Gasoline Question

**SilentTrouble** · 12-24-2011, 01:10 PM

My local station sells 90 octane "alcohol free" gasoline here... There is also a station that sells 93 octane and lower normal gas as I would call it with 10% or something alcohol.

I know from exp that alcohol free gas tends to lend me better mileage in my daily driver. How about performance wise in my TA. Im not running excessive CR -- that I know of. Is there any benefit to no alcohol or gas with a 10% blend?

**cpop98ws6** · 12-24-2011, 01:18 PM

I think what you mean is ethanol not alcohol. The ethanol will hurt your gas milage very little and its not good for rubber fuel lines or gaskets. On the other hand its a little better for peformance. But with as little as 10% in the gas you wont see much of a difference. I would go with the 93 regular gas if it is available .

**SilentTrouble** · 12-24-2011, 05:17 PM

Lol I know its ethanol....even if it is a hydroxy C-OH functional group alcohol. The sign just blatantly says "NO ALCOHOL" which i thought was humorous. I know its bad for old cars. Mine being a 2001 TA I figured the rubber like compounds they use in newer stuff is designed to withstand the abuse from ethanol. I was wondering if basically if 93octane ethanol blend is better/worse than 90 octane no ethanol fuel. Obviously octane is a measurement of combustion energy required so assuming a vehicle needs 93 in no way would 90 be a viable alternative. But given the two assuming your vehicle was designed for the lesser would there be a benefit to pay a little more money for no ethanol 90 than 93 with ethanol blend?

Man thats confusing.

**pajeff02** · 12-24-2011, 06:58 PM

Octane is better thought of in terms of "resistance to self-ignition" rather than combustion energy. The higher the octane, the less likely is is that a fuel will pre-ignite in the combustion chamber and cause "knock" under load. The simple fact of having a higher octane fuel in your engine does not always equate to more power as there have to be appropriate adjustments in timing to take advantage of its properties. In fact, dumping a load of 100 or higher octane fuel in most cars will actually reduce performance as the combustion event will be slightly delayed. Our cars utilize both low and high octane spark tables and as a result a higher octane fuel actually does result in better performance as it is combined with increased ignition advance, up to a point.

With ethanol, the stoichiometric ratio is actually lower than that of straight gasoline. This means that the engine has to ingest more blended fuel to make the same power as straight gasoline. I think E10 is around 14.4:1 whereas pure gasoline is 14.68:1. Not a huge difference, but the more ethanol you have in the blend the more fuel the engine needs. The benefit of alcohol is that by its nature it is both "high octane" and also has a cooling effect. In the real world, you probably won't see a whole lot of difference between the two options available to you, at least that you will actually notice. Given the choice though, I would prefer to run straight gasoline in an engine.

**SilentTrouble** · 12-28-2011, 04:16 PM

Thats what i needed to know guys. Thanks!

**Lunatikgixxer** · 12-28-2011, 10:52 PM

I dumped some race gas in my car a few weeks ago, about 1/3 ratio mixed with the 93 octane. Seemed like it performed better and ran smoother for sure. It wouldnt hurt anything am i correct?

**pajeff02** · 12-29-2011, 03:53 AM

Shouldn't be a problem.

**Nowhereman** · 12-29-2011, 03:57 AM

Shit can the ethanol if at all possible.
Here in CA., 91 octane is considered High test or premium.
I can find 100 octane in a few places north of my town but, you pay thru the nose for it.

**2002ssslp** · 12-29-2011, 06:23 AM

Originally Posted by Nowhereman

Shit can the ethanol if at all possible.
Here in CA., 91 octane is considered High test or premium.
I can find 100 octane in a few places north of my town but, you pay thru the nose for it.

Same thing here in New Jersey. 100 octane Sunoco is 7.99/gal. but 93 octane is available for only ( ONLY ? ) 3.79/gal. Give me the early 70's when Sunoco 260 was 102 octane and only 65 cents per gal. with all the lead you could want.

**allbaugh_04** · 12-29-2011, 08:47 AM

Yea, but there were too many hippies and disco balls then...

**cpop98ws6** · 12-29-2011, 08:49 AM

Originally Posted by 2002ssslp

Same thing here in New Jersey. 100 octane Sunoco is 7.99/gal. but 93 octane is available for only ( ONLY ? ) 3.79/gal. Give me the early 70's when Sunoco 260 was 102 octane and only 65 cents per gal. with all the lead you could want.

Where are you getting Sunoco 100 octane at? I want some!

**FMBL** · 12-29-2011, 09:24 AM

I used to co to a small county airport to get aviation fuel 105 octane for about 2.50 a gal 20 years ago.

**Nowhereman** · 12-29-2011, 09:41 AM

Originally Posted by 2002ssslp

Same thing here in New Jersey. 100 octane Sunoco is 7.99/gal. but 93 octane is available for only ( ONLY ? ) 3.79/gal. Give me the early 70's when Sunoco 260 was 102 octane and only 65 cents per gal. with all the lead you could want.

Yup, I ran a Chevron garage as night manager many years ago.
We used to sell Chevron custom supreme at 105 octane.
It looked like grape juice and every guy filled up on that stuff on Friday nights.
Didn't matter what you drove, it ran better on that stuff and smelled great going into the tank.
I ran that shit in my VW bug that had 1800cc barrels, twin paxton superchargers with twin holly two barrel carbs and cam.
My friends called my bug the "Thing" cause it ran like a raped ape and ate up Porsches with ease.
That little car won me a lot of beer and buds back then... (heavy sigh)