Originally Posted by letsgetthisdone
(Post 11661319)
This was my thinking. That SS absorbs heat slower than aluminum, thus it doesn't radiate it to the other side as fast.
Now Im even more confused:lol: |
Heat exchangers aren't trying to block heat, they're trying to dissipate it. My thinking on these shields was that I was trying to block heat from reaching the balljoint boots.
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Originally Posted by V.8MR
(Post 11661322)
I don't think its a question of speed, rather a ratio of heat on 1 side vs the other. We are trying to block radiating heat. Not absorb it and dissipate it(like a radiator)
Also I have some gold foil I was going to install but I think its just not necessary. |
Aluminim radiators are usually due to weight savings from what I'm told. The old copper ones are better, but heavy. Copper is closer to Al than SS on the therm conductivity scale, FWIW.
I was told Al top hats on brake rotors transfer less heat to hub assys. I'm no an engineer nor chemist, so I'd have to research it. I sometimes confuse Specific Heat Capacity with conductivity LOL |
Originally Posted by letsgetthisdone
(Post 11661328)
Heat exchangers aren't trying to block heat, they're trying to dissipate it. My thinking on these shields was that I was trying to block heat from reaching the balljoint boots.
I dont wanna go completely off topic but how to the Ti brake shields work? Its almost like then ned to absorb and then dissipate immediately so the pistons dont get hot which in turn doesnt boil the fluid. |
Originally Posted by heel2toe
(Post 11661327)
Is that a fact? I thought it was the exact opposite? Why is it when people are Tig welding AL they will often times preheat the metal with an oxy torch prior to welding so it doesnt burn through? I thought thats bc AL heats up slower and it pulls the heat out so quickly?
Now Im even more confused:lol: |
Looks like if I ever start ballin again I'm gonna order a sheet of Ti from McMaster-Carr and redo these heat shields... :p
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Originally Posted by letsgetthisdone
(Post 11661338)
Looks like if I ever start ballin again I'm gonna order a sheet of Ti from McMaster-Carr and redo these heat shields... :p
I'm not even sure if my nibbler would cut Ti......? |
The issue is heat radiation. Not conduction or convection.
There will be no physical contact to the rotor and the shield so no conduction, convection is a non issue due to the airflow. So as far as radiation, we are blocking infrared light. As I read, you can think of radiated heat like a heat lamp. The radiated heat is not affected by air etc. Its "light" if you will. So realistically, either material will work in this regard. SS has less conductivity of heat thus the heat will not pass through it. Temp differential on the heated side vs non heated side where as aluminum will efficiently transfer the heat from 1 side to the other(which is why its good for radiators and heat sinks). But I'm no engineer haha so I could be dead wrong{thumbup} |
so it's a wash and we can go with what's cheapest. woohoo
:D Thinking about it..... Steel makes sense, though. Our cars have steel heat shields everywhere. As mentioned above, aluminum is good for drawing in and dissipating heat, which Is different than blocking it. The parts aren't touching, so no heat sink needed. Space in between = block heat. Not trying to reduce it. I.E. Exaust heat shield. Parts touching = absorb and radiate heat to reduce it. I.E. Radiator. Right? LOL |
Originally Posted by kaj
(Post 11661353)
so it's a wash and we can go with what's cheapest. woohoo
:D Thinking about it..... Steel makes sense, though. Our cars have steel heat shields everywhere. As mentioned above, aluminum is good for drawing in and dissipating heat, which Is different than blocking it. The parts aren't touching, so no heat sink needed. Space in between = block heat. Not trying to reduce it. I.E. Exaust heat shield. Parts touching = absorb and radiate heat to reduce it. I.E. Radiator. Right? LOL Radiated: Think infrared light. Convection: Heating surrounding air and thus anything the air contacts. Conduction: Similar to electrical conduction, requires physical contact. |
Originally Posted by V.8MR
(Post 11661375)
3 ways to move heat
Radiated: Think infrared light. Convection: Heating surrounding air and thus anything the air contacts. Conduction: Similar to electrical conduction, requires physical contact. |
Originally Posted by kaj
(Post 11661445)
Correct. I'm referring to the efficiency of different metals in protecting against those methods.
A good analogy is when sitting around a camp fire. You raise your hand to shield your face from the radiating heat of the fire. It doesn't matter what your hand is made of so long as it blocks infrared from passing through it. Just need to block the "light" from the source. The other 2 methods don't come into play. The shield makes no contact with the rotor for conductive heat. And there is ample air flow to prevent convection in any meaningful sense. |
Originally Posted by letsgetthisdone
(Post 11661336)
Damnit, I'm all wrong...HAHA. Aluminum has a higher specific heat than stainless steel. WTF...lol
Originally Posted by kaj
(Post 11661353)
so it's a wash and we can go with what's cheapest. woohoo
:D Thinking about it..... Steel makes sense, though. Our cars have steel heat shields everywhere. As mentioned above, aluminum is good for drawing in and dissipating heat, which Is different than blocking it. The parts aren't touching, so no heat sink needed. Space in between = block heat. Not trying to reduce it. I.E. Exaust heat shield. Parts touching = absorb and radiate heat to reduce it. I.E. Radiator. Right? LOL But to say its a wash doesnt seem like an acceptable answer in my mind. One must be better than the other for one reason or another.
Originally Posted by V.8MR
(Post 11661375)
3 ways to move heat
Radiated: Think infrared light. Convection: Heating surrounding air and thus anything the air contacts. Conduction: Similar to electrical conduction, requires physical contact. I think the heat is being transferred via convection but we may disagree on that too:lol:
Originally Posted by kaj
(Post 11661445)
Correct. I'm referring to the efficiency of different metals in protecting against those methods.
So lets break this down. Same shape size distance exposed to the same heat source we agree that the AL will take longer to heat up vs SS. The AL will also cool down much quicker relative to the SS. However Im not sure cooling down faster even matters if you think about it as were looking for heat protection during operation. So who cares how quickly it cools down; it's irrelevant. If AL heats up slower than so far I'd say it's in the lead here. However its not that simple because while it may take longer to heat up thats only giving you a said window of extra protection which is good but isnt the whole story. So what happens once they are both at the same temperature? Its the AL or the SS transferring the energy to the boots at the same rate now? I think since the SS will hold the heat it wont transfer as much to the boot. So now Im thinking that SS might actually be preferred:lol: But at the same time if its holding the heat vs dissipating it into the air then itsnt it now radiating that heat all around it thus heating up the boot? Im still extremely confused here. I always thought for these heat shields AL was the preferred choice but never thought much of it. Now that Im trying to break it down Im beyond confused and seems the more I know the more I realize that I don't know.:beer: |
Originally Posted by heel2toe
(Post 11661327)
Is that a fact? I thought it was the exact opposite? Why is it when people are Tig welding AL they will often times preheat the metal with an oxy torch prior to welding so it doesnt burn through? I thought thats bc AL heats up slower and it pulls the heat out so quickly?
Now Im even more confused:lol: Aluminum radiates heat throughout the metal very well compared to other metals. You weld aluminum and you are heating the entire piece. You weld steel and the heat stays near the Heat Affected Zone (relatively). If you want a heat shield, Titanium is best followed by steels. Aluminum and copper do not make good heat shields. |
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