Radiator construction

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jas0162 said:
I had an aftermarket 2 row aluminum radiator in my 68 when i plowed into a damn deer in the middle of the night in the middle of nowhere. The radiator was bent into a banana shape and the fan beat the **** out it before i got stopped. I bent the fan blades back and drove on home, no leaks. No way a brass one would have survived that. Im sold on the aluminum ones
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Damn, that was lucky. I've seen deer stop a semi. I've seen an elk kill a guy and his wife and that bastard walked away and died about 500 yards off the road. It looked like that car hit a wall or something. We were the second people on the scene. It was horrible.

I've damn near hit elk on my dirt bike. They just don't care.
 
gzig5 said:
Have you done any testing of the cooling efficiency of an unpainted aluminum radiator vs one painted black?
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I know for sure painting the tanks won't do anything because those parts aren't intended to shed heat anyway, they are just tanks to hold the coolant. And just an assumption but unless you manage to fully coat all of the fins and tubes through the entire thickness of the core (not easy) I highly doubt it will affect the heat transfer ability. "Radiator" is a misleading name anyway, they don't work off radiation they work off convection. Black vs. white surfaces only affect radiative heat transfer, like from an old-school cast iron stove that sits in the middle of a room. You feel the heat coming off it even if the air isn't moving around.

I was worried about painting my radiator at first, I was looking for special "radiator paint" then I did a common-sense reality check and just used some simple Krylon combo black paint+primer (less coats needed without a separate primer). Could still be a real thing though I don't have evidence to say it's not true.
 
MopaR&D said:
I know for sure painting the tanks won't do anything because those parts aren't intended to shed heat anyway, they are just tanks to hold the coolant. And just an assumption but unless you manage to fully coat all of the fins and tubes through the entire thickness of the core (not easy) I highly doubt it will affect the heat transfer ability. "Radiator" is a misleading name anyway, they don't work off radiation they work off convection. Black vs. white surfaces only affect radiative heat transfer, like from an old-school cast iron stove that sits in the middle of a room. You feel the heat coming off it even if the air isn't moving around.

I was worried about painting my radiator at first, I was looking for special "radiator paint" then I did a common-sense reality check and just used some simple Krylon combo black paint+primer (less coats needed without a separate primer). Could still be a real thing though I don't have evidence to say it's not true.
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Actually, you can't shed thermal energy, unless it is radiated through the air or conducted through contact. Thermal radiation is the movement of thermal energy from one mass to another. Convection is the flow of air due to thermal energy and differential temperatures. Heat sink with no fan is a good example of convection cooling. aka, heat rises. Put a fan across the heatsink and it really isn't convection anymore because the fan causes the air flow.

We proved that painting the inside surface of our product's aluminum enclosure matte black reduced the internal temperature up to 8% in a convection environment. That was enough for us to add that cost to manufacturing so the product could exceed its performance ratings with enough margin. I was just curious if they had done any testing. I'm fairly certain the difference is measurable, but whether it is significant enough to add the cost is a different equation.
 
gzig5 said:
Actually, you can't shed thermal energy, unless it is radiated through the air or conducted through contact. Thermal radiation is the movement of thermal energy from one mass to another. Convection is the flow of air due to thermal energy and differential temperatures. Heat sink with no fan is a good example of convection cooling. aka, heat rises. Put a fan across the heatsink and it really isn't convection anymore because the fan causes the air flow.

We proved that painting the inside surface of our product's aluminum enclosure matte black reduced the internal temperature up to 8% in a convection environment. That was enough for us to add that cost to manufacturing so the product could exceed its performance ratings with enough margin. I was just curious if they had done any testing. I'm fairly certain the difference is measurable, but whether it is significant enough to add the cost is a different equation.
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Right, technically the thermal energy has to conduct from the water, through the aluminum, then through the coating/paint before it can be "carried away" by the air. I was making the point that "radiators" work through heat being conducted into the air flowing through the core; if there's no forced air flow through the rad then the heat just hangs around and builds up. I remember working problems in my heat transfer class that dealt with combined conduction and convection, in those scenarios the fluid flowing over the outside has its own "convection coefficient" where the heat transfer equals the convection coefficient times the exposed area, times the difference in temperature between the surface and surroundings. IIRC in most cases the fluid was flowing continuously over the surface as if it was forced so convection could either be with forced fluid or fluid that moves 'naturally' due to the hotter parts closest to the surface being less dense. I must confess though that class was very difficult I'm by no means an expert on the subject lol.
 
MopaR&D said:
Right, technically the thermal energy has to conduct from the water, through the aluminum, then through the coating/paint before it can be "carried away" by the air. I was making the point that "radiators" work through heat being conducted into the air flowing through the core; if there's no forced air flow through the rad then the heat just hangs around and builds up. I remember working problems in my heat transfer class that dealt with combined conduction and convection, in those scenarios the fluid flowing over the outside has its own "convection coefficient" where the heat transfer equals the convection coefficient times the exposed area, times the difference in temperature between the surface and surroundings. IIRC in most cases the fluid was flowing continuously over the surface as if it was forced so convection could either be with forced fluid or fluid that moves 'naturally' due to the hotter parts closest to the surface being less dense. I must confess though that class was very difficult I'm by no means an expert on the subject lol.
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I'm an Electrical Engineer, but they made me take Thermo "to broaden my knowledge" whether I wanted to or not, so I'm semi-dangerous in this arena. They made the ME's take a circuits class too. Poor bastards...
All good. I guess when I see "convection" I automatically jump to a heat sink in a neutral environment from an air movement standpoint where there is only casual air movement, no fans. This kind of application is the most challenging to design for and still deliver a product that is small enough but puts out enough power with a good service life. In the same way, it's hard on our car's cooling system when they don't have a 60 mph headwind pushing air through the radiator. Surface area of the tubes and fins becomes very important.
 
AndyF said:
It doesn't really matter for any of the projects I work on, either work just fine. Race cars usually get an aluminum radiator while street cars and resto mods get the factory style. I put a factory Cordoba radiator in my '72 Duster just because it looks original that way. I don't think I'll have any trouble keeping the big block cool with the factory radiator and it looks stock. A lot of aluminum radiators look like a Pep Boy mess under the hood. I prefer a cleaner look on my projects.
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Oh Yah That looks like a real stock set up ya got there. LOL
I would not change a thing the concourse judges may spot it.
 
gzig5 said:
I'm an Electrical Engineer, but they made me take Thermo "to broaden my knowledge" whether I wanted to or not, so I'm semi-dangerous in this arena. They made the ME's take a circuits class too. Poor bastards...
All good. I guess when I see "convection" I automatically jump to a heat sink in a neutral environment from an air movement standpoint where there is only casual air movement, no fans. This kind of application is the most challenging to design for and still deliver a product that is small enough but puts out enough power with a good service life. In the same way, it's hard on our car's cooling system when they don't have a 60 mph headwind pushing air through the radiator. Surface area of the tubes and fins becomes very important.
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LOL oh man you got that right, I'm an ME and trying to take Physics 2 (E&M) and Circuits was like trying to learn Chinese... Thermo is my favorite subject but when it comes to electricity none of it makes sense to me.

I thought I was good at heat transfer (actually a separate course from Thermodynamics) until I took this past grad-level class, holy crap talk about a reality check.
 
The level of expertise on this forum never ceases to amaze me. Definitely some heavy hitters. All the way up from the backyard garage mechanics who have lived cars as a lifestyle all the way up to design and R&D work in fields way beyond what the factory engineers even contemplated when our anachronistic machinery (far from outdated, I might add) was designed and built.
 
Just seen this thread and still want to read all the replies first but my initial thoughts from what I remember ...aluminum holds more pressure than brass...is lighter weight and is cheaper. I think that brass dissipates heat better or I should say faster but I don't really have any evidence per se to back that up ...it's something I was kind of told a long time ago when I was about 17 years old.
I only need a single row aluminum radiator for 410 inch small block, and I like that as opposed to a heavier multi row brass core.
 
As i see there is a group of very knowledgeable people here, i would like to ask a question.
Im having a cooling issue with a non mopar,custom built rad.
The cores are staggered.
Three rows, but one is offset and i think its screwing with the airflow?
It should cool a small block without issue and it does not.
 
Unfortunately, there’s a lot more to keeping a car cool than just the cooling system. But that radiator sounds like a turbulence nightmare. What is the rest of the combination like, and more importantly, no lean condition or vacuum leaks or timing issues. Make sure the tuning is right. Is there fan shroud with no more than one inch of clearance ar the fan? Mechanical or electrical fans? High flow thermostat and water pump in place?
 
Tooljunkie said:
As i see there is a group of very knowledgeable people here, i would like to ask a question.
Im having a cooling issue with a non mopar,custom built rad.
The cores are staggered.
Three rows, but one is offset and i think its screwing with the airflow?
It should cool a small block without issue and it does not.
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Off the top of my head I wish I knew something about a staggered design, because I don't, I don't understand why one would be necessary.
What vehicle is it, like what's the front end look like?
 
1975 engine. Quadra-jet. I just overhauled carb as there was no change on idle mixture screws.
That improved engine running.
I replaced timing chain,as there was 12 degrees on crank before distributor started to move.
So if anything its running a heck of a lot better, no change whatsoever in cooling.
Electric fan. Hayden 18”.
 
Its a 49 ihc truck body on a 75 blazer chassis. 350/4 bbl and headers.
 
AndyF said:
It doesn't really matter for any of the projects I work on, either work just fine. Race cars usually get an aluminum radiator while street cars and resto mods get the factory style. I put a factory Cordoba radiator in my '72 Duster just because it looks original that way. I don't think I'll have any trouble keeping the big block cool with the factory radiator and it looks stock. A lot of aluminum radiators look like a Pep Boy mess under the hood. I prefer a cleaner look on my projects.
View attachment 1715359396
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Where's my "That's friggin' cool" button!
 
69_340_GTS said:
You don't braze a brass radiator, Soldering is what is used. Brass radiators are soldered together, and this is also how you repair them.
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But you can braze a hole shut or repair a crack. Yes, brazing and stick welding for that matter is a dying art.
 
MopaR&D said:
LOL oh man you got that right, I'm an ME and trying to take Physics 2 (E&M) and Circuits was like trying to learn Chinese... Thermo is my favorite subject but when it comes to electricity none of it makes sense to me.

I thought I was good at heat transfer (actually a separate course from Thermodynamics) until I took this past grad-level class, holy crap talk about a reality check.
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And not to betray my age but I was also required to sort out a Wheatstone Bridge in one of my core classes. Baffled me then and frankly I have never used it in thirty plus years in the field. Instructor was adamant that we understand it. He was maybe 90! Hah! I would love to throw a 4-20MA loop on him today! All that for a Mechanical guy! Never understood some of the rationale behind curriculum. I ended up helping establish curriculum for Mechatronix classes at a couple universities. I can assure you there was no Wheatstone bridges included!
 
Sublime one said:
And not to betray my age but I was also required to sort out a Wheatstone Bridge in one of my core classes. Baffled me then and frankly I have never used it in thirty plus years in the field. Instructor was adamant that we understand it. He was maybe 90! Hah! I would love to throw a 4-20MA loop on him today! All that for a Mechanical guy! Never understood some of the rationale behind curriculum. I ended up helping establish curriculum for Mechatronix classes at a couple universities. I can assure you there was no Wheatstone bridges included!
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Haven't heard that term for decades.
 
Garrett Ellison said:
The level of expertise on this forum never ceases to amaze me. Definitely some heavy hitters. All the way up from the backyard garage mechanics who have lived cars as a lifestyle all the way up to design and R&D work in fields way beyond what the factory engineers even contemplated when our anachronistic machinery (far from outdated, I might add) was designed and built.
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GE,
I totally agree with you, the collective knowledge on here could give NASA boys a run for their money! Some of the guys on here are exceptionally well educated but also super smart and talented. Those traits are not always exclusive! Hah!
 
Sublime one said:
And not to betray my age but I was also required to sort out a Wheatstone Bridge in one of my core classes. Baffled me then and frankly I have never used it in thirty plus years in the field. Instructor was adamant that we understand it. He was maybe 90! Hah! I would love to throw a 4-20MA loop on him today! All that for a Mechanical guy! Never understood some of the rationale behind curriculum. I ended up helping establish curriculum for Mechatronix classes at a couple universities. I can assure you there was no Wheatstone bridges included!
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Funny you mention that, one of the natural gas instruments we are evaluating for research uses a Wheatstone bridge in the detector unit. I don't know how it works or why it's there but I read it in the user's manual! LOL
 
MopaR&D said:
Funny you mention that, one of the natural gas instruments we are evaluating for research uses a Wheatstone bridge in the detector unit. I don't know how it works or why it's there but I read it in the user's manual! LOL
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I was going to suggest that the Wheatstone is a powerful little tool for instrumentation, but you beat me to it. Fun stuff.
 
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