I know that 93 octane is better gas than 91 octane. What’s the difference between 93 octane with 10% ethanol and 91 octane with no ethanol?
From my understanding, ethanol creates more carbon build up. (could be wrong) But that’s really as much as I know when talking fuel. I know it goes through more refining when a higher octane, but how much does ethanol affect the fuel quality?
If this is a repost, please link or merge.
93 octane is not better gas, it’s just a different octane level. The higher the octane level, the more compression the fuel can withstand before detonating (igniting). (took that from wikipedia because it was better stated than what I could articulate). Hence why high compression engines and cars with advanced timing run high octane fuel. So it’s not “better” it’s just less volatile.
This is the reason why you should always run the recommended octane level from the manufacturer. There is ZERO benefit to running 93 octane in an engine that calls for 87. In fact, you will probably lose power and fuel efficiency if you do.
93 makes your vtecs bigger.
Ethanol should cause less carbon build up
People don’t like ethanol in certain applications because it eats fuel lines and causes other issues but its mostly older vehicles.
Why would you run 91 or 93 in a turbo vehicle with a normal compression? example being my Subaru.
Hopefully these dont seem like dumb questions, just trying to get an understanding on fuel and why certain fuels are used on certain cars.
Ethanol gas murders engines if it sits for more than a couple months, especially small ones. If it’s a snowblower, lawnmower, ATV, snowmobile etc. always try to go for ethanol free.
Turbo boost increases compression. So it may be a low compression motor, but once you force compressed air into the cylinder, your compression goes up.
91 octane ethanol free is better than 93 with 10% ethanol I believe. There was a pretty good discussion on s2ki about it.
As joe said it gunks up in small motor stuff and eats away the hose because of the ethanol if it isn’t run
I’ve been running E85 in my evo for about a year and about 11 months it’s been sitting lol. The hoses are all fine still. My paper filter in my sending unit got trashed but that has been about the only ill effects.
My exhaust tip has pretty much no carbon build up
I would run 93 in your Subaru
Subaru motors are horrible so just do it. Lol.
I posted this in another thread on here a while ago…
I tried some 93oct Ethanol free from the REZ and noticed a gain in mileage. That’s about the only benefit you’ll see though, depending on your driving habits.
What people generally don’t know is that the Natives, or whoever else is selling E0, aren’t doing any of us a favor unless you are using it in marine apps or small gas engines. See, the thing about fuel containing 10% Ethanol is that it was added to the fuel as a supplement to having no lead. The lead was originally introduced to reduce the affect of knock on such a volatile substance as gasoline. The introduction of 10% Ethanol helped do two things; oxygenate the fuel for a better, more complete burn and increase the octane and knock resistance.
All cars since the early '90s have been designed with that fuel in mind. Your car will run it’s best with 10% Ethanol in the fuel. My suggestion would be to stick with using a good quality fuel such as Sunoco, Exxon, Hess, Shell, Mobil, or BP.
When the US started phasing out lead in gasoline MTBE was oxygenate of choice. Ethanol didn’t come around until much later as states started to realize that with MTBE’s high water solubility any time even a tiny bit of it was leaked it would contaminate huge swaths of ground water. States started banning MTBE, but the laws on the books still required some kind of oxygenate in fuels, so ethanol was ushered in even though it’s a terrible replacement. Then the corn lobby realized they could make a killing selling a major food crop as fuel and the science of how terrible corn based ethanol was as a fuel got pushed aside for spin doctor version about how it’s going to save us from buying oil from evil brown people in the middle east. Even after people started realizing how bad corn ethanol was for our economy these same lobby groups still managed to push through E85.
I missed the first line there, I was like “I know I’ve read this word for word somewhere before.”
Side note: This was me on my way to the shop yesterday with 3 gummed up carbs, all running like shit thanks to 10% ethanol gas. (And my cousins failing to put Sta-Bil in when they borrowed them)
Bah!
Got me on a technicality . . . I forgot all about MTBE.
Thank you, I know what the turbo does to force air in but didnt think about compression. Make sense
I knew I read at one point about this somewhere but couldn’t remember where I saw it. I wanted to look back but couldn’t find it here.
All I’ve been running in both honda and subaru. I usually say away from any station without 93.
Did you slap them? That blows.
the way I see it, if you’re in some street car with a factory tune the difference is probably undetectable.
I have a programmable flash tune (SCT) on my truck. I was running a 91 performance tune for a year now and messing around with 91 and 91 non ethanol. My conclusion is that I gained 1-2mpg (highway) from the non-ethanol. At the time 91 non ethanol was $4.19 a gallon and 91 with 10% was around $4 a gallon. I’m not entirely sure it’s worth the extra $5 to fill my truck with non ethanol (26 gallon tank) from a cost stand point.
Now I’ve switched to my 93 tune this past month and I’m running 93 with 10% Ethanol because the price difference isn’t all that much from 91 w/ 10% (2-5 cents a gallon at sams club) plus I’m testing out my mpg and performance. So far seeing a slight loss in MPG from the 91 w/ 10%. But many factors may take a part in that… weather, driving habits… etc. I’m also not seeing any performance increases from my 93 to 91 tune.
I don’t think that answers your question but just sharing my .02
I agree with this… you’re throwing money away if you fill with 93 on a factory tune.
my svt requires 91 octane. I choose to use the ethanol free because i notice a difference in MPGs. im about 5 mpg higher than when i use 91 with 10%. only difference. no added power, no carbon difference, only MPGs.
[BED Comment] Corn (Ethanol) is the worst thing to happen to the US since its existence [/BED Comment]
worse than Obama?