Waldemar

Was driving with a friend in his Prius and he complained about the effect of ethanol on his fuel economy. According to http://en.wikipedia.org/wiki/Ethanol_fuel E10 should only have a 3% effect, but other reports are giving a much more substantial drop.

Since I was doing a 550 mile road trip (Seattle to Glacier Park in Montana) I decided to try it half with E10 and half ethanol free. Not entirely scientific - there's a wee bit (timed it for the low fuel light coming on) of gas left in the tank, and the terrain and speeds in the second section (ethanol free) usually result in poorer economy (the first half was mostly on 70 mph freeways, much of the second half was 75 mph, and a chunk on 70 mph two-lane roads clogged with RVs). Nonetheless, I maintained about 28 mpg in the first section, and was flirting significantly with a combined 29 mpg in the second half on the MID without a reset (therefore, about 30 mpg on that tank). Will try again on the return trip, staying with ethanol free all the way. It was the same price, after all, in the places I got it as the E10 at the neighboring stations.

http://pure-gas.org/ will give you a listing of ethanol-free stations in your area, if you care to try this. Would be great to get a more scientific readout on this, but I'd be interested in what others experience.

waldemar

csmeance

E10 gives worse MPG because it has lower power output per gallon than traditional 100% gasoline. As well E10 has a higher octane so gas stations mix it into lower octane gas to have a final blend of 91/92/93 vs. having purer gas which is 91/92/93.

Plus Ethanol holds water and even though it's rated for a higher octane, the motor can start pinging/knocking and retard the timing for less power so the car will have to work harder to move the same amount, thus consuming more gas.

jisleyjr

What is the octane rating on E10? The reason i ask is i have seen various pumps with the 10% ethanol label and be rated at 87 or 89, Flying J in Sioux Falls, Sd as it labeled as 93 octane.

I know some people are going to freak out about this but i have tried putting a gallon or up to 3.4 of E85 in the summer and then topping off with ethanol free 91 octane or 92 octane. I'll have to look at my excel file (i record every tank of fuel) and see if there we deviations in mpg during those tanks. Top of my head there were not. Not enough of one for me to join the 'ethanol is terrible' bandwagon anyway.

Glacier Park is a beautiful area. I assume you are going to drive the 'road to the sun' (i think that is the name)?

csmeance

The Octane rating on E10 is whatever you want to mix it to. With 100% gas you HAVE to refine the gas to 87, 89 and 91/93. With E10, you have a mucher higher octane of Ethanol (113 octane) so if you mix 10% ethanol into 90% gas this is how it works out:

For 87 Octane -> 10% 113 Octane Ethanol + 90% 84 Octane Gasoline
For 89 Octane -> 10% 113 Octane Ethanol + 90% 86 Octane Gasoline
For 91 Octane -> 10% 113 Octane Ethanol + 90% 88 Octane Gasoline
For 93 Octane -> 10% 113 Octane Ethanol + 90% 90 Octane Gasoline

Ethanol has a much lower value of energy per gallon than Gasoline does and leads to a loss in MPG. As well ethanol and Gasoline tend to seperate and thus your motor could be ingesting gasoline that's 3 Octane below what it should have at some point, and then is ingesting a much higher rate of ethanol it was designed for at others (both causing damage!)

As well Ethanol increases the vapor pressure of gasoline (makes it more prone to evaporate and turn into a gas so less is going into your engine and more is floating out of your tank when you fill up!) and causes a loss of actual fuel!

And lets not forget it's solubility in water, Ethanol and water mix together fairly well while gasoline and water don't. This means that water can easily be stored by ethanol and cause a TON of issues with your engine since water does not compress nor ignite! Add onto that an issue with internal parts rusting (I've gone though 3 fuel senders in my 7 before they gave me an updated part to resist corrosion) and Lexus had to issue a recall because of it.

Also add onto it that our dead zone is increasing quite a bit in the ocean due to corn crops and all the issues with it being grown and you have a giant ball of reasons as to why ethanol is BAD for cars and the environment.

The only benefit I see is that it's cheaper and lowers our oil consumption by 10%.

Costco

One of the main reasons why ethanol is so prevalent is because the corn crop is so subsidized.... hell, it's in almost everything we eat in one form or another, why not feed it to our automobiles too?

FWIW, my friend's Evo X, tuned with bolt-ons averaged 18mpg. When he got a bigger fuel pump to keep up with the demand for fuel delivery and got it tuned on E85, his average sunk to 13mpg.

There are pros though. E85 is quite a bit cheaper than 91 (highest you can get around here), the car runs a lot smoother, and best of all, it makes a LOT more power. IIRC he got something like ~40 AWHP just from going to E85 + tune. With the added fuel consumption, I think he is barely spending less than he would if he was running 91. Other downsides are decreased range, obv., and E85 pumps aren't exactly everywhere.

fsttyms1

^ I laugh at how people use it because its cheaper but in the end we end up paying more for it in the way of taxes due to all the subsidies involved with it. Ethanol is shit and needs to be removed from our fuels.

i see about on average 60 less miles per tank when there is 10% in the fuel or winter blends in my TL. (and that number comes from 450k miles of driving the TL so its not just a short trip ore one time test)

csmeance

E85 is great for cars like those that can be tuned to take advantage of them! However like you just said youself even though you get more power, you loose a lot of gas mileage b/c it has less energy than regular gasoline! It would have been a LOT better if they added 10% ethanol to gas and gave gas across the board a boost in octane so regular was 90, mid 93, and premium 96/98 octane. With that little bit more increase we could take a lot more advantage of the fuels that we have by keeping with high compression ratios and as well help this trend out with FI cars like all the ford, BMW, MB, etc cars that are all going Turbo for the masses!

Costco

I would prefer pure gasoline as well but you cannot deny the benefits for the aftermarket. If you want to make power, E85's increased knock resistance compared to 91/93 is a great benefit and the availability of it is still much better than 100 octane's.

The last thing my friend was looking for was the cheaper price. If he was worried about it in the first place he wouldn't have gotten an Evo X. In addition, a miles/tank measurement is not nearly as accurate as a hand calculation of miles/gallon

At least you guys don't get doubly screwed... here in CA we're stuck with 91 as the highest octane fuel and we have 10% ethanol blends everywhere.



I think building engines that are made to withstand ethanol would be nice for future engines.... I don't know the molecular level of science behind it, but allegedly ethanol blends run cleaner than pure gasoline. I'm still not 100% behind it but I'm eager to see how my friend's plugs turn out given the extra fuel delivery.