Active Power Cars GT40 Build...

put brake fluid in a container, at room temperature, mesure the volume, then heat up to200° and see how much it expands....
had a experience with rear engined car (Renault Alpine) that clutch did not just fully disengaged when car was really hot..... re-lined clutch pipes and problem was put away....
 
There is no harm in the brake fluid being 200 degrees. I wouldn't want the A/C low pressure line getting heated to 200 degrees ahead of the compressor.

I'll be insulating to not have the tunnel hot.

I believe that, regardless, the tunnel must be insulated or it'll be like having a full time space heater next to you that you cannot control, while at the same time working against the AC to control the cabin temp.

On hot days, I can see that as a problem when you cannot open a window to let out the heat as you would a conventional car, and the little window slot is not sufficient for ventilation. I would like to avoid any excessive heat getting into the cabin as much as possible.

AC was a huge item for me, so I purchased the entire kit from Chris, but I fear that the radiant heat from the tunnel will make it harder to control the cabin temp.

Have you settled on the insulation media that you intend to use?
 
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put brake fluid in a container, at room temperature, mesure the volume, then heat up to200° and see how much it expands....
had a experience with rear engined car (Renault Alpine) that clutch did not just fully disengaged when car was really hot..... re-lined clutch pipes and problem was put away....
Fahrenheid or "our way" Celcius Paul.
Me thinks they are talking F, not C.
200F = 95C.
But agreed, I also have my brake & clutch lines seperated from my cooland pipes and other heatsources and insulated with aircraft spec sleeves. The cooler the better.
 
Fahrenheid or "our way" Celcius Paul.
Me thinks they are talking F, not C.
200F = 95C.
But agreed, I also have my brake & clutch lines seperated from my cooland pipes and other heatsources and insulated with aircraft spec sleeves. The cooler the better.
both are hot anyway... I supposed they meaning Fahrenheit... any way in my project they are separated also. from heat sources ...
 
both are hot anyway... I supposed they meaning Fahrenheit... any way in my project they are separated also. from heat sources ...
Yes - I was thinking in terms of Fahrenheit and not Celsius. My apologies for the confusion. Brake fluid in a your garden variety automobile is exposed to engine bay heat, so I believe the fluid is designed to withstand it, knowing there are limits, of course. 150-200 degree Fahrenheit ambient isn't crazy, and brake rotors can get so hot under hard braking that they glow which means a fair amount of that heat goes right back into the fluid - heat from multiple sources is unavoidable.

I wanted to use the real estate in that tunnel to maximum advantage, but if anyone here has actually has this setup (running brake and clutch through the tunnel along with coolant tubes) in a running and driving car, I'd love to hear if you have experienced any issues that you can trace back to such a setup. It's not too late to change the layout, but I'd really like to keep it the way it is if I can - just makes for a cleaner install, IMO.
 
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Fahrenheid or "our way" Celcius Paul.
Me thinks they are talking F, not C.
200F = 95C.
But agreed, I also have my brake & clutch lines seperated from my cooland pipes and other heatsources and insulated with aircraft spec sleeves. The cooler the better.

I would like to know more about the aircraft spec sleeves you are referring to, if you don't mind. My thought was to insulate the coolant tubes with fiberglass wrap. I don't know what your experience is with fiberglass wrap, but it is amazing for heat insulation for headers which, as you know, can get very hot.

On hot aluminum coolant tubes, I gather the heat would be almost non-existent outside of the wrap. I think header wrap will work on both tubes as the material is thin enough, but it'll be a tight fit. As long as they fit side by side in the tunnel with a little room left over for heat-related expansion, that's all I care about. Should cut the heat down by 90 percent in there and barely detectable, if at all, in the cabin - While at the same time, insulating the brake and clutch lines from any excessive heat.

The concern I have with this approach is its affect on cooling efficiency - namely, the heat not radiated out at the coolant tubes may translate into higher temps in other places, but honestly, having heat emanating from that tunnel doesn't sound like a good thing at all. That would make controlling cabin temp more challenging, especially on hot days. Keeping excessive heat off of the human occupants is just as important as keeping excessive heat off the components, IMO - Race car or no....

I may be overthinking this, but I try to weigh the pros and cons of decisions like these (and learn from others who have done similar things) before putting them into practice.
 
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Neil

Supporter
put brake fluid in a container, at room temperature, mesure the volume, then heat up to200° and see how much it expands....
had a experience with rear engined car (Renault Alpine) that clutch did not just fully disengaged when car was really hot..... re-lined clutch pipes and problem was put away....
Hydraulic (brake) fluid expansion at high temperature can indeed cause problems. Silicone brake fluid is particularly noteworthy in this regard. Quite a few builders have noted throttle creep as engine bay temperature went up when using hydraulic throttle setups.

In the early days of NASA there were ideas of using metal cylinders filled with silicone as linear actuators. Their stroke was to be controlled with an electrical heater around the cylinder. ...another tidbit of useless knowledge. :)
 
Hydraulic (brake) fluid expansion at high temperature can indeed cause problems. Silicone brake fluid is particularly noteworthy in this regard. Quite a few builders have noted throttle creep as engine bay temperature went up when using hydraulic throttle setups.

In the early days of NASA there were ideas of using metal cylinders filled with silicone as linear actuators. Their stroke was to be controlled with an electrical heater around the cylinder. ...another tidbit of useless knowledge. :)
Understood, but define high temp. We're talking about 150-200 F / 66-93 degrees Celsius, ambient (under normal driving conditions). I don't think that happens at those temps. Dot 3 and certainly Dot4 are designed for those temps, and beyond, as far as I know. Under racing conditions, temps go up for sure.
 
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Brian Kissel

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I have used this from McMaster Carr. They have a lot of different styles. This one is a heat dissipating cover and works well. They also have a nice silicone and fiberglass style that I use in our foundry to keep molten metal from damaging our hydraulic lines. Works well. Check out their website, lots of options.
Regards Brian
 
I have a question in to a Ebay seller. They carry a 2 part, closed cell polyurethane pour foam. If it can tolerate long term exposure to 220 degree tubes. I'm thinking make a mold from wood, 3D print spacers to keep in place, and make an insulated multi tube solid foam rectangle that will have brake lines, radiator tubes, a heater tube and maybe even the A/C high pressure line in a single solid rectangular block of foam that can slide into the tunnel. All of the tubes on one end will have to be staggered so all of the connections can be made. Perhaps the brake lines and be left long and bent after sliding the tube in.
 

Brian Kissel

Staff member
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Sorry, I didn’t notice my previous link sucked.
Try this one.

Regards Brian
 

Neil

Supporter
Understood, but define high temp. We're talking about 150-200 F / 66-93 degrees Celsius, ambient (under normal driving conditions). I don't think that happens at those temps. Dot 3 and certainly Dot4 are designed for those temps, and beyond, as far as I know. Under racing conditions, temps go up for sure.
Some places in an engine bay can reach much higher temperatures due to radiant heat. I was talking about thermal expansion due to Delta-T. In some applications it is not a factor; in others it is a problem.
 
My thoughts about sleeving aluminium coolant pipes.
I know what happens when moisture gets trapped between the wrap with mild steel headers who are wrapped.
Aluminium is a great heat conductor but doesn't like moisture as it will corrode heavely. So I would never heat wrap my coolant pipes, I rather have my coolant pipes radiant the heat and vapourise any moisture that traps inside the tunnel.
I used heat insulation mats on top of the tunnel to keep the heat out of the drivers compartment.
My brake & clutch lines run over the insulation inside the drivers compartment and are covered by a large U shape aluminium tunnel cover that slides over the tunnel.

Only pipe work that runs through my tunnel ar the two aluminium cooland pipes and one copper radiator vent pipe that runs from top rad to expansion tank.
 
Merford Aluglass 6.5mm thermal insulation. I used bulkhead connectors for my brake & clutch lines so pipe work can be taken out easely.
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Wont see anything with the cover on top. Brake & clutch lines where sleeved before the cover was placed.
One of the bulkhead connectors (clutch) can be seen below right
1672980216466.png

I used Roundit 2000 NX for all my sleeving including my electrical wires.
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Hey Matt, glad to see another active power cars kit. My father had been working on his for a few years but passed away before finishing it, that was alittle over a year an half ago an I’ve been trying to wrap my head around it since.
 

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Brian Kissel

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I agree with JP on the aluminum lines, but I've always used high quality stainless for coolant lines. I have never, and never will use header style wrap on headers for exactly the reasons JP states. I have seen mild steel headers completely trashed due to a poor wrap job.

Regards Brian
 
not insulated yet but my coolant tubes will be wrapped with same sleeve JP mentioned. I seperated, my coolant runs inside tunnel and brake&clutch out side in center console. I also put a Recirculator on clutch so fluid cools down..
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Hey Matt, glad to see another active power cars kit. My father had been working on his for a few years but passed away before finishing it, that was alittle over a year an half ago an I’ve been trying to wrap my head around it since.

Hey, Mike. Sorry to hear about your father. I'm sure he'd be very proud once you complete it, and it's a wide body too! Love it. I wouldn't have it any other way.

As a whole, the project is daunting, but I try to think of it in terms of lots of smaller projects, and attack it that way - Small projects that can be chipped away at. How far along are you? Does the pic you attached show the current state? I'd like to hear more about what you've done.
 
My thoughts about sleeving aluminium coolant pipes.
I know what happens when moisture gets trapped between the wrap with mild steel headers who are wrapped.
Aluminium is a great heat conductor but doesn't like moisture as it will corrode heavely. So I would never heat wrap my coolant pipes, I rather have my coolant pipes radiant the heat and vapourise any moisture that traps inside the tunnel.
I used heat insulation mats on top of the tunnel to keep the heat out of the drivers compartment.
My brake & clutch lines run over the insulation inside the drivers compartment and are covered by a large U shape aluminium tunnel cover that slides over the tunnel.

Only pipe work that runs through my tunnel ar the two aluminium cooland pipes and one copper radiator vent pipe that runs from top rad to expansion tank.

There are definitely disputes I have been seeing on various forums regarding fiberglass wraps over the years - I've used it myself in other applications with success (mild steel headers). Both sides have valid arguments. Indeed, heat does generate moisture - that is a fact.

Improper wrapping will accelerate corrosion and shorten the lifespan of the the parts in question, however, this is aluminum, and its corrosion resistance is quite impressive. It doesn't rust per se, but obviously, it can corrode. I'm having to spend many hours cleaning up my G96/01 that has surface oxidation. Not a fun process, and I don't know which is worse, trying to remove surface rust from steel, or removing oxidation from aluminum.

That said, these are not daily drivers, and in reality most of the replicas I've seen have very low mileage. In other words, How much of a factor could corrosion even be (it's a legitimate question)? I've personally never seen a GT40 replica with more than a few thousand miles on them. If there is corrosion that finally becomes serious enough to address, I'm guessing that's going to be long after I'm gone. When that time comes, it can be the future owner's project to replace the coolant tubes.

That's my thinking, of course (and I could be totally wrong) - I'm not a metalurgist, and I don't play one on TV - which is also why I'm hoping someone who has actually wrapped (or something similar) the coolant tubes and has enough years on them to share their experience in the longer term can comment. I couldn't have been the only person to actually want to try this, and I see some other members who have expressed interest in doing something similar, so additional input isn't just helping me (although I certainly appreciate it) - it's potentially helping others who are entertaining the same thing.

Of note, that tunnel will have air flowing through it, I imagine, and that also should help mitigate moisture-related issues, shouldn't it?

For anyone interested in the properties of aluminum (focused on corrosion resistance), I read this and thought it was pretty good..


Nice setups, gents, and thanks for the input and pictures so far. It gives me something to think about.
 
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