Its not cool to have coolant pipe leaks!

Karl and Huss, are you referring to heat transfer while doing the joint sweating? I don't have a lot of experience with copper plumbing work, how is that an issue?

Sorry, no - heat transfer in operation. The copper will dissipate more heat into the tunnel than the SS tubing, that's all. Could be handled with the closed cell foam insulation cut to fit & slid in place from the top side, I imagine. That would require carpet, console, eBrake removal for access, though....
 
Sorry, no - heat transfer in operation. The copper will dissipate more heat into the tunnel than the SS tubing, that's all. Could be handled with the closed cell foam insulation cut to fit & slid in place from the top side, I imagine. That would require carpet, console, eBrake removal for access, though....
Do they make pipe insulation in that size or something close enough? Pretty cheap and easy to use. I guess it depends on whether your priority is pulling a maximum amount of heat out of the cooling system or keeping it out of the passenger compartment. Perhaps you could vent the tunnel and achieve both goals.
 
The copper will dissipate more heat into the tunnel
Thanks Huss, that makes more sense.

On one hand, that is the goal - to remove the heat from the coolant as Carl says. On the other hand, true that would make the interior hotter. And in my case that is a real problem due to the excessive ambient heat and uncomfortably hot driving conditions where I'm living. I wonder just how much more heat the use of copper would be in the tunnel area compared to the stock steel tubes.

Thinking back, I was entertaining the idea of relocating the radiator to the rear trunk in order to lower cockpit temps, and improve coolant circulation. I will reroute the heater and A/C lines, but decided not to relocate the rad. And I will add better insulation to the cockpit area. Guess now I'll have to focus more on the tunnel.

I'm reminded of Cliff's idea of ventilating the tunnel from underneath to help remove heat. If I wind up having to cut open the tunnel (vs pulling the tubes out without cutting it open), then I will do something different with the cover to let air move freely through the area. I know there is the possibility of air coming up through the holes of the tunnel into the interior, but hopefully they can be sealed off.
 
It's easy enough to test if the tunnel is getting too much heat transmitted through it, put your hand on the tunnel...obviously with the carpet removed. I had my stripped out spider with no insulation, carpeting or center console and with the engine in the front the trans tunnel would radiate a lot of heat, nice in the winter but a bitch in the summer. You might be trying to solve a problem that is not really a problem.
 
You might be trying to solve a problem that is not really a problem.
Agree, that's why I asked the question: "I wonder just how much more heat the use of copper would be in the tunnel area compared to the stock steel tubes."
 
Agree, that's why I asked the question: "I wonder just how much more heat the use of copper would be in the tunnel area compared to the stock steel tubes."

I once thought, Briefly. of using the finned boiler copper pipes to run coolant to the front an back to add extra cooling. but I would have to cut the bottom tunnel. but in theory it would cool.

Odie
 
I guess that would bring the same trade-off suggested earlier here; increased cooling capacity for the engine, and increased occupant compartment heating.
 
Agree, that's why I asked the question: "I wonder just how much more heat the use of copper would be in the tunnel area compared to the stock steel tubes."

Need one of those math geeks who can extrapolate radiant heat data based on material properties of the chosen SS vs chosen Copper, and temp of coolant passing through feed tube...
 
I am not that math guy...

Designer (by degree and avocation) and OTJ learned seat of the pants engineer (as in knows enough to be trouble but doesn’t know enough to ensure I won’t kill you).

I can tell you that stainless transfers less heat than regular steel and much much less heat than copper. It radiates less as well as being a poorer conductor. Stainless would be preferable to other materials from a heat transfer perspective.

Compared to my Miata, which cooks me in all weathers, a slightly warm floor from heat transfer to the tunnel isn’t likely to be that noticeably different between stainless and copper especially as there are limited contact points between the car and the tubing.
 
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Need one of those math geeks
I am not that math guy...
So I was only half right. :D

Special K's comment about contact points between the cooling tubes and the chassis/body brings a thought. While I would not want to insulate the pipes themselves (prefer to REMOVE as much heat from the coolant as possible), it might help to insulate the mounting points between the pipes and the chassis. Obviously adding insulation between the lower tunnel and the interior compartment will also help, as has been mentioned already.
 
Here’s a thought, remove the two end caps on the tunnel and you could clearance the inner pipe supports (ie find a way to cut them or otherwise enlarge them) and put whichever pipes into a standard pipe insulation solution from a big box store and then reattach the end caps. I recall someone pulling those in a past thread.

This could make it easier to do the install job as well as locate the pipes securely and insulate the car from the heat transfer. You might even be able to replace the heater pipe at the same time with some finagling.
 
Ah, the Miata foot warmers. That car really was miserable in the summer as the trans tunnel would really heat your feet.
I still think you guys are chasing a phantom problem. Currently the 77 has no carpet or insulation on the shifter tunnel...guess I need a sticky note on my forehead to do the palm test on the tunnel while driving it.
 
Not yet but with global warming I'm sure we will be there in a few years.
I might add that when it's over 85 degrees (with big humidity here) I have no interest in driving old Fiats.
 
I went out for a drive in the 77 and tested the temps in the transmission shifter tunnel. Outside temps were around 65 and my thermostat seems to be stuck open so engine temps were a tick above the low mark. The tunnel was warm to the touch but not even close to hot. I hit it with my infrared thermometer and it showed 85 degrees which sounds hot but really just felt "comfortable" to the touch (no carpeting or insulation on the tunnel at the moment). Try this same thing with a 124 spider and odds are you will burn your hand.
 
So i think I have a plan. I have exhausted a number of suppliers in terms of SS pipe plus its too hard bend into shape and to bead in situ. To top it off the EZbeaders don't come in the correct size to bead it anyway as others have pointed out and the material is too hard to bead easily. So here is my thought process:

1. Copper has been used in auto cooling systems with great reliability for many years. I know the materials will be suitable and reliable.
2. Copper has been used with success by fellow X owners as replacement cooling tubes in a variety of configurations.
3. I can bead it in situ without the need to remove the tunnel (see tool below). I plan on soldering the front sections and beading the rear coming out of the tunnel
4. Copper will outlast me. I don't have a care about making the underneath of the car pristine for the next unfortunate sole who wants to attempt to maintain this car after I'm dust!
5. Copper is cheaper than SS and available in 1 3/8" OD so it will fit nicely into the tunnel.
6. In terms of removing the tunnel, cutting it, redesigning it etc. I have no interest in opening that Pandora's box. Some here have done fantastic work in this areas but they have the car on a rotisserie, they have the space, a lift and the welding capability. I do not. But I am good at solving problems and seeing it through to a job well done. Trust me the job wont look half arsed and it will function well.

That addresses the coolant tubes

Now as far as the heater pipes. Internally I can replace the pipe that runs inside the shifting tunnel in the cabin as its accessible. I've already rebuilt the heater box with a new valve, replacement pipe from MWB and had the core boiled out and pressure tested. This leaves the pipe that's in the tunnel. My plan is to retire it in place and bypass it external to the Tunnel. See crude drawing below.

Check out this beading tool. Looks promising. Ive ordered one and plan to use it to bead the copper tubes.


https://www.facebook.com/JobberDo/
upload_2018-10-17_17-33-58.png
 

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Gets my unneeded thumbs up of approval. I like the plan and am good with the logic. Full speed ahead!

Good luck and looking forward to seeing the solution installed.
 
Running the heater tube outside the box is a great solution. On the rat X I run the two heater tubes in the cabin on the passenger side against the tunnel, think this is where the AC lines run. Both heater lines are 100% heater hose, no metal lines although I did think about running copper tubing for the straight run. Pretty sure your carpet would cover the lines but running the one outside and next to the lower box is also a great solution.
 
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