We have a few gas stations nearby that sell mid grade (89 octane) for the same price as regular 87 octane, and it has got me to wondering how they can do that, and why anyone would buy the regular?

I have wondered how ethanol content effects octane rating?
I currently purchase premium (93 octane) pure gas with no ethanol from the same station for my SS. On long trips where I have to refuel on the road, I still run 93 octane, but notice that sometimes my fuel mileage suffers.

In my LT1 (2.2), I run regular 87 octane, but notice that I get better mileage from some stations than others on long trips. (It's not just the wind/direction)

I know that ethanol is not as efficient as gas as far as fuel mileage goes, so I am wondering if ethanol increase the octane rating?

I would doubt that mid grade would be the only ethanol grade since there is no separate tank for mid grade it is just a blend of regular and premium. I don't know what if any affect a little ethanol will have on gas but I was told that E85 is 105 octane.

We have a few gas stations nearby that sell mid grade (89 octane) for the same price as regular 87 octane, and it has got me to wondering how they can do that, and why anyone would buy the regular?

I have wondered how ethanol content effects octane rating?
I currently purchase premium (93 octane) pure gas with no ethanol from the same station for my SS. On long trips where I have to refuel on the road, I still run 93 octane, but notice that sometimes my fuel mileage suffers.

In my LT1 (2.2), I run regular 87 octane, but notice that I get better mileage from some stations than others on long trips. (It's not just the wind/direction)

I know that ethanol is not as efficient as gas as far as fuel mileage goes, so I am wondering if ethanol increase the octane rating?

Yes, ethanol is used to INCREASE octane ratings.

I noticed this primarily in the northern states....Dakotas for example. The pumps there listed several different octane ratings. And expressly indicated the upper level gas was enhanced with ethanol. They also gave one or 2 grades of gas in "non blended". Ethanol enhanced grades was slightly less in cost, if I remember correctly (I think Sinclair was the predominant brand).

I am not saying that mid grade is the only grade that they add ethanol, I mentioned that when I travel I fill up with premium at other stations on occasion. I notice a drop in mileage sometimes, and wondered if maybe these had ethanol vs my pure gas?

Also, Are you sure that ALL stations mix to get mid grade? I thought only some did that? I just wonder why my local station sells mid grade 89oct at the same price as regular 87oct? Could the mid grade have more ethanol and thus boost octane rating?

If E85 has an octane rating of 105, that may be my answer... Yes, ethanol increases octane rating, but not necessarily MPG or performance?

I'm just trying to learn.

Come on, I know there are some real scientists out there.....

I thought I answered your question as you asked it.
"I know that ethanol is not as efficient as gas as far as fuel mileage goes, so I am wondering if ethanol increase the octane rating?"

If this is a new question, "Also, Are you sure that ALL stations mix to get mid grade?"....no I am NOT sure. But it COULD/WOULD be a cheap way, except it may increase the percentage of ethanol in the mixture.

There is a gas station up by my trailer that sells 89 for the same as 87. Everytime I get the 89 in any of my vehicles I get a check engine light. I thought it was just a fluke the first time, but I have tried with our other cars and get the same result. Nobody that lives out there has had the same problem, but I am using the Chicago blend of gas 95% of the time so maybe it is the switch to the rural gas that causes it. Long story short I just get the regular 87 or the premium 92 to avoid this problem.


SPPD

I thought I answered your question as you asked it.
"I know that ethanol is not as efficient as gas as far as fuel mileage goes, so I am wondering if ethanol increase the octane rating?"

If this is a new question, "Also, Are you sure that ALL stations mix to get mid grade?"....no I am NOT sure. But it COULD/WOULD be a cheap way, except it may increase the percentage of ethanol in the mixture.

Snoopy, sorry about that I should have quoted nss79 as I was replying to his message at the same time you were posting your response....:red:

I noticed while on vacation that when I use the gas with ethanol I didnt get as good of mileage as regular gas.

I noticed while on vacation that when I use the gas with ethanol I didnt get as good of mileage as regular gas.

.5%-1.0% drop in fuel economy, which can be made up by using cleveandhhr's driving techniques.

Most of central Florida stations all sell gas with "up to" 10% ethanol blended gas and it is for all grades. I'm using 87 octane and my mileage has dropped about 10% since the push for the blending of ethanol. I shouldn't complain as I'm still getting ~30 mpg, but I had been getting 33-36 mpg on the highway when the car was new in '06.

Methanol and Alcohol require about twice as much fuel as gas. 14.7 to 1 is the optimum mixture for gas and with alcohol it is about 6 to 1.
Methanol and Alcohol have very high octane rating and produces very good power when set up right but mileage is TERRIBLE!
In my race car I used about a gallon of gas per pass, when I switched to Alcohol I used about 2.5 gallons per pass but it was MUCH faster with no other changes. Alcohol also runs cool so it allowed me to almost eliminate my cooling system to save weight helping performance even more.

If my thinking is right (I could be wrong) a 10% Ethanol mix should hurt your mileage about 5%. My problem here is we do not know which ones have Ethanol or not. All pumps at all stations say "May contain up to 10% Ethanol" But nobody I have asked knows if or how much. So for my testing I try to use the same grade gas from the same gas station so atleast I am trying to compare apples to apples.

Methanol and Alcohol require about twice as much fuel as gas. 14.7 to 1 is the optimum mixture for gas and with alcohol it is about 6 to 1.
Methanol and Alcohol have very high octane rating and produces very good power when set up right but mileage is TERRIBLE!
In my race car I used about a gallon of gas per pass, when I switched to Alcohol I used about 2.5 gallons per pass but it was MUCH faster with no other changes. Alcohol also runs cool so it allowed me to almost eliminate my cooling system to save weight helping performance even more.

If my thinking is right (I could be wrong) a 10% Ethanol mix should hurt your mileage about 5%. My problem here is we do not know which ones have Ethanol or not. All pumps at all stations say "May contain up to 10% Ethanol" But nobody I have asked knows if or how much. So for my testing I try to use the same grade gas from the same gas station so at least I am trying to compare apples to apples.


Now that's interesting. :bow:
If I understand what you are saying, adding Ethanol to gas can give you more power, thus the higher octane rating, BUT will decrease mileage.
Of all the things I have heard (and my past beliefs)That makes the most sense.

here in tampa you cant go to a gas station that doesnt have ethanol. I personaly am not a fan of it... My mpg has dropped and performance seems off.

I do not know if it will help or hurt performance with Ethanol but it will hurt mileage. For it to help the performance the computer would need to add a lot more fuel. I do not know how well the O2 sensor corrects for or with Ethanol. If it does not compensate for the alcohol it will hurt mileage and performance. E85 in a gas motor could run it lean and burn pistons if extra fuel is not added. Add extra fuel mileage goes way down but there is the potential for better performance. Alcohol is very corrosive and rusts most everything and it destroys many different types of O-rings to.
Alcohol does not light off easily in cold weather so it is very difficult to get your car started wen it is below about 40*.
Also Alcohol really works best with higher compression or boost so on a low compression motor even if richened up it may not help performance as much.
Another problem with alcohol as the volume of it you have to use. If your street car was to run on pure alcohol you would need about 50 gallon tank in your car just to have a decent fuel range. That would add a bunch of weight further hurting perfomance and mileage. Or you would have to fill up all the time. A gallon of Alcohol does not put out as much energy or BTU's as gasoline does but since it takes so much more alcohol you end up with more when it is at the right mixture.
So in my opinion there is nothing better than alcohol for race cars and it is the worst for daily drivers. Generally Ethanol is 10% or less alcohol so the changes are not as drastic but still there.

Eh! According to a Canadian study ethanol doesn't burn any greener either.

http://www.cbc.ca/canada/manitoba/story/2007/03/30/ethanol-emissions.html

As you said, it takes twice as much alcohol then gas..so in the case of stock street cars, all it does is displace the amount of gas available, it does nothing otherwise.To take advantage of alcohol, one would have to be "tuned' for it. Higher octane means you can "add" in more timing without the "knock" or detonation.On modern computer controlled cars your stuck with the factory tune on reg gas unless you go aftermarket or stage upgrades from the dealer.Thus you cannot take advantage of the higher octane ratings,unless, your already operating on the fringes and the higher octane smooths this out.Not all vehicles are alike despite being the same make model.This is why some models operate better on high numbered gas even though it recommends lower grade while the guy next to you can operate on low grade with no problems.Confused yet?

Here is a very interesting article on Ethanol mileage. http://ecomodder.com/forum/showthread.php/ethanol-scam-ethanol-advocates-giving-slanted-mpg-numbers-5790.html

He is saying a 10% Ethanol is up to 30% mileage loss.

Here is a very interesting article on Ethanol mileage. http://ecomodder.com/forum/showthread.php/ethanol-scam-ethanol-advocates-giving-slanted-mpg-numbers-5790.html

He is saying a 10% Ethanol is up to 30% mileage loss.

Somethings not correct about that quote:confused: if in fact, you provided that accurately. It is well documented through testing, by the DOE...vehicle manufacturers....and the ethanol association group themselves that E-85 (85% ethanol) computes to a 27-30% drop in mileage. How can a lesser quantity of ethanol, 10%, compute to the same loss of mileage?

I'm not questioning the loss of mileage overall, only the numbers that are stated. I AM NOT A SUPPORTER of ethanol, in it's current state of supply. But I do request legitimate/valid information.:D

And curly.....if in fact your source is stating those numbers, I would be highly suspect of the rest of the content (Iwill read it later, when more time is available).

I just said it is interesting reading. I said he is saying 30% loss from 10% Ethanol. My personal opinion is that it is more than the 3% DOE and the manufacturors claim but less than the 30% that guy is claiming.

I can not verify that here because all of our gas pumps just say "May contain up to 10% Ethanol" We do not know which ones have it and which ones if any do not. I do know I have got some strange mileage numbers from time to time that did not make sense.

I do believe that E85% has to be more than a 27%-30% drop as those numbers just do not add up. Pure Alcohol takes almost 2.5 times as much fuel so 85% should be much worse than 27-30% in my opinion. Or a considerable loss in power or a combination of the two. If they are running it lean on E85 they are taking a chance of hurting the motor.

Just to throw in my 2 cents worth. If you knew you were going to run only ethanol, then you could build a motor that was optimized for it, with VERY high compression. The efficiency gained by the higher CR would largely offset the loss in btu/lb of the fuel itself, so the big problem is that the carmakers need to produce motors that will run on everything from 100% gasoline to 100% ethanol (in many cases) and can't bump up the CR to take full advantage of the ethanol properties.

You can run higher compression ratios with alcohol but it does not change anything that it still requires almost 2.5 times more alcohol than gas. Many race cars are using 17 to 1 compression you could not do that on any motor that would run gas and Ethanol. Would run good on Ethanol but self destruct with gas.
Yes, if you designed a car to run on only Ethanol you could run higher compression. Alcohol does produce more torque so you could possibly use a smaller motor to offset some of it. Still you would end up with worse mileage and or worse performance. Bottom line is there is nothing good about Ethanol / Alcohol / Methanol in a street car. The higher the percentage the worse it gets.
There are also other problems such as you have to have larger fuel tank (more weight) more corrosive, and it absorbs moisture from the air and the fumes can be terrible. Also it is very bad about getting water in the oil or washing down the rings. There are ways to get around some of those problems but you can not get around the fact it requires more fuel.
There is nothing that makes Ethanol good for a street vehicle. Great for race cars but I can not see any benefits for a street car.

Plus..if you've ever been around alcohol cars..its always started with a shot of gas to get the cylinders firing.Straight alky doesn't like the cold. Its a diluter of gas when used at the pumps..serves no purpose then to offset the amount of real gas in a given gallon. Consider where its used in performance other then primary fuel...as a cooler (injected water alky mix) to obtain highr boost/timing and or compression with out detonation..because it "slows down" the burn rate of gas( which by the way is what octane does).Which is why it takes twice as much to make he same BTU's as gas.And as Curly said..its very hard on oil, it washes down the cylinders and dilutes the oil. And in pure form is a danger to handle...just watch any F1 race.

Well here is another one of my opinions and I do not know this for a fact only my opinion for what it is worth. There are somethings I know about Alcohol and some I do not.
I believe Alcohol is not as volitale or explosive as gas so in that respect it is safer. Alcohol burns cooler and slower than gas. But it does burn clear or a very light blue flame with no smoke and gas burns bright orange with black smoke so you can see it much easier. Not being able to see the flames can be dangerous.
When you are in a race car at 150 plus MPH there is no good fire.

I come from Subie community and we tested e85 and ethanol in general on turbocharged vehicles. Generally we found that the factory ecu can compensate for up to 33 percent ethanol by volume. When one considers that most unleaded sold is 10% ethanol than you can run a third of your fuel tank full of e85 and ecu will compensate for the extra amount of oxygen in a mix and one can save $3 per fill up in comparison with full tank of premium, plus one would end up with the tank full of 98+ octane fuel. I ran my 300+ hp Sti on 30% mix of e85 and the engine performed flawlessly, it ran smoother, less noisy with great power delivery across the range. Buschur racing is the company that tunes full e85 WRXs and Evos with great success and gets crazy power... And most modern vehicles have fuel lines and pumps suitable for ethanol.

dont know if this info applies exactly to this thread but i also think it has been addressed int his forum a little bit also. e85 causes about a 30% drop in efficiency because your engine has to use more fuel to get the same bang as gas(or iso-octane for our chemist{its mostly iso-octane}). overall in my opinion ethanol is what is killing our mpg over the us. i just want it to go away. and unless your car is setup to run ethanol(e85 to be exact) dont be pumpin a full tank of this into your car. it eats rubber and precaustions need to taken account for this.

I know this is an old thread, but since my HHR decision was partly based on OEM E85 compatability (vs. doing a fuel management modification) I wish to clear up some misunderstandings:

Ethanol boosts octane when mixed with regular gas. E85 is about 109, E100 is 113. It is used to replace MBTE which was used to boost octane before.
Ethanol does increase performance, and keeps your fuel system nice and clean, and burns cleaner at the tailpipe, but to burn at the air mixture of gas (since ethanol has more of its own oxygen) you need more fuel at a given air ratio and this is the only variable that NA cars can mess with currently. This is an increase in overall fuel consumption (but far higher gas mileage as a percentage of the fuel).
It is not an issue with turbo cars as you can simply up the pressure for the same mileage, but for NA applications on non-optimized engines (no variable compression) you burn more E85 than you do gas (and you get more power as a consequence).
On E10 there is no loss in mileage. Driving style makes the difference here.
On E85 there is an approximate 25% drop but if E85 costs 25% less its moot.
In either case your 'gas mileage' goes up because you are using less petroleum. On E85, the HHR goes about 109 miles per gallon of gas.
Because the engine is flex fuel, the engineers designed the 'penalty' to go to the E85 in terms of tank range, if the engine was optimized for the alcohol burn properties, there would be no penalty. You could get more power with less fuel, or just more power (see turbo apps). Those engines aren't here yet.

re: blends - check with your station, not all stations blend, some have 3 tanks in the ground (its a relic of leaded and unleaded fuels, they only sell midgrade because after the high test and cheap stuff, they have a tank in the ground and it would go to waste, some sell diesel others retrofit E85, the rest sell a mid grade - think of how much cheaper gas would be if the refineries only had to spend time refining 2 octanes not 3...)

re: ethanol % - in FL, I don't know about elsewhere, all stations have to have E10 at the minimum. No exceptions on vehicular (marine/aviation is different)

Seth

There are a few stations around here that sell non ethanol gas at a premium price (~$0.10/gallon) . I had read that they bring in marine grade gas (?). I have a tank of it my car now as I wanted to see if my milage improves in the HHR.

Prior to the mandated 10% ethanol, I was getting ~33-35 mpg in the HHR, but since the introduction, my mileage has dropped to ~29-31. I see the same drop in gas mileage with my other cars.

The Algore contingent has forced the 10% ethanol on the masses, which was just another ploy to subsidize the midwest corn farmers by growing corn for fuel, rather than corn for food. My political editorial comment.

There are a few stations around here that sell non ethanol gas at a premium price (~$0.10/gallon) . I had read that they bring in marine grade gas (?). I have a tank of it my car now as I wanted to see if my milage improves in the HHR.

Prior to the mandated 10% ethanol, I was getting ~33-35 mpg in the HHR, but since the introduction, my mileage has dropped to ~29-31. I see the same drop in gas mileage with my other cars.

The Algore contingent has forced the 10% ethanol on the masses, which was just another ploy to subsidize the midwest corn farmers by growing corn for fuel, rather than corn for food. My political editorial comment.

Yes and The Algore contingent has made the price of feed and food go up by doing so !

Not to start a war or anything, but food v. fuel is a debunked myth. They are not diverting any food away by growing animal feed corn and refining it into a fuel and it has not caused any rise in overall food prices.
Because Ethanol competes with gas it has kept fuel and gas prices lower than they would have been had there been no alternative/competition.
The rise in food prices is due to higher demand for food (India/China) and the rise in fuel prices/cost of transport overall.

Seth

P.S. re: algore stuff - not everyone buys into ethanol for its environmental properties. Some like it because its not imported and is a local industry and is renewable.

The recent addition of a new station near my work allowed me to start using ethanol. I noticed a slight negative difference in the performance of the V6 engine in my Ford Escape, however the mpg went up by about 2 miles per gallon.