Fuel
- Thread starter AK Range sledhead
- Start date
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Thielio20
Well-known member
We're running 2 gallons of AV from Chena Marina in every tank with 90. One skidoo turbo and one polaris boost. Both run great.
Where is the pump exactly at Chena Marina. I live up the hill on the ridge and have been getting my AV gas at the East Ramp at the main airport for years for my sleds.
All my experience with octane and engine response is with 2 stroke engines.
High octane when you have a stock compression and timing engine only makes for poor bottom end performance.
When did 4 stroke car engines running fuel from the 70’s and 80’s become applicable to 2 stroke snowmobile engines? (News flash the 80’s are over!!!)
I’m simply saying running higher octane “to be safe” is just an exercise in poor performance.
As for your thought about running high octane forcing you to rebuild your engine? Can’t help you with that misplaced fantasy……..
Too high of octane that burns slower than the engine is designed for certainly won’t hurt it though……..
For some stupid reason 2019 850 axys liked 2 gallons of av gas per 10 gallons it would gain 300 rpms tested it more than a few thinking it was snow conditions but it wasn’t.
heating the gas via top of heat exchanger is another problem if you are trying to extract every pony you can get I paid for them I’d like to use them.
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TheBreeze
Well-known member
I love fuel talk. I do not believe anyone can differentiate throttle response changes when running low percentages of high octane (ie 1-2 gallons per tank of av/100ll/110/C12 Etc.) mixed with fresh fuel.
Half and half, maybe. Straight, likely in a back to back comparison. Assuming they have covid and can't smell the difference in exhaust smell lol.
However, it is a common misconception that high octane is always an indicator as to burn speed, speed of vaporization/etc. It sometimes has correlation, however, many of the very high octane fuels, also vaporize very well, and burn very quickly.
There are two stokes that spin 15,000 rpm. Can't do that on low octane, and fuel that burns and vaporizes slowly. Sunoco Maximal for example.
Half and half, maybe. Straight, likely in a back to back comparison. Assuming they have covid and can't smell the difference in exhaust smell lol.
However, it is a common misconception that high octane is always an indicator as to burn speed, speed of vaporization/etc. It sometimes has correlation, however, many of the very high octane fuels, also vaporize very well, and burn very quickly.
There are two stokes that spin 15,000 rpm. Can't do that on low octane, and fuel that burns and vaporizes slowly. Sunoco Maximal for example.
I saw something on Motor Trend TV a month or two ago doing dyno runs to compare power for 87 and 92 pump gas, and 100 octane race gas (I don't remember any word of ethanol, so pretty sure it was all eth-free). I remember the mule being an LS crate motor, but it may have been a 350; either way, it was running modern pistons and heads, and the compression was 10:1. There was no improvement in power going to high-octane fuel. In fact, the most power by a slight margin was from the 87. They could overshoot the timing more without getting knock with the higher octane, but that was the only advantage. The take-away is that more octane is not a power benefit in itself: the advantage is a safety margin and/or the ability to run higher compression or boost.
So there shouldn't be any power benefit to running more than eth-free premium on an unmodified Boost (or any factory sled), and in a perfect world you should never have a reason to run any more than that. Trouble is, blindly trusting v1.0 products (especially in powersports) is a recipe for failure. In general too, the safety margin benefit is more likely to come into play on a high-performance mountain sled, even unmodified, than a performance street car (assuming it's got modern EFI). You've got more extreme conditions, more moisture exposure, and less sophisticated engine management. To be honest, if it were me, I'd mix in a couple gallons of high octane or avgas until the current mapping is proven, or a new one comes out and some people get some miles on it. Once we get to that point, or next year on a '23 Boost, I'd see no reason to keep adding octane.
So there shouldn't be any power benefit to running more than eth-free premium on an unmodified Boost (or any factory sled), and in a perfect world you should never have a reason to run any more than that. Trouble is, blindly trusting v1.0 products (especially in powersports) is a recipe for failure. In general too, the safety margin benefit is more likely to come into play on a high-performance mountain sled, even unmodified, than a performance street car (assuming it's got modern EFI). You've got more extreme conditions, more moisture exposure, and less sophisticated engine management. To be honest, if it were me, I'd mix in a couple gallons of high octane or avgas until the current mapping is proven, or a new one comes out and some people get some miles on it. Once we get to that point, or next year on a '23 Boost, I'd see no reason to keep adding octane.
My main riding buddy swore the same thing on his 07 xrs but usually over octane mean less performance
I'm a Eastern SD native also and do remember the 85 octane in the hills. I always found it funny that the Western side and much Higher elevation part of SD had such low octane fuel at the pumps. But in Watertown (my home town) we had 90-93 octane at almost all gas stations and still to this day! Luckily the Hills don't seem to get snow anymore so I don't have to deal with 85 octane BS.. Just silly that a place with one of the longest snowmobile / ATV trail systems in the world and hosts the Sturgis Bike Rally is still in the 1980's with the octane levels. (its changed some recently but still)
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Thielio20
Well-known member
Ok so kind of hard to explain but hear me out. If you go to the actual “chena marina” hanger that google maps takes you to, turn left toward the air strip, then take a right just before you hit the runway (don’t drive onto the strip), it’s about 200 feet and on the right under a little shelter with a light. You’ll see the hose reel and the pump. You’ll need an airplane tail number so I usually just use one from an old receipt nearby.
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Jaynelson
Well-known member
Exactly how hot do you think several gallons of below-freezing fuel with constant cooling is getting from a 100 F heat exchanger that's also using the entire tunnel as a heat sink? I bet the fuel in your car on a spring day is warmer.
4 stroke vs 2 and turbo why do we use ice to cool the fuel in a 9 second 1/4 mile car. As I have said in the past if anyone had tunned a big bore or turbo 2 stroke with a carb for max performance would know this is a bad idea
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jim
Well-known member
I have ran ethanol, non-ethanol, av gas, race gas, octane booster in turbos, mods, 2-stroke, 4-stroke sleds, bikes, planes and autos. Any pump gas varies in performance depending on the mix/season and where you get it. Av and race gas are the most consistent. At the end of the day, pick a brand and try to stick with it...and run it. I've always ran the recommended octane...If you detonate, add some octane until it stops. I add royal purple octane booster if I need it because it doesn't alter the fuel density or tune, is cheap, available and it works. If you don't detonate, leave it alone and just stay consistent. And that said, I have seen way more issues and burn downs when someone runs a different fuel mix because they leaned it out too much, not because it detonated. Just find your preference and run it and stay consistent.
