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Venture Lite tunnel icing

Bugbear

Extreme
Joined
Dec 24, 2007
Messages
54
Location
Anchorage, Alaska
Here's the result of running the exhaust system straight back out the rear bulkhead and isolating it with an aluminum sheet from the front of the muffler to the rear bulkhead. No ice buildup.
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Bugbear said:
Here's the result of running the exhaust system straight back out the rear bulkhead and isolating it with an aluminum sheet from the front of the muffler to the rear bulkhead. No ice buildup.
That's excellent and exactly what I was hoping for. Everyone will want that now; you should patent your design! Any problems with heat build-up with the muffler enclosed? I have parts bought for the tailpipe extension but was unsure about enclosing the muffler. BTW, would you mind giving a brief description of how you did the work and any tips? Difficulties? What gauge aluminum used? etc. That would be great, thanks.
 
Well, after shutdown, the deck behind the seat gets so hot from residual heat from the exhaust that I can't hold my hand there for long. Used a piece of plywood atop the passenger seat mounts for some space.
Wrapped the exhaust with header tape.
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Mounted an inch and half X eighth inch aluminum angle to each side using two quarter inch bolts at each end and spaced off with 1 inch plastic spacers.
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Welded up a fixture to secure the exhaust tubing at the rear bulkhead.
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Riveted half inch angles to .063, 5052 alum. sheet for stiffness to prevent oil canning (stretching).
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Glued 4 inch wide X eighth inch thick neoprene to straps.
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Fastened every thing together using 3/16th inch aircraft maintenance style nutplates rivited onto the two basic structure angles and 10-32 stainless machine screws. Pop rivets ain't gonna cut it.
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Bugbear said:
Well, after shutdown, the deck behind the seat gets so hot from residual heat from the exhaust that I can't hold my hand there for long. Used a piece of plywood atop the passenger seat mounts for some space.
Thanks for the description of the work. So, the heat build-up is not good then - that could damage anything being carried on the rear rack or possibly the seat. There must be some way around the heat issue like putting in a venting hole w/screen or something at the rear to allow heat to escape. But doing that in a way that would prevent snow entry would be a challenge. I guess if only the pipe from the rear of the muffler to where it exits the tunnel was enclosed there would still be ice build-up?
 
Don't think at this point that there's a problem with heat during operation because when I first rode the thing a short distance with nothing on the deck, the deck was cold at shut down. The temperature on the deck immediatly behind the seat kept rising. I just don't want to melt any plastic sitting there. Probably not enough heat there to do that anyway.

I'm going to dismount the skid at the rear and raise the rear of the machine later today in order to take a look and get things back together from opening it to take a peek and the photo. I'll report back.

'Course, doing any thing different is speculation. Your guess is as good as mine.
 
I wonder if a guy had a small vent that had a blade in it that was driven by the exhaust if it would pull enough heat out of that space?Kind of like the roof mounted vents on buildings but much smaller scale.As long as motor is running and exhaust blowing the fan no snow would ever get in through the vent.
 
Apparently this mod has no heat issues. I just crawled up and forward on the top of the track and got a good look at the exhaust system and the structure from below. There was not a sign of over heating. The black powder coating on the steel structure above the muffler and exhaust tubing showed no signs of heat.

I'd speculate that the residual heat is there in the two up configuration but not noticeable 'cause its covered up and is not high enough to damage what's covering it.

Afte the ride on Saturday,(temp. averaged 3 deg. F.) some very wet slush fell out of the front part of the skid when I got it up on the trailer. That's never happened before. Got one bucket of melt water at thaw out in the garage. Previously I got three buckets.
 
So, it seems like there is ice build-up on the outside of the tunnel now (on the running boards and around the rear grab bar)? Did you have that before (mine didn't ice up in those areas, just underneath and around the rubber snow deflector)? I'm wondering if that is occurring because of the sides being heated from the exhaust now and also the warm air exiting at the rear.

I'm trying to get a picture of what you have done; so the front of the muffler area is open; i.e. the plate does not curve up and contact the tunnel or extend right to the front? If so, could that be a concern for debris, sticks etc. Sorry, I don't mean to sound negative, just trying to get the idea and weigh the pros and cons because I'm in the process as well.
Thanks
 
Yeah, iceing is different now. Glad you brought that up. Got a little oven there probably. We'll see. Here's a photo from two years ago.
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The aluminum sheet is flat and ends just fwd of the muffler. No lip or debris barrier. Everything fwd of the muffler is open.
 
very nice excicution of your idea bugbear. I really like the attention paid to the relief of the neoprene at the drop brackets...very sweet detail. so how do you feel about this fix now that you have completed it?
 
Thanks. At present, I'm happy with it. We'll see more as I get more time on it. May have lucked out in finding a happy medium with covering up maybe just the right amount. No doubd about it, it's a little oven in there. Well, anyway, even a blind squirrel can find a nut once in awhile.

You can see that now there is icing to some extent on the exterior. That is a new development but it's no issue. Half of the one ride I've had so far was on a lake for probably 15 miles in a foot of power. Hit max rpm several times just to enjoy the torque. I wonder about the hurricane in the tunnel. There is evidence of melt water on top of the aluminum sheet and there was some slush which fell out. The edge sealing is pretty tight. Maybe too tight. Maybe some drainage provision would be in order. Wish now that I'd extended the exhaust out a little more.
 
R&D is like that, as soon as you build a concept it becomes easier to see functional modifications... what else would we do with all our spare time if we didn't re-work our designs or those of others.
 
Was thinking this afternoon that there is room on the right side of the rear bulkhead for a vent. If one knew there was a pressure differential between the front of the tunnel and the rear, and rear pressure was less.
Well, the thinking never ends.
 
The track must act like a pump to some degree, although there may be a bit of venturi going on at the restricted area between the muff and the track. The heat is going to melt snow somewhere, I guess it is just a matter of where it is the least objectionable. I will be looking forward to hearing how this works and what changes you make.
 


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