Which would you rather use?

If you had the choice of using 91 octane with no Ethanol or 94 octane with Ethanol? I've been using the 91 because the only 94 I can get is at a "full serve" station and I'd rather not have some kid spill gas on my paint. What does everyone else think?

captinbakslap said:

If you had the choice of using 91 octane with no Ethanol or 94 octane with Ethanol? I've been using the 91 because the only 94 I can get is at a "full serve" station and I'd rather not have some kid spill gas on my paint. What does everyone else think?

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The Si was designed to run on 91. That should be all you need to know.(on a stock tune, of course)

I only use 93 because 91 isn't available in my area. All we have is 87/89/93.

Does the station actually say there's no ethanol? Most gasoline is E10 at most.

REBELXSi said:

The Si was designed to run on 91. That should be all you need to know.(on a stock tune, of course)

I only use 93 because 91 isn't available in my area. All we have is 87/89/93.

Does the station actually say there's no ethanol? Most gasoline is E10 at most.

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I believe Shell 91 is ethanol free

I’ve heard turbo charged engines like the ethanol. Any truth to this?

Ethanol gives a bit of a power boost, while lowering gas mileage - so it depends on what you want. On a recent road trip, I was able to fill up with Premium ethanol-free gas (Shell) at a station in Alabama. I recorded (manually, not the computer) my best gas mileage ever in my hatch - 41.3 mpg @70-75mph on the freeway. Usually the best I can get is 36-38 with Shell Premium here at home (Georgia) which does have ethanol in it.

"Ethanol contains about one-third less energy than gasoline. So, vehicles will typically go 3% to 4% fewer miles per gallon on E10 and 4% to 5% fewer on E15 than on 100% gasoline.3" - https://www.fueleconomy.gov/feg/ethanol.shtml

captinbakslap said:

I believe Shell 91 is ethanol free

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Where did you hear this? If so, that'd be pretty useful. My father can only run ethanol-free in his vintage motorcycles and has to drive more than hour away to buy it.

b4gel said:

Where did you hear this? If so, that'd be pretty useful. My father can only run ethanol-free in his vintage motorcycles and has to drive more than hour away to buy it.

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don't know how reputable this is but.. https://www.quora.com/In-Canada-She...thanol-free-fuel-available-for-sale-in-Canada

Yes ethanol is extremely beneficial to turbo cars. It cools the combustion process chemically which reduces the chance for "knock". Up to e15 is what these cars are perfectly fine to operate on.

The ethanol fuels of today were introduced because they could use less petroleum based additives to increase the octane ratings. Simply because ethanol has such high anti knock properties.

This is a double edged knife. Means fuel companies can start with a lower octane rated base fuel and add "up to 10%" ethanol to meet octane requirements. So 87 starts out around 84-85 octane and relies on the ethanol to get to 87 octane. Part of the reason i try to suggest everyone including base models use better fuel as much as possible.

I have using PetroCanada 94 octane for about 18 months. I find that this gasoline gives more power and the engine was dynotuned with the 94.
For the economy, it's something else....I prefer not to count, it's an SI, you have to pamper it!

If you are looking for pure gas: https://www.pure-gas.org/

As for me, I use whatever grade I know is pure gas. The octane only matters for knock. I know that there is no ethanol in the 91 that is sold at Essos in the Fredericton area so that is what I get. I also get it for my small engine things such as snow blowers and mowers.

And remember, you can test the gas easily yourself. A glass/transparent plastic vessel with a marked measure of water. Add the gas, shake, let settle and if the part that looks like water increased past the mark you made on the vessel, you know you there is ethanol as it will bond to the water and change the height of the water portion in the vessel.

94 with ethanol is much better than 91 without ethanol, especially if tuned.

360glitch said:

94 with ethanol is much better than 91 without ethanol, especially if tuned.

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Agreed I'd rather run 87 with ethanol than 91 with none

PowerPerLiter said:

Agreed I'd rather run 87 with ethanol than 91 with none

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I'm not sure I'd take it that far. It would be interesting to see someone test that out and see which fuel makes knock control happier.

360glitch said:

I'm not sure I'd take it that far. It would be interesting to see someone test that out and see which fuel makes knock control happier.

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Exaggerating but i would like to see that too. Probably would be supplier dependent as to the results.

360glitch said:

It would be interesting to see someone test that out and see which fuel makes knock control happier.

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Another good test idea for Project Farm!