i have a 2010 m8 boondocker race gas turbo what race gas are you guys using, I ride at 6000 to 9000 feet im getting mixed reviews any help would be nice
which fuel to use
- Thread starter Unregisteredf650
- Start date
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mynewuseddoo
Well-known member
You can use premium pump gas
run whatever fuel you want/ is readily available, and then run an appropriate amount of boost.
I run different amounts of boost depending on types of fuel I can get at the time.
What kind of boost are you wanting to run, that would help people hep you.
Help us help you... we're here for you
I run different amounts of boost depending on types of fuel I can get at the time.
What kind of boost are you wanting to run, that would help people hep you.
Help us help you... we're here for you
Yes, boost is the factor...not whether you have a so called pump gas turbo or race gas.
At that elevation I would not run straight pump gas above 7lbs of boost with the stock head. With retarded timing you may get around 9.
At that elevation I would not run straight pump gas above 7lbs of boost with the stock head. With retarded timing you may get around 9.
G
Gobig510
Well-known member
100LL
I've had two race gas M8's, put some good seat time both of them and never burned one down. This is my system...
I only use 91 pump gas and 100LL from the airport, ride 7,000ft to 11,000ft.
100LL? Yup, I know there are naysayers out there saying 100LL doesn't have enough lead, but that's B.S. People run 91 octane in there stockers and that is UNleaded, no lead. 100LL at least has some lead, and if you look at the MON ratings and lubrication ratings, it isn't far from race fuel, but it is far from the price. If I remember right 100LL has a 104 MON rating and 110 Sunoco has a 105 MON rating. Not to mention I heard race fuels can be pretty inconsistent, but airplane fuel has to meet specific standards, because well... you're flying. I pick up my 100LL from the airport, don't need a special license or anything like that, here in CO you can just drive up to the pump and pay with a credit card, about $4 a gallon.
I usually just have mine set at 13lbs of boost. If I'm running 7,000ft I run straight 100LL. 9,000ft I put in a few gallons of 91. If I'm up mostly doing 10,000ft plus I might do about half 91. It's pretty easy to see if you aren't running high enough octane by your EGTs. I tried running a 50/50 mix of 91 and 100LL at around 8,000ft and I could tell after about a minute of riding that my EGTs were quite a bit hotter than normal for the same amount of throttle. Why mess with mixing 91 at all? It's true it would be safer to just run straight 100LL or race gas all the time, but as you go higher up in elevation, atmospheric pressure goes down, resulting in lower pressure in your cylinder. All of the fuel won't combust in your chamber, you'll just be throwing some of the race gas out the exhaust without a lower octane. Running straight 100LL at 10,000ft mine just seemed a little boggy. Threw in some 91 and she perked up.
You could also just change your boost instead of running different fuels. If you set your boost at say 10lbs at 7,000ft and used a specific octane number, you could probably run 15lbs of boost with the same octane at 11,000ft. After awhile you learn to get a feel for it. You can usually tell if your sled isn't running right. Always better to over-octane first and then cut it back over time and watch your EGTs and knock sensor...
I might just be getting lucky with the specific airport fuel I use, but don't knock it unless you try it...
I've had two race gas M8's, put some good seat time both of them and never burned one down. This is my system...
I only use 91 pump gas and 100LL from the airport, ride 7,000ft to 11,000ft.
100LL? Yup, I know there are naysayers out there saying 100LL doesn't have enough lead, but that's B.S. People run 91 octane in there stockers and that is UNleaded, no lead. 100LL at least has some lead, and if you look at the MON ratings and lubrication ratings, it isn't far from race fuel, but it is far from the price. If I remember right 100LL has a 104 MON rating and 110 Sunoco has a 105 MON rating. Not to mention I heard race fuels can be pretty inconsistent, but airplane fuel has to meet specific standards, because well... you're flying. I pick up my 100LL from the airport, don't need a special license or anything like that, here in CO you can just drive up to the pump and pay with a credit card, about $4 a gallon.
I usually just have mine set at 13lbs of boost. If I'm running 7,000ft I run straight 100LL. 9,000ft I put in a few gallons of 91. If I'm up mostly doing 10,000ft plus I might do about half 91. It's pretty easy to see if you aren't running high enough octane by your EGTs. I tried running a 50/50 mix of 91 and 100LL at around 8,000ft and I could tell after about a minute of riding that my EGTs were quite a bit hotter than normal for the same amount of throttle. Why mess with mixing 91 at all? It's true it would be safer to just run straight 100LL or race gas all the time, but as you go higher up in elevation, atmospheric pressure goes down, resulting in lower pressure in your cylinder. All of the fuel won't combust in your chamber, you'll just be throwing some of the race gas out the exhaust without a lower octane. Running straight 100LL at 10,000ft mine just seemed a little boggy. Threw in some 91 and she perked up.
You could also just change your boost instead of running different fuels. If you set your boost at say 10lbs at 7,000ft and used a specific octane number, you could probably run 15lbs of boost with the same octane at 11,000ft. After awhile you learn to get a feel for it. You can usually tell if your sled isn't running right. Always better to over-octane first and then cut it back over time and watch your EGTs and knock sensor...
I might just be getting lucky with the specific airport fuel I use, but don't knock it unless you try it...
M
mynewuseddoo
Well-known member
In a boosted system, I would say the O2 content would drop and your cylinder pressure would stay the same at 13 psi boost pressure, or what ever pressure you had your system set at. The turbo inlet pressure will drop as it will be affected by ambient air changes. Your compressor wheel will spin faster to draw more air in and maintain your charge pressure though.
Gobig, are you running a stock 09 head on your M8?
fyi, I run a different turbo system (cutler stage II) & my "mix" if I run avgas is very close to what gobig is saying. Around 50/50 av/91 at 11k for 13psi.
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wasatchcomm
Well-known member
i ride 3k-6k mostly,
2010 m8 stock head bd rg kit
straight 100LL (avgas)
i have tried 2 gal 91 mixed with 100LL
and ran it at 9lbs at around 4k-5k, i got octane code flashing at me a couple times, i stopped turned down boost to 8.5 and never saw the octane code again.
as said by the other guys on here,
what is your target boost you want to run?
and average elevation?
then get your fuel right for those answers.....
its funny how when i first got my turbo and installed it i was so nervous the thing was going to blow up.
they are so easy to tune.
never be without one again....
2010 m8 stock head bd rg kit
straight 100LL (avgas)
i have tried 2 gal 91 mixed with 100LL
and ran it at 9lbs at around 4k-5k, i got octane code flashing at me a couple times, i stopped turned down boost to 8.5 and never saw the octane code again.
as said by the other guys on here,
what is your target boost you want to run?
and average elevation?
then get your fuel right for those answers.....
its funny how when i first got my turbo and installed it i was so nervous the thing was going to blow up.
they are so easy to tune.
never be without one again....
G
Gobig510
Well-known member
Pressure
Mynewuseddoo- relatively speaking you are right, 02 content does drop with altitude but your cylinder pressure will also be affected as well. Cylinder pressure should equal ambient air pressure plus boost. So if ambient at 5,000ft is 10 and ambient at 10,000ft is 5, effective cylinder pressure should be 10+your boost and 5+your boost respectively... The compressor wheel does spin faster, but I don't think it is a prefect compensation, so that is why altitude does have an effect on boosted engines, not as much as naturally aspirated, but still an effect... Ya I am running stock 08 head...
Mynewuseddoo- relatively speaking you are right, 02 content does drop with altitude but your cylinder pressure will also be affected as well. Cylinder pressure should equal ambient air pressure plus boost. So if ambient at 5,000ft is 10 and ambient at 10,000ft is 5, effective cylinder pressure should be 10+your boost and 5+your boost respectively... The compressor wheel does spin faster, but I don't think it is a prefect compensation, so that is why altitude does have an effect on boosted engines, not as much as naturally aspirated, but still an effect... Ya I am running stock 08 head...
Boost and elevation change. Elevation with a turbo will change h.p. at the rate of 1/2 pound of boost per 1000 ft. In other words, at 10,000 ft elevation it takes 5 psi more to have the same power as it does at sea level, everything else being the same. IE intake air temp.
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mynewuseddoo
Well-known member
Yes, it will take more pressure to creat the same power at higher elevation. But 13 psig is 13 psig no matter what elevation you are at though.
I am sorry but 13psi at sea level is not the same as 13psi at lets say 10,000 ft. elevation! All that you are talking about is gauge pressure. You need to look at absolute pressure not gauge pressure. They truly are different. What the engine sees is atmospheric pressure plus gauge pressure and that is absolute pressure. An example would be 13psi plus atmospheric pressure at sea level of 14.7 would equal 27.7 absolute pressure which is a little under 2 atmospheres, or a little under a pressure ratio of 2 on a turbo compressor map. At 10,000 ft elevation you would have an atmospheric pressure of around 9.7psi plus your 13psi gauge pressure which would be around 22.7psi absolute pressure. Which is a little more than a pressure ratio of 1.5 on a turbo compressor map. In other words, to have the same h.p. at 10,000 ft elevation, it would take an additional pressure of 5 psi gauge pressure to have the same h.p. as you would at sea level.
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mynewuseddoo
Well-known member
Ok, blind leading the blind here, sorry I mentioned anything lol. I agree on the HP loss and the need for higher boost pressure to compensate for the oxygen loss from elevation. You guys are confusing everything that happens AFTER the compressor though. Have fun in lala land fellas.
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Gobig510
Well-known member
Physics must be in lala land
I don't think this is the thread to debate this, since the poor guy just wanted to know about what fuel to run. But since we were described as being in lala land I thought I should respectfully state something in defense.
Taken word for word from my physics 101 book in college: "It is important to note that pressure gauges register the pressure above and beyond atmospheric pressure. This is called GAUGE PRESSURE. Thus, to get the ABSOLUTE PRESSURE, P, we must add the atmospheric pressure, PA, to the gauge pressure, PG: P=PA+PG. If a tire gauge registers 220 kPa, the absolute pressure within the tire is 220 kPa+ 101 kPa (atompheric pressure)=321 kPa, equivalent to about 3.2 atm (2.2atm guage pressure)."
I agree, the concept is a little difficult. It seems that if my tire pressure gauge reads 40psi in my tire at sea level and then 40psi at 10,000ft, the tire would have the same pressure in it at both elevations, 40psi! Wrong, 40psi is giving you gauge pressure, you will have effectively less absolute pressure in your tires at 10,000ft than at sea level even though the gauge reads 40psi at both places... The physics book translates this to scuba diving as well. Diving to the same depth at elevation will result in the diver experiencing less absolute pressure than at sea level. The same thing goes for a turbo. The gauge reading 13 pounds of boost in the charge tube is meaning 13 pounds of boost on top of atmospheric pressure. Since atmospheric pressure goes down with increase in elevation, overall your turbo has "less absolute boost" as you go up in elevation, meaning less absolute power as well.
The turbo is a compressor, it will compress air the charge tube to the set level, say 13psi. This 13psi is 13psi gauge pressure. Therefore compact air going into your cylinder is 13psi plus atmospheric pressure, which again, goes down with elevation increase.
Oh but you might be thinking, "doesn't the waste gate start releasing air after an absolute pressure in the charge tube? Therefore it doesn't matter if you are at elevation or not because the waste gate is going to release after it has the set absolute pressure in their regardless of atmospheric pressure. So if I set it to 15psi, it will be that specific pressure no matter what regardless of elevation because it is a closed system." Thinking that, however, would be wrong because you only balanced one side of the equation. The turbo compressor system isn't really closed. The waste gate is going to release after a specific pressure in the charge tube, but where is that pressure going? Outside the system! Therefore you have atmospheric pressure pushing back on the system. Remember Newton's laws? For every action there is an equal and opposite reaction. Thus, when that waste gate released after building 15psi, that 15psi is actually gauge pressure, because atmospheric pressure was inside the charge tube as well as outside! Lowering atmospheric pressure with altitude is going to lower both sides of the equation, meaning that 15psi gauge reading is gauge pressure. Your absolute pressure and effective pressure in those sweet arctic cat pistons is going down as a result of decreased atmospheric pressure.
One last way to think about it. Say you had a beautiful orange and white 2012 proclimb with one of those sweet new standalone ECU PUSH turbos running 15 pounds of boost at 6,000ft elevation. However, you were a little man that could crawl into your charge tube and held a barometer. What would the barometer read? 15psi? Nope, it would read 26.4! Why? Because atmospheric pressure is 11.4 at 6,000ft! Now you crawl out of your charge tube with the barometer and stand on the sled, now it reads 11.4. The compressor system is sucking air outside of the system and then spitting it out the other side of the system, exposing itself to the pressure outside of the compressor system, atmospheric pressure...
Just because a turbo causes many magical things when it comes to snowmobiles, doesn't mean it can defy physics...
I don't think this is the thread to debate this, since the poor guy just wanted to know about what fuel to run. But since we were described as being in lala land I thought I should respectfully state something in defense.
Taken word for word from my physics 101 book in college: "It is important to note that pressure gauges register the pressure above and beyond atmospheric pressure. This is called GAUGE PRESSURE. Thus, to get the ABSOLUTE PRESSURE, P, we must add the atmospheric pressure, PA, to the gauge pressure, PG: P=PA+PG. If a tire gauge registers 220 kPa, the absolute pressure within the tire is 220 kPa+ 101 kPa (atompheric pressure)=321 kPa, equivalent to about 3.2 atm (2.2atm guage pressure)."
I agree, the concept is a little difficult. It seems that if my tire pressure gauge reads 40psi in my tire at sea level and then 40psi at 10,000ft, the tire would have the same pressure in it at both elevations, 40psi! Wrong, 40psi is giving you gauge pressure, you will have effectively less absolute pressure in your tires at 10,000ft than at sea level even though the gauge reads 40psi at both places... The physics book translates this to scuba diving as well. Diving to the same depth at elevation will result in the diver experiencing less absolute pressure than at sea level. The same thing goes for a turbo. The gauge reading 13 pounds of boost in the charge tube is meaning 13 pounds of boost on top of atmospheric pressure. Since atmospheric pressure goes down with increase in elevation, overall your turbo has "less absolute boost" as you go up in elevation, meaning less absolute power as well.
The turbo is a compressor, it will compress air the charge tube to the set level, say 13psi. This 13psi is 13psi gauge pressure. Therefore compact air going into your cylinder is 13psi plus atmospheric pressure, which again, goes down with elevation increase.
Oh but you might be thinking, "doesn't the waste gate start releasing air after an absolute pressure in the charge tube? Therefore it doesn't matter if you are at elevation or not because the waste gate is going to release after it has the set absolute pressure in their regardless of atmospheric pressure. So if I set it to 15psi, it will be that specific pressure no matter what regardless of elevation because it is a closed system." Thinking that, however, would be wrong because you only balanced one side of the equation. The turbo compressor system isn't really closed. The waste gate is going to release after a specific pressure in the charge tube, but where is that pressure going? Outside the system! Therefore you have atmospheric pressure pushing back on the system. Remember Newton's laws? For every action there is an equal and opposite reaction. Thus, when that waste gate released after building 15psi, that 15psi is actually gauge pressure, because atmospheric pressure was inside the charge tube as well as outside! Lowering atmospheric pressure with altitude is going to lower both sides of the equation, meaning that 15psi gauge reading is gauge pressure. Your absolute pressure and effective pressure in those sweet arctic cat pistons is going down as a result of decreased atmospheric pressure.
One last way to think about it. Say you had a beautiful orange and white 2012 proclimb with one of those sweet new standalone ECU PUSH turbos running 15 pounds of boost at 6,000ft elevation. However, you were a little man that could crawl into your charge tube and held a barometer. What would the barometer read? 15psi? Nope, it would read 26.4! Why? Because atmospheric pressure is 11.4 at 6,000ft! Now you crawl out of your charge tube with the barometer and stand on the sled, now it reads 11.4. The compressor system is sucking air outside of the system and then spitting it out the other side of the system, exposing itself to the pressure outside of the compressor system, atmospheric pressure...
Just because a turbo causes many magical things when it comes to snowmobiles, doesn't mean it can defy physics...
M
mynewuseddoo
Well-known member
I'll just PM ya
i would like to run 12 to 14 lbs of boost always ride revy 6000 to 8000 ft
