There is no lead in E85 and you can still make a turbo spool quicker on that than with leaded race gas as seen from the results of people from this board. Im sure a tuner will chime in and give feedback since they see it more often.

 

I already know that e85 has a greater exhaust gas volume. My question was to compare pump gas to race gas.

 

Woah woah woah!!!!

The science behind the faster spool has zero to do with octane.. has to do with volume and energy content!

Everyone know that on a gallon per gallon basis, E85, Methanol, and even nitro-methane has less energy than gasoline. What everyones WRONG assumption is that is the case when using the fuel, which has zero basis in chemistry. With any fuel you tune to lambda = .085 or greater to produce safe power. At those points e85, methanol, and nitro-methane will produce MORE power due to the added volume of fuel needed to achieve those lambda.

It has nothing to do with "octane" but it is proportional to volume need to achieve the correct lambda.

 

^^^^^^^^^^
Awsome explanation!
So it totally has to do with exhaust gas volume, and nothing else.

 

Figgie's explanation is good, but it's not the chief reason.
The truth is that E85 spools faster for one major reason, and it's not due to fuel volume.

The alcohol in E85 has a drastic cooling effect, the cooling effect literally allows more o2 to enter the cylinder, due to density (heat or lack thereof). The more O2 you have getting into the cylinder the more energy/heat you will have in the exhaust.

The same goes with proper intercooling. With no cooling effect (meth, nitrous, E85, or intercooler) your boost onset will slightly farther to the right on the graph, and it has everything to do with o2 density sitting in your combustion chamber.

Simple trick to test. When you have a HOT motor, ice the hell out of the intake manifold, charge piping and intercooler. Your spool will improve a bit. Although nothing like running E85.

Edit: Also don't confuse being able to add more fuel to help improve spool with energy in the fuel, again it's the reaction thats needed for the release of energy. When you add fuel to try and "fuel splash" for a little bit better spool it's due to the flame front propagation being slowed with a richer mixture, which literally slows the burn down a tiny bit allowing more of the fuel to burn in the exhaust, just like timing only not as drastic. A good way to check this is adding fuel won't actually augment the activation point of your turbo - that very instance where your turbo starts to build boost like a runaway freight train. Increasing O2 density Via a drastic cooling effect (E85) will augment this activation point, because the motor becomes more efficient at this point.

 

I find it difficult to accept that e85-induced charge cooling has more impact on spool than exhaust volume. If this is true, we might expect a significant improvement in spool from other charge cooling methods like spraying water or CO2 on the IC.

I think any spool improvment from e85 is primarily attributable to the 30% additional fuel volume it requires, producing approximately 30% additional exhaust volume too.


Craig

 

It requires 30% additional fuel because it contains 33% less energy by volume.
So that throws the energy argument out the window.

Spraying water on an intercooler isn't the same as increasing o2 density via spraying it 1 inch from a valve. Or direct injection which has a drastic cooling effect on combustion chamber and it contents, but actually increases exhaust gas temps.

In addition If you sprayed 30% more fuel, and it increased exhaust gas volume by 100%, that would mean 100% of your exhaust was fuel. I'm not sure what you're using for a catalyst, most of us are using good old Oxygen and other atmospheric gases augmented by our lady love the turbo.

 

It requires 30% additional fuel because it contains 33% less energy by volume.
So that throws the energy argument out the window...

hmmm... i'm not positive, but i don't think that's correct. approximate energy contents for the two are:

- gasoline 125,000 btu/gal
- ethanol 85,000 btu/gal

that's closer to a 50% difference, not 33%.

i believe that E85 requires approx 30% additional fuel because of the stoichiometric difference - 14.7:1 for gasoline and 9:1 for ethanol.

... Spraying water on an intercooler isn't the same as increasing o2 density via spraying it 1 inch from a valve...

i don't believe i stated that it was. i merely stated that if improvement in turbo responsiveness (spool) when running e85 was primarily attributable to a charge-cooling effect, then i would expect to see similar gains in spool from other means of charge cooling such as IC sprayers.

consider a hypothetical AIT of 100 degrees F running gasoline, and 100 - x degrees running E85... compare turbo responsiveness of each - if there is improvement, and if that improvement is attributable, primarily (as you stated), to e85's charge cooling effect, then any method of charge cooling that effects a similar change in AIT (minus "x" degrees from baseline) should result in a similar improvement in spool.

No?


craig

 

Beau

bad news

it is infact, 100% attributable to volume.

They talk about Nitromethane but it is applicable to methanol, ethanol and e85

http://www.supraforums.com/forum/showthread.php?p=7762222

and the site that they plaguerized that from..

http://www.smokemup.com/tech/fuels.php.

TADA!! It is infact all due to fuel volume





Craig

I have to agree with you that it is not the charge cooling. It can not be. As things stand the issue with charge cooling being the contributor is , You MUST give the fuel time to remove some of that heat from the air to the fuel itself. time is what is missing but in the end, you take the "heat" energy away from the air and you transfer it to the fuel itself (in a perfect 100% efficent transfer of energy which does not exsist) and reach a balance in temprature. But the temprature will never be lower than ambient, unless you put some nitro-methane into methanol to lower the temprature.

 

Spool is not 100% affected by fuel volume (maybe 95%), there is also the affect of exhaust gas temperature that affects how a turbo spools as well. The hotter the exhaust gas temp, the more heat energy in the turbine and the quicker the spool.

 

Here's a graph comparing the dynos of the same car back to back going from 93oct pump gas to E85. No other changes were made, the ProEFI's Flex Fuel sensor analyzes the ethanol content and makes the necessary ignition timing changes. This is a Precision 74GTS turbo, SP400 trans, with an SP 3" Boost Activated Exhaust Cutout.

Dyno in RPM

Dyno in MPH

Reid

 

My spool is about the same even when playing my stereo REALLY loud, so this must prove its not affected by VOLUME.. ;P

haha, sorry I couldn't resisist.

I think most oxygenated fuels will have this affect.. Take Q16 vs C16. I have noticed there is usualy a small im provement in spool time when switching between the 2 fuels. Granted pure fuel volume has a larger affect, but I think when talking about E85, they kinda go hand in hand.

I think mabey we're getting exhaust VOLUME, and HEAT energy mixed up. If more fuel goes in, its gonna mean more gasses come out, mabey its not as hot as gasoline, but the actual volume of matter is greater..

I could be wrong, its late and I've had a long day.

 

My spool is about the same even when playing my stereo REALLY loud, so this must prove its not affected by VOLUME.. ;P

haha, sorry I couldn't resisist.

I think most oxygenated fuels will have this affect.. Take Q16 vs C16. I have noticed there is usualy a small im provement in spool time when switching between the 2 fuels. Granted pure fuel volume has a larger affect, but I think when talking about E85, they kinda go hand in hand.

I think mabey we're getting exhaust VOLUME, and HEAT energy mixed up. If more fuel goes in, its gonna mean more gasses come out, mabey its not as hot as gasoline, but the actual volume of matter is greater..

I could be wrong, its late and I've had a long day.

Well see that smoke'em up site.

the math coincides to what I am saying. E85, methanol etc get more power as you are just adding more fuel to achieve the correct lambda.

As I mentioned before. everyone tunes to lambda/AFR and NOT to the gallon. Just happens that AFR tells you exactly the mass (in non scietific term by using lbs, cursed american measuring system) of the fuel needed to get the lambda = 1. Simple math to calculate the .85 lambda equivalent.

As a matter of fact.

I recall John Reed did infact do this experiment. No changes in ignition timing. Only change was going from Gasoline and then going to E85 and adding the required fuel to not pop the motor.

Let me search for it...

well here is one.

No changes except for fuel

http://www.supraforums.com/forum/showthread.php?t=496645&highlight=E85

 

Craig E85 is indeed 33%ish less energy/volume than Gasoline, not 50%. People use the average of 30% for lambda when its really 33% because it's an easy number to remember. The lambda number coincides with energy/volume somehow, why I don't know it just does. My guess is has to do with the number of molecules that a given volume of air has to react with-within the fuel volume. Just assuming there.

The volume of exhaust gas is due chiefly to the change in O2 density in the combustion chamber. not in chiefly the fuel amount. Fuel weight (the weight of the fuel has nothing to do with energy just density for energy volume) doesn't spool the turbo it's a combination b/t velocity, density(gaseous) and heat (energy-mass).

Here is how you proove it. Test EGT temps with and without E85, you'll need an open element probe not a slow working thermocouple, and you'll log the increase in EGT over that of Gasoline.

Now take Gasoline and richen it up by 30% any increase in spool you get there, will be due to the slow burn you expereience by an over rich condition, fuel will be burning down the throat of the exhaust valve still as they open.

Craig, I'm saying that cooling the air charge will improve spool, however by the time you chill air 130 degrees at an intercooler, it will more than go up another 100 degrees by the time it hits the combustion chamber. But that's not a good example not just for the increase in temperature at the port again, but because it's too difficult to measure what is effecting what (intercooler pressure drop, intercooler piping pressure drop, involvment of intercooler volume etc...

What I'm saying is spraying E85 in a port 1 inch before the valve doesn't give the air much time to heat back up before it goes back into the comubstion chamber. And even though it's physically cooling the combustion chamber waaay more than gasoline would, the increase in O2 density in the chamber actually increases EGTs and therefor exhaust energy. Not due to the weight of the fuel. Mind you I'm saying Chiefly, I'm not saying it has no effect.





Showing just E85 with no other changes Figgie doesn't disprove nor proove what you're saying, it's just a fact we both agree on. The addition of E85 fuel with no other changes alone will improve power. Now power improves due to the cooling effect. GMs E85 capable vehicles when tuned for no timing increase will show an improvement in power just due to cooling, it's an awesome fuel.

Let's take this for an example. Lets say the motor processes 450 CFM worth of air. So without any combustion, we just cram 450 cfm through a motor being turned at XXXX RPM, to eliminate the reaction. And lets measure the wheel speed of the turbo of this air that we'll preheat to 1300 degrees or therebouts.

And if we measure wheel speed of the turbo at I'll pretend 35,000 rpm (including the appropriate restriction on the intake side of the turbo being plumbed back into our machine feeding the air into the motor - in effect putting a load on the turbo)... If we start introducing liquid volume water, gasoline, E85, whatever... It's not going to enhance it enough so that the atomized fluid will now improve the turbine speed another say 10,000 rpm... ... In fact, it might actually slow it, the heavier air while having more density will likely decrease in speed due to being heavier, thus nothing gained, nothing lost.

Increase weight decrease speed, nothing gained nothing lost. The energy is coming from the reaction, and since it's still at lambda there is no more FUEL energy, therefore it is chiefly a cooling effect, more catalyst per volume (Oxygen) to react with the fuel (which is energy, based on chemcial reaction not dead weight of the fuel)

 

Showing just E85 with no other changes Figgie doesn't disprove nor proove what you're saying, it's just a fact we both agree on. The addition of E85 fuel with no other changes alone will improve power. Now power improves due to the cooling effect. GMs E85 capable vehicles when tuned for no timing increase will show an improvement in power just due to cooling, it's an awesome fuel.

Let's take this for an example. Lets say the motor processes 450 CFM worth of air. So without any combustion, we just cram 450 cfm through a motor being turned at XXXX RPM, to eliminate the reaction. And lets measure the wheel speed of the turbo of this air that we'll preheat to 1300 degrees or therebouts.

And if we measure wheel speed of the turbo at I'll pretend 35,000 rpm (including the appropriate restriction on the intake side of the turbo being plumbed back into our machine feeding the air into the motor - in effect putting a load on the turbo)... If we start introducing liquid volume water, gasoline, E85, whatever... It's not going to enhance it enough so that the atomized fluid will now improve the turbine speed another say 10,000 rpm... ... In fact, it might actually slow it, the heavier air while having more density will likely decrease in speed due to being heavier, thus nothing gained, nothing lost.

Increase weight decrease speed, nothing gained nothing lost. The energy is coming from the reaction, and since it's still at lambda there is no more FUEL energy, therefore it is chiefly a cooling effect, more catalyst per volume (Oxygen) to react with the fuel (which is energy, based on chemcial reaction not dead weight of the fuel)

I am not going to argue with you.

do the math. Balance the chemical equations. Once you get that answer, THEN you can argue. The bad part is, once you do get the answer, you will have disproved your own thereom on chemical reaction alone without getting into latent heat of vaporization for each of the fuels.

I'll start you off

Ethanol + O2 => H2O + 2CO2
Methanol + O2 => 2CO2 + 4H2O
Gasoline (use the chemical Octane to simplify) + O2 => ???

Then use the molar heat of each and there is your answer.
Here is a hint...the extra elements do not come for free

 

If you cut through all of that, what you're saying is the spool is due to the WEIGHT of the fuel in the exhaust stream, I just want to be clear you know that is what you're saying.

Lets take fuel pressure shall we? If you have port pressure at 40 psi. And you're fuel pressure is 40 PSI, you're not going to be injecting much fuel into that port due to equal pressure...

I'm not saying the power of the reaction comes from no where figgie, what I'm saying is the cooling effect is[/] the reason for the ability for the added reaction. The cooling effect at the throat of the valves (which is the convergence point) sees a pressure drop. The chief restriction in any engine, this cooling effect is transferred to the cylinder, the low pressure literally makes room for a more dense fuel and air charge.

It's not the dead weight of the fuel it's the increased density of the O2 + fuel (due to a cooling effect causing a pressure drop) which facilitates the added vigor to the reaction.

If your port + fuel was at X PSI, and the cylinder was at the same PSI there won't be any movement of air. All of a sudden, a supercooling effect of E85, due to the loss of energy (heat) that occurs during evaporation of the alcohol drops the pressure from there into the cylinder. If the pressure drops there, while maintaining O2 Mole count, it will allow for even greater cylinder filling...

Here is how I can prove my point.

Direct Injection has the exact effect that I'm talking about, and it uses regular off the shelf fuel.

Direct injection has such a homogenous charge directly sprayed onto a piston top (sometimes two different fuel injection events) that the heat energy lost literally drops the pressure in the combustion chamber before the ignition event. Mind you this is using less fuel as Stoich -due to homogenous atomization (surface area for chemical bonding) - is actually less for direct injection. Stoich for DI is closer to 16.5:1 not 14.7:1

It's a prooven fact that one of the benefits of DI is the result of greater cylinder filling due to the cooling effect (the pressure drop in the cylinder) which allows for greater and more dense air charge.

 

As for DI, You are talking about going from 10000+psi rail pressures to 150 psi -300+ psi in the cylinder.

two words. PHASE CHANGE. Something that does not, will not take place in the port injection.

Prove your point by doing the math.

changed my mind:

I am a man of numbers. I want temp deltas pre and post fueling and also as the air/fuel mixture goes into the cylinder. Pre is simple- AIT sensor. Post fuel, that is the big trick.

 

lol ^^ you basically said what I said, I just simplified it more.

 

so in short... using e85 will make my laggy turbo not as laggy. but still laggy.

 

and what is the WOT afr in ..:1 that is used for e85?

 

That depends on the ethanol blend and amount of boost but you will be somewhere in the 8.0-1 range.

 

It's an undeniable fact that ethanol spools a turbo faster than gas, my initial question that is the theme of this thread is: Is there any spool difference between pump gas and race gas (even if astronomically small)? and why?

 

So, if what your saying is true, then if the car is MAF based we should theoretically see higher airflow values when running on E85 vs 93..

Right?

 

I could be wrong, but I seriously doubt this is the case.