Can 89 Octane gets better gas mileage?

[Insomniak]

Originally posted by: Ronstang

And none of you have any idea how an internal combustion engine really works or know anything about how octane affects them now do you? You guys are simply wrong.

Care to educate us?

Far as I know an internal combustion engine based around fuel injection sprays a set volume of aerosolized gasoline into the chamber which is then compressed by the cylinder before being ignited by the spark plug.

The octane rating largely affects two things: How much hydrocarbon content is in the gasoline (and thus how much energy can be released during combustion), and how much the mixture can be compressed before spontaneously igniting.

Logic would dictate to me that if a fuel injector is spitting a set amount of fuel into a cylinder chamber per combustion, and a cylinder chamber were combusting a set number of times per driveshaft rotation, then barring any change in a driver's shifting style, mileage wouldn't change.

Theoretically, I suppose a higher octane rating releasing more energy on combustion could result in a *technical* increase in the power produced by the engine, but I doubt it would be anything overly significant, if even noticable.


But, I certainly don't claim to be an expert - I do claim to be open minded, so if you know better, out with it. I wanna know.

 

[Ronstang]

Originally posted by: Insane3D
http://auto.howstuffworks.com/question90.htm

All extra octane does is increase the flash point of the gas when it's compressed. 93 octane fuel can be compressed more before it ignites from compression than 87 octane. This is only useful in cars that have a higher compression ratio, and call for it. Putting higher octane fuel in a vehicle that requires 87 is useless and a waste of money.

For example, my Mustang calls for 87 octane from the factory, but I replaced the heads with high performance aluminum ones that raised the compression, so I now need the higher octane stuff to keep from detonating.

Octane has no effect on mileage...

Hope this clears things up...

Edit:

Frosty beat me to it...

It can definitely have an indirect affect on gas mileage. If a car has a knock sensor and you run a lower than recommended grade the computer will cut back on the timing which impacts efficiency and can definitley cost you mileage. My SHO is a perfect example and thus I get better mileage with 93. If an older car that needs premium is "retuned" to use a lower grade of gasoline the same thing happens.

 

[Insane3D]

Generally, it has little to no effect on gas mileage. The octane itself is not affecting the mileage, the car's ECU is in that case. I was speaking to the octane content itself...

 

[Ronstang]

Originally posted by: Insomniak

Originally posted by: Ronstang

And none of you have any idea how an internal combustion engine really works or know anything about how octane affects them now do you? You guys are simply wrong.

Care to educate us?

Far as I know an internal combustion engine based around fuel injection sprays a set volume of aerosolized gasoline into the chamber which is then compressed by the cylinder before being ignited by the spark plug.

The octane rating largely affects two things: How much hydrocarbon content is in the gasoline (and thus how much energy can be released during combustion), and how much the mixture can be compressed before spontaneously igniting.

Logic would dictate to me that if a fuel injector is spitting a set amount of fuel into a cylinder chamber per combustion, and a cylinder chamber were combusting a set number of times per driveshaft rotation, then barring any change in a driver's shifting style, mileage wouldn't change.

Theoretically, I suppose a higher octane rating releasing more energy on combustion could result in a *technical* increase in the power produced by the engine, but I doubt it would be anything overly significant, if even noticable.


But, I certainly don't claim to be an expert - I do claim to be open minded, so if you know better, out with it. I wanna know.

Octane has nothing to do with the "power" contained within a blend of gasoline...it is only a measure of resistance to knock or more simply resistance to burn. All gasoline has the same exact BTU content thus no "extra power" is in a higher grade of gasoline. If an engine needs a higher octane by design then it will run the most efficient when that grade is used...the higher power comes from the engine and it's "tune", not the gasoline. The higher grade simply allows for higher compression and more aggressive spark timing, due to it's resistance to burn, and thus you get more power.

Cars that need a higher octane gas will be less efficient when running lower grades for the most part. On new computer controlled vehicles with knock sensors the computer retards spark timing to compensate for lower octane gas and usually results in less efficiency and lower mileage....plus less power. Older vehicles that have no computer controls will knock if a lower grade of fuel than required is used and that causes engine damage and reduced efficiency and mileage can also occur. If you retune an older engine to run on lower octane then needed in optimal tune you reduce it's efficiency, power, and mileage at the same time.

The other fallacy about octane ratings is that using 93 gives you the most power. It only does if your engine requires it, if it does not you get LESS power. Because higher octane is "resistance to burn" if you do not have high enough compression to warrant the higher octane you engine has a harder time igniting the higher grades of gasoline which can result in incomplete combustion and lower power. I love it when someone brings a Mustang to the dyno that only requires 93 octane yet he stopped by the speed shop and bought some Sunoco 108 only to make less power than normal. Missinformation is a bitch.

 

[IGBT]

..the lower octane gas has more BTU's per gallon then high octane gas. Octane boosters displace total energy but slow combustion to reduce knock.

 

[Insomniak]

Originally posted by: Ronstang

Originally posted by: Insomniak

Originally posted by: Ronstang

And none of you have any idea how an internal combustion engine really works or know anything about how octane affects them now do you? You guys are simply wrong.

Care to educate us?

Far as I know an internal combustion engine based around fuel injection sprays a set volume of aerosolized gasoline into the chamber which is then compressed by the cylinder before being ignited by the spark plug.

The octane rating largely affects two things: How much hydrocarbon content is in the gasoline (and thus how much energy can be released during combustion), and how much the mixture can be compressed before spontaneously igniting.

Logic would dictate to me that if a fuel injector is spitting a set amount of fuel into a cylinder chamber per combustion, and a cylinder chamber were combusting a set number of times per driveshaft rotation, then barring any change in a driver's shifting style, mileage wouldn't change.

Theoretically, I suppose a higher octane rating releasing more energy on combustion could result in a *technical* increase in the power produced by the engine, but I doubt it would be anything overly significant, if even noticable.


But, I certainly don't claim to be an expert - I do claim to be open minded, so if you know better, out with it. I wanna know.

Octane has nothing to do with the "power" contained within a blend of gasoline...it is only a measure of resistance to knock or more simply resistance to burn. All gasoline has the same exact BTU content thus no "extra power" is in a higher grade of gasoline. If an engine needs a higher octane by design then it will run the most efficient when that grade is used...the higher power comes from the engine and it's "tune", not the gasoline. The higher grade simply allows for higher compression and more aggressive spark timing, due to it's resistance to burn, and thus you get more power.

Cars that need a higher octane gas will be less efficient when running lower grades for the most part. On new computer controlled vehicles with knock sensors the computer retards spark timing to compensate for lower octane gas and usually results in less efficiency and lower mileage....plus less power. Older vehicles that have no computer controls will knock if a lower grade of fuel than required is used and that causes engine damage and reduced efficiency and mileage can also occur. If you retune an older engine to run on lower octane then needed in optimal tune you reduce it's efficiency, power, and mileage at the same time.

The other fallacy about octane ratings is that using 93 gives you the most power. It only does if your engine requires it, if it does not you get LESS power. Because higher octane is "resistance to burn" if you do not have high enough compression to warrant the higher octane you engine has a harder time igniting the higher grades of gasoline which can result in incomplete combustion and lower power. I love it when someone brings a Mustang to the dyno that only requires 93 octane yet he stopped by the speed shop and bought some Sunoco 108 only to make less power than normal. Missinformation is a bitch.

Fair 'nuff. Thanks for clearing it up.

Chemically, octane has more energy contained in the bonds that are broken during combustion, I was aware, but your point about the pressure explains it.

 

[Ronstang]

Originally posted by: IGBT
..the lower octane gas has more BTU's per gallon then high octane gas. Octane boosters displace total energy but slow combustion to reduce knock.

Complete BS.

 

[Insane3D]

Originally posted by: Ronstang

The other fallacy about octane ratings is that using 93 gives you the most power. It only does if your engine requires it, if it does not you get LESS power. Because higher octane is "resistance to burn" if you do not have high enough compression to warrant the higher octane you engine has a harder time igniting the higher grades of gasoline which can result in incomplete combustion and lower power. I love it when someone brings a Mustang to the dyno that only requires 93 octane yet he stopped by the speed shop and bought some Sunoco 108 only to make less power than normal. Missinformation is a bitch.

Oh really? All the extra octane would do is give the gas more resistance to igniting solely from compression. Since the spark plug is igniting the gas, I don't see where it would be "harder to ignite" from an artificial source...

The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites.

Also, they could take advantage of the extra octane by cranking the timing...IIRC.

 

[DVad3r]

My car can run on 87 oct but we always fill up with 91. Highway wise we get around around 75 k more give or take as opposed to regular. Better mileage, better for the engine and envioroment. In europe all gas is 91 +

 

[Insomniak]

Originally posted by: Insane3D

Originally posted by: Ronstang

The other fallacy about octane ratings is that using 93 gives you the most power. It only does if your engine requires it, if it does not you get LESS power. Because higher octane is "resistance to burn" if you do not have high enough compression to warrant the higher octane you engine has a harder time igniting the higher grades of gasoline which can result in incomplete combustion and lower power. I love it when someone brings a Mustang to the dyno that only requires 93 octane yet he stopped by the speed shop and bought some Sunoco 108 only to make less power than normal. Missinformation is a bitch.

Oh really? All the extra octane would do is give the gas more resistance to igniting solely from compression. Since the spark plug is igniting the gas, I don't see where it would be "harder to ignite" from an artificial source...

The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites.

Combustibility is affected by pressure as temperature is affected by pressure. Energy of reaction and all that. Lower pressure = lower "temperature" (not really, but similar) = more energy needed to cause a reaction = less combustible no matter what.

Originally posted by: Insane3D
Also, they could take advantage of the extra octane by cranking the timing...IIRC.

Timing? I don't think so....now by cranking compression ratio, yes, theoretically they could, but then you open a whole new can of worms in terms of damaging cylinder heads, bending valves and all kinds of other madness.

It's not something I would really want to muck with.

 

[DAGTA]

Originally posted by: Insane3D
I replaced the heads with high performance aluminum ones that raised the compression

How much does something like that cost? I assume it varies based on the engine, but what did it cost in your case? Did you do it yourself?

 

[Insane3D]

Originally posted by: Insomniak

Originally posted by: Insane3D

Originally posted by: Ronstang

The other fallacy about octane ratings is that using 93 gives you the most power. It only does if your engine requires it, if it does not you get LESS power. Because higher octane is "resistance to burn" if you do not have high enough compression to warrant the higher octane you engine has a harder time igniting the higher grades of gasoline which can result in incomplete combustion and lower power. I love it when someone brings a Mustang to the dyno that only requires 93 octane yet he stopped by the speed shop and bought some Sunoco 108 only to make less power than normal. Missinformation is a bitch.

Oh really? All the extra octane would do is give the gas more resistance to igniting solely from compression. Since the spark plug is igniting the gas, I don't see where it would be "harder to ignite" from an artificial source...

The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites.

Combustibility is affected by pressure as temperature is affected by pressure. Energy of reaction and all that. Lower pressure = lower temperature = more energy needed to cause a reaction = less combustible no matter what.

Why would those variables change simply from using a higher octane rating?

 

[Ronstang]

Originally posted by: Insane3D

Originally posted by: Ronstang

The other fallacy about octane ratings is that using 93 gives you the most power. It only does if your engine requires it, if it does not you get LESS power. Because higher octane is "resistance to burn" if you do not have high enough compression to warrant the higher octane you engine has a harder time igniting the higher grades of gasoline which can result in incomplete combustion and lower power. I love it when someone brings a Mustang to the dyno that only requires 93 octane yet he stopped by the speed shop and bought some Sunoco 108 only to make less power than normal. Missinformation is a bitch.

Oh really? All the extra octane would do is give the gas more resistance to igniting solely from compression. Since the spark plug is igniting the gas, I don't see where it would be "harder to ignite" from an artificial source...

It is true. Resistance to burn is not limited to the diesel effect, it also applies to normal ignition. I confirmed my suspcions about this with an engineer at Shell in charge of gasoline blending and octane. I have seen it when putting race gas in a car that is not tuned to take advantage and it shows on the dyno too. There is no way a "resistance to burn" could discriminate between compression induced ignition or that from a spark plug.

Think of it this way. Gasoline burns optimally when the combustion brings it right to the verge of "auto-ignition" before the spark ignites it. At this point the flame front travels the fastest and the result is a more complete burn. If your car does not have enough compression to warrant 108 octane race gas then when the spark plug fires the ignition has to overcome the octane because the air/fuel charge is not compressed enough to promote optimal flame front and the result is a slower and more incomplete burn in most cases. You end up wth less power for a very expensive fuel.

 

[Insane3D]

Originally posted by: DAGTA

Originally posted by: Insane3D
I replaced the heads with high performance aluminum ones that raised the compression

How much does something like that cost? I assume it varies based on the engine, but what did it cost in your case? Did you do it yourself?

The heads were $1100 a pair, complete with all valvetrain. On a pushrod motor like the 302 (5.0L), it's fairly easy to change them. I had a shop do them simply because they had to take the heads off anyway because they messed up a job they were doing, so I paid $0 labor to have them put them on. I've done heads on 5.0L's before though, and it's fairly simple.

On newer overhead cam motors...it's much more complicated...

 

[Insane3D]

Originally posted by: Ronstang

Originally posted by: Insane3D

Originally posted by: Ronstang

The other fallacy about octane ratings is that using 93 gives you the most power. It only does if your engine requires it, if it does not you get LESS power. Because higher octane is "resistance to burn" if you do not have high enough compression to warrant the higher octane you engine has a harder time igniting the higher grades of gasoline which can result in incomplete combustion and lower power. I love it when someone brings a Mustang to the dyno that only requires 93 octane yet he stopped by the speed shop and bought some Sunoco 108 only to make less power than normal. Missinformation is a bitch.

Oh really? All the extra octane would do is give the gas more resistance to igniting solely from compression. Since the spark plug is igniting the gas, I don't see where it would be "harder to ignite" from an artificial source...

It is true. Resistance to burn is not limited to the diesel effect, it also applies to normal ignition. I confirmed my suspcions about this with an engineer at Shell in charge of gasoline blending and octane. I have seen it when putting race gas in a car that is not tuned to take advantage and it shows on the dyno too. There is no way a "resistance to burn" could discriminate between compression induced ignition or that from a spark plug.

Think of it this way. Gasoline burns optimally when the combustion brings it right to the verge of "auto-ignition" before the spark ignites it. At this point the flame front travels the fastest and the result is a more complete burn. If your car does not have enough compression to warrant 108 octane race gas then when the spark plug fires the ignition has to overcome the octane because the air/fuel charge is not compressed enough to promote optimal flame front and the result is a slower and more incomplete burn in most cases. You end up wth less power for a very expensive fuel.

I guess I'll take your word for it, but everything I've read about octane is it increases resistance to ignition from compression...not from a artificial source like a spark. Also, the extra octane could be utilized somewhat by advancing the timing a good deal could it not?

 

[Ronstang]

Originally posted by: Insane3D

Originally posted by: Ronstang

Originally posted by: Insane3D

Originally posted by: Ronstang

The other fallacy about octane ratings is that using 93 gives you the most power. It only does if your engine requires it, if it does not you get LESS power. Because higher octane is "resistance to burn" if you do not have high enough compression to warrant the higher octane you engine has a harder time igniting the higher grades of gasoline which can result in incomplete combustion and lower power. I love it when someone brings a Mustang to the dyno that only requires 93 octane yet he stopped by the speed shop and bought some Sunoco 108 only to make less power than normal. Missinformation is a bitch.

Oh really? All the extra octane would do is give the gas more resistance to igniting solely from compression. Since the spark plug is igniting the gas, I don't see where it would be "harder to ignite" from an artificial source...

It is true. Resistance to burn is not limited to the diesel effect, it also applies to normal ignition. I confirmed my suspcions about this with an engineer at Shell in charge of gasoline blending and octane. I have seen it when putting race gas in a car that is not tuned to take advantage and it shows on the dyno too. There is no way a "resistance to burn" could discriminate between compression induced ignition or that from a spark plug.

Think of it this way. Gasoline burns optimally when the combustion brings it right to the verge of "auto-ignition" before the spark ignites it. At this point the flame front travels the fastest and the result is a more complete burn. If your car does not have enough compression to warrant 108 octane race gas then when the spark plug fires the ignition has to overcome the octane because the air/fuel charge is not compressed enough to promote optimal flame front and the result is a slower and more incomplete burn in most cases. You end up wth less power for a very expensive fuel.

I guess I'll take your word for it, but everything I've read about octane is it increases resistance to ignition from compression...not from a artificial source like a spark. Also, the extra octane could be utilized somewhat by advancing the timing a good deal could it not?

Yes, higher octane allows for increased ignition timing which if the engine's design supports it will give you more power because the more advance (up to a point) means you are igniting a mixture that is still being compressed so you end up with a more complete burn which unleashes the most power form the mixture.

 

[IonYou]

Higher octane gasoline burns slower. Doesn't matter if it is ignited by spark or not.

 

[Ronstang]

Originally posted by: IonYou
Higher octane gasoline burns slower. Doesn't matter if it is ignited by spark or not.

That is what I said.

 

[IonYou]

Originally posted by: Ronstang

Originally posted by: IonYou
Higher octane gasoline burns slower. Doesn't matter if it is ignited by spark or not.

That is what I said.

I know but I just wanted to back up what you were saying in case Insane3d didn't believe you. He kept insisting that everything he's read about octane is it increases resistance to ignition from compression...not from a artificial source like a spark.

 

[Ronstang]

Originally posted by: IonYou

Originally posted by: Ronstang

Originally posted by: IonYou
Higher octane gasoline burns slower. Doesn't matter if it is ignited by spark or not.

That is what I said.

I know but I just wanted to back up what you were saying in case Insane3d didn't believe you. He kept insisting that everything he's read about octane is it increases resistance to ignition from compression...not from a artificial source like a spark.

Thanks, I know.....I was simply messing with you.

 

[IGBT]

Originally posted by: Ronstang

Originally posted by: IGBT
..the lower octane gas has more BTU's per gallon then high octane gas. Octane boosters displace total energy but slow combustion to reduce knock.

Complete BS.

The Low-Down on High Octane Gasoline

The Low-Down on High Octane Gasoline
From the Federal Trade Commission

Are you tempted to buy a high-octane gasoline for your car because you want to improve its performance? If so, take note: the recommended gasoline for most cars is regular octane. In fact, in most cases, using a higher-octane gasoline than your owner?s manual recommends offers absolutely no benefit. It won?t make your car perform better, go faster, get better mileage or run cleaner. Your best bet: listen to your owner?s manual.

The only time you might need to switch to a higher-octane level is if your car engine knocks when you use the recommended fuel. This happens to a small percentage of cars.

Unless your engine is knocking, buying higher-octane gasoline is a waste of money, too. Premium gas costs 15 to 20 cents per gallon more than regular. That can add up to $100 or more a year in extra costs. Studies indicate that altogether, drivers may be spending hundreds of millions of dollars each year for higher octane gas than they need.

What are octane ratings?
Octane ratings measure a gasoline?s ability to resist engine knock, a rattling or pinging sound that results from premature ignition of the compressed fuel-air mixture in one or more cylinders. Most gas stations offer three octane grades: regular (usually 87 octane), mid-grade (usually 89 octane) and premium (usually 92 or 93). The ratings must be posted on bright yellow stickers on each gasoline pump.

What?s the right octane level for your car?
Check your owner?s manual to determine the right octane level for your car. Regular octane is recommended for most cars. However, some cars with high compression engines, like sports cars and certain luxury cars, need mid-grade or premium gasoline to prevent knock.

How can you tell if you?re using the right octane level?
Listen to your car?s engine. If it doesn?t knock when you use the recommended octane, you?re using the right grade of gasoline.

Will higher octane gasoline clean your engine better?
As a rule, high-octane gasoline does not outperform regular octane in preventing engine deposits from forming, in removing them, or in cleaning your car?s engine. In fact, the U.S. Environmental Protection Agency requires that all octane grades of all brands of gasoline contain engine cleaning detergent additives to protect against the build-up of harmful levels of engine deposits during the expected life of your car.

Should you ever switch to a higher octane gasoline?
A few car engines may knock or ping ? even if you use the recommended octane. If this happens, try switching to the next highest-octane grade. In many cases, switching to the mid-grade or premium-grade gasoline will eliminate the knock. If the knocking or pinging continues after one or two fill-ups, you may need a tune-up or some other repair. After that work is done, go back to the lowest octane grade at which your engine runs without knocking.

Is knocking harmful?
Occasional light knocking or pinging won?t harm your engine, and doesn?t indicate a need for higher octane. But don?t ignore severe knocking. A heavy or persistent knock can lead to engine damage.

Is all "premium" or "regular" gasoline the same?
The octane rating of gasoline marked "premium" or "regular" is not consistent across the country. One state may require a minimum octane rating of 92 for all premium gasoline, while another may allow 90 octane to be called premium. To make sure you know what you?re buying, check the octane rating on the yellow sticker on the gas pump instead of relying on the name "premium" or "regular."

For More Information:

You can file a complaint with the FTC by contacting the Consumer Response Center by phone: toll-free 1-877-FTC-HELP (382-4357); TDD: 202-326-2502; by mail: Consumer Response Center, Federal Trade Commission, 600 Pennsylvania Ave, NW, Washington, DC 20580; or through the Internet, using the online complaint form. Although the Commission cannot resolve individual problems for consumers, it can act against a company if it sees a pattern of possible law violations. The FTC publishes free brochures on many consumer issues. For a complete list of publications, write for Best Sellers, Consumer Response Center, Federal Trade Commission, 600 Pennsylvania Ave, NW, Washington, DC 20580; or call toll-free 1-877-FTC-HELP (382-4357), TDD 202-326-2502.

 

[Ronstang]

Originally posted by: IGBT

Originally posted by: Ronstang

Originally posted by: IGBT
..the lower octane gas has more BTU's per gallon then high octane gas. Octane boosters displace total energy but slow combustion to reduce knock.

Complete BS.

The Low-Down on High Octane Gasoline

The Low-Down on High Octane Gasoline
From the Federal Trade Commission

snip

Ok, where in all that does it say lower octane gas has more BTUs?

 

[IGBT]

Text

I was wondering if you could explain to me why there is less energy in higher octane (a.k.a AKI) gas.

The above statment is indeed true, there is less energy (BTU's per pound) in higher octane fuels than in lower octane fuels. Higher octane fuels (like octane itself) have a benzene type of structure (ring structure), while lower octane fuels have a parafine type of structure (linear chain structure). Now as too why this difference in structure has a bearing on energy content, I believe this is due to the differences in the bonds that hold the individual atoms together. There is just not as much energy stored in the ring structures. So when the molecule is oxidized, its energy state drop is less than in a lower octane molecule.

The idea to remember here is that all matter seeks its lowest energy state. The lower the energy state, the more stable it is. Also, if an atom has an oportunity to reduce its energy state, it will indeed take it (like in the combustion chamber of your engine). So a some what gaurded statement to make is that as the stability increases (high octane), you give up some energy content. This is indeed a simplified explanation.

Now the other question (if I can properly read between the lines), is if it is indeed possible to produce a fuel with a high AKI rating, and the energy content of a lower octane fuel. Yes and no. There is a range of energy content around any particular AKI rating, but there are limits. This range can be increased/decreased with the use of additives, construction, and blending. All this is relative, and I'll leave TEL, nitro, ect. out of the equa- tion. What you should remember is to use the fuel that just meets the re- quirements of the engine- and that's it. This will give you the best perform- ance, and at the lowest price. And for those that claim a peformance increase when they switch to premium, well that is because you found a fuel that better matches what the engine needs. Not because you just put in some sort of wonder fuel (this is where anti-knock sensors confuse the issue).

It should also be noted that mixture quality, spark profile, and combustion chamber design are just some of the factors that affect the octane requirement. This would be another way to get the higher energy/lower octane fuels to work. Ironically, this was the reason for the design of the stratified charge engine in the earlier part of this century (so it could use the unheard of compression ratio of 6 to 1 with the low octane fuels of the time).

> I have been told several times that not only will we not get anything out of the racing fuel (well over 103) found at race tracks, but according to some folks I spoke to at Dinan and other places (I have the chip in my car) we could even loose a bit of performance. Is this because (at least in part), that the fuel ignites so slowly at these very high levels (AKI) ??

Wow. Wise folks. The reason for the loss of performance is because of the points made above. It has less energy per unit volume, you can't take ad- vantage of it (unless you increase your compression ratio), so you are wasting your time (and money). It does have cool factor though. About the best per- formance increase you could hope for, is to convince your competitors of its merits. They fork over huge sums of money to go faster (to of course keep up with you). You go faster (because your not using it), they think it is be- cause of the racing fuel, and it reinforces the illusion. Just don't try it with anyone that reads the list. Oh, and keep it quiet.

 

[IGBT]

The above statment is indeed true, there is less energy (BTU's per pound) in higher octane fuels than in lower octane fuels. Higher octane fuels (like octane itself) have a benzene type of structure (ring structure), while lower octane fuels have a parafine type of structure (linear chain structure). Now as too why this difference in structure has a bearing on energy content, I believe this is due to the differences in the bonds that hold the individual atoms together. There is just not as much energy stored in the ring structures. So when the molecule is oxidized, its energy state drop is less than in a lower octane molecule.

 

[EyeMWing]

Originally posted by: EKKC

Originally posted by: rmrf

Originally posted by: EKKC
i would buy 80 octane gas if it exists and cost less than $3.

gas prices gas prices gas prices gas prices gas prices...

and your car would wear out 10x faster than mine

where do trucks fill up their tanks? i never see 18 wheelers fill up at gas station. they using some low-grade 40-octane diesel thing?


edit: does sunoco or whatever sitll have their ULTRA 94? (remember the joke with the Nintendo 64 then called ULTRA 64?) does it now cost like, 5 bucks a gallon?

Trucks fill up at truck stops. I get my gas at a truck stop. And Diesel doesn't have an octane rating - it's just diesel. A completely different fuel with very little relationship to gasoline.