 10% ever since I bought my car...and I did go for pure gasoline for a month...to test some theories....

The 10% actually gives me better mileage...and the stations who sell it (Sunoco) are always ~10c lower than everyone around them. It's a no-brainer for me.

theres about 1-2 stations down here within a reasonable driving distance that still sell pure gasoline. some of our guys will run it at the track and have picked up a few tenths... however, i am unaware of the track conditions on the different days so it could be a moot point.

[Oracle]

Originally Posted by DGthe3

Not quite. Its been shown that midrange blends (20-30%) seem to have hit a sweet spot where they can provide better fuel economy than regular gasoline.

There was an article on a study that found that blends up to 30% ethanol showed infiticimal losses in fuel economy. sadly i cant quote that article because it was published by Chemical and Engineering news, which I only have in magazine form. Most areas blend ethanol when it is in season, a few areas blend year round. Ethanol is an oxygenate, used basically to make sure your fuel has enough oxygen to complete combustion in the cylinders and reduce harmful emissions. its there to displace other oxygenates that have been used in the past such as MTBE. MTBE (methyl tertiary butyl ether) was toxic and could contaminate water sources, making it a very dangerous addative. Ethanol is also a very clean solvent. it can actually clean the engine of grime, carbon buildup, gum buildup, ect ect ect.

As per Ethanols faults: it is a polar compound, making it a hydrophillic substance. that means it will pick up and carry water. all ethanol should be checked for water content before being blended with gasoline. once blended I would assume that the gasoline would be a stronger solute than water, meaning that the little bit of water in the ethanol would fall out. since this is done at the blending racks the water would be separated by the filters at the pump and would never make it into your gas tank. second is that if you have an older car with seals that are soluble in ethanol then they can be damaged by this. so if your thinking of putting any oxygenated fuel in your vintage 69 camaro.... dont... please. otherwise any vehicle less than 20 years old is fine because they use different materials.

The skinny: you wont see a drop in fuel economy or HP. if your fueling up your GT500 with it then it will actually do you good by acting as a detergent. so just keep on truckin

[bob2the2nd]

Originally Posted by Oracle

There was an article on a study that found that blends up to 30% ethanol showed infiticimal losses in fuel economy. sadly i cant quote that article because it was published by Chemical and Engineering news, which I only have in magazine form. Most areas blend ethanol when it is in season, a few areas blend year round. Ethanol is an oxygenate, used basically to make sure your fuel has enough oxygen to complete combustion in the cylinders and reduce harmful emissions. its there to displace other oxygenates that have been used in the past such as MTBE. MTBE (methyl tertiary butyl ether) was toxic and could contaminate water sources, making it a very dangerous addative. Ethanol is also a very clean solvent. it can actually clean the engine of grime, carbon buildup, gum buildup, ect ect ect.

As per Ethanols faults: it is a polar compound, making it a hydrophillic substance. that means it will pick up and carry water. all ethanol should be checked for water content before being blended with gasoline. once blended I would assume that the gasoline would be a stronger solute than water, meaning that the little bit of water in the ethanol would fall out. since this is done at the blending racks the water would be separated by the filters at the pump and would never make it into your gas tank. second is that if you have an older car with seals that are soluble in ethanol then they can be damaged by this. so if your thinking of putting any oxygenated fuel in your vintage 69 camaro.... dont... please. otherwise any vehicle less than 20 years old is fine because they use different materials.

The skinny: you wont see a drop in fuel economy or HP. if your fueling up your GT500 with it then it will actually do you good by acting as a detergent. so just keep on truckin

Then explain to me why in my engines class I took in college last I was told and shown how and why engines lose both HP and fuel economy using ethanol?

Using a normal gasoline engine we went through every type of fuel you could think of (about 10) and went through the pro's and con's. Basically diesel came out best followed by gasoline (with biodiesel much lower). People mix in ethanol because it saves the manufactures a couple of cents for every gallon produced, while having only a slightly negative effect on HP and fuel economy... but it is there. If it wasnt we would be running pure ethanol engines.

As stated almost perfectly by RonC there are less BTU's in ethanol which cause the drop in efficiency.

Im just going to take a guess but I would have to think that the study you read probably had an engine adjusted for a ethanol/gas mix, thats the only way an engine is not going to see a performance drop. In engines that dont do that there will always be less HP and gas mileage.

edit: I also have to assume this is the difference between a mechanical and chemical engineering stand point. The chemical engineer is arguing why in a perfect world it works and the mechanical engineers are arguing that it isnt a perfect world thus it doesnt.

[Oracle]

Ethanol saves the manufactures a little bit of cash because of a tax waver for oxygenating the fuel. like i said before adding ethanol adds oxygen to the fuel resulting in a more complete burn of the gasoline. for engines that naturally run rich in fuel (not race engines, race engines are normally spot on in the tuning or actually run a bit lean. production motors are run rich to run cooler and increase their life expectancy) is where you will see the benefit. at the same time Ethanol has less potential energy, a negative side effect from short chain of ethanol, not leaving very much to be burned. so overall on a production engine you have less net potential energy but greater kinetic energy because more of the gasoline gets burned.

If you burned straight ethanol you will gain horsepower but lose a lot of fuel economy. thats because of two things, first everybody knows ethanol has a higher octane, allowing for greater compression and more aggressive tuning. the second is that because the molecule chain is so short it burns very very fast. to put this in perspective Diesel engines produce power very low because diesel fuel is a large molecule. that large molecule takes a long time to burn, hence the low RPMs give it the time to do that. you will also notice diesel power falls off very quickly at above 3000 rpms because your no longer burning all of the fuel. Ethanol has the opposit, reletively weak low RPMs because it doesnt need all that time to burn, so it wastes time after everything is spent. but once you rev up the motor to say 7k (just an estimate) rpms then your burning it all just about as quick as possible and will produce your best power in that range. Diesel provides better fuel economy because of two things: the molecule is larger so holds more PE, and friction increases exponentially with rpms, so it produces maximum power where frictional losses are minimal. Gasoline is kind of the middle child between these two fuels.

so overall when your talking about an all OEM engine that is tuned to run rich you wont be burning all that fuel, thus hurting your fuel economy. if you add ethanol your going to burn more of that fuel making up for its lesser BTUs up to, as the study shows, approx. 30%. from a chemical engineer standpoint it would say that adding ethanol is throwing away PE dont do it. from a Mechanical engineer standpoint you dont need to add oxygen to burn all your fuel, just tune the thing right. so dont do it. we do it to fix problems created by fixing problems.