S
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 /\
Last edited:
weight to hp comparisons 2012 cats vs 2012 RMK
- Thread starter barry1me
- Start date
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).
S
so how many hp"s does 177 loose at 10000 feet?
T
N E one ever heard of MCX in sweden? They have a nytro 18o hp kit and they claim the same hp at any altitude. Thus not having to change the clutching ever. The bottom line is that a properly sized turbo can make more boost to maintain the same overall hp when on boost.
Arctic cat is not making 177 hp at 13 psi at 10000 ft. I can garentee that! it is probally more like 16 lbs of boost at 10000ft. Again it is maintaining a PSIA versus just straight psi. So absolute pressure. If you have heard of any of the MCX guys they say it feels like there is no turbo it is just a very powerful motor.
T
Thats exactly what they are doing. It is not rocket science, also a turbo that is effecient in a 5 psi of boost window not going to be oversized. Alot of the yamahas run turbos that are capable of 20+ and run then at 14 lbs. without lagg issues at high altitude.
I think that alot of the guys talking here don't know much about 4 stroke turbos in general.
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.
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.
S
?????????????
quote.
"Good news too for the avid horsepower crowd that likes to ride out West. The Turbo has an altitude compensation feature that maintains full power at any elevation
quote.
"Good news too for the avid horsepower crowd that likes to ride out West. The Turbo has an altitude compensation feature that maintains full power at any elevation
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.
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....
Well it just doesnt make sence that AC would build a turbo 4 stroke that pushes 177Hp efficiently at 10,000 feet and not more HP in lower elevations. Well besides maybe the stresses it would put on the engine at lower elevations. I dont see a whole lot of sence buying one riding anything below 4000 feet-ish. This sled would need a serious upgrade before Id buy one.
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.
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.
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.
R
The Assault is 15# heavier than the RMK Pro, 6# heavier than the RMK Std.
Thus concluding:
Polaris Pro RMK 800: 533 lbs.
* 23# lighter than a M8 HCR [I know, its not a SP, the HCRs are heavier].
* 44# lighter than a Freeride 8 [unsure of wt differences to a Summit X, I'm sure the FR is heavier]. (Wow, didn't realize the eTecs were that heavy...)
"Polaris Assault 800: 548 lbs.
Arctic Cat HCR 800: 556 lbs.
Ski-Doo Freeride 800: 577 lbs."
Thus concluding:
Polaris Pro RMK 800: 533 lbs.
* 23# lighter than a M8 HCR [I know, its not a SP, the HCRs are heavier].
* 44# lighter than a Freeride 8 [unsure of wt differences to a Summit X, I'm sure the FR is heavier]. (Wow, didn't realize the eTecs were that heavy...)
"Polaris Assault 800: 548 lbs.
Arctic Cat HCR 800: 556 lbs.
Ski-Doo Freeride 800: 577 lbs."
H
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!
Wow, I'm almost speechless !! Do most Doo guys actually believe the Pro is uglier than an XP ??? I guess there is just no accounting for a total lack of good taste. XP's look like a locust that's been dug out of a pile of cow poop and in all honesty, they don't perform much better (except in the eyes of the blind-loyal Doo crowd).
Mile High you are exactly right. Nothing to be said about that. But what I think people are trying to say is arctic cat designed this turbo sled with all of this in mind so that when you are at 10,000ft this sled will produce 177hp. And arctic cat nor anybody else is talking about the losses from the heat due to its never a static number. Theres a ton of variables with the heat factor, and I could imagine that on a cold day say 40 mph down the trail there probably wouldnt be much if any. But I could be wrong and AC could just not care. The average joe wouldnt know any different.
Yeah it seems the auto manufactors leave their turbo set-ups with quite a bit of play room before you compromise the efficiency and you start blowing oil out the seals of the turbo.(At the least) Not sayin you should push that threshold cuz turbo life goes out the door. But like you said vehicles are different game.
They operate, but as you increase elevation efficiency decreases.
The Twin-Turbo Ford has a major problem operating at anything above 9k feet.
The Twin-Turbo Ford has a major problem operating at anything above 9k feet.
hmmm what major problem does the 6.4L have? I have ran stock, 275hp spartan tuning, and both pulling a 29ft 10,000lb trailer at 9k and above!? Truck never missed a beat....I could hold 40+ pounds of boost and hold EGTs at 1400 minutes on end no problem. FWIW I have been designing exhaust and manifold, and Turbo outlet design with Ford/GM/Chrysler/Cummins/IH for the last 7 years.
T
The effeciency may decrease but I would guess it is not going to fall off the map. If they are marketing 177 hp at 10000 ft they will be 177 hp at 10000ft. Not at 13 lbs of boost though. It will likely be 3-4lbs of boost different from sea level to 10000 ft. I can't beleive some people don't understand how this works.