91 vs. 93 Octane
05-25-2006, 12:31 PM
#61
Tech Resident
it's easy to take random quotes out of a description that sound like they support you when read, but when taken in the big picture, they don't. this is how michael moore "reports". he takes quotes that sound like they support him, but when they're factored in the real conversation, they don't.
octane does not equal power, as said in this quote from your paragraph:
this is the truth:
higher octane DOES NOT add to power. lower octane DECREASES POWER. running a lower octane takes away from power because your engine lowers its timing to compensate for the knock. the lowered timing decreases your power. if you go back up to an octane that doesn't make your engine knock, you get the power back. THIS IS WHAT THE ARTICLE IS REFERRING TO! octane DOES NOT add power. it keeps you from having your power taken away. octane is NOT nitrous - it is NOT a power adder. therefore, if your engine is not knocking, the timing is not advanced and you DO NOT GAIN POWER. this is why 93 octane does not add power over 91. your engine isn't decreasing timing by running 91 octane because it doesn't have to. the only way 93 octane will show more power is if the engine is knocking on 91 octane. get it now? you do NOT gain 4% power by switching to 93 octane unless your engine NEEDS 93 OCTANE, most likely like the car they tested in your tainted link. it's not octane making your car run slower when you use less octane, it's timing.
no, i'm saying you don't understand what you just read
octane does not equal power, as said in this quote from your paragraph:
A counter example to this rule is that ethanol blend fuels have a higher octane rating, but carry a lower energy content.
"It might seem odd that fuels with higher octane ratings burn less easily, yet are popularly thought of as more powerful. The misunderstanding is caused by confusing the ability of the fuel to resist compression detonation (pre-ignition = engine knock) as opposed to the ability of the fuel to burn (combustion).
When this occurs, if a fuel with below recommended octane is used, then the engine will knock. Modern engines have anti-knock provisions built into the control systems and this is usually achieved by dynamically de-tuning the engine while under load by increasing the fuel-air mixture and retarding the spark.
Originally Posted by Mr Incredible
So you're saying that switching back from 91 to 93 in the same test/engine will not regain the lost power?
05-25-2006, 01:10 PM
#63
Tech Resident
heh. all octane is is a component in the gasoline with certain combustion properties that helps determine how fast or slow the gasoline is combusted. octane has the affect on combustion that putting water in your alcohol has on getting drunk. the more water you add, the longer it takes you to get drunk...but you'll have less of a hangover afterwards since you won't get dehydrated.
okay okay, bad analogy. the point is, if your fuel's octane was too low, your engine would explode because it would combust so incredibly quickily it would be like a bomb going off. it's just an additive to gasoline that makes it, well, less explosive. it has actually no effect on gasoline's ability to be a fuel.
that's how i LOOK at it. what is octane actually? well, it's an additive to gasoline that tells you how much the fuel can be compressed before it spontaneously ignites. viola.
okay okay, bad analogy. the point is, if your fuel's octane was too low, your engine would explode because it would combust so incredibly quickily it would be like a bomb going off. it's just an additive to gasoline that makes it, well, less explosive. it has actually no effect on gasoline's ability to be a fuel.
that's how i LOOK at it. what is octane actually? well, it's an additive to gasoline that tells you how much the fuel can be compressed before it spontaneously ignites. viola.
05-25-2006, 02:12 PM
#66
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Does altitude have any effect on the different octane levels? I thought I read something that you could get away with a lower rating at a higher altitude. I could just be on crack though...
Some places only offer 89 and 87 out here.
Some places only offer 89 and 87 out here.
05-25-2006, 03:19 PM
#67
Originally Posted by BORN2LOSE
Does altitude have any effect on the different octane levels? I thought I read something that you could get away with a lower rating at a higher altitude. I could just be on crack though...
Some places only offer 89 and 87 out here.
Some places only offer 89 and 87 out here.
goto a gas station high enough in the mountains, and 89 octane might be the best you can buy...
think of it this way... you have 100 molecules of air and your shoving them into a space.. it makes a pressure.. say 50psi... then you take 70 molecules and put them in a space the same size.. now the pressure is only 35psi...
its similar to lowering the compression in your motor.
05-25-2006, 08:12 PM
#68
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It isn't an ego thing, by the way. Just trying to understand more at the end of the day than at the beginning.
I don't wish to argue endlessly about octane, thanks. Get something out of what I brought to the discussion or don't...your choice. I'm not here to win anything.
There's better running and better power when I use 92 than when I use 87. Believe me or don't, I don't care.
I don't wish to argue endlessly about octane, thanks. Get something out of what I brought to the discussion or don't...your choice. I'm not here to win anything.
There's better running and better power when I use 92 than when I use 87. Believe me or don't, I don't care.
05-25-2006, 09:20 PM
#69
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Originally Posted by Mr Incredible
It isn't an ego thing, by the way. Just trying to understand more at the end of the day than at the beginning.
I don't wish to argue endlessly about octane, thanks. Get something out of what I brought to the discussion or don't...your choice. I'm not here to win anything.
There's better running and better power when I use 92 than when I use 87. Believe me or don't, I don't care.
I don't wish to argue endlessly about octane, thanks. Get something out of what I brought to the discussion or don't...your choice. I'm not here to win anything.
There's better running and better power when I use 92 than when I use 87. Believe me or don't, I don't care.
just like stated above several times, thats because our f-bods are tuned and rated to run at that specific rating, and that TIMING IS PULLED OUT WHEN LOWER RATINGS IS USED DUE TO KNOCKING, TO PROTECT YOUR ENGINE
put it this way try taking the knock sensor out of your car and then run 87 sure it will run just the same as your precious 92 but im sure you have many of problems
and as chaco says you will have a major ping on your hands
