E15 gasoline

[xBiffx]

You are a ChemE and you don't understand why using 87 vs 91 drops your mileage in a turbo engine? And you blame the "bad" 84 octane gas that uses Ethanol as a booster? Considering all gasoline is blended, and many markets sell 85 octane or lower as regular, it seems weird for a ChemE to be whining about blended Gasoline. Why would ethanol as a booster be any worse than any other booster in 84 octane base stock, except for the lower heating value?

IMHO, "Pure gas" would have Tetraethyllead in it, just like my AvGas. But I realize "pure gas" is a marketing term, as there is no "gasoline" hydrocarbon molecule.

I understand why it drops completely. Not seeing anywhere that I said I didn't get why it was happening.

 

[Zorba]

I understand why it drops completely. Not seeing anywhere that I said I didn't get why it was happening.

Well you were comparing your mileage with 87 E10 and 91 E0, and then saying the difference was solely based on the ethanol content. That implies you don't understand the affects of octane rating in a turbo charged engine.

 

[xBiffx]

Well you were comparing your mileage with 87 E10 and 91 E0, and then saying the difference was solely based on the ethanol content. That implies you don't understand the affects of octane rating in a turbo charged engine.

Guess you looked over where I also looked at 87 E0 too. I also said that it was also things other than ethanol in the case of 87 E10. I said it was starting with shitier gas that then ethanol was added to in order to increase the octane rating.

Look, they used to sell 87 E0, 89 E10, and 91 E0 here in Iowa. The 89 was marketed as "super unleaded" as was actually cheaper (quite a bit) than the 87 "regular unleaded." They made that 89 by taking that same 87 E0 and adding in 10% ethanol giving it an effective octane of 89. It also was generally the same MPG for my truck as the 87 too due to the effects of ethanol (less energy).

About a year ago that all changed. Today the choices are 87 E0, 87 E10, and 91 E0 (and E10 some places). There is no more 89. The way they make the 87 E10 is to take 84 octane fuel and add 10% ethanol. Now, this new fuel shows roughly a ~10% MPG drop in my truck vs. the old 89 blend or the always been there 87 E0. 91 doesn't give me MPG really. It might be 0.2 so its basically nothing. But it does run better, especially when towing/hauling/gunning it from stops.

So please, tell me how starting with shitier gas isn't the problem here? Tell me how the ethanol isn't a problem here? I mean, who needs a degree when you can observe that?

 

[Zorba]

Guess you looked over where I also looked at 87 E0 too. I also said that it was also things other than ethanol in the case of 87 E10. I said it was starting with shitier gas that then ethanol was added to in order to increase the octane rating.

Look, they used to sell 87 E0, 89 E10, and 91 E0 here in Iowa. The 89 was marketed as "super unleaded" as was actually cheaper (quite a bit) than the 87 "regular unleaded." They made that 89 by taking that same 87 E0 and adding in 10% ethanol giving it an effective octane of 89. It also was generally the same MPG for my truck as the 87 too due to the effects of ethanol (less energy).

About a year ago that all changed. Today the choices are 87 E0, 87 E10, and 91 E0 (and E10 some places). There is no more 89. The way they make the 87 E10 is to take 84 octane fuel and add 10% ethanol. Now, this new fuel shows roughly a ~10% MPG drop in my truck vs. the old 89 blend or the always been there 87 E0. 91 doesn't give me MPG really. It might be 0.2 so its basically nothing. But it does run better, especially when towing/hauling/gunning it from stops.

So please, tell me how starting with shitier gas isn't the problem here? Tell me how the ethanol isn't a problem here? I mean, who needs a degree when you can observe that?

Octane has nothing to do with the quality of gas, but its resistance to knock. All gasoline products are made of blends, so there is no such thing as "pure gas 87" and "pure gas 84 plus ethanol," there is a decent chance the fuel off the pipeline is the same gas, and the "pure gas" has a different octane booster in it.

Hell, high quality AvGas starts as a lower octane base stock and then tetraethyllead is added to bring the octane rating up to 100 or 130. But I guess Avgas is cheap low quality gas, because it includes a booster, right?

 

[xBiffx]

Octane has nothing to do with the quality of gas, but its resistance to knock.

Where did I say otherwise?

All gasoline products are made of blends, so there is no such thing as "pure gas 87" and "pure gas 84 plus ethanol," there is a decent chance the fuel off the pipeline is the same gas, and the "pure gas" has a different octane booster in it.

What part of my description didn't you understand that you have to repeat it? I described exactly how blends for here in Iowa are made. Not sure what wasn't clear about that.

Hell, high quality AvGas starts as a lower octane base stock and then tetraethyllead is added to bring the octane rating up to 100 or 130. But I guess Avgas is cheap low quality gas, because it includes a booster, right?

I flew single engine planes for years. I don't need a lesson on AvGas either.

Are you done lecturing? Because nothing you've said contradicts anything I stated. Also, you seem to forget that a profit is to be made. The reason for the change here in Iowa was simply that. By using lower grade, and therefore cheaper gasoline as a starter, they save money. Eliminating 89 octane was for no other reason than dollars.

 

[crashtech]

It does save refiners money if they can use a lower quality gasoline in any given situation, that shouldn't really be debatable.

 

[xBiffx]

It does save refiners money if they can use a lower quality gasoline in any given situation, that shouldn't really be debatable.

That and 84 clearly is a lower grade fuel than 87 or 91. I really don't know where he was going with that.

 

[crashtech]

Some of it is semantic, I am calling gas with higher percentages of high octane reformate "high quality," because it is more expensive and... has higher octane. But overall quality can't be measured just by that.

 

[xBiffx]

Some of it is semantic, I am calling gas with higher percentages of high octane reformate "high quality," because it is more expensive and... has higher octane. But overall quality can't be measured just by that.

True. And when I called the gas "shitier" its because its a lower grade gasoline that produces shitty results in my truck.

Minimum grade, regular, mid-grade, premium...the only difference is usually the octane at a given station. So I am saying regular is definitely "shitier" than premium. Minimum grade is the "shitiest", then.

Now when you compare Top Tier to say the neighborhood convenience store with two pumps, then yes, I'd agree that would have to do with quality and not just octane ratings or fuel grades.

 

[Mark R]

Octane has nothing to do with the quality of gas, but its resistance to knock. All gasoline products are made of blends, so there is no such thing as "pure gas 87" and "pure gas 84 plus ethanol," there is a decent chance the fuel off the pipeline is the same gas, and the "pure gas" has a different octane booster in it.

Generally not these days, since emissions regulations mean that organometallic octane boosters are not used for road gas because they can foul catalytic converters and shorten the life of precious-metal spark plugs.

Higher octane road gas is a different blend with more aromatics and olefins. A high octane blend and a low octane blend can be combined at the pump to produce intermediate octane blends.

There are many factors that contribute to the "quality" of gasoline, not just octane:
vapor pressure
Initial and final boiling points
Oxygen content

Vapor pressure is a difficult one; the gas needs to be volatile enough to evaporate in cold weather, so that carburetted cars can start. However, it must not be so volatile that you can get vapor lock in the carb lines. At the same time, it must be sufficiently low that the vapor doesn't get out of the gas tank when the car is sat in the sun.

Boiling points are related to vapor pressure. They must be low enough that the fuel evaporates in the cylinder and doesn't wash it out, even when cold.

Oxygen (e.g. in ethanol) bulks up the fuel, and screws up the mixture. Too much oxygen and the engine will run lean, unless a closed loop mixture control system has sufficient range to accommodate it.

One of the problems with ethanol is that it raises the vapor pressure of the hydrocarbon content of the fuel, but itself, it has a very low vapor pressure, giving poor vaporisation in cold temperatures and excessive vaporisation in high temps. This can lead to poor vaporisation with carburreted cars. Similarly, high concentrations of ethanol can lean out the mixture during the cold-start program on EFI cars (the cold-start program usually isn't lambda controlled)

 

[crashtech]

Cold start is never in closed loop, it can't be since the sensor has to be hot to work. Modern O2 sensors have heaters to get them going quicker.

 

[Zorba]

Some of it is semantic, I am calling gas with higher percentages of high octane reformate "high quality," because it is more expensive and... has higher octane. But overall quality can't be measured just by that.

Well this. I guess, to me low quality and "shitty" implies something different to me than "slightly less refined and meets all specifications of the end user."

To me shitty gas implies gas with a lot of contaminants or maybe a gas with a lot of heavies that will varnish your fuel system. Or like Mark was saying a gas that won't evaporate or atomize correctly in the cylinder.

When I used to design propane processing equipment, the countries that depended on refined propane definitely had much shitty propane than the US were a lot of it comes from natural gas processing. For example, in Argentina we had a blender mix tank blow up because they had so much Heptane and Octane in the propane (the heavies condensed out in the tank and no one every drained them off). So, in my experience, less refined doesn't necessarily mean shittier.

I am not expert in refining or gasoline, but I guess I am one of those engineers that gets caught up on word usage.