Does E85 make more power than gasoline in flexfuel vehicles?

[M104]

Today something interesting happened on a long drive. Decided to fill up with standard gas, I like to do it once every few months as it appears to be good practice to remove the deposit build up made by E85.

My car has a flexfuel conversion kit which works with an ethanol content sensor. To be clear, all it does is increase how long the injectors are spraying based on the the ethanol content. Fuel trims aren't affected granted there's no issue with the fuel system keeping up with the injectors flowing more fuel.

What happened is that the car felt like it lost some power and torque in the 2000 to 3000 rpm range once filled up with gasoline and I was thinking I had an issue. It also downshifted on a incline on the highway which never happens usually.

I'd like to hear from owners of flexfuel vehicles if this is common or unusual. It makes sense since there should be more spark advance with higher octane fuel but it seems unusual to be able to feel that much difference between regular gasoline and E85.

 

[Chris142]

E85 can make more power than gas with the proper tune

 

[kschachn]

You might find some information in one of these previous threads:

G

Thread 'More power with E85'

Jul 22, 2012

Ford claims that running their FlexFuel 5.0 on E85 boosts output from 360 HP to 375 HP. Now I know why my new 300 feels peppier on E85.

Click here for article.

• G-MAN
• Replies: 23
• Forum: Gas Engine Alternate Fuels

Thread 'Running e85?'

Jan 18, 2021

I've decided to try e85 in my 2018 Taurus. It is flex fuel. What are the pros and cons of doing this? Does it effect engine life, motor oil, etc? I know you'll experience a drop in fuel economy. I have notice the engine seems quiter and smoother.

• mpack88
• Replies: 50
• Forum: Fuels and Fuel Additives: Gasoline and Diesel

A

Thread 'Experimenting with E85'

May 11, 2022

Nothing really radical, but new to me. My Buick Verano T has the flex-fuel capable LHU engine, and I am looking for a way to beat the high cost of gasoline. The 2.0L turbo requires 91 octane minimum, so I have to run premium all the time. If I'm patient enough, I will run two transactions at the pump to get 50/50 89 and 93 octane, which should be pretty close to 91. But most of the time, I'm in a hurry and fill it up with 93, that is running $5.00 per gallon.

Yesterday, I decided to try a half-tank of E85 mixed with the 93 that was in the tank. After 200 miles, the fuel economy seems to...

• A_Harman
• Replies: 159
• Forum: Fuels and Fuel Additives: Gasoline and Diesel

• 

P

Thread 'Fan of E85 - 2 year review'

Aug 4, 2018

So my C300 can run either E85 or premium. I have opted to run mainly E85 as I have a station 1/2 mile from my house and despite the large MPG hit I typically break even on cost versus premium. Now two years and ~25k miles later of mostly E85 (90%) I thin I can throw some change into the pot on E85.

When I first bought the car I ran a good 5-6 tanks of premium (93 octane) typically from Chevron before I learned of E85 on a trip to Tennessee where E85 was cheap cheap cheap. I have a white car and noticed the rear would just load up with soot after 2 tanks of regular gas. After two tanks of...

• pezzy669
• Replies: 13
• Forum: Fuels and Fuel Additives: Gasoline and Diesel

K

Thread 'E85 Experiment'

Oct 20, 2019

Fill up my tank today with E85 for the first time ever.
I'll post later in the week with results of mpg change ðŸ‘

• kstanf150
• Replies: 22
• Forum: Fuels and Fuel Additives: Gasoline and Diesel

S

Thread 'Noob E85 Q'

Jan 13, 2011

Alright, I new here but I've heard of E85 and have thought of running it at times but was always tolded it'll mess my truck up(like running diesel in it) My trucks a 2000 F150 and has no notes saying I can or can not running it. Its the 4.2 v6 engine. Also, could I run this in my 80s-vic and 91 camaro with out problems. I'm not talking running it fuel time but maybe throwing a few gallons in with regular.

I know this has probly been asked a lot before but I just want too make 110 percent sure.

• Sal69
• Replies: 15
• Forum: Gas Engine Alternate Fuels

J

Thread 'So I converted a car to E85 today'

Jun 27, 2015

Hi,
I went ahead and converted a car to E85 today.

Here it is, please excuse the dirty engine:

That's it, bye.















Just kidding. If more cars only came from the factory with the freedom to put whatever the [censored] I want into the tank built in...

So let's get going, shall we? Usually the conversion a pretty straight forward job, because the newer piggyback boxes come with a harness that just clips between the injector and the connector. I wanted to build a harness like that, but the injectors on this car have the notch on the plug offset, and...

• JohnnyMerrill
• Replies: 67
• Forum: Gas Engine Alternate Fuels

 

[racer12306]

Is it be possible that when the sensor sees regular gasoline that it doesn't just revert to previous maps, it goes to a more safe mode?

After a couple tanks of gas, does the issue go away?

Alcohol tends to have more punch than gasoline but needs more fuel to get that punch.

 

[Tdog02]

Owners manual has a lot of useful information about using flex fuel. Miles per gallon will go down a bit, the giddy up will go up. We may all be using more of the flex fuel if the speculation market keeps sticking it to us. The summer travel season is about to be expensive.

 

[melk]

My 2012 Pentastar van is setup for E85 from the factory but I have never run it and have no desire to… but I guess it’s good to know I could in case of emergency.

Then again, I don’t believe I have ever seen E85 at a pump in the Southeast

 

[skyactiv]

I didn’t read

 

[M104]

Thanks kschachn, very interesting read.

 

[bdc101]

E85 is higher octane so the engine will put in more timing as it notices, through the knock sensor, that it can add in timing. This will give you a bit more h-pees.

But the injectors are adding more fuel (more volume of fuel per a given amount of air) so even though the engine may make more horsepower, it uses more fuel than it would using normal gasoline. So you lose some emm-pee-gees or (umm-puh-guhs if that's your preferred vernacular)

 

[TnT_M]

Today something interesting happened on a long drive. Decided to fill up with standard gas, I like to do it once every few months as it appears to be good practice to remove the deposit build up made by E85.

My car has a flexfuel conversion kit which works with an ethanol content sensor. To be clear, all it does is increase how long the injectors are spraying based on the the ethanol content. Fuel trims aren't affected granted there's no issue with the fuel system keeping up with the injectors flowing more fuel.

What happened is that the car felt like it lost some power and torque in the 2000 to 3000 rpm range once filled up with gasoline and I was thinking I had an issue. It also downshifted on a incline on the highway which never happens usually.

I'd like to hear from owners of flexfuel vehicles if this is common or unusual. It makes sense since there should be more spark advance with higher octane fuel but it seems unusual to be able to feel that much difference between regular gasoline and E85.

I'm curious to know what makes you think that E85 leaves deposits? In my experience alcohol (E85) burns much cleaner than gasoline.

As far as your question, E85 in the USA has an octane rating of ~106. If regular gas is 87 octane then you are up 19 points. The ECU will advance timing to compensate for this. When the ECU advances timing, yes it is possible to make more power. Our 2014 T&C is Flexfuel and we have been using E85 on and off for a few years and pretty regularily in the last 8 months. I don't notice too much difference but this thing is a dog compared to my 2012 Ram with a CTD.

Anyway, how it works in my brain.

 

[kschachn]

Bottom line though, considering the fairly significant energy density difference between EtOH and octane if there is more power it must come at the expense of fuel consumption.

 

[RDY4WAR]

E85 has more power potential than E10 or straight gasoline. There's two mechanisms by which this is possible. The first is the heat of combustion where ethanol has a slightly higher BTU/lb of stoich air compared to gasoline. The second is the heat of vaporization where ethanol has a much better cooling factor. The cooling factor has a bigger impact on low to mid rpm torque which likely explains your power loss.

 

[TnT_M]

Bottom line though, considering the fairly significant energy density difference between EtOH and octane if there is more power it must come at the expense of fuel consumption.

we see about 15-20% drop in mileage but prices are 20% or greater so E85 makes economical sense for us.

 

[robbobster]

It can if tuned for it. Sometimes the spec is buried and not widey marketed.

He’s an example, the L83/5.3L GM V8 is tuned for 87 octane and has two output ratings.

But the 6.2, which is tuned for premium fuel, has the same rating for gas and E85.

 

[kschachn]

Tuned is one thing. Increased compression ratio is another.

 

[bdc101]

Bottom line though, considering the fairly significant energy density difference between EtOH and octane if there is more power it must come at the expense of fuel consumption.

The truth is a bit more complicated. Like @RDY4WAR mentioned, the "heat of combustion" is the amount of heat energy that can be obtained from the fuel during combustion. However, he was only partly correct: ethanol has lower heat of combustion than gasoline (on a mass basis or BTU/lb like he said) BUT its stoichiometric ratio means that more fuel must be added to the same amount of air in order for it to be completely combusted. It has a higher heat of combustion at stoichiometric ratio (which will necessarily require more ethanol than it did for gasoline). I hope that doesn't sound like nitpicking because what he meant to say was correct, just the way he stated it wasn't quite right.

To get back to your conclusion though, other fuels have different octanes and different stoichiometric ratios; but the octane (which is just how we define the fuel's resistance to pre-ignition), the stoich ratio, and the heat of combustion are not really related. It's not like if a fuel has higher octane then it automatically has lower heat of combustion or vice versa. It's just that the fuels that are available to burn in typical spark-ignition engines happen to land in certain spots with regard to their chemistry. At this point we are getting into a weird intersection of the sciences of thermodynamics, chemistry, and mechanical engineering which has always been fascinating to me!

 

[RDY4WAR]

I'm not sure how my statement was wrong.

Gasoline = 20,012 BTU/lb ÷ 14.7 AFR = 1,361 BTU/lb of stoich air
Ethanol = 12,506 BTU/lb ÷ 9.0 AFR = 1,390 BTU/lb of stoich air

 

[y_p_w]

Ethanol adds oxygen to the mixture. That’s supposedly one reason why it tends to result in fewer deposits, but I understand that it can increase power equivalent to compressing more atmospheric oxygen.

 

[bdc101]

E85 has more power potential than E10 or straight gasoline. There's two mechanisms by which this is possible. The first is the heat of combustion where ethanol has a slightly higher BTU/lb of stoich air compared to gasoline. The second is the heat of vaporization where ethanol has a much better cooling factor. The cooling factor has a bigger impact on low to mid rpm torque which likely explains your power loss.

I'm not sure how my statement was wrong.

Gasoline = 20,012 BTU/lb ÷ 14.7 AFR = 1,361 BTU/lb of stoich air
Ethanol = 12,506 BTU/lb ÷ 9.0 AFR = 1,390 BTU/lb of stoich air

Like you said the heat of combustion is higher when combusted in stoichiometric ratio (true), but then you stated it was in BTU/lb which (like you showed in your second post) is lower than gasoline, not higher (20k for gas vs 12.5k for ethanol). You were right that when combined at stoichiometric ratio there is more heat released -- but then it's not in units of BTU/lb. It's just in BTUs. (You could have said there is higher heat of combustion of the "charge air mass" which is how they would describe the proper combination of fuel and air in a textbook.)

Ethanol adds oxygen to the mixture. That’s supposedly one reason why it tends to result in fewer deposits, but I understand that it can increase power equivalent to compressing more atmospheric oxygen.

Yes, this is why lots of dragsters like to use alcohol fuels, because there is an oxygen atom within the ethanol molecule, which is why the stoichiometric ratio is so different. You need less oxygen drawn in with atmospheric air to combust the same amount of fuel, because you already have some oxygen to start off with. Methanol has even more oxygen (percent by mass at least) and top fuel guys get into nitro too! You can put just a sh** ton of nitromethane into an engine compared to gasoline.

For further reading on the subject (not so much on top fuel dragsters, but on the theory and math behind internal combustion engines) this book is a textbook on the subject and I think you can find PDFs of it for free: https://www.amazon.com/Internal-Combustion-Engine-Theory-Practice/dp/0262700263

I would have to dig through my library to confirm, but I think this book is the one i was thinking of, which is more aimed at the hobbyist and talks a lot about different fuels: https://www.amazon.com/David-Vizards-Build-Horsepower-Design/dp/1934709174

 

[kschachn]

The truth is a bit more complicated. Like @RDY4WAR mentioned, the "heat of combustion" is the amount of heat energy that can be obtained from the fuel during combustion. However, he was only partly correct: ethanol has lower heat of combustion than gasoline (on a mass basis or BTU/lb like he said) BUT its stoichiometric ratio means that more fuel must be added to the same amount of air in order for it to be completely combusted. It has a higher heat of combustion at stoichiometric ratio (which will necessarily require more ethanol than it did for gasoline). I hope that doesn't sound like nitpicking because what he meant to say was correct, just the way he stated it wasn't quite right.

To get back to your conclusion though, other fuels have different octanes and different stoichiometric ratios; but the octane (which is just how we define the fuel's resistance to pre-ignition), the stoich ratio, and the heat of combustion are not really related. It's not like if a fuel has higher octane then it automatically has lower heat of combustion or vice versa. It's just that the fuels that are available to burn in typical spark-ignition engines happen to land in certain spots with regard to their chemistry. At this point we are getting into a weird intersection of the sciences of thermodynamics, chemistry, and mechanical engineering which has always been fascinating to me!

No, it’s not nitpicking at all. However, some of those things can be compensated for in a “regular” engine, but some things have to be designed in from the beginning. So being able to recover some of those benefits in a street engine is impossible.

And I used the word octane as the main chemical component in gasoline, not the octane rating. Every octane rating has the same energy content depending on the adjuncts used to achieve that rating.