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QUOTE"Others said this but it should be noted that turbo sleds still lose power at elevation".
arctic cat says your wrong /\
arctic cat says your wrong /\
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QUOTE"Others said this but it should be noted that turbo sleds still lose power at elevation".
arctic cat says your wrong /\
Every other turbo manufacture in the world says Arctic Cat is wrong. Corky Bell says Arctic Cat is wrong, Garret Turbo says they are wrong.
The power loss is much less than a NA motor but it is still there.
I can tell you my turbo car has less power at Eisenhower tunnel (11,000') than it does in Fort Collins (4900'). It is an easy butt dyno, does not pull as hard, takes longer to spool and produces less boost in both PSI and milligrams per second of air moved (data logging).
Can AC just be increasing the boost electronically as you increase elevation? Is that how they keep it 177hp at sea level and 10,000ft?
The air is thinner at 10k feet than it is at say 2k feet. The turbo has to work harder to create the same boost at 10k than 2k. Harder work on a turbo means it starts operating outside it's efficiency range. When a turbo operates outside it's efficiency range it creates extra heat, extra heat means less power.
NO way Cat is producing the same power at 10k that they are sea level.
For the conversion for how much power they lose at 10k, it is hard to say. It depends on a lot of things. Intake temp has a lot to do with it, as well as the turbo they are using, the boost it is pushing, the A/R of the turbo etc.
I will post tonight some more info from "Maximum Boost" Corky Bell's book about forced induction. Bottom line is that you still lose power, not near as much but it is still there.
To get this discussion back on track, what does that turbo pig (4-stroke) cost? If you like the Cat, buy the Pro-Climb 8 (2-stroke) take the extra money and slap a boondockers kit on it and it will destroy that 1100 Turbo.
does cat have enough play engineered into it though for those who plan on modding it? most likely not, so it maybe that they spend quite a bit more money to make "big hp" up high....I think I would go 800 and add my own kit to it though....I think everyone on here understands that you make less power at 10k vs 2k feet. Im going to bet Cat is making 177hp at 10k feet and atleast 177hp at sea level. Im also going to bet that Cat also has enough R&D in the design window for operating range on the turbo that in stock conditions the turbo will work efficently.
All we have to do is have someone bring a dynometer to a highmark and throw a AC 11T on it....no big deal.
I think everyone on here understands that you make less power at 10k vs 2k feet. Im going to bet Cat is making 177hp at 10k feet and atleast 177hp at sea level. Im also going to bet that Cat also has enough R&D in the design window for operating range on the turbo that in stock conditions the turbo will work efficently.
All we have to do is have someone bring a dynometer to a highmark and throw a AC 11T on it....no big deal.
the assaults are 15 pds(if I remember the number right) heavier then the rmk's...so subtract another 15 off there, earlier this season there were several threads with pics showing brand new pro's on scales and they were right on polaris's claimed weights.....
"Which sled is the lightest?
The Polaris Assault, thanks to a 40-pound diet from its 2010 version. Here are the wet weights (full of fuel and oil, carrying a spare belt and OEM-supplied tool kit):
Polaris Assault 800: 548 lbs.
Arctic Cat HCR 800: 556 lbs.
Ski-Doo Freeride 800: 577 lbs." (Quote from snowest mag)
I think the Pro is ugly but you are a a bit hard on them aren't you? That Cat looks pretty good though, almost as good as a Doo!
Sea Level
NA motor: 14.7 lbs of air pressure (1 bar, or barometric pressure)
turbo motor: 10 lbs of boost (+14.7 lbs with the 1 bar) total pressure is 24.7 psi
At 11k'
Baromtric pressure is 10 psi (roughly)
NA motor: getting 10 lbs of (atmospheric) pressure bringing air in
Turbo motor: Getting 10lbs of atmosphere pressure plus 10 lbs of turbo boost for a total of 20 PSI. So this turbo is moving 4.7 lbs of pressure LESS. So yes the turbo can work harder to make up that 4.7 lb pressure drop but in doing so the turbo will start to operate out of it's efficency range and create more heat.
Whenever you compress a gas (o2) something you create heat. Decompression creates cold (the reason why a spray can gets cold when using). Anyone that has filled up a nitro bottle, an oxygen tank or anything else like that (scuba tank) will know that the tank gets hot when you fill it up (compressing the gas).
That extra heat means there is less "air" going into the motor. The air is thinner. Really with a turbo you are increasing grams of air per second entering the motor. Since the air at elevation is already less dense then the motor is already getting less air because it higher in elevation, now increase the temperature of that air and it gets even "thinner".
The turbo also has to spin faster to move more air in order to compensate. Spinning this fast is probably not feasible without eventually damaging the turbo (shaft).
Here is a similar explanation:
http://www.coloradoevo.com/forums/showthread.php?t=3065&pagenumber=
Loss of power is much less with a turbo but to say there is NO loss is simply not true.
well maybe AC doesnt engineer there sleds....actually from what I have seen from the manufactures I am beginning to think they slap them together and first year sleds are all there 'beta testers'. Granted my first year 11 PRO has been flawless thus far. Coming from automotive engineering I know that all diesels and turbo gas applications have turbos that will work well within the efficeincey (sp) at all altituges at GVWR plus max towing capacities. But automotive is a different story.
They operate, but as you increase elevation efficiency decreases.
The Twin-Turbo Ford has a major problem operating at anything above 9k feet.
They operate, but as you increase elevation efficiency decreases.
The Twin-Turbo Ford has a major problem operating at anything above 9k feet.