Why do you think Polaris improved the 800 HO motor?

Teth-Air · Oct 18, 2017

Did many guys have a heating problem when the RMK was actually run in deep snow as it was intended? Or does anyone think the 2018 changes are just a precursor to a new motor design for 2019?

I personally feel that both Cat and Polaris will be answering to Ski-doo's 850 with a 860 or bigger motor for 2019.

It would make sense to me that bigger jugs would need better cooling and that is why we are seeing Polaris test this for 2018.

SnowJunkie82 · Oct 18, 2017

Running in deep snow I have never had a cooling issue. However, on marginal snow or the trail I am always fighting it. A lot of these sleds see a ton of these miles so its nice to see Polaris tweaking this.

Hopefully your right in your predictions that this is lead up to a new big motor, but even if it isn't it was a good upgrade!

Staple_STI · Oct 18, 2017

Teth-Air said:
Did many guys have a heating problem when the RMK was actually run in deep snow as it was intended? Or does anyone think the 2018 changes are just a precursor to a new motor design for 2019?

I personally feel that both Cat and Polaris will be answering to Ski-doo's 850 with a 860 or bigger motor for 2019.

It would make sense to me that bigger jugs would need better cooling and that is why we are seeing Polaris test this for 2018.

Great questions.. and I sure hope they are testing it for a bigger motor. Personally I never had issues with the 163 3", it was much better on the trail than my13 as well.

niner · Oct 18, 2017

I think they need extra cooling for the factory turbo next year. 800 cc is plenty of engine with a little boost.

ABMax24 · Oct 18, 2017

IMO the cooling issues on the pro have nothing to do with the thermostat temp setting, its because there simply isn't enough cooler area to dissipate the heat in marginal snow conditions. I'm also not a believer that a turbo needs more cooling, on identical machines my turbo pro always runs cooler on the trail vs a stock motor machine, I believe this is because my motor turns slower on the trail due to the clutching burning less fuel producing less heat.

The only thing i think this might do is keep the cases cooler creating a cooler more dense air charge into the motor to make more power.

S.W.A.T. · Oct 18, 2017

Is the 800 not enough as is?

BILTIT · Oct 20, 2017

S.W.A.T. said:
Is the 800 not enough as is?

At 8000+ ft, no the 800 is not enough. It basically becomes like a 600 at sea level.

BILTIT · Oct 20, 2017

ABMax24 said:
IMO the cooling issues on the pro have nothing to do with the thermostat temp setting, its because there simply isn't enough cooler area to dissipate the heat in marginal snow conditions. I'm also not a believer that a turbo needs more cooling, on identical machines my turbo pro always runs cooler on the trail vs a stock motor machine, I believe this is because my motor turns slower on the trail due to the clutching burning less fuel producing less heat.

The only thing i think this might do is keep the cases cooler creating a cooler more dense air charge into the motor to make more power.

This I disagree with. It has a ton to do with the thermostat. I swapped mine to an external bypass T-stat and with a power claw track I see normal easy riding temps of 98 and about 105 when pushing it hard in the mountains. The stock tstat is too small and does not flow enough. Saying that, yes the cooler is not very large and that is the next restriction in cooling once the tstat is upgraded. The cooler becomes an issue once you have little snow to cool with.

ABMax24 · Oct 20, 2017

BILTIT said:
This I disagree with. It has a ton to do with the thermostat. I swapped mine to an external bypass T-stat and with a power claw track I see normal easy riding temps of 98 and about 105 when pushing it hard in the mountains. The stock tstat is too small and does not flow enough. Saying that, yes the cooler is not very large and that is the next restriction in cooling once the tstat is upgraded. The cooler becomes an issue once you have little snow to cool with.

Believe what you want, but I find it funny that my "too small" stock thermostat keeps my turbo pro under 60c at all times in good snow and even on most trail conditions, which is only 9c above t-stat opening temperature.

jhurkot · Oct 21, 2017

Needed more flow for the 900 next year.

S.W.A.T. · Oct 21, 2017

BILTIT said:
At 8000+ ft, no the 800 is not enough. It basically becomes like a 600 at sea level.

I would like to know where you spend a great amount of time above 8000ft.

If most people can't access a area with 170-180 hp they probably have no business being there IMO. Just creates a whole other level of circumstances

BILTIT · Oct 21, 2017

Anytime i am in the mountains is 6-8500ft, so not sure what you are getting at.

S.W.A.T. · Oct 21, 2017

BILTIT said:
Anytime i am in the mountains is 6-8500ft, so not sure what you are getting at.

Where? The reason I ask is because not many places are accessable in BC above 8000. Boulder has some but not much. And that being said if you are spending that much time above 6500 would you not be more efficient and effective with clutching and gearing for higher elevations.

BILTIT · Oct 21, 2017

Yes i run clutching/gearing for that height. A have a mountain sled and a flatland sled. Still would be nice to have more power. After having a 910 at 2200ft, an 800 at any higher elevation is not enough.

Keith Brown · Oct 21, 2017

ABMax24 said:
IMO the cooling issues on the pro have nothing to do with the thermostat temp setting, its because there simply isn't enough cooler area to dissipate the heat in marginal snow conditions. I'm also not a believer that a turbo needs more cooling, on identical machines my turbo pro always runs cooler on the trail vs a stock motor machine, I believe this is because my motor turns slower on the trail due to the clutching burning less fuel producing less heat.

The only thing i think this might do is keep the cases cooler creating a cooler more dense air charge into the motor to make more power.

Your ascertation that your turbo pro runs cooler at a lower RPM then the equivalent naturally aspirated machine under the same load, seems unusual to me. Typically a higher RPM, lower torque demand within the normal operating range of an engine would provide better cooling given the water pump would have a higher output. That is unless the turbo unit is considerably more efficient which is highly unlikely.

takethebounce · Oct 22, 2017

2018 changes were an attempt to reduce warranty claims, Hurkot has just about bankrupted Polaris with rebuilds.

Polaris would do best to abandon everything to do with the Cleanfire. The Current HO port timing has gone even further backwards and making even less compression than previous versions.

Dragonalain · Oct 22, 2017

Keith Brown said:
Your ascertation that your turbo pro runs cooler at a lower RPM then the equivalent naturally aspirated machine under the same load, seems unusual to me. Typically a higher RPM, lower torque demand within the normal operating range of an engine would provide better cooling given the water pump would have a higher output. That is unless the turbo unit is considerably more efficient which is highly unlikely.

I have not told many ppl this either but my t-pro very seldom gets hot on the trail. I only ever use one scratcher and have a 2.8 track. Only thing I think that makes the sled run cool is I have a boost-it water to air cooler and I thing the two coolers are close enough that the air cooler keeps the engine coolers cold.

hpjunkie · Oct 22, 2017

jhurkot said:
Needed more flow for the 900 next year.

I don't think Polaris will ever use a 900 decal on a sled again! Bad mojo. lol more likely 860, 880, etc for marketing.

knocksum · Oct 26, 2017

A bigger 800 might excite a few. Adding another jug would excite alot more. 1200 triple and I would put some cash down.

Outlaw Motorsports · Oct 28, 2017

takethebounce said:
2018 changes were an attempt to reduce warranty claims, Hurkot has just about bankrupted Polaris with rebuilds.

Polaris would do best to abandon everything to do with the Cleanfire. The Current HO port timing has gone even further backwards and making even less compression than previous versions.

As a Polaris dealer with over 100 Axys RMK’s sold and even more serviced I’d seriously beg to differ. We have seen 2 engine failures since the launch of Axys, one the tip of a piston ring broke off on a rental unit. Not good but in the world of high output engines it does happen from time to time. The 2nd the customer had the high elevation no start issue that triggered a re flash of the 2016 RMK’s and inadvertently pulled the harness from the oil pump looking for reasons of no start. Again a manufacturer issue but this one lead to human error magnifying the problem. I’d call this a 1.5% failure rate.

Polaris has an incredible mountain sled now that is designed for quick acceleration and precise handling. It is the best technical mountain snowmobile in the busnines and finally one of the most reliable. If you want to drag race up the sugar bowl in a straight line an 850 or ascender may get the edge but one is unproven and the other way outside of the 1.5% failure rate in 2017, neither platform can do what Axys can do.

I for for one would hate for Polaris to push out an unreliable factory turbo or bigger bore engine to keep up with the keyboard/cabin worriers, when the current machine is as good as it is. If they can crank things up and maintain the reliability they’ve had with the Axys then sign me up!

Why do you think Polaris improved the 800 HO motor?

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