Why does E85 fuel run cooler and make more power? | Fuel Tips

Staff
By Staff Writer
Aug 27, 2021 | Fuel Tips, Sponsored Content | Posted in Features | From the Oct. 2021 issue | Never miss an article

Does E85 run cooler and make more power than traditional gasoline because a website says so? No, it’s because science says so. And while you can, in fact, argue with science, rarely will you win. 

The key player here is the heat of vaporization,” explains Zachary J. Santner, technical specialist at Sunoco. Heat of vaporization, also referred to as enthalpy of vaporization, refers to the amount of energy a liquid absorbs from its surroundings as it changes from a liquid to a gas. 

When things evaporate,” Santner explains, “they actually absorb heat from the surroundings.” As each molecule flies away and leaves the nest, so to speak, it takes some energy with it. As a result, the liquid left behind has a lower average energy.

All liquids have an enthalpy of vaporization. For gasoline, it’s about 150 btu per pound. For ethanol, that figure climbs to 360 btu. (For a real-life example of enthalpy of vaporization at work, notice how rubbing alcohol cools the skin as it evaporates.)

Then add in the fact that an engine requires 30% to 40% more E85 than traditional pump fuel to make combustion–so that’s even more cooling at work. “So anywhere ethanol evaporates, it’s cooling,” Santner adds.

Ethanol can make more power, too, since it contains more oxygen–about 34% oxygen by weight. “More oxygen means more fuel,” Santner explains, “so more horsepower.”

[E85 Ethanol Fuel: How to corn your way to more horsepower]

But this isn’t a free lunch. Not only will the engine drink more E85, but that E85 can be trickier to store because it wants to evaporate and absorb moisture quicker than gasoline. A closed container–and closed vents in a fuel cell, if so equipped–are paramount.

Santner points to a possible suspect for E85’s bad rap regarding its short shelf life: the gasoline component of the mixture. Pump E85 is required to contain only 51% to 83% ethanol, and the gasoline component could well be 83 octane. Sunoco E85-R, he notes, always contains 85% ethanol along with Sunoco race fuel–so about 100 octane for the petroleum part.

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jimgood
jimgood New Reader
8/25/21 10:04 a.m.

Then the question becomes, should you use it in YOUR car?

https://fuelandfriction.com/weekend-warrior/e85-dont-do-it-unless-you-know/

frenchyd
frenchyd UltimaDork
8/25/21 11:49 a.m.

In reply to jimgood :

Just look for the flex fuel emblem on the back of your vehicle.  I'm seeing it more and more often.  Including 2 recent Toyota Prius.
    Or if you're ordering a new vehicle spend the $99  it costs to order it.  My truck saved me that back in lower fuel costs in the first month. 

Colin Wood
Colin Wood Associate Editor
8/25/21 12:00 p.m.

In reply to jimgood :

Yeah, there are definitely applications in which ethanol works best, and we actually touched on that when we upgraded our Corvette Z06 project to run on E85: 

E85 Ethanol Fuel: How to corn your way to more horsepower

As much as I'd love to just start pumping my lowly Honda Fit full of ethanol, that would probably do more harm than good for me.

RJStanford
RJStanford GRM+ Memberand New Reader
8/25/21 1:47 p.m.

I was unable to get the oil temperatures in my first daily/HDPE car down in midsummer - of course, the fact that I was trying to track a 4500lb 470whp AMG E63 in central Texas might have been to blame.  Adding a massive oil cooler didn't do the trick, but installing a standalone E85 flex fuel sensor and kit (basically just waited for a fuel pulse, checked the ethanol content, and kept the injectors open x% longer) dropped the temperatures down just enough.

20% worse fuel economy wasn't a great side effect, but it was a lot better than overheating the oil!

frenchyd
frenchyd UltimaDork
8/25/21 2:33 p.m.
Colin Wood said:

In reply to jimgood :

Yeah, there are definitely applications in which ethanol works best, and we actually touched on that when we upgraded our Corvette Z06 project to run on E85: 

E85 Ethanol Fuel: How to corn your way to more horsepower

As much as I'd love to just start pumping my lowly Honda Fit full of ethanol, that would probably do more harm than good for me.

No you cannot just add the fuel to your gas tank.   You have to have the sensor to  detect what percentage of ethanol you have and adjust the engine accordingly. 
       But if you did have  the sensor telling your car,  you would gain power, Lose about 20% fuel mileage, but still save money. 
    On my truck I get 24 mpg ( V8, 4x4 using 87 octane @ $3.09/9 ) when I use E85 @$2.09/9  I get about 21-22 mpg. ( it's sooooo tempting to feel the extra power )  Save about $20.00 a tank full but lose about 40 miles of range. 

infernosg
infernosg Reader
8/25/21 3:15 p.m.

So my understanding has generally been that E85 is for knock-limited engines and it was a means to increase boost or advance timing. I always thought that if your engine wasn't knock-limited (e.g. naturally aspirated Wankel) then there wouldn't be any benefits. This thread and some quick Google-ing seems to suggest otherwise in that there's still a small power benefit to be had. Thoughts?

frenchyd
frenchyd UltimaDork
8/25/21 3:38 p.m.

In reply to infernosg :

There is a site here where GRM showed that properly jetted any car gains from E85. 
  It's when they tested fuels.  Including Race gas.  Methanol made the biggest improvement. ( but that stuff is toxic )  E 85 next and way below it was racing gas. 
    
     Now 10%  is not earth shaking gain. But more power for less money?  What's wrong with that?  

infernosg
infernosg Reader
8/25/21 3:52 p.m.

In reply to frenchyd :

For modern vehicles that are essentially already prepared, sure. In my specific case to run E85 I'd need: some new fuel lines, higher-flowing injectors, a flex-fuel sensor and maybe a fuel pump to facilitate the extra flow. Then there's setting up the sensor with the ECU and adjusting the tune. I'm not sure if this is difficult or if the sensor takes care of the enrichment based on ethanol content alone. Since I wouldn't likely be advancing timing and don't have forced induction it's not like I would need multiple maps. If the benefit after all that is around 10% I'm okay with leaving it on the table, for now. The lower running temperature is actually more enticing to me if it can reign in oil temperatures like someone else mentioned. I'll have to add this to the list of nice-to-haves eventually just like drive-by-wire throttle control.

malibuguy
malibuguy GRM+ Memberand HalfDork
8/25/21 6:10 p.m.

I splash in a couple gallons of E85 on a mostly full tank on my turbo tercel when I stop by the gas station near the track.  No flex sensor, just overly rich toyota tuning that I take advantage of.  I do not rely on it, but I use it for a touch ofknock insurance due to no intercooler atm

frenchyd
frenchyd UltimaDork
8/25/21 6:54 p.m.
infernosg said:

In reply to frenchyd :

For modern vehicles that are essentially already prepared, sure. In my specific case to run E85 I'd need: some new fuel lines, higher-flowing injectors, a flex-fuel sensor and maybe a fuel pump to facilitate the extra flow. Then there's setting up the sensor with the ECU and adjusting the tune. I'm not sure if this is difficult or if the sensor takes care of the enrichment based on ethanol content alone. Since I wouldn't likely be advancing timing and don't have forced induction it's not like I would need multiple maps. If the benefit after all that is around 10% I'm okay with leaving it on the table, for now. The lower running temperature is actually more enticing to me if it can reign in oil temperatures like someone else mentioned. I'll have to add this to the list of nice-to-haves eventually just like drive-by-wire throttle control.

I'm the last guy to ask regarding these subjects but I've read where the required maps are already on your cars ECM all you need is the sensor and a way to input the feeds 

RichardSIA
RichardSIA Dork
8/25/21 10:21 p.m.

Then add in the fact that an engine requires 30% to 40% more E85 than traditional pump fuel to make combustion

And that it will destroy older fuel systems.
I have nothing compatible with fermented corn syrup.

frenchyd
frenchyd UltimaDork
8/26/21 12:29 a.m.
RichardSIA said:

Then add in the fact that an engine requires 30% to 40% more E85 than traditional pump fuel to make combustion

And that it will destroy older fuel systems.
I have nothing compatible with fermented corn syrup.

Please let me correct your statements.  First if your hoses are rubber you are correct. But you are also breaking the law.  If you buy rubber hose from the hardware store for fuel line in your car you're breaking a law that's been in place now for over 70 years.  Butyl  hose or more modern versions of it has been required for fuel line since before I was born.   
   Second, gas tanks etc will fill up with crude after decades. Alcohol is good at cleaning it out. But sometimes overwhelms has filters and plugs them. Change the filters.  It's a part of regular maintenance.  
Third, some cheaply made replacement products don't comply with all standards. Most people look at price before quality and buy what seems to be the best bargain. Often that's false economy. When your reasonably new parts fail early have you ever heard  the place that sold them say , " yes those parts are cheap junk it's my fault"?    It's easy to blame the failure on something you don't understand or have heard bad things about on the internet.  Forgetting that ethanol has been used in Gasoline since the 1970's.  
   Methanol is also an alcohol but it's commonly made from coal.  It does ruin  carbs and fuel lines. And it's toxic as heck. Drink some you go blind and then you die. But it's not in gasoline.
Ethanol is. Ethanol is in beer Booze and wine. I assume you've drank some of those?  Did you go blind and die?   See,  there are several kinds of alcohol and they aren't all the same. 
     Finally it's possible that you used too much Ethanol.   Alcohol isn't as sensitive as Gasoline is. It will burn still extremely rich. And you'll only lose a little power compared to gasoline if it was that much to rich. 
    Yes you will burn more E85 than straight gasoline. Part of that is because you're making more power. And more power requires more fuel. But yes some extra fuel is required because of the extra oxygen  in the chemical make up of alcohol over gasoline. Because of that it's common to advance the timing to regain some more power and extra power requires more fuel. My truck with Flex Fuel uses about 10% more.  But I save $20.00 a tankful  because it's cheaper.  Figuring the lost fuel mileage I still come out ahead $10.00 per tank. 
  

Cedricn
Cedricn New Reader
8/26/21 3:19 a.m.

15 years ago e85 was the big thing here so every pump had it. Nowdays its getting a little bit harder to come by though. But since it was available everywhere its a very common thing among tuned cars, especially on highly strung turbo engines where hundreds of hp can be gained. All kind of ol E36 M3 boxes has been run with it aswell since it was cheaper to run mostly, most handle it surprisingly well. 

infernosg
infernosg Reader
8/26/21 10:32 a.m.

In reply to frenchyd :

Again, if it's modern vehicle with a modern ECU (looking at you, GM), sure. My car in question is a 35 year-old Mazda RX-7 that's been heavily modified and is using a somewhat out-of-date (~10 years old) aftermarket ECU. The factory ECU is long gone. I poked around the software and I did find that, despite its age, I'm able to define correction tables for fuel, timing and boost based on fuel composition. It looks like it's defaulted to E85 since the correction is +38% across the board for fuel. It also has a "correction scalar," which does exactly what it sounds like; it adjusts the correction based on the actual fuel composition. E.g. if E42 is measured it'll scale the corrections by 50%. Seems pretty straightforward but I'd still need everything I outlined above. I also just realized I don't have any spare 0-5V inputs so I'd need an expansion module. One of these years I'll upgrade to a new ECU with more inputs and DBW control so maybe then I'll play with E85 as well.

frenchyd
frenchyd UltimaDork
8/28/21 10:51 a.m.

In reply to infernosg :

Carbs are so easy to set for E85. And the extra 10% power it represents.  
   On my SU's I pull the jet and either buy or redrill the old jet to flow 20% more fuel.  The needle still works and chances are it's remarkably close. But if the needle needs to be slightly richened in one spot.  Pull  the needle, chuck it in a drill, and in that area of the needle. Using extremely fine grit sand paper dress a little off and put it back together. 
 If your carb just uses Jets before drilling them out check what sort of bevel or radius it has and replicate it when you're done drilling them out. A drill bit doesn't put a nice round hole in the jet like a ream  does, but if it's not flowing enough drill it bigger.  I have a few reams but not enough. Yet it's easy work and the results are the cheapest power you'll gain. 
  Thank you Iowa Farmers. 

frenchyd
frenchyd UltimaDork
8/28/21 11:52 a.m.

In reply to infernosg :ECM's  are magic black boxes to me.  Later with OBD2 at least say "hey dummy,  look at this gidget". And according to internet myths you can hook a laptop to them and have a discussion about how you want things. 
I see it done on movies sometimes  but usually following some typing there is special  effects showing sparks and metal clanging.  

Alfaromeoguy
Alfaromeoguy HalfDork
9/11/21 11:02 p.m.

In reply to frenchyd :

you consume more e85 per mpg than gas.. how did you save money by using more?

Alfaromeoguy
Alfaromeoguy HalfDork
9/11/21 11:12 p.m.

In reply to frenchyd :

richard sia.. it pretty much ignored on the alfa romeo bb, for saying things like this.. he claimed he moved to nevada., because the sate was going to take away his car.. he also stated that the state had taaken away someone he knows auto collection,, we all pressed him for the facts..none ever came.... hes kind of a conspiracy type of person...so let him rant,, he will go away. like on the alfa romeo bb

frenchyd
frenchyd UltimaDork
9/12/21 10:17 a.m.
Alfaromeoguy said:

In reply to frenchyd :

you consume more e85 per mpg than gas.. how did you save money by using more?

Unleaded regular costs $3.09 locally. E85 costs $2.09 So I save a dollar a gallon or so. I refill when I need 20 gallons. So I save $20 per refill. But I use 2 gallons more so I actually net only $10 a refill savings. But it's still a savings of $10.  
 Plus all that extra power!!!!!!  

 

David S. Wallens
David S. Wallens Editorial Director
9/15/21 4:03 p.m.

In reply to frenchyd :

I believe this is the article that you're talking about: The Fuel Truth.

And E85 might not be for everyone. But with our Z06, it lowered those engine temps while delivering more power and also costing less than race fuel, so it was win/win/win. 

Opti
Opti Dork
9/15/21 8:21 p.m.

I ran the ND miata on E85 without a sensor. I did have an E85 tune but the car never knew what fuel was in it. I tested a couple stations a couple times, loaded the e85 tune, and would check it every few months. Never had a problem.

It made a larger difference over the 93 than the 93 tune made over stock.

I haven't seen something e85 hasn't made more power in. Not saying it doesn't exist, just haven't seen it.

I've heard rumblings that e85 isn't long for this world, who knows though.

I'll probably move the 1le to it (with a flex sensor) and the Firechicken to it (without a flex sensor) since I already have the injectors for it.

frenchyd
frenchyd UltimaDork
9/15/21 8:28 p.m.

Yes that's the one.  Thank you for all the hard work that went into doing that.   You did it in the best manner of Consumer reports and believe me that is a high compliment indeed at least as far as I'm concerned.   
  Oh, I hate it when they test something I like and point out the flaws etc.  However as a grown up I understand not everybody has my priorities. I digress. 
     Yes, E85 is a win, win, win., well except at LeMons and Champ Car racing. When you're limited to 24 gallons. 

    Some day I'd like to see part 11 of that series.  Where you test a car with high compression (11.5-1  if you're asking ) or some  boost.   (6-20psi ) 

    Then you could use 93 octane pump as your base, 100 octane racing, 110 octane racing. E85, 100% methanol. 
    With a dash of water?  Windshield washer fluid?  

    
   

z31maniac
z31maniac MegaDork
9/15/21 9:58 p.m.
frenchyd said:

Yes that's the one.  Thank you for all the hard work that went into doing that.   You did it in the best manner of Consumer reports and believe me that is a high compliment indeed at least as far as I'm concerned.   
  Oh, I hate it when they test something I like and point out the flaws etc.  However as a grown up I understand not everybody has my priorities. I digress. 
     Yes, E85 is a win, win, win., well except at LeMons and Champ Car racing. When you're limited to 24 gallons. 

    Some day I'd like to see part 11 of that series.  Where you test a car with high compression (11.5-1  if you're asking ) or some  boost.   (6-20psi ) 

    Then you could use 93 octane pump as your base, 100 octane racing, 110 octane racing. E85, 100% methanol. 
    With a dash of water?  Windshield washer fluid?  

    
   

What do you want tested? Plenty of high comp cars are boosting and using E85. You don't need a GM sensor to run flex fuel with a tune and data logging. High compression, 11:1? That's normal these days. 

These days the BRZ/GR86 run 12.5:1, the Miata runs 13:1. I know I pick on you a lot, but you constantly share information that was relevant in the late 70s-early 80s as though it applies to engines now. I mean bringing up "jetting" when fuel injection has been the standard for nearly 4 decades.

frenchyd
frenchyd UltimaDork
9/16/21 12:09 p.m.

In reply to z31maniac :

I'm sorry I'm old and have a limited knowledge /interest in the latest greatest.  
     I picked the numbers I did because if you have the latest/greatest the tech is already there and all you need to do is hire it done.  
     Most of the people who read this are grass roots kind of guys. They buy what they can afford to lose if it blows up, or is otherwise destroyed in a racing accident. 
     That means cheap and cheap gets you old/ obsolete.    Now you can follow the herd and on a good event wind up in mid herd. Or you can use the Gray matter and find the overlooked underappreciated. And maybe do better. 
 

One final point. Almost all racing cones down to who has the latest greatest?  Autocross SCCA NASA. ETC ETC ETC. 

 The  one exception is vintage racing.  Technology stops.   If you're racing Ford Model A's in a race for gentlemen. You can't show up with a new Mustang. Prewar cars stop in 1939, Trans Am cars stop with the end of factory involvement. So those small blocks are frozen in time.    You aren't made obsolete by the next expensive new thing. 
 When I raced my Black Jack with a tiny budget I could race the same engine/trans etc for decades.  Every other decade I'd put a fresh set of rings in it.   Maybe grind the valves. Still as competitive as ever. 
     Plus you don't need to come up with a great big wad of cash at once.  Find some tired out car. Pick it up for little more than it's scrap value. Then build it according to your budget. With prudence and practice you'll learn how to wring the most out of your car without going broke. 
      

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
9/16/21 12:24 p.m.
RichardSIA said:

Then add in the fact that an engine requires 30% to 40% more E85 than traditional pump fuel to make combustion

And that it will destroy older fuel systems.
I have nothing compatible with fermented corn syrup.

How old?

The fuel system in my '72 Ford was ethanol friendly.  

frenchyd
frenchyd UltimaDork
9/16/21 12:44 p.m.
Pete. (l33t FS) said:
RichardSIA said:

Then add in the fact that an engine requires 30% to 40% more E85 than traditional pump fuel to make combustion

And that it will destroy older fuel systems.
I have nothing compatible with fermented corn syrup.

How old?

The fuel system in my '72 Ford was ethanol friendly.  

My 1953 MGTD can be easily modified to run on E85.  Probably a lot faster than you can hook up a lap top and change what's needed to run E85. ( I'm guessing ) 

z31maniac
z31maniac MegaDork
9/16/21 1:06 p.m.
frenchyd said:

In reply to z31maniac :

I'm sorry I'm old and have a limited knowledge /interest in the latest greatest.  
     I picked the numbers I did because if you have the latest/greatest the tech is already there and all you need to do is hire it done.  
     Most of the people who read this are grass roots kind of guys. They buy what they can afford to lose if it blows up, or is otherwise destroyed in a racing accident. 
     That means cheap and cheap gets you old/ obsolete.    Now you can follow the herd and on a good event wind up in mid herd. Or you can use the Gray matter and find the overlooked underappreciated. And maybe do better. 
      

Totatally understand that. Just keep in mind, 70s Jag V12 knowledge doesn't really translate to relatively modern engines. 

For example, the BRZ/GR86 engine I'm referencing went on sale in late 2012, meaning it was designed and tested for a few years before that.........so it's already nearly a 15-year old engine. 

frenchyd
frenchyd UltimaDork
9/16/21 1:59 p.m.
z31maniac said:
frenchyd said:

In reply to z31maniac :

I'm sorry I'm old and have a limited knowledge /interest in the latest greatest.  
     I picked the numbers I did because if you have the latest/greatest the tech is already there and all you need to do is hire it done.  
     Most of the people who read this are grass roots kind of guys. They buy what they can afford to lose if it blows up, or is otherwise destroyed in a racing accident. 
     That means cheap and cheap gets you old/ obsolete.    Now you can follow the herd and on a good event wind up in mid herd. Or you can use the Gray matter and find the overlooked underappreciated. And maybe do better. 
      

Totatally understand that. Just keep in mind, 70s Jag V12 knowledge doesn't really translate to relatively modern engines. 

For example, the BRZ/GR86 engine I'm referencing went on sale in late 2012, meaning it was designed and tested for a few years before that.........so it's already nearly a 15-year old engine. 

Would you be surprised that the stock compression on a 1981 V12 was 12.5-1?  
 That in 5 liter  form that V12 made 502 horsepower in 1966 designed to run on the 83 octane pump gas the French had? 
   4 valve heads originated with the Peugeot of 1916? Turbo charging originated in the 1930's 

    Why am I so focused on Vintage ?  Because I'm like most of you. I hate to lose to the newest, latest, expensive thing. 
 That's a game none of us want to play. But we like to race, go fast, test our skills.  
 Autocrossing will always be dominated by the newest. So Will SCCA, NASA, and most other racing.  
  Vintage racing freezes technology. You can compete for decades on a tiny budget. Every other decade a fresh set of rings, maybe a valve job?  No more the trick of the week.  Plus no contact racing!!! This Ford Falcon was bought for pocket change.  Raced with the Trans Am boys and does remarkably well. You don't need the last word in vintage racing to have fun. 

z31maniac
z31maniac MegaDork
9/16/21 2:36 p.m.

In reply to frenchyd :

Ugh, the US and Europe use different measurements for Octane. What's 97 in the EU is roughly 91 here. And no, I don't believe any engine was ever designed to run on the US equivalent of 75 octane. You don't even see if that low at high altitude. I can't even find anything that shows it was ever produced. 

My apologies, I'm just making myself look like a jerk. 

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
9/16/21 3:59 p.m.

In reply to z31maniac :

Ladas were designed to run on something like 67 octane.  Maybe 76.  It's a really low number.

 

Model Ts, and anything with a Ricardo designed flathead chamber (used as late as the 50s in the Ford flathead six) were designed to run on basically anything flammable, down to kerosene.

frenchyd
frenchyd UltimaDork
9/16/21 6:12 p.m.

In reply to z31maniac :

No problem. yes American V12's after 1981 had 11.5-1 compression and the rest of the world got 12.5-1 compression. Timing was pulled back from 38degrees to 17 degrees.   So if you use a 100+ octane fuel like E85 you can advance the timing  to normal. Free horsepower!    Lots of it!   
     Before that the compression on V12's was 7.8-1 !!!

      Now add some cams with more than 3/8ths of an inch lift and some duration. The engine might come ALIVE.   The local cam grinder ( who does mainly pulling tractors ) will do that sort of work for modest money.  
     I'm sure there are other cars where a modest amount of work will give a major improvement. Benz, BMW, older Caddy's  Buick?  

 

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