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Originally Posted by Chocaholic

Literally all modern fuel injected cars would do just fine on either. I’d probably go for for the non ethanol fuel more for political reasons than anything.

Right, I figure a modern car that is running fuel system components that aren't affected by the ethanol, is going to be fine with either. I was assuming there'd be a few differences, but that it would ultimately come down to personal preference.

Originally Posted by berettafan

Yep, **** the corn lobby.

That's kind of what I was expecting.

Originally Posted by Bob Kontak

Ethanol pops fast like low octane gasoline but it does pop good, increasing octane.

I would set aside conspiracy theories about how the big oil man is out to get you. If it says 93, it's 93, and will work fine and deliver more power under the right stress conditions than 92, no ethanol.

I thought ethanol burned slow (hence the lower power output and the increased octane leading to less knocking) and was why folks use it on crazy turbos so they don't get knocking.

Originally Posted by red-beard

The 92 Octane fuel without ethanol has more energy.

If it is truly dry, ethanol has 53,956 BTU/gallon while gasoline has 116,090 BTU/gallon. The 93 Octane has 109876.6 BTU/gallon. But all this will do is reduce your mileage by ~5%. The real problem is it attracts moisture, which means up to 10% water, which will make 98267.6 BTU/gallon, or almost 15% less mileage. Reality is it will be somewhere in between.

The 93 Octane fuel CAN produce more power IF the engine has higher compression and the timing is set properly. But between 92 & 93, it won't be much,

The other thing, that pure gas will probably be a LOT more expensive, since it is not made in the giant batches like the E10. So any mileage gain will be lost in the $/gallon. And any performance gain by the 93 Octane will be minimal.

Part of WW2 air war was won by 120 octane fuel

Excellent point about the cost. I think the Katy Buc-ees has a 50 cent premium on their 92 ethanol free vs 93-10%.

Originally Posted by petrolhead611

Here in the UK we pay at least 7USD/Imperial gallon for. 95 octane, and nearly 8USD for 99 octane which some high performance cars demand.

I'm sure that you already know this, but the octane ratings are calculated differently in the UK vs the US. So what I can get here (premium) is 92 or 93, which would, I think be roughly equivalent to your 98 or 99. In the example in my original post, I think the last time I was at the gas station with the two different gases, the price was ~$2.75 for 93 w/10% ethanol and ~3.25 for 92 w/0% ethanol.

https://www.economist.com/babbage/2012/09/17/difference-engine-who-needs-premium

In the fuel test, the compression is raised until the engine begins to “knock”—ie, the fuel in the cylinder ceases to burn smoothly and instead detonates before it can be ignited by the spark plug. The cylinder pressure at which this occurs is then compared with that achieved while the engine is running on a reference fuel (a mixture of iso-octane and n-heptane). The ratio of the two pressures provides the RON of the fuel in question.

A better way of measuring a fuel’s ability to resist knocking under load is the so-called motor octane number (MON) test. This uses a similar test engine, but with a preheated fuel mixture, a higher engine speed and variable ignition timing. Because it uses more real-world conditions, the MON rating is typically eight to ten points lower than the equivalent RON figure.

In Europe, the octane rating on the pump is simply the RON figure. America, by contrast, uses the average of the RON and the MON figures, called the AKI (anti-knock index). Thus, 97 octane “super unleaded” in Britain is roughly equivalent to 91 octane premium in the United States.