Which gas to use? 91 OCT w/ethanol or 88 OCT w/o ethanol

[Snow Junkie]

I have been pondering this question for a while and have heard a few opinions but I would like the some thoughts from the SW squad.

I am wondering which will be better for power, wear, performance, ect between using 91 octane fuel with 10% ethanol or 88 octane without ethanol in my sled. Cost difference is not really that important but it is about $0.15 (or less) more for non ethanol gas.

Any and All comments are appreciated.

 

[Jeff C]

Junkie:

I would approach this question from the point of view of Altitude.

As far as power is concerned, the lower octane you have the more explosive the fuel vapors will be = more power. Higher compression motors require higher octane levels to prevent detonation. That is all octane does is retard the explosion until the spark plug actually fires.

As you go up in elevation, less octane is required to retard preignition. That is why you see gas stations in areas of high elevations, lowering octane levels.

From the standpoint of "wear", ethanol is more likely to wash certain oil film off the moving parts of the engine than non ethanol fuels. Oil manufacturers have addressed this with an additive package designed to resist washing. Other manufacturers clearly state that their oil is not recommended for use with ethanol (But those are the minority).

In general, you could use the 91 octane down low, and if you are in the mountains, you probably could get away with using 88 octane fuel.

I personally would not mess with it and run 91 all the time..........

 

[Snow Junkie]

Thanks for the reply, good information. I am 90% at 8,000ft +. I just wish that we could get away from ethanol in our fuel, why are burning food as fuel anyways! (<----rant)

 

[CO 2.0]

Not sure where you are from, but this may help you find 91 non ethy close to you.

http://pure-gas.org/

 

[Snow Junkie]

Thanks for posting that link. I have looked at that site and it is awesome! For me personally 88 Oct non ethanol is way closer than 91 Oct non ethanol. Certianly 91 Oct non is the best option, which I plan to use whenever possible.

 

[89sandman]

I just can't imagine wanting to hassle with getting non ethy. pull up to the pump, grab the premium handle and fill up. have ran 91 10% in all my toys for years and many miles and never had a problem. We ride 4-7k and have never seen a failure from running 10%.

 

[Bowfisher]

What sled are you riding? Is it stock or modded? If you are stock and it calls for 91 you'll be fine with 88 at your elevation. I'm running 89 non ethanol starting around 5500'-6000' and never have a problem. I'd go out of my my to fuel up with non ethanol, thankfully I don't have to. That being said I have ran 91 10% ethanol and don't notice a difference but I will not let that sit in the sled for long.

 

[Dartos]

As far as power is concerned, the lower octane you have the more explosive the fuel vapors will be = more power. Higher compression motors require higher octane levels to prevent detonation. That is all octane does is retard the explosion until the spark plug actually fires.

..........

I have seen this train of thought posted a lot over the years and it does not appear to be accurate from the research I have done. For pump gas all grades have about the same energy.

REFERENCE LINK: There is little difference in energy content of regular versus premium gasoline. They both contain about 111,400 British Thermal Units of energy per gallon.

 

[Jeff C]

I have seen this train of thought posted a lot over the years and it does not appear to be accurate from the research I have done. For pump gas all grades have about the same energy.

REFERENCE LINK: There is little difference in energy content of regular versus premium gasoline. They both contain about 111,400 British Thermal Units of energy per gallon.

Well if that is true, fantastic! I would still sway buy the lower octane cheaper fuel if your engine does not need the higher levels of octane

 

[Mort2112]

A different opinion...

A nice succinct article on octane.

http://www.bellperformance.com/blog/bid/101182/What-Does-Octane-Do-In-Gasoline-Octane-Ratings

I burn Chevron 91 Oct. 10% in mine with a stabilizer.