The octane rating ONLY refers to the gasolines resistance to ignition, nothing else.


"Octane rating does not relate to the energy content of the fuel (see heating value). It is only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Where the octane number is raised by blending in ethanol, energy content per volume is reduced.
"

Right from the wiki article...

Also, I HATE ETHANOL.

 

This is my understanding as well,

The higher octane is usually needed for high performance engines due to a higher compression, I believe the reason hi octane is needed for "power tuners" is that it retards the timing so the spark comes as late as possible in the compression stroke, higher pressure can cause pre-detonation or knock requiring the need for a fuel that is less likely to ignite easily....

The performance comes from the engine, not from the gas....

 

correct. unless they use ethanol to increase the octane, displacing gas, which lowers the energy per volume.

isn't ethanol awesome?!

so they plant corn, on huge fields that used to be full of trees, that were cleared by diesel bulldozers, with diesel tractors, then fertilize it with diesel tractors and chemicals and pesticides, then use millions of gallons to water it, grow it, then more diesel tractors to harvest it. Then electricity from coal plants to refine it into Ethanol, where the government subsidizes the whole process to give you a fuel that will ruin your engine and results in less power and MPG. All under the guise of 'saving the world'... CRIMINAL ineptitude.

 

Lol, you know with that kind of thinking that means the Chevy Volt is powered by coal.......

 

+2

It was the main reason why I didn't understand why the previous owner was using 91 in my Burb. In my Twin-Turbo car, I ONLY use 91 or higher.

 

yea, and acid and lead... not to mention, who's paying road tax on the electricity they are using?!

 

Hope you all remember this come 2012.

 

Which is why most of the programmers can just increase the timing a little and pick up a smidgen of hp. Without more air, fuel, an compression ration, it's hard to wring more power from an IC engine.

 

Well mine says run 87 octane and the cost of fuel today thats what I run.

 

My friend owns a race boat, and they tried 92 one day over the 87... WAY less power from the engine... so they switched back to the mfg suggested 87... power came back! it was designed for that fuel.

I will be towing a 6,000 lb boat for a 100 miles this Saturday, so I will fill up w/92. Not for the power, but so if the engine gets hot, it doesn't have to retard the timing, lots of altitude and hills on this trip... by not retarding the timing, I shall get the normal amount of power from it...

My dad's excursion same way; 87 most days, 92 when towing... (he tows 13,000 lbs)

87 makes the engine ping to all hell when towing that much...

then back to 87 for me...

they have E85 in my area too, but I ran the $/mile... Gas won by .03c a mile!