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2012 AK sled build

My tunnel frame & skin was 27 lbs 9 oz. When I'm done this time I expect it to be 23-24 lbs.

Carbon would without a doubt be lighter, but I wonder what the weight would be once you factor in running boards and suspension mounts?

I think the ideal setup would be a small amount of chromoly just for the front & rear suspension mounts, running boards and the rest all CF.
 

Well...I literally can't go backwards anymore. Only forward progress from here haha.
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It could be very light when combined ultralight tubeframe and carbon plates stiffening.. Hmmm.. Ideas flowing..
Whole frame could be way under 40lbs..
 
Yeah I wish there was lighter weigh cooling. I found a aluminum radiator I think would work but it's 10-14lbs with the fan. I think the extrusion is .9lbs/ft. What else could we use for cooling?


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kinger said:
Yeah I wish there was lighter weigh cooling. I found a aluminum radiator I think would work but it's 10-14lbs with the fan. I think the extrusion is .9lbs/ft. What else could we use for cooling?


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Could a radiator really have the same effectivness and save weight over tunnelcooler elements? I meen you have cold snow spraying over thoose elements.....can it get more efficient than that!?

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whitewheels said:
Could a radiator really have the same effectivness and save weight over tunnelcooler elements? I meen you have cold snow spraying over thoose elements.....can it get more efficient than that!?

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Well two different schools of thought here. The exchangers are probably the best with heat transfer and the snow hitting them like you say. However they contribute to large amounts of ice and slush under there. My thought process on the radiator would be to put it in the rear of the tunnel moving weight to the rear, but also with a carbon fiber tunnel or at least carbon skin lined tunnel and no heat, snow wouldn't stick under there. It also eliminates any issues in poor snow conditions with overheating.

The net weight penalty may be small in the garage but could be a 30-50lb advantage out in the snow. It sure it's just a idea at this point.


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My rear cooler is about 4.85 lbs (old fish scale), front cooler is 3.35 lbs. I think it'd be hard to come up with an alternative cooling system that was less than 8 lbs. If I do a 3 pass rear cooler and ditch the front cooler, the rear cooler should be around 7 lbs. The CMX extrusion is light.

Kinger had me wondering so I cut a 12" piece CMX extrusion.
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Snow/ice buildup is definitely something to consider. My buddy who rides a turbo viper said they don't get any buildup on the back(no rear exchanger) while the other brands get large amounts of snow/ice.

I'm painting my tunnel skin next month for this exact reason. Bare aluminum is the absolute worst.
 
This is something I can agree on. The oem nytro had terrible ice/snow build up.....so I tried to move as much as possible to the rear (to even out the weight on the front heavy nytro). I ditched the oem radiator and put extrutions/elements in the back under tunnle....plus exhaust.....I have very little ice build up but you can clearly see that the "cold" bare aluminium spots is coated with ice.
I actually added some weight when I did this. Both in added extra material but also in coolant.

I just assumed nikolai is using this sled in powder not in poor snow conditions. Also the element can take a beating (backcountry riding) when a radiator is more fragile

....what I'm saying is that under tunnle heat exchangers are the way to go on a mountain sled in my opinion. I'll bet there is a way to calculate how much or how little you need. Not to overheat and not to get unneccesery weight

Heres how mine look. It holds very little snow and ice. The dropbrkt gets the most...
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Actually, skidoo gen 4 has something good. Rear cooler is in rear frame, that way you have large cooling area, stiff tunnel and only small amount of coolant. Have been thinking how to make such a system, two alu sheets together and some pass to coolant too.
 
Got the tunnel skin all cleaned up and ready for paint. Trimmed/fixed a few spots that had been bugging me. As pictured it's 8.65 lbs and that's using .040 7075. I think that's about as light as you can possibly get without going CF. I'm painting it in May when my dad has a bunch of time off and will post a painted weight.

With more tubework a guy could probably use something lighter(thin uhmw sheet or CF plate) just to block the snow but my tunnel skin is still structural.

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It was 9.37 lbs when I put the sled together a couple years ago.
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I'm starting on the tunnel frame next, have a bunch of stuff to do.

- add some 1/4" running board tubes
- finish welding the rear 1/2" tube
- cut the battery bracket off
- remove all rivets (will have to drill openings in the tubes)
- add a rear grab handle
- grind some welds off from the previous tube work
- fix some welds
 
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What is the approx sq ft? Looks like about 3-4lbs if it was carbon. Be hard to replicate that shape out of flat plate carbon. Mine will have to look simpler then that in order to be made low tech in my garage.


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There's no need for a 2 piece tapered tunnel. If I were to do another one I'd just angle it up to match the height it's at now but make it straight.

.040 7075 is .5875 lbs/sq ft so my tunnel should be 14.72 sq ft.
 
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