How much race fuel?

I run straight race gas, only because of the elevation I ride, 10k-13.7K, and for the safety factor (for the motor). Yes I could probably get away with some form of mixed fuel, but in snowmobiling, the factors related to that are always changing, at least out in the mountains. The amount of load on the motor is affected by the amount of snow you are riding in, the elevation and temperature affect how your motor runs and how it burns fuel, etc. Basically, you may not have any detonation issues 99% of the time running very little high octane fuel, but then you get a 4' storm like we just did (god I love Feb. in CO) and are riding at 13k', well, trying to tow out a blown sled in that much snow in the mountains just sucks all around.

Kestrel2126 said:

I run straight race gas, only because of the elevation I ride, 10k-13.7K, and for the safety factor (for the motor). Yes I could probably get away with some form of mixed fuel, but in snowmobiling, the factors related to that are always changing, at least out in the mountains. The amount of load on the motor is affected by the amount of snow you are riding in, the elevation and temperature affect how your motor runs and how it burns fuel, etc. Basically, you may not have any detonation issues 99% of the time running very little high octane fuel, but then you get a 4' storm like we just did (god I love Feb. in CO) and are riding at 13k', well, trying to tow out a blown sled in that much snow in the mountains just sucks all around.

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so with straight race gas at 10k + ft elevation your running at least 16lbs of boost then right? If i was to run straight race fuel in my sled at 12-13lbs of boost it would run like garbage, compared to the way it does on pump gas with just a little race gas to make up for the crappy pump fuel and hopefully getting it back close to the 91 octane rating its suppose to have to begin with. (not trying to be a dick, just curious, because race fuel is expensive as hell around here... $8-10/gallon, so when we run race fuel we always run big boost to justify wasting the money)

Actually I usually run right around 13PSI, and my sled runs great on straight RG. I do have the Race Gas turbo setup, as opposed to the Pump Gas turbo kit you have, so maybe that plays into this, although I have no idea how or why that would be. I am also curious as to how you can run Boondockers pump gas kit at that much boost without problems. Not real familiar with that kit, I just thought you could only bump it up to around 10 PSI safely. You are correct in the running big boost comment though, I am able to bump up my boost significantly when I want to and have the tolerance to do so in most cases (because of the fuel). However, I don't feel like I am wasting money in doing so

Jkinzer said:

so with straight race gas at 10k + ft elevation your running at least 16lbs of boost then right? If i was to run straight race fuel in my sled at 12-13lbs of boost it would run like garbage, compared to the way it does on pump gas with just a little race gas to make up for the crappy pump fuel and hopefully getting it back close to the 91 octane rating its suppose to have to begin with. (not trying to be a dick, just curious, because race fuel is expensive as hell around here... $8-10/gallon, so when we run race fuel we always run big boost to justify wasting the money)

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I also ride colorado at 10K-13K and even with the 08 head 13-1 compression ratio at 50/50 108 motor my AFRs are at 12.7-13.2 at wot and any lower it either fouls plugs or as Kinzer stated it runs like crap!! I run 12-14 psi all day

with the 800 cfi motor having four injectors there is no limit to a pump gas turbo... you can run boost levels from 4lbs of boost up to 20 if you change out the waste gate actuator. you just have to be at proper elevation and/or have the right fuel. the highest boost i have taken mine to is 19.8lbs... i dont run an intercooler because of the extra lag they create so i could only do so for aobut 5 minutes... or one good pull before the charge temps would go through the roof. with BD's Pump Gas set up, no intercooler, no blow off valve, basic kit, we are able to run 12-14lbs depending on the ambient air temperature and still run safe charge temps below 200 degrees. My sled is a one off custom from the ground up, the motor has completely been redone by Indy Dan, and my head has lower compression than a stock 2010 head. i talk to the guy's at BD almost on a weekly basis about what we have found that we are able to do with boost levels, octane ratings and elevation. and we have changed a lot of the local guys from running straight race fuel down to mainly pump as well because of the performance gains that are to be had, and you dont lose any of the reliability factor if done right.

Well not really sure what to tell you guys. I've been through 1 set of plugs this year (early season trying to tune maps), and put up 246 HP on the dyno. Sled runs crisp and strong with 2500 Miles on it. Not sure as to what the variable is here, but my sled runs great on straight RG.

I run 3 gal 110 race gas and the rest 91 octane pump gas (non ethanol). Run 9 lbs boost on this Aero 66 setup. It runs flawlessly and WAY better than it ever did running straight race gas and 14 lbs boost. Dont know exactly why...but it rips at this ratio. It starts easier, doesn't foul plugs, the bottom end is clean and crisp and the top end is outstanding!!. EGTs between 1150 and 1200 most of the time. I ride at 6,000 to 9,000 ft and have the latest 2010 update on my sled as well as the Jan 11th flash in ECU.

Just my 2 cents....for whatever its worth.

Great thread...btw