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Old 09-03-2005, 07:42 AM   #1
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Thumbs up The Truth About Gasoline

Here is some info about gasoline


A number of myths about octane have grown over the
years. There is a widespread perception that the greater the
octane the better the performance. However, once enough
octane is supplied to prevent engine knock, there is little, if
any, performance improvement. One exception to this would
be in vehicles equipped with knock sensors. In these vehicles,
if octane is insufficient, the computer will retard the timing to
limit engine knock. If the vehicle is operating in the “knock
limiting” mode (retarded timing), using a higher octane fuel will
allow timing to be advanced, resulting in some level of
performance increase. However, even in these vehicles,
tests have shown that there is no perceptible performance
improvement from using a fuel of higher octane than that
recommended by the vehicle manufacturer.
Another myth is that using a higher octane fuel will result
in improved fuel economy (increased miles per gallon). Octane
is nothing more than a measure of anti-knock quality.
Fuel economy is determined by a number of variables including
the energy content of the fuel. Some premium grades of
fuel may contain components which increase energy content.
In those cases, fuel economy may improve slightly as a result
of higher energy content, but not as a result of the higher
octane. Two fuels of identical octane could have different
energy content due to compositional differences.
Consumers need only use a gasoline meeting the
vehicle manufacturer’s recommended octane levels. If engine
knocking occurs on such fuels and mechanical causes
have been eliminated, then the consumer should purchase
the next highest octane gasoline (above the manufacturer's
recommendation in the owners manual) that will provide
knock-free operation.

go HERE for more info
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Old 09-06-2005, 10:20 AM   #2
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Good point did you ever hear of cars driving on hemp oil?
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Old 09-08-2005, 07:23 PM   #3
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Re: The Truth About Gasoline

Since you brought this up, I think I might add to it on the economic level... gas prices.

First things first, say goodbye to cheap gas because it is gone for good. Just a part of history. Why is that you might ask? Do the middle eastern countries hate us? Probably, but that's no reason to not sell us oil for fair prices. Is our world running out of oil? Hardly. In fact, geologists say that we're not even at the 50% depletion mark yet. There's plenty to go around, but the fact is that the "easy oil" is gone. Whatevers left in the oil reservoirs is becoming increasingly harder to extract. It costs a great deal more money to extract oil really deep within the Earths surface, and they compensate for that cost by... you guessed it... raising prices on the oil. That's one of the major factors in gas prices going higher, but what contributes to it the most is probably the massive economic boost of the two gargantuan nations in our world: China and India. These two countries are building like there's no tomorrow, and due to the size of the nations and their populations of over 1 billion people each, they are consuming mind boggling amounts of oil. Then there's the war in Iraq, which we all know about.

Anyway, fact is, unless we cut down on our oil consumption, gas prices will not go down. Instead they will go up. At this rate, expect it to be in the $4 maybe $5/gallon range very soon.

Theoretically, if all vehicles in the USA were to improve their economy by just 1 mile per gallon, our daily gas consumption would drop down by approx. 1.5 billion gallons. Leave that monster in the garage tonight.
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Old 11-13-2005, 09:48 PM   #4
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Re: The Truth About Gasoline

I've heard that using higher octane is better (on the long run) for the health of your engine. I don't exactly know what 'health' entails, but I've heard that using high octane gas extends the life of the engine. Is there any truth to that?
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Old 11-18-2005, 03:46 AM   #5
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Re: The Truth About Gasoline

Yeah, that can be true. Some gasolines have a higher concentration of cleaners in their Premium grades. Just like Shell. As far as I know, the Premium grade of Shell has that V-Power.
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Old 11-20-2005, 08:43 PM   #6
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I disagree, using higher octane than what the engine needs has no benefits other than making your wallet lighter. I'm not so sure I buy any of these gas gimmicks either, like V-Power ot Techron. There might be something there, but I doubt its worth the extra money. I buy the cheapest gas I can find. IMO, gas is gas.
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Old 11-21-2005, 05:37 AM   #7
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As I know, the octane number only indicate how fast the gas will burned.
While there are another factor about the quality of the gas, energy. How much the energy is released when the fuel is burned.
Using higher octane number than the engine's need is wasting money, but higher energy could do something, but the air/gas ratio must be re-adjust.
Also, the fuel should contain some kind of lubricants (if needed by the engine) for lubricating the exhaust valve.

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Old 11-23-2005, 07:04 PM   #8
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Re: The Truth About Gasoline

Quote:
Originally Posted by andyhs
As I know, the octane number only indicate how fast the gas will burned.
While there are another factor about the quality of the gas, energy. How much the energy is released when the fuel is burned.
Using higher octane number than the engine's need is wasting money, but higher energy could do something, but the air/gas ratio must be re-adjust.
Also, the fuel should contain some kind of lubricants (if needed by the engine) for lubricating the exhaust valve.

Andy

Octane is gasolines resistance to combustion. The higher the octane number the higher the the resistance. The air/fuel mixture in some engines can be ignited prematurely by number of factors. Overheating, advanced timing, high compression, hot carbon contaminates....etc. In a normally functioning engine, the only reason for higher octane fuel is for engines with higher compression. Higher octane fuel only provides a power boost over lower octane fuel when the lower octane fuel is pre-igniting. The "energy" in gasoline is the same over all grades and brands. The lubricant in gasoline (lead) has long been eliminated with the advancement of hardened valve seats.
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Old 11-25-2005, 07:57 PM   #9
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Fact: Although the higher octane in premium fuels may not effect the engine (yea, yea, except in knock) there are certain premium fuels that have excellent additive packeages that can really help an engine. Most of these additives are types of dergents that help clean carbon deposits off valves and combustion surfaces.

Fact: the octane number is reached by the (R+M)/2 method. You may have seen this on the gas pump, if not look sometime. The fuel is tested in a variable compression, single cylinder engine. It is tested in the research method (I believe at 1000 rpm) and and then in the motor method (I believe at 2000 rpm). These numbers are then added and diveded by two (averaged). The numbers come into play by increasing the compression until knock is acheived.

I forget how they derive the number from the compression setting, but the higher the number, the higher the resistance to detonation, not the resistance to combustion. We want the fuel to combust, but not controlled.

I am sure somebody will inform me of the actual rpm numbers, and i am sure somebody else is going to knock the detergent part, go ahead, you're retarded.
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Old 01-04-2006, 07:55 PM   #10
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Re: The Truth About Gasoline

I am not disagreeing with any of you, but why would they sell 100 octane unleaded and 110 leaded race fuels at the Shell station down the street if they only reduce knocking? Please don't say because they know that someone's gonna buy it.
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Old 01-05-2006, 10:56 AM   #11
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He's got a point, I've bought cheap 85 OCT gas and my car worked fine. So wondering the difference I purchased the expensive 91 or 93 OCT gas and i swear my car accelerated faster and got more MPG, i don't know if it was better for the environment or not but i know the performence results.
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Old 01-05-2006, 11:08 AM   #12
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Re: Re: The Truth About Gasoline

Quote:
Originally Posted by SuperStock96
I am not disagreeing with any of you, but why would they sell 100 octane unleaded and 110 leaded race fuels at the Shell station down the street if they only reduce knocking? Please don't say because they know that someone's gonna buy it.
If you look most of those stations with 100 or 108 or even 110 on the street have a pump to can rule. Most wont allow pump to car filling.



The higher octanes such as racing fuels AND aviation fuels are for higher compression engines that require alot of timing.

If you use too much of a high octane that is not recomended for said engine it can screw alot up.


They do help reduce knocking especially with these engines(race) that run so close to detonation.
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Old 01-13-2006, 03:42 AM   #13
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Re: Re: The Truth About Gasoline

Quote:
Originally Posted by Cat Fuzz
The "energy" in gasoline is the same over all grades and brands.
There is more energy available in lower octane fuel. At least that's what I was taught in college. I imagine that has something to do with the torque capabilities of diesel engines.
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Old 02-15-2006, 09:34 AM   #14
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Re: The Truth About Gasoline

They sell those higher octane fuels (100, 110) for two reasons. One, some older cars around the time where lead was popular in gas need them. Two, some idiots will actually buy high octane gas they don't need. Lead was an additive that boosted the octane rating severely. They could take gas that wasn't even 87 octane, add lead, and it'd perform like octane in the 90's. And by perform, I mean resist uncontrolled combustion. Putting 92 octane in an engine that requires 87 octane makes no difference at all. Overall the Octane rating is just a percentage of octane in the gas. Octane is a carbon chain of 8 carbons. Now you'll be like "How can you have more than 100 percent octane?" And I'll answer, go back to high school chemisty. Well, seriously, there is nonane, 9 carbons, decane, 10, and so on up to 12 that is used in gasoline. The longer chains are less common; however, 1 percent of the longer chains (higher than octane) count as more than 1 percent octane, because they resist uncontrolled combustion a lot better.

As for detergents... Ok premium gasolines do have detergents, which can help engine performance, because they also tend to lubricate the upper cylinder, and all the fuel injection/carb parts. BUT, the amount you pay for that in 5 gallons, is enough for you to run to Advance Auto Parts and buy Red Line fuel injector cleaner to do the same thing for 100 gallons. Just get what you're car needs 87 or w/e, and then go and buy you're own additives if you really want them.
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Old 02-15-2006, 02:09 PM   #15
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Re: The Truth About Gasoline

All Right, it seems we have to break this down barney style for you. Once again, octane number is representative of a fuels resistence to detonation. The previous post concerning octane being a hydrocarbon molecule with eight carbons and blah blah blah is true. The purpose of these high octane fuels is generally for racing. In a racing aplication you crank up the ignition advance, boost compression and do lots of other things that would normally destroy an engine without the proper octane fuel.

What is the difference between 89 and 93 octane at the pump? Not much other than a little higher octane and possibly some addative packages, detergents and what not.

Does your car need it? I don't know, if your edecated enough to be able to get on this forum and type something you can probably look it up in your owners manual.
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