Mr Wong said to get your order in early limited number of production. That is great snowcheck to get the latest I like.
850 Engine thread (840cc)
- Thread starter mountainhorse
- Start date
As someone said earlier. I want to know if they changed piston rod length?
Longer stroke w same rod length means more side forces, and, comparing two pistons of same total hight, wouldn't lower compression hight be better for piston rock than higher?
Longer stroke w same rod length means more side forces, and, comparing two pistons of same total hight, wouldn't lower compression hight be better for piston rock than higher?
S
snowmobiler
Well-known member
single rings.better and lighter.
2019 850
If my math is correct the 800 is supposedly in the area of 155-158 hp. that should put the new 850 at 9% more power around 168-171hp
I cant wait to see someone put some 88mm pistons in there [ 900.15 cc] or some 89 mm pistons [920 cc]. Should be able to get into the high 190's
If my math is correct the 800 is supposedly in the area of 155-158 hp. that should put the new 850 at 9% more power around 168-171hp
I cant wait to see someone put some 88mm pistons in there [ 900.15 cc] or some 89 mm pistons [920 cc]. Should be able to get into the high 190's
Polaris claims a 9% increase in HP. So if the 800 HO is at 154 HP a 9% increase takes it to 168HP. If the 800 HO is at 160 HP a 9% increase takes it to 174 HP.
I'd say it is somewhere between those two marks.
The real question is how many grams does it pull under the same conditions as the 800ho? Who cares what the hp number is.
J
JJ_0909
ACCOUNT CLOSED
Burandt said he's pulling 4 extra grams with a more aggressive helix. YMMV.
It does matter actually...
Your weights depend on RPM, primary spring, helix, secondary spring, gearing etc.
For example, a light spring with a light weight and corresponding helix can give you similar performance in many situations.
Track speed is also irrelevant... ground speed (GPS) is a better indication of setups for clutching and suspension/track.
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Your weights depend on RPM, primary spring, helix, secondary spring, gearing etc.
For example, a light spring with a light weight and corresponding helix can give you similar performance in many situations.
Track speed is also irrelevant... ground speed (GPS) is a better indication of setups for clutching and suspension/track.
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Had two Rev Summit 800ho's, over 6k miles, and no ring issues, FWIW. They could have their fair share of other issues with nun durability, TRA, DPM, reeds, most fixable. The 800R's pre-etec had self-inflicted issues in 07. Original doo 800 had a piston recall for 01, and self-inflicted carb issues in 02. Most of these motors were very good durability-wise with the stock pipe, and people who owned them know it. Change the pipe and you better know what you're doing jetting- and DPM-wise.
It would be interesting to find out what those 68gm's were pushing against for a spring... and for secondary setup.
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In choosing carefully the 74mm stroke, Polaris worked really hard to keep this powerplant compact... and keep inertial forces in check.... keeping the sled, "flickable" (ha, there... I said it )
Should be interesting to see the true #'s of this power plant, the old 900 Cat twin bore and stroke were 85x76 to make it a 862, as someone said earlier, let the HP wars begin, hopefully Polaris did their home work on the new 840 as they have not been successful over 800cc in the past
My opinion
Heres my Opinion... FWIW.
Two completely different animals.
The Rotax-850 has a much larger stroke and smaller bore than the Polaris 840 mill.
Rotax 82mm x 80mm bore/stroke 849cc
Polaris 85mm x 74mm bore/stroke 839cc
Polaris had an 80mm stroke sled in their stable in 05/06... and I'm glad that they opted for the shorter stroke at 74mm.
One is direct port injected (Polaris) the other is Direct injected.
We'll see next season, when the actual production sleds are in the hands of consumer what the REAL number are.
I can say this though, just from a physics perspective, the engine with lower rotational mass will have less influence over the chassis in directional changes.
Rotax had to go with large bolt on bob-weights in the crank and an active vibration cancellation system built into the clutches to deal with the vibrations inherent in the big stroke engines without needing the extra heft of a counterbalance like they did in the 1000 SDI.
The 840cc Patriot Mill is definitely not throttle body injected though.
It is a Semi Direct [port] Injected (SDI)
I agree, that the Rotax/Ficht Direct injection is a more advanced system.... it is still not a closed loop system however.
Both are running, from the control end of things, as a speed-density injection system.
Though, when building a sled... you have to factor in if you actually need Direct Injection.
For BRP, that answer was yes, and they worked with Rotax and Ficht to make it happen in a quality way.
If you can get the fuel economy and power that is needed from a simpler SDI system ... makes sense.
Polaris has had Direct injection in their stable before in PWC.
DI is more complicated, and has more expensive components.
It has proven to be a reliable system however for Rotax and SkiDoo.
Again, we'll see if the new 840 from Polaris is what it claims to be in the hands of the consumers... around this time next year. Polaris is monitoring even more engine parameters than before, getting as close as a non-closed-loop injection system can get to a closed control type of performance, IMO.
I also will admit, that Rotax/Doo has shown better quality in the components and engines.
After working on both following crashes or engine issues. I tip the scales in favor of the Polaris for ease/speed of repairs. It just seems that you have to take less apart 'to get to things' on the Poo compared to the Doo.
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Heres my Opinion... FWIW.
Two completely different animals.
The Rotax-850 has a much larger stroke and smaller bore than the Polaris 840 mill.
Rotax 82mm x 80mm bore/stroke 849cc
Polaris 85mm x 74mm bore/stroke 839cc
Polaris had an 80mm stroke sled in their stable in 05/06... and I'm glad that they opted for the shorter stroke at 74mm.
One is direct port injected (Polaris) the other is Direct injected.
We'll see next season, when the actual production sleds are in the hands of consumer what the REAL number are.
I can say this though, just from a physics perspective, the engine with lower rotational mass will have less influence over the chassis in directional changes.
Rotax had to go with large bolt on bob-weights in the crank and an active vibration cancellation system built into the clutches to deal with the vibrations inherent in the big stroke engines without needing the extra heft of a counterbalance like they did in the 1000 SDI.
The 840cc Patriot Mill is definitely not throttle body injected though.
It is a Semi Direct [port] Injected (SDI)
I agree, that the Rotax/Ficht Direct injection is a more advanced system.... it is still not a closed loop system however.
Both are running, from the control end of things, as a speed-density injection system.
Though, when building a sled... you have to factor in if you actually need Direct Injection.
For BRP, that answer was yes, and they worked with Rotax and Ficht to make it happen in a quality way.
If you can get the fuel economy and power that is needed from a simpler SDI system ... makes sense.
Polaris has had Direct injection in their stable before in PWC.
DI is more complicated, and has more expensive components.
It has proven to be a reliable system however for Rotax and SkiDoo.
Again, we'll see if the new 840 from Polaris is what it claims to be in the hands of the consumers... around this time next year. Polaris is monitoring even more engine parameters than before, getting as close as a non-closed-loop injection system can get to a closed control type of performance, IMO.
I also will admit, that Rotax/Doo has shown better quality in the components and engines.
After working on both following crashes or engine issues. I tip the scales in favor of the Polaris for ease/speed of repairs. It just seems that you have to take less apart 'to get to things' on the Poo compared to the Doo.
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The 840cc Patriot is made in Osceola Wisconsin.
Good ole USA.
Good ole USA.
Regardless the Polaris will get more of it to the ground and perform better without the need for a
Double Wobble Slipper Clutch System.
No need for a Teeter Totter rear suspension and flex edge tracks either.
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I wonder why Polaris didn’t step over Doo and build a 900. Is there something about the 800cc ish engine size that limits going much bigger? So the aftermarket is going to do “bigger bores” lol on the Poo 850 just like Trygstad did with the 850/927. Wonder why Polaris didn’t spit in Ski Doos corporate face with a 900/950 and put them in the back seat engine wise for a couple seasons.
I can't wait to see how Turbotater does his 962 with this engine!
With the 800, he was taking his 910 big bore and building a custom (and expensive) 74mm stroker crank to make the 962.
And now he won't have to stroke it. He'll just punch the stocker out to a 962!!
Can't wait!
With the 800, he was taking his 910 big bore and building a custom (and expensive) 74mm stroker crank to make the 962.
And now he won't have to stroke it. He'll just punch the stocker out to a 962!!
Can't wait!
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