Any advantage to ethanol free gas?


TEXAS GT

2006 Twin Turbo
Mark IV Lifetime
Le Mans 2010 Supporter
I have the option in my area to buy ethanol free gas (although it’s only 91 octane) and I use it in my twin turbo ‘06. Is there any advantage to using it in my 2021 NFGT?
 

GTinTN

GT Owner
Jan 17, 2019
169
Brentwood, TN
I have heard this debate several times before and like politics people often have a mindset and defend it vigorously.
For me, I use 93 octane in my 2005 and have no issue using gas with ethanol.
Arguments against ethanol are usually that you do not get as good gas mileage and it is hard on certain engine parts. I have gas powered lawn mowers, weed eaters, blowers and have never experienced any engine problems even when they sit idle for months (during the winter). All my equipment has been used for many years. I also have a boat that is only run April or May through early Novembe haver and use ethanol gas in it and it still runs great after 22 years!
So for me, I do not see a big downside in using gasoline with ethanol.
 

extrap

GT Owner
Mark II Lifetime
Jul 16, 2020
918
Gainesville FL
Mercury Marine has FAQs with quite a few ethanol related questions https://www.mercurymarine.com/en/us/faq/ ... including this one:

Question: What should be done when storing boats with ethanol-blended fuels for extended periods?

Answer: Follow the instructions for normal storage preparation found in the Operation, Maintenance & Warranty manual. When preparing to store a boat for extended periods of two months or more, it is best to completely remove all fuel from the tank. If it is difficult or not possible to remove the fuel, maintaining a full tank of fuel with a fuel stabilizer added to provide fuel stability and corrosion protection is recommended. It is best to add the stabilizer and fuel treatment to the tank at the recommended dosage, run the engine for 10 minutes to allow the system to be cleaned, shut off the fuel valve to interrupt the fuel supply and allow the engine to run until it stops, and top off the tank until it’s full to reduce the amount of exchange with the air that might bring in condensation. Do not cap the tank vent and do not fill with fuel to the point of overflowing. Some extra space should be maintained in the tank to allow for expansion and contraction of the fuel with temperature changes. A partially full tank is not recommended because the void space above the fuel allows air movement that can bring in water through condensation as the air temperature moves up and down. This condensation could potentially become a problem.

Mercury Marine Quickstor can help maintain fuel systems in storage. Quickstor contains oxidation inhibitors to reduce oxidation and gum formation, metal-chelating agents to protect metal components from corrosion, and water-absorbing agents to reduce the presence of free water.
 

jaxgt

GT Owner
Mark IV Lifetime
Jul 12, 2006
2,640
FWIW, I was told modern cars are fine with ethanol in gas. I have def had problems with vintage cars having fuel pumps 'dissolve' or fail, with the 'experts' telling me it was from ethanol. Likewise, my lawn equipment provider recommends I use ethanol free for our Stihl devices.
 

2112

Blue/white 06'
Mark II Lifetime
I have had ethanol eat soft parts in Carburetted boat engines.

Ethanol absorbs water so storing it can be an issue. If Octane is equal I would choose ethanol-free but if 10% ethanol buys me a point or two in octane, and I am using it within 8 weeks or so, I would use it
 
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GT@50

GT Owner
Mark II Lifetime
Dec 14, 2019
430
Issaquah
I have had ethanol eat soft parts in Carbureted boat engines.

Ethanol absorbs water so storing it can be an issue. If Octane is equal I would choose ethanol-free but if 10% ethanol buys me a point or two in octane, and I am using it within 8 weeks or so, I would use it
What's a carburetor?
 

DakotaGT

GT Owner
Mark II Lifetime
Dec 9, 2012
1,486
Sioux Falls, South Dakota
I just rebuilt the Motorcraft 4300 carburetor for my Pantera. Gaskets were all disintegrating, most likely from some ethanol in the fuel at some point. I avoid ethanol (even 5%) like the plague in all of my old cars, but it is generally fine in all of the modern fuel systems. I still make sure all of my fuel tanks that are going into storage for more than a few months are filled with ethanol-free fuel, due to the propensity for ethanol to absorb moisture over time. I do like the octane boost and intake cooling effects from ethanol though, and as long as your injectors and pump are up to the increased fuel capacity needs, ethanol can be terrific stuff...
 

ChipBeck

GT Owner
Staff member
Mark IV Lifetime
Le Mans 2010 Supporter
Feb 13, 2006
5,682
Scottsdale, Arizona
Gentlemen,

I'm a Chevron Dealer in Arizona where all of our fuel is 10% ethanol and the highest octane available here is 91. I HATE ethanol. Modern cars that are driven regularly are fine with E-10. I drive both of my GT's multiple times a month so no problems. BUT.....when E-10 sits for long periods of time it causes problems. I own a dozen motorcycles that don't get ridden much and they are a mess with E-10. If I could avoid ethanol in any vehicle that's not driven often I would.

Chip
 

2112

Blue/white 06'
Mark II Lifetime
What's a carburetor?
That little 1250cfm gold and silver thing on top of my Big block Fords.
.
 

PeteK

GT Owner
Apr 18, 2014
1,624
Kalama, Free part of WA State
Like many of you, I’ve engaged in this debate too many times to count. But based on my personal experience over the past 20 years or so, here goes again:

First, understand that the ethanol % is variable and “up to 10%” (yes, I know, last year a combination of legislation and EPA guidance now allows up to 15%, on pumps so marked—an outright sop to the farm lobby). Over the past 2+ decades, those percentages gradually increased to where practically all available gasoline is at or near that upper limit.

Unlike GTinTN, my experience with a wide range of small engines in lawnmowers, chainsaws, snow blowers, and other power equipment indicates that the higher the % ethanol, the worse problems I had with keeping those carburetted engines running reliably, with a few exceptions. Honda and Stihl engines seemed to digest the stuff, even if it sat for several months, however most other brands gave me headaches, such that I finally gave up on my olde Snapper mower (B&S engine) and bought an electric battery lawnmower.

Fuel injection systems don’t have those problems because they are essentially sealed from outside air, so don’t absorb moisture. Now, the gas in the tank can absorb moisture, so it’s not a good idea to let a car sit for many months without burning down or draining the old fuel and refueling it (time for my usual message of “it’s a car, drive it!”). But if you don’t drive it as often as you should, and can get the real 100% dead dinosaur juice, by all means, do so.

The 100% gas is often called “rec gas” for recreational gas. And thus, it’s often sold at marinas and in places where people use ATVs, snowmobiles, and the like. I try to buy that for my small engines, but it’s not worth the bother or extra $ for me to go out of my way to put in my GT, since I DO drive it often!
 

TEXAS GT

2006 Twin Turbo
Mark IV Lifetime
Le Mans 2010 Supporter
The problem with water absorption and deterioration of fuel systems in older cars (and boats) is well known but my question was in reference to my 2021 GT. I gather there is no downside to the ethanol itself but what about the 2 point octane reduction from 93 to 91? Is the new GT going to adjust to run well with ethanol free 91?
 

dreimer

GT Owner
Mark II Lifetime
Feb 8, 2018
109
Ponte Vedra Beach, FL
In my area of FL, we have lots of ethanol-free gas. In my 2006, I use 93 octane gas that has 10% ethanol; my car has pulley and tune for that, and I drive the car relatively often (3-4K/year). In my 1986 Ferrari 328 GTS I use 89 octane ethanol-free. I don't drive that car as often.

For my 1988 911 NA, I use mostly 93 octane w/ ethanol. I was back and forth 93 w/ ethanol and using 89 ethanol free. My fuel pump started leaking a few years back, but no idea if it was related to ethanol. I drive the 911 a decent amount, including on the track, and my mechanic suggests I use the 93 w/ octane, especially since I drive it often.

I use ethanol free in tractor and small engines (generator, tractor, weed whacker, leaf blower.) I think the ethanol killed my prior leaf blower and weed whacker.

There is a really good app called "Pure Gas" which finds the closest ethanol-free to you, even when you are on the road.

FWIW - the landscape companies are ALWAYS filling their stuff at the ethanol free pumps. Before I found the Pure Gas app, that is how I found ethanol free. Looked for landscaper trucks.
 

Nafod

GT Owner
Mark IV Lifetime
I asked the delivery specialist this question. 91 non ethanol or 93 E-10. he told be the car was tuned for 93 octane. Runs fine on 91 non E.
He stated he would run the 91 non ethanol, due to corrosion issue.
 

06fordgt

GT
Mark II Lifetime
Le Mans 2010 Supporter
Nov 8, 2006
1,897
Toronto Canada
my experience is 91 no ethanol. The other f brand recommends this as well. They suggest , do not run ethanol gas.
 
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Indy GT

Yea, I got one...too
Mark IV Lifetime
Jan 14, 2006
2,512
Greenwood, IN
The problem with water absorption and deterioration of fuel systems in older cars (and boats) is well known but my question was in reference to my 2021 GT. I gather there is no downside to the ethanol itself but what about the 2 point octane reduction from 93 to 91? Is the new GT going to adjust to run well with ethanol free 91?

As has been pointed out and PeterK referenced in his post, this topic is quite polarizing and position entrenched in peoples mind. I agree with all the “issues” brought up in the earlier posts and put special emphasis on Chip’s post being in the retail fuel business (and for a long time). Go search his earlier post on boutique blends in and around the Arizona area. A very worthwhile read. Affinity for water absorption leading to phase separation and fuel system gasket deterioration have been identified as negatives.

On the plus side ethanol does possess a high chemical octane. My old engineering textbook “Internal Combustion Engines and Air Pollution” by Edward Obert lists the values of 107 octane points Research (R) and 89 octane points Motor (M) ratings for ethanol. And since the fuel octane rating shown on the retail pump is a balance of both octane ratings (R+M)/2 adding the high Research octane ethanol to gasoline raises the gasoline pump posted rating.

TEXAS GT’s original thread questions was-

I have the option in my area to buy ethanol free gas (although it’s only 91 octane) and I use it in my twin turbo ‘06. Is there any advantage to using it in my 2021 NFGT?

Let’s answer this question first. Ford has certified our GT’s to run on 91 octane fuel. See the 91+ sticker on the inside of the GT fuel door. I live in a geographical area which has 93 octane available. Many states especially out West do not offer 93 octane, only 91 octane premium. See Chip’s post. So if you want to use 91 octane ethanol free fuel in your GT, that’s fine. From an octane perspective and attending internal combustion chamber damage which could occur with fuel use less than 91 posted octane, the engine does not care. Just give the engine 91+ pump posted octane fuel.

Now from a power perspective, the question is a bit more complex. As I read the above posts, I believe GTinTN is the only one to bring up the issue of “gas mileage”. Now as owners of high dollar vehicles is it likely gas mileage is not high on our ownership priority but ethanol blended fuel DOES lead to lower gas mileage. Why? The amount of chemical energy in a fuel is established by how many BTU’s per unit volume or mass is present. This chemical energy available is what the engine converts into power to move the vehicle. Thus we would like to use a fuel with the highest level of energy available for conversion into work. If the engine efficiency at converting chemical energy into work is say 25% (assume invariant with octane) and I use gasoline with a rating of 20,000 BTU/lbm, I will get 5,000 BTU/lbm of the fuel converted into power or work. But if I use a fuel with a rating of 23,000 BTU/lbm of energy I will get 5,750 BTU/lbm converted to work. Obviously I want to use the highest energy density fuel available.

Pump gasoline is a blend of many different constituents and varies constantly with season or refiner. Thus its energy density varies as well depending what the refiner has on hand (and price of blending additives) to get the required octane which must be delivered to the selling pump. As a generalized assumption for this discussion let’s use the value of 20,556 BTU/lbm which is the listed value Obert uses for “isooctane” and is the reference fuel used to determine the octane rating of sample fuel. Ethanol has an energy density of 12,780 BTU/lbm so you can see alcohol added to gasoline significantly lowers the available energy density of the fuel. If we blend 10% ethanol to the isooctane base fuel, the resulting blend has an energy density of 19,778 BTU/lbm or a 4% reduction in energy available for conversion into work. Thus if you vehicle requires say 5.5 gallons/hour of the 20,556 BTU/lbm fuel to sustain 75 mph on the interstate and you want to go the same speed and you feed the engine lower energy content fuel (19,778 BTU/lbm) you need to supply the engine MORE fuel to sustain 75 mph and thus lowers your miles/gallon.

But there are other considerations as well. Ethanol’s chemical formula is C2H6O which is important because the liquid ethanol brings it own Oxygen to the combustion process. Likely the other constituents in the gasoline blend are chemically made from just Carbon and Hydrogen atoms, no Oxygen. Thus combustion has oxygen from the intake air as well as the ethanol. This can enable a fuel injector to dump more fuel into the combustion process because there is more oxygen in the cylinder charge to burn, and expand the piston to produce power. Most modern vehicles utilize wide-band oxygen sensors in the exhaust flow to sense the amount of residual oxygen in the combustion products. It can then schedule more fuel to the engine to stay within the control limits. This still results in lower mpg overall but does return the engine to given power for a required customer input.

So I use race fuel in my racecar and I have several options from my fuel supplier-

Product Ethanol Content Research Octane Motor Octane BTU/Lbm energy
260GTX 0% 103 93 18,240
260GT 3.7% 105 95 17,900
260GT+ 4.7% 110 98 17,400

Which fuel should I use? (I usually opt for the 0% ethanol)

Hope this helps educate some on the complexity of the topic. :)
 
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TEXAS GT

2006 Twin Turbo
Mark IV Lifetime
Le Mans 2010 Supporter
OMG! That was more than I bargained for but very informative. Very detailed response. Thank you. But you made my mind up when you pointed out the gas cap door approved 91 octane😆
Corn is for eating!
 

B.M.F.

GT Owner
Mark II Lifetime
Jan 29, 2009
1,613
Minnesota
I mix 4 gallons of E85 and 11 gallons of 87 octane gas and it makes 94 octane. My
2016 twin turbo e63 Mercedes wagon pics up 100whp over pump 91. 6mph in the 1/4 lol I also have had my 05 ford gt on E85 with stock gas tank for 11 years now. It’s made 1450whp on pump E85 and ive driven the car from Minnesota to Georgia being able to hit pumps the whole way. Gas mileage sucks but if you want to make gobs of power out of cheap pump gas it’s the only fuel to use..

You may use 30% more fuel to make the same power as you can on c16 race fuel but it’s about 6$ a gallon cheaper to do so.
 
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TEXAS GT

2006 Twin Turbo
Mark IV Lifetime
Le Mans 2010 Supporter
At the risk of showing my ignorance, I’m going to ask Indy GT one more question. Using your race gas chart at the bottom of your post, and using the (R+M)/2 formula, am I right in noticing that as the ethanol content increases the octane rating goes up but the power goes down? I know enough to know that octane ratings are not related to power, only knock resistance but I never thought about the power dropping if ethanol is the additive used to raise the octane rating.
 

B.M.F.

GT Owner
Mark II Lifetime
Jan 29, 2009
1,613
Minnesota
At the risk of showing my ignorance, I’m going to ask Indy GT one more question. Using your race gas chart at the bottom of your post, and using the (R+M)/2 formula, am I right in noticing that as the ethanol content increases the octane rating goes up but the power goes down? I know enough to know that octane ratings are not related to power, only knock resistance but I never thought about the power dropping if ethanol is the additive used to raise the octane rating.
The power does not go down as octane goes up with ethanol. The more octane the more power you can make but with ethanol based fuel the chances of detonation go down versus gas. As the octane goes up so does the amount of fuel needed to make x amount of hp. The more ethanol content the more fuel it takes to make a given hp over gas. e85 is around 28-30 but can be as high as 40% more fuel over gas to make the same amount of power on gasoline race fuel.

For instance, we have made 1700whp with e85 out of the pump. It's only octane rated at 105 octane. It would take a c16 race fuel to make the same power which is 116 octane. e98 which is straight ethanol minus the 2% so you cant drink it. Has to leave plant with 2% gas otherwise its consumable. I have 100% here as i am 11 miles from blender and well connected in ethanol stuff and it takes like corn alcohol lol.

At the end of the day like i said in last post. For hp junkies you can not beat Ethanol for making gobs of cheap hp on a pump gas that is available in a lot of places, given you have the proper fuel system to handle the extra amount of fuel needed over racegas..
 

Indy GT

Yea, I got one...too
Mark IV Lifetime
Jan 14, 2006
2,512
Greenwood, IN
At the risk of showing my ignorance, I’m going to ask Indy GT one more question. Using your race gas chart at the bottom of your post, and using the (R+M)/2 formula, am I right in noticing that as the ethanol content increases the octane rating goes up but the power goes down? I know enough to know that octane ratings are not related to power, only knock resistance but I never thought about the power dropping if ethanol is the additive used to raise the octane rating.
TEXAS GT your question is totally valid and does not show ignorance. You are absolutely correct in understanding the disassociation of octane rating to power. The two metrics are separate and distinct. The oil companies have spent billions of advertising dollars trying to cajole the buying public to believe that if you fill your auto tank with their “premium” fuel (which carries higher profit margins) you will immediately give the customer more power. Unfortunately the buying public is quite gullible and believes the myth.

As I mentioned above, all the “premium recommended” engines offered by OE’s are set up to require 91 octane anti-knock rating. This is the highest baseline premium fuel available nationally. In some states, refiners offer a 93 octane premium which is certainly acceptable to 91 octane required engines. But will the engine deliver more power if you fill up with 93 octane fuel?

In the past with carburetor engines and centrifugal/vacuum advance spark mechanisms the answer was easy. NO power gain was to be realized because the engine spark advance curve (advancing spark as Rpm increased) was mechanical and was only dependent on engine speed. But modern engine controllers have become electronic and much more sophisticated. Most modern engines have knock sensor transducers (singular or multiple) located in strategic locations around the engine. These transducers “listen” for an acoustic signature measured during engine development and found to indicate detrimental engine “knock”. When the knock sensors “hear” engine knock (which is bad) it/they notify the Engine Control Unit (ECU) which starts adjusting engine parameters over which it can vary to silence the knock.

One of the first modifiers is to retard engine spark. This strategy fires the spark plug earlier in the power compression cycle to give the combustion mixture longer time to burn before the cylinder pressure peaks at or near piston Top Dead Center (TDC). You want the air/fuel mixture to “burn” ideally with a constant burn wave front from ignition source to the corners of the combustion charge. You do not want the mixture to “explode” all at once which causes engine knock (detonation). And can result in internal engine damage. In fact higher octane fuels burn at a slower rate than lower octane fuels to give the combustion process more time to burn all the fuel. Other options available to the ECU are to turn on the radiator fans to try to lower coolant temperature and ultimately if the knock sensors are still triggered, the ECU can limit engine power by not allowing the throttle position requested by the driver to some low power point to protect the engine from internal detonation damage. The dreaded “limp-mode” track racers sometimes experience. Especially supercharged engines (hot inlet charge temperatures even with an intercooler) on hot summer days.

So back to the answer. If you feed lower octane fuel (say 87 octane) to a modern engine requiring say 91 octane (OE recommended) the ECU will likely note knock thru the sensors and pull spark and power. Performance will be less but the engine protects itself from the owners poor gasoline choices. The marketing advertised Hp ratings are based on feeding the engine the required octane fuel. Typically an asterisk at the bottom of the page. Now if you feed higher octane fuel (say 93 octane) to an engine OE required to have 91+, you might get a bit more power but maybe not. It all depends on the engine ECU and what spark curves are built into the schedule. Some controllers might allow more advance to the spark if there is no knock indicated, some may just go to a fixed amount of advance determined during engine development to be optimum for a 91 octane fuel. So it depends on the ECU architecture.

Fuels blended with ethanol do increase the overall octane of the fuel. Noted by my chart of available racing fuels from which I can choose. And the (R+M)/2 octane (although not shown in my chart) of the fuels verifies this observation. But as you correctly note octane is increasing yet specific energy (BTU/Lbm) is decreasing. Again it depends on the spark advance logic built into the ECU. Some controllers may increase spark advance until the threshold of knock is sensed and then back off a bit. If an ECU employs this logic, the higher octane ethanol blended fuel may allow the ECU to increase spark advance and increase fuel delivery (bad for mpg but good for power). And thus the engine could deliver slightly more power than advertised because of the higher octane fuel it is using. Just understand the slight increase in possible power is NOT because the fuel has more energy (it has less with ethanol) or higher octane, it is because the ECU has increased spark advance to take advantage of the octane property of the fuel.

Hope this helps answer your question.
 
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