E-85 on stock engine

[quarterliter]

Would running e85 on a basically stock ninja 250 engine give any performance gains?

I used to think this was false, but upon realizing that the stoichiometric ratio for e85 was 9.765:1 vs gasoline's 14.7:1 got me thinking about just how much less energy dense was the 85% ethanol concoction. With max rich power AFR of 12.5 and 6.975 respectively.

I came up with the fact that pure gasoline has between 112,000 and 116,000 btu of energy per gallon. Now e85 has a lower concentration of energy. Somewhere around 82250 btu/gal.

Another thing to think about is the effect that the evaporating ethanol in the fuel will have on cooling intake charge temps, allowing the bike to be tuned even richer.

Is there a mathematical way to calculate the potential gain or loss of e85?

Has anyone had any experience with ethanol performance gains in carbureted engines? Dyno proven results are a plus!

http://www.afdc.energy.gov/fuels/fue...ison_chart.pdf

http://ethanolpro.tripod.com/id213.html

[sharky nrk]

Generally the answer is no. The lower energy density of E85 makes it a poor candidate for an engine like the 250R, high revving, small displacement and carb'd.

High performance forced induction engines can make alot of power because it is quite knock resistant and you can throw alot of fuel at it to compensate.

[quarterliter]

I understand what your saying. But I was more curious if the greater volume of fuel used in the combustion process offset the lower energy density.

[sharky nrk]

Originally Posted by quarterliter

I understand what your saying. But I was more curious if the greater volume of fuel used in the combustion process offset the lower energy density.

That is how it is used to make power in applications where you can get an appropriate amount of oxygen; the 250 is not really easy to do so.

[quarterliter]

What do you mean by appropriate amount of oxygen?

[sharky nrk]

Originally Posted by quarterliter

What do you mean by appropriate amount of oxygen?

In order to net the same energy output (assuming mechanical and thermal losses are the same or changes are negligible) you have to increase the amount of fuel to equivalent gasoline energy levels with the additional appropriate oxygen. The mechanical function of an engine is essentially an air pump. Your not changing the pump by changing the fuel type. Your going to move essentially the same amount of air volume (oxygen). A forced induction engine can make additional use of the fuel by increasing positive pressure and making use of the greater knock resistance. So additional appropriate oxygen.

[Flying]

Originally Posted by quarterliter

What do you mean by appropriate amount of oxygen?

The stoichiometric ratio you mentioned in your first post. We can only practically achieve that with forced induction if we use E85/methanol etc.

[sharky nrk]

I suppose another way of saying this is since the lack of energy density of the E85 is close to proportional to the additional volume needed to compensate, the only real way you make additional power through E85 is to be able to take advantage of its knock resistance through more aggressive tuning options and or a greater volume of oxygen. On the 250R that is not nearly as simple as on a forced induction engine in which you can simply "turn up the boost".

[quarterliter]

Originally Posted by sharky nrk

Your not changing the pump by changing the fuel type. Your going to move essentially the same amount of air volume (oxygen).

I know that the volume of air moved will be the same. But with that same volume of air, more ethanol can be burned than gasoline. That is what I am saying. That the "air pump" does not have to move more air. A greater volume of combustible fuel with a lower energy density can net more horsepower. That is why nitromethane makes more horsepower than gasoline. Because of the much larger quantity of fuel that can be burned with the same amount of air.

[Alex]

But that's the rub. You can't just add more E85 until the amount of power evens up. At some point when the mixture becomes too rich (too much fuel, too little oxygen), the combustion effectiveness goes down, and you lose power and fuel economy. In most non-boosted engines, that point will happen well before you can get back to the same amount of hp regular gas would provide.

[quarterliter]

To burn one part fuel for maximum power, you only need 6.975 parts air for ethanol. Vs one part fuel and 12.5 parts air for gasoline. I only need about half as much air to burn the same amount of fuel when using ethanol.

[sharky nrk]

Originally Posted by quarterliter

To burn one part fuel for maximum power, you only need 6.975 parts air for ethanol. Vs one part fuel and 12.5 parts air for gasoline. I only need about half as much air to burn the same amount of fuel when using ethanol.

Just FYI based on my past research (IIRC) that is a close number for pure ethanol. The effective power ratio for E85 is closer to 9:1

[sharky nrk]

Originally Posted by Alex

But that's the rub. You can't just add more E85 until the amount of power evens up. At some point when the mixture becomes too rich (too much fuel, too little oxygen), the combustion effectiveness goes down, and you lose power and fuel economy. In most non-boosted engines, that point will happen well before you can get back to the same amount of hp regular gas would provide.

exactly

[Alex]

[Alex]

(i meant for that to point to the prior post, but I'm OK with how it turned out. )

[quarterliter]

Originally Posted by Alex

You can't just add more E85 until the amount of power evens up. At some point when the mixture becomes too rich (too much fuel, too little oxygen), the combustion effectiveness goes down, and you lose power and fuel economy. In most non-boosted engines, that point will happen well before you can get back to the same amount of hp regular gas would provide.

I am very aware of the fact that more fuel does not equate to more power, there is a sweet spot. You would shoot for the target AFR that I mentioned above as a start. But in a boosted engine or non boosted engine, that optimum value is the relatively the same. I just don't see how boost is required. I know you can take advantage of the higher octane and cooler charge with timing and boost, but I don't see it as a necessity.

I have no experience tuning e85 engines so the power AFR that I used was from a website that is linked in the original post. Take a look at that chart, I would like to know your opinion on it then.

[quarterliter]

AFR of 8.5:1 for ethanol
AFR of 12.5:1 for gasoline

Use the energy per gallon of fuel divided by the optimum air fuel ratio. This will give you btu per unit of air.

Gasoline:
116,000/12,5= 9280

e85
82000/8.5=9650
(4% greater than gasoline)
This is how I thought of this situation. The idea of using valid AFR's that were agreed upon to make basically maximum power, was to negate the calculations shortcoming of more fuel (lower AFR) more power (in theory).

[sharky nrk]

Originally Posted by quarterliter

AFR of 8.5:1 for ethanol
AFR of 12.5:1 for gasoline

Use the energy per gallon of fuel divided by the optimum air fuel ratio. This will give you btu per unit of air.

Gasoline:
116,000/12,5= 9280

e85
82000/8.5=9650
(4% greater than gasoline)
This is how I thought of this situation. The idea of using valid AFR's that were agreed upon to make basically maximum power, was to negate the calculations shortcoming of more fuel (lower AFR) more power (in theory).

Nothing you have pointed out is theoretically incorrect. Given the proper fuel and ignition control, the ability to replace lost energy density with volume, with E85 you can gain somewhere between 0 - 5% power theoretically.

I have seen the chart you posted before, and while max torque is generated at something close to 35% excess fuel, max thermal efficiency and rapid flame movement is somewhere closer to 15 to 20% excess fuel. These are just general numbers I am familiar with in the Subaru tuning community. These values also require an even greater advance in ignition timing to achieve.

My point was not that you couldn't tune an engine to run on E85 as well you could gasoline, and or make more power; my point was that the setup on a stock ninjette is not friendly to make "worthwhile" if any gains on E85. E85 tends works well in high VE applications with high intake charge temperatures. Things forced induction vehicles have. Also in a forced induction application you have to run richer than the max torque ratio of 12.5, typically down towards 11 to 11.5 to combat against detonation. E85 burns in such a way that you can run a ratio close to max torque production on an aggressive engine.

[DaBlue1]

Have a look at this thread where Racer x fiddled with E85. As a matter of fact there are a few thread about E85 in the 250.

https://www.ninjette.org/forums/show...e85#post620574

[Flying]

Dividing the energy given by a gallon of fuel by the AFR is a specious way of going about it. The chemical bonds in the fuel ultimately provide the energy, not the air.

There is no doubt that burning ethanol is stoichiometrically efficient, ETOH is incredibly light and volatile compared to octane. It has a relatively simple combustion reaction and thus burns very cleanly.
But at the end of the day, a given volume of E85 contains fewer calories/joules/btus than the same volume of E10 because octane dominates ethanol in the number of C-H and C-C bonds per unit volume.

[sharky nrk]

Originally Posted by Flying

The chemical bonds in the fuel ultimately provide the energy, not the air.

There is no doubt that burning ethanol is stoichiometrically efficient, But at the end of the day, a given volume of E85 contains fewer calories/joules/btus

These are the parts that I was trying to convey. The chemistry bits were out of my wheelhouse, I'm an ME not CHEN or PETE lol

[ninjunk]

this thread is awesome, not very often you see such intelligent responses on a forum.

the one thing i haven't seen mentioned yet, and the big reason you LOOSE from ethanol, is that the latent heat of combustion (the amount of energy required to break the chemical bonds and set in motion a combustion reaction) is much much greater for ethanol. It is absorbing more energy out of the engine than gasoline, so even though it contains slightly more BTU's per stoichiometric air mass unit, it is going to result in less net heating of the combustion charge.


If you wanted to take advantage of the greater heat of E-85 you could do so by increasing compression ratio, which would improve your 'Carnot' efficiency, increasing the heat/pressure at the point of combustion, you would also advance your timing to give the slower-burning ethanol more time to begin the reaction. Not to mention the obvious mods to the carb to increase fuel flow 20-40%.

The biggest drawback in a carb'd motor is how quickly it absorbs moisture. Modern cars have pressurized and sealed fuel systems that are pretty good at keeping out air. A gravity fed, atmospheric vented fuel system absorbs water into E-85 so quick that it will go bad in less than a month. 2 weeks is about what i was getting before i had to totally drain and refil the fuel system.

Not to mention that the jetting is all over the map, has to get fatter everywhere and that means new needles, emulsion tubes, pilot jets, and main jets. They probably don't even make fat enough metering components for the carbs on the ninja.

[quarterliter]

Originally Posted by ninjunk

this thread is awesome, not very often you see such intelligent responses on a forum.

the one thing i haven't seen mentioned yet, and the big reason you LOOSE from ethanol, is that the latent heat of combustion (the amount of energy required to break the chemical bonds and set in motion a combustion reaction) is much much greater for ethanol. It is absorbing more energy out of the engine than gasoline, so even though it contains slightly more BTU's per stoichiometric air mass unit, it is going to result in less net heating of the combustion charge.


If you wanted to take advantage of the greater heat of E-85 you could do so by increasing compression ratio, which would improve your 'Carnot' efficiency, increasing the heat/pressure at the point of combustion, you would also advance your timing to give the slower-burning ethanol more time to begin the reaction. Not to mention the obvious mods to the carb to increase fuel flow 20-40%.

Alright I guess I wasn't aware of the increased heat absorption that ethanol possesses. My intentions of this thread may have been misunderstood, I wasn't stating that e-85 on a stock engine was a way to make more power. I saw some evidence that made it seem like it could be possible, and had some ideas behind that. I wanted to see if my theoretical ideas would yield what I had thought. And I now am convinced that e85 is not a way to make power on these engines. On a stock one that is. Thanks everyone for the input!

[Roark]

Originally Posted by quarterliter

Alright I guess I wasn't aware of the increased heat absorption that ethanol possesses. My intentions of this thread may have been misunderstood, I wasn't stating that e-85 on a stock engine was a way to make more power. I saw some evidence that made it seem like it could be possible, and had some ideas behind that. I wanted to see if my theoretical ideas would yield what I had thought. And I now am convinced that e85 is not a way to make power on these engines. On a stock one that is. Thanks everyone for the input!

You were wrong from the beginning..

when you assumed these engines could "make power"

[fast1075]

A carbed engine set up for gasoline, if simply switched to E85 will run too lean. It can work if you can get it rich enough. Not REAL easy with carbs. With fuel injection, you up the pulse rate and duration to match.

I one ran methanol (yes, a different animal) in a 350 Honda. I basically had to remove the idle jets to get enough fuel in it to idle. The mains were HUGE, and I had to add thunder jets to keep it happy. Needless to say fuel economy completely sucked. A whole tank of fuel to get to school and back. It wasn't long before I used up the 55 gallon drum of fuel my dad's buddy gave me, and it was back to slow again. It got real exciting when the carbs iced wide open.