Does high octane "suck" in the prius?

[windstrings]

Seems there is a bit of confusion about higher gas mileages related to octane levels. What confuses even more is the Ethanol thing.

While higher octane only cost more and does little or nothing to help gas mileage in the prius, the higher number relating to its higher octane only adds confusion.

The addition of alchohol lowers the octane rating and tends to have worse gas mileage.

Seems we have to remember that lower octane due to additives do not always reflect the same results as the same octane rating due to true refinement procedures in the gas production process.

Correct me if I'm wrong but it seems lower octane gases are actually less explosive but the prius is designed for those gases so does as good if not better than higher octane.
Yet the same lower rating due to the addition of alchohol "Ethanol" may not give the same results.

I still get confused trying to find a sure way to tell whether I'm getting Ethanol with a low octane rating verses regular gas?

anyone have any clues?

I just traveled 2000 miles from Washington State to texas and never was able to figure it out.

http://www.wanderings.net/books/is-high-oc...55039852f14b98c
http://www.wanderings.net/books/surprising...7f1245033b65aec

[cwerdna]

<div class='quotetop'>QUOTE(windstrings @ Jun 4 2006, 08:04 PM) [snapback]265798[/snapback]</div>

The addition of alchohol lowers the octane rating and tends to have worse gas mileage.
[/b]

Ethanol is an octane booster and is being phased in to perform that function in place of MTBE. Yes, having ethanol mixed w/the fuel should yield worse gas mileage (it does w/E85 on flex fuel vehicles vs. straight gasoline or E10).

[windstrings]

<div class='quotetop'>QUOTE(cwerdna @ Jun 4 2006, 08:19 PM) [snapback]265800[/snapback]</div>

Ethanol is an octane booster and is being phased in to perform that function in place of MTBE. Yes, having ethanol mixed w/the fuel should yield worse gas mileage (it does w/E85 on flex fuel vehicles vs. straight gasoline or E10).
[/b]

Did you mean flex vehicles with E10? and straight gasoline with E85?

[Jack Straw]

zzz

[V8Cobrakid]

I've tested this theory over the past week. It seems to give the car a tiny boost... but only at higher speeds in a way. It's strange. maybe it was all plecibo effect.

Then again, i was running 100 octane.

[cwerdna]

<div class='quotetop'>QUOTE(windstrings @ Jun 4 2006, 08:49 PM) [snapback]265815[/snapback]</div>

Did you mean flex vehicles with E10? and straight gasoline with E85?
[/b]

I guess I should clarify since my statement was a little confusing.

I meant to say if you run a flex fuel vehicle on E85, it should yield worse mileage than if it ran on E10 or E0 [straight gasoline]. By extension, I'd imagine that a non-flex fuel vehicle should get worse mileage running on E10 compared to running on E0.

[NuShrike]

Lower octane is a good thing by itself because it's heptane that gives us the majority of the reaction. Octane is like the carbon rods in the reactor that slows down the chain reaction to control it.

The rest is as been said, petro diluted with something other than heptane or octane, you have to look at the energy content of it, and ethanol has less per volume.

However, there's this statement from Wikipedia which states:
If gasoline is run at its prefered max power air fuel mixture of 12.5:1, it will release approximately 19,000 BTU of energy, where ethanol run at its prefered max power mixture of 6.5:1 will liberate approximately 24,400 BTU, and Methanol at a 4.5:1 AFR liberates about 27,650 BTU.

My interpretation is gasohol is not being run at the proper compression to extract the maximum possible energy out of ethanol due to the mixing.

[windstrings]

<div class='quotetop'>QUOTE(cwerdna @ Jun 4 2006, 10:16 PM) [snapback]265848[/snapback]</div>

I guess I should clarify since my statement was a little confusing.

I meant to say if you run a flex fuel vehicle on E85, it should yield worse mileage than if it ran on E10 or E0 [straight gasoline]. By extension, I'd imagine that a non-flex fuel vehicle should get worse mileage running on E10 compared to running on E0.
[/b]

I guess thats where my confusion was... the number "10" and the number "85" I assumed was an octane rating since I seem to see alot of 87 etc, but I see its really the percentage of alcohol?

Again, I am miffed at how to tell whether I am getting ethanol or pure gas when pulling up to a station.

[keydiver]

<div class='quotetop'>QUOTE(NuShrike @ Jun 5 2006, 07:13 AM) [snapback]265904[/snapback]</div>

Wikipedia which states:
If gasoline is run at its prefered max power air fuel mixture of 12.5:1, it will release approximately 19,000 BTU of energy, where ethanol run at its prefered max power mixture of 6.5:1 will liberate approximately 24,400 BTU, and Methanol at a 4.5:1 AFR liberates about 27,650 BTU.

My interpretation is gasohol is not being run at the proper compression to extract the maximum possible energy out of ethanol due to the mixing.
[/b]

Those aren't compression ratios, they're Air-to-Fuel ratios. So, what it is saying is that it takes almost twice as much ethanol to extract only 26% more BTU's than gasoline.

[windstrings]

<div class='quotetop'>QUOTE(NuShrike @ Jun 5 2006, 04:13 AM) [snapback]265904[/snapback]</div>

Lower octane is a good thing by itself because it's heptane that gives us the majority of the reaction. Octane is like the carbon rods in the reactor that slows down the chain reaction to control it.

The rest is as been said, petro diluted with something other than heptane or octane, you have to look at the energy content of it, and ethanol has less per volume.

However, there's this statement from Wikipedia which states:
If gasoline is run at its prefered max power air fuel mixture of 12.5:1, it will release approximately 19,000 BTU of energy, where ethanol run at its prefered max power mixture of 6.5:1 will liberate approximately 24,400 BTU, and Methanol at a 4.5:1 AFR liberates about 27,650 BTU.

My interpretation is gasohol is not being run at the proper compression to extract the maximum possible energy out of ethanol due to the mixing.
[/b]

Wow!... very interesting!.... seems alcohol and methanol is actually more explosive or at least has more energy than gasoline if the fuel air mixture is proper for the given product being used as fuel!

Does this mean that ethanol and methanol would actually give "better" gas mileage if the car was tuned and built just for the one product such as methanol or ethanol?