Important >>> Ski-Doo Summit 850 TURBO OEM at long last!!!!!!

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Aug 8, 2011
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Does anyone have some good pics of how the air intake setup works on this sled? It looks to have a solenoid that opens and closes a direct intake path. Does it also have a valve setup on the pressure side of the turbo? Is there any other exhaust valves other than the wastegate that is electrically operated?
 

sledhead_24_7

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This is a perfect set up for guys at elevation, that want no hassle. Or “no turbo lag” if so that has been my biggest hold up from installing a turbo for years. Absolutely cannot stand the bottom end lag. Especially since the 850 is really really responsive out of the hole stock. Hard to give that up.

More hp will come once the need for it arises. A 40ish hp advantage over the rest of the field is pretty good at elevation.

I know I’ve spent more money than the difference between turbo and N/A options to get way less hp in return. Such as big bores, nitrous, pipes etc.
 

goridedoo

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Anyone have any insight as to how much more power they would be able to make with this setup running straight 91? I assume that will be the big hurdle when adding more boost.
 
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goridedoo

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It's tuned for 91, like all 800/850 sleds.
Yep, question is- Looking into the future, how much more boost will be able to be ran with straight 91. I don't see the factory ever releasing a sled that requires race or av gas.
 

caper11

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Nov 2, 2008
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This is a perfect set up for guys at elevation, that want no hassle. Or “no turbo lag” if so that has been my biggest hold up from installing a turbo for years. Absolutely cannot stand the bottom end lag. Especially since the 850 is really really responsive out of the hole stock. Hard to give that up.

More hp will come once the need for it arises. A 40ish hp advantage over the rest of the field is pretty good at elevation.

I know I’ve spent more money than the difference between turbo and N/A options to get way less hp in return. Such as big bores, nitrous, pipes etc.
I installed a BD sidekick and used my own recipe of a clutch setup.
There was absolutely no lag in that G4, felt like a 200hp stock bottom end G4
The recommended clutching from BD is/was thrown in the garage.
 

turboless terry

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Anyone who doesn't think this is awesome is crazy or too biased to see the trees in the forest. I had a silber 850 on 5 psi on pump. No trouble in 2 years. It had the best bottom end of any turbo i ever had but you still lose half of that quick bottom end snort the 850 has for a split second. A split second later you had way more power. My buddy said exact same bottom end. If that is true that is the game changer. Every mpi I've rode has a minor little and annoying stutter down low. The venting is already worked out by the factory which wasn't on the silber. It would cook wires and hoses on epic snow days like what they rode in. You can hammer on it at any elevation. Can't on pump with others. A one year warranty is better than an aftermarket version. If you want more power, buy the more expensive aftermarket version with no warranty. Nothing wrong with that.
 

BeartoothBaron

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Don't do it i'm saying to myself...But I do enjoy arguing turbo misinformation.
Not sure exactly what you're referring to, but if it's about the surge limit, you would be correct. I was thinking of the choke limit, although in looking at some small turbo compressor maps, it could be they're actually against the compressor speed limit. I do understand the basics of compressor mapping and sizing and what I said about a smaller vs. bigger turbo still holds, even though I've never owned a turbo'd sled (which in itself means nothing; be nice if someone who's actually sized 2S turbos could chime in). I'd love to know what turbo Doo used. If it's something off-the-shelf, it'd be easy to drop some points on the compressor map and see how right or wrong I am.
 

big_red1a

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Oct 23, 2008
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Not sure exactly what you're referring to, but if it's about the surge limit, you would be correct. I was thinking of the choke limit, although in looking at some small turbo compressor maps, it could be they're actually against the compressor speed limit. I do understand the basics of compressor mapping and sizing and what I said about a smaller vs. bigger turbo still holds, even though I've never owned a turbo'd sled (which in itself means nothing; be nice if someone who's actually sized 2S turbos could chime in). I'd love to know what turbo Doo used. If it's something off-the-shelf, it'd be easy to drop some points on the compressor map and see how right or wrong I am.
It is a BRP (Rotax) turbo made in house ("completely between these walls")
 
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BeartoothBaron

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Yeah, it's definitely nothing off-the-shelf, although I've gotta believe Rotax gets their turbos from one of the big manufacturers (Garrett and Borg-Warner make a lot of OE turbos, to name a couple). Whoever makes it, a compressor map would be a trade secret, so that's out of the question. I'd love to see that one though, because the pressure ratios we're talking about, around 1.4, are at the very bottom of a typical compressor map.

With regard to HP, seems the system just limits the turbo so the engine never "sees" higher than seal level pressure, allowing it to operate the same envelope as a NA 850 on pump gas. What's not clear to me is why HP has to drop, or at least at the same rate as NA, above 8k. I still think it's probably a very small turbo at the end of its envelope, but it could be some other limitation preventing more than ~4psi. So, who wants to be the first to turn one up and see what happens?
 

8emup

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I've been waiting for this. But, I want more than a 1 year warranty so waiting to see what snow check looks like. I ride over 8000 ft in Utah and I really like their solution it makes total since to me. My other thought they will probably add a little more horse power like they did with the side by sides. I do believe they will also bring to this other models as this was a lot of money to develop. When they start adding to trail sleds the horse will probably go up for mtn sleds. Exciting times!!!
 

PaulAnd

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Is it possible they detuned the 850 motor with lower compression then brought back the power to the stock 165HP level?
Might still be running boost at lower elevations?
Just thinking out loud


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