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I recently made a beaver tail mod that adds air scoops on each side of the snowflap (see photo). The intention of the side scoops is to improve cooling by channeling more air into the tunnel during challenging trail conditions. This untested modification might be beneficial for trail conditions that provide only air and no snow dust to the tunnel mounted coolers. To test if there is a benefit I intend to modify one machine in our riding group and then compare cooling with another unmodified but otherwise identical machine. We will see.
5162D3EC-8E4B-4F14-82B7-EBCE79F78D0D.jpeg What do you think?
 

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Discussion Starter #2
Apparently no one has a opinion on this potential cooling improvement. I am hoping it can eliminate or reduce the need for scratches. Attached is a photo of a second machine that has been modified to channel more cooling air into the tunnel. With the exception of the beavertail this machine is identical to another machine in our riding group. Both machines have occasionally had a need for scratchers to keep the engine cool. We intend to compare one machine with the other and report back with results because I would think someone might be interested.
 

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I thought for sure guys who have the machines would comment. I don’t have that machine and I find it hard that this setup would help in cooling. Rads use air but it’s airflow through the fins, not onto them. I don’t think there will be enough airflow. Scratchers as you know are designed to throw cold snow and ice on the coolers ultimately cooling the system.
 

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I find it hard that this setup would help in cooling. Rads use air but it’s airflow through the fins, not onto them. I don’t think there will be enough airflow.
Radiator fins increase surface area exposed to air but eliminating thin fins does not eliminate cooling. Liquid cooled snowmobiles made before the turn of the century had heat exchangers mounted below the running boards. Back then most operating conditions transferred heat with only air flowing across (onto) these aluminum extrusions. Attached photo of a sectioned tunnel heat exchanger extrusion shows a decent amount of surface area exposed to the torrent of air inside the tunnel. We have all seen the air blowing everything about the shop when when you free spin the track above 30 mph. The air in the tunnel is moving forward but going down the trail the air entering the back of the tunnel is moving backward. The track/tunnel makes a pretty good fan with a terrible inlet condition. The side scoops on the snow flap is designed to improve this inlet condition. On those hard ice, no snow dust, overheat condition days keeping the snowflap low is also critical. This also speaks to this modification.
 

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Well now that you explained it, it all makes sense now. I kinda felt old after your “turn of the century” statement though lol. Then I realized my Sabercat touches on that design with heat exchanger tubes on the running boards to connect the rear exchanger.
 

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I think the design is outstanding. Should be OE standard issue.
I question eliminating scratchers though?
Skid still needs some lubrication when running glare ice.
To be honest, all scratchers are horrible in one way or the other.
But it's better to have them, and not need them, than the other way around.
 

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Discussion Starter #8
I think the design is outstanding. Should be OE standard issue.
I question eliminating scratchers though?
Skid still needs some lubrication when running glare ice.
To be honest, all scratchers are horrible in one way or the other.
But it's better to have them, and not need them, than the other way around.
On my old 7000 in 25,000 miles I only had one occasion to drop the scratchers. That occasion was with you and it was questionable whether it was needed. That 7000 had a radiator. My 6000 without radiator has occasionally overheated (hot light on) during no snow dust conditions. When this has happened I have bent down and felt the plastic. The plastic was running cool. Not saying the plastic can not get hot because I know it is possible but it just has not happened to me.
 

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I don't think that is going to add much to the cooling effect. Conduction with snow on the heat exchanger and the energy for the phase change from ice to water will be dominate. It isn't the right type of heat exchanger for air cooling. Spend the $70 on cable scratchers.
 

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Duraflex scratchers, studs and 1/2 of a bottle of Redline Water Wetter and my temp light has never been on.

Disclaimer: I have no more proof water wetter works as someone else has any proof it doesn't work. I just use it.
 

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Discussion Starter #11
I don't think that is going to add much to the cooling effect. Conduction with snow on the heat exchanger and the energy for the phase change from ice to water will be dominate. It isn't the right type of heat exchanger for air cooling. Spend the $70 on cable scratchers.
If my little air scoops do not add much cooling it will because they do not channel much air. Extruded aluminum heat exchangers are chosen to survive a brutal environment. Good point on the effectiveness of snow-dust cooling as water goes from a solid to liquid to a gas. I had a 2005 660 Turbo that had minimal tunnel heat exchangers with half of the surface area of the current machines and it still stayed cool with snow dust. That machine was quickly overheating on those occasional no snow dust conditions. In those same conditions the new machines will probably cool without boiling over but the cooling is marginal with hot light on. My experiment addresses this condition.
 

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Discussion Starter #12
Duraflex scratchers, studs and 1/2 of a bottle of Redline Water Wetter and my temp light has never been on.

Disclaimer: I have no more proof water wetter works as someone else has any proof it doesn't work. I just use it.
Good tips for readers of this forum. Last year I addressed the cooling issue in another way. This year when I had the snow-flap idea I had to follow it thru just because (retired engineer). I also put the beavertail on a buddy’s machine because that machine will give more valid test results. Conditions that create overheating does not come up every day or even every year however if another identical machine overheats and his does not than we may have something. We will see.
 

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I don't have an opinion either way on this, but I do like the engineering factor, of thinking outside the box, and am interested in the results
 

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I am curious to see what you find for results. Sometimes it is hard to validate what really works, but you are trying by comparing similar sleds.
I see some benefit from adding to the flap. There is a lot of air that moves with the track. The benefit may be highlighted by the amount of snow dust and chunks that get deflected along with the air.
I am a little leery of believing that air alone can cool much better with a heat exchanger setup. The term "exchanger" is already an indicator. They do exchange heat. Now, if the exchanger is wet, it will conduct more heat transfer. The extra airflow and a wet exchanger will likely cool more.
This is an odd example, but somewhat related. Geothermal systems use the loop field to exchange heat. Put that loop in dry ground and it doesn't work very well. There isn't enough transfer without moisture carrying the heat. That same loop field in ground temp air will be almost useless. Direct water energy transfer is just more efficient. (The difference is staggering, around twenty four times more efficient than air transfer alone.)
Our heat exchangers work well when they have snow/water hitting the surface. The very mention of using scratchers confirms that it does work.
I hope that the changes to the flap can help fix the problems with cooling. I have never been a big fan of scratchers for a list of reasons. It would be a much better solution to have a flap that works.
 

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Discussion Starter #15
I know that finding a cooling improvement that the manufacturers overlooked is not very probable but it sure would be gratifying. Snowmobile cooling performance varies greatly machine to machine. I had a early 4-stroke 660 turbo that had tiny heat exchanger extrusions that performed well with snow dust but not so well when pelted by hard ice particles. Before that I had a Yamaha SRX that no heat exchangers on the top of the tunnel but instead had heavy full length coolers under the running boards. Do to their location these heat exchangers would rarely see snow dust. Despite this the machine never got hot during my watch (7000 miles). Both the early Ski Doo Rev and Polaris Rush snowmobiles had provision to mount the snow flap a short fixed distance from the track. In my opinion this style looked like a dog tail between the legs. Both styles came with monkey motion. One has to wonder about the functional intent of this snow flap mounting.
 

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Have you had a chance to try this yet?
Yes and the preliminary report does show anything significant. My two friends have similar 6000 model machines. They both on occasion have had cooling problems to a similar degree. This year one got the beavertail modification and the other did not. Last week we had a day with snow conditions that created cooling problems. On two occasions I read the temp numbers on their gages. On one occasion one ran about 10 degrees cooler. On another occasion with higher speeds the other ran about 10 degrees cooler. This is very preliminary but I was hoping for something more significant. More to follow.
 

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Correction above “the preliminary test does not show anything significant”.
 

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Yeah, that makes sense. To echo what was said above, that surface/shape is not good for air cooling, it is designed to melt snow/ice. If it had more delicate, longer, thinner fins, then maybe. I think you'd have better luck cutting holes in the side of the tunnel, and adding scoops facing forward to push air into the tunnel. There is negative pressure behind the front of the bodywork, so the scoops facing toward that negative pressure might draw in a lot of cool air.
 

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Yes and the preliminary report does not show anything significant. My two friends have similar 6000 model machines. They both on occasion have had cooling problems to a similar degree. This year one got the beavertail modification and the other did not. Last week we had a day with snow conditions that created cooling problems. On two occasions I read the temp numbers on their gages. On one occasion one ran about 10 degrees cooler. On another occasion with higher speeds the other ran about 10 degrees cooler. This is very preliminary but I was hoping for something more significant. More to follow.
More follow up. Just got back from a saddle bag trip with the two machines that occasionally struggle to stay cool. The machine with the beavertail modification did not show a significant improvement. So concludes the experiment. We all observed that with those hard packed conditions with no snow dust more speed seemed to help with cooling. My solution continues to work but I will continue to search for a solution that is practical for everyone. If anybody has a good idea this is a good spot to share it.
 
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