I too was surprised to see the amount of mis-information in this thread, though i probably shouldn't be. A low compression engine will not detonate on e-85 just because of the fuel used, it MAY detonate if the a/f ratio hasn't been adjusted to run on e-85, but then the cause is a poor state of tune and being lean and not the fuel itself. E-85 itself burns very cool and when tuned properly is pretty resistant to detonation when tuned correctly. I've been fortunate enough to be able to do some dyno testing with different octane fuels, and anyone who tells you that arbitrarily running higher octane will help performance is a fool.... If e-85 is used properly it's an excellent fuel for performance purposes, i have a friend who has a 70 chevelle, twin turbo 540 that made 1455hp to the wheels using e-85.

 

E-85 is 110 octane. Octane is a rating of how much compression a particular fuel will take before combustion occurs. In an open non compressed environment higher octane fuels burn longer. However, under compression the explode with more force and faster leading flame edge. In an engine that is designed to run higher octane you see added performance. If you put higher octane in an engine that is designed to run on 87 you are throwing your money away. Infact some cars will actually perform poorer when higher than recommended octane fuel is used. As High Octane pointed out on elevation is that there is less oxygen which richens the mix in itself. It also lowers your compression ratio because less air pressure and density so also lowers the octane requirement, hence why 85 is available as the highest grade in high elevations. I misspoke on predetonation at high elevation, its more like your choke is on. EFI takes care on alot of this be adjusting fuel mix and timing. Also oxygenated fuels take care of some of this as well because of their included oxygen that after combustion takes up volume in the cylinder forcing the piston down more efficiently.

 

That's basically what i was stating, the lowest octane you can get away with, without detonation is what you should be using. I've got the dyno sheets around here somewhere that proved the point too, although in some cases having the safety net of a little higher octane outweighs the minimal performance advantage to running a lesser fuel.

 

So the non-oxygenated gas they sell at the pumps here in MN(which is always premium) and is labeled for use in motorcycles, small engines, and other non-catalyst vehicles is just another ploy by big oil to dupe us in to purchasing the most expensive gas?

 

Essentially, yes.... If you don't need to run premium, you're wasting your money by running it as it won't help with performance. Most (if not all) four wheelers are designed to be run on 87 octane, the added octane serves no other purpose than to drain your wallet at a slightly higher rate. Now if you've added compression or timing to the mix, then it may be necessary to go up a few octane points to avoid pre-ignition or detonation.

 

I'm not concerned about the octane rating or performance concerns by going with premium. I understand that it does not benefit to run a higher grade gas if the vehicle is not modified to the point of needing it. I was looking at why they only offer non-oxygenated gas in premium and it's benefits(if any). From what I could find the regular gas in the pumps(87 octane and mid-grade) are oxygenated(primarily with ethanol) which cause a leaner running condition and subsequently less emissions. Sooooooooooo, the non-oxygenated gas should help atv's, cycles, small engines, etc since running lean is not the best way to go. Still not clear why they don't offer it in 87 octane other than draining our wallets more.

 

Leaner, but not by much. And if the argument that Ethanol burns cooler than petro hold any weight, then the slightly leaner condition would be offset by the "cooler" burning Ethanol.

 

Good info Mega XP! I might just go back to the 87 on my 800sp since they run a little rich anyway but will stick with the non-oxygenated stuff in my street bikes and lawn mower.

 

I'm in the petroleum service business, and this is right on.

 

I like to add this additive once and awhile use it in the atv and sled

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