So Really, What octane to run?

[SafetyBob]

Yes, there is more to it, but i was trying to keep it simple, in response to the original question. I agree it is a good idea to have one shop do the mods, or at least have people that work together, and will exchange good info.

 

[portgrinder]

Octane "slows" the fuels burn - thereby avoiding detonation or preignition.

I believe it has a higher flash point, but once its burning, it burns at the same speed.

In my opinion, running anything less than 91 at any elevation on any newish sled is asking for trouble. Ya, I hear the science behind running lower octane in the hills......BUT..... How long can you hold your sled wide open "on the farm" before you end up in a fence, Whereas you can do 1-2 minute pulls up in the hills quite easilly. More heat buildup = more chance of towing your sled home.

Work out the difference per tank between 87 and 91, its hardly a big deal.

 

[Interceptor]

I believe it has a higher flash point, but once its burning, it burns at the same speed.

Exactly what I meant - your wording is a little more accurate than how I put it

 

[ICLIMB]

"octane" is basically used to combat detonation and heat. If your not modded and your manufacturer doesn't require it your throwing away money. But like someone said there will be a performance loss. Same holds true for those that mix race fuel when it isn't needed.

With the stock head on my M7 it runs snappier with 87 v. 91

Does anyone know where to find info on how this new ethanol blended gas will affect our sleds?

 

[SafetyBob]

"octane" is basically used to combat detonation and heat. If your not modded and your manufacturer doesn't require it your throwing away money. But like someone said there will be a performance loss. Same holds true for those that mix race fuel when it isn't needed.

With the stock head on my M7 it runs snappier with 87 v. 91

Does anyone know where to find info on how this new ethanol blended gas will affect our sleds?

Ethanol has a lower energy content than 91 octane, by that i mean less BTU's per gallon. If you are really interested go to wikipedia and do a search for gasoline, under octane rating there will be a energy content table.
Thanks Diann

 

[Ron]

"octane" is basically used to combat detonation and heat. If your not modded and your manufacturer doesn't require it your throwing away money. But like someone said there will be a performance loss. Same holds true for those that mix race fuel when it isn't needed.

With the stock head on my M7 it runs snappier with 87 v. 91

Does anyone know where to find info on how this new ethanol blended gas will affect our sleds?

Less energy 3%+=less power & might be more chance detonation on performance sleds. The 09 Polaris Dragon is set for Ethanol with a jumper wire to a higher performance map for non Ethanol, 91 Octane.

 

[revpilot]

This explains things fairly well http://www.2-stroke-porting.com/altiden.htm My sled runs best on low octane at altitude but I carry a race fuel concentrate and add 2 ounces per gallon of gas I have left in my tank when we get to the hills and I turn on the laughing gas.

 

[Killerk]

Sleds, and most other engines are set-up and owners manuals written for a "worst case scenario" which is sea level.
Sleds need to be clutched for elevation due to less dense air which means less HP.
Also jetting can come into play if carbureted.
Sleds do not get different heads, compression, timing, etc. (stock) for high altitude.(from the factories)
They are all set up the same regardless of where the sled is shipped.
So basically there is no need to run the recomended fuel which is meant for sea level at higher elevations.
I'm sure there is a formula that could be used for reference.
If you run high octane fuel in a stock sled at a high elevation, you are throwing money away IMO.
I have run 85/87 in my F-7 and now My M1000 at 6-10,000 feet and never had an issue.
As some have stated, my F-7 ran worse on 91.
IMO run the least amount of octane possible without causing detonation.

 

[Scott]

"octane" is basically used to combat detonation and heat. If your not modded and your manufacturer doesn't require it your throwing away money. But like someone said there will be a performance loss. Same holds true for those that mix race fuel when it isn't needed.

With the stock head on my M7 it runs snappier with 87 v. 91

Does anyone know where to find info on how this new ethanol blended gas will affect our sleds?

Yeah.
If you run higher octane and you don't need it, you ARE throwing money away...and you WILL have a performance loss.

I ONLY burn regular in my wife's 06 600 rmk...especially above 3500 feet...which is the elevation of our driveway.