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Radiator core differences

Wietse

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Hey guys,

Now with the warmer weather i see my temperatures often exceed 200* when standing still for some time. (185* termostat)

I know my radiator is not the original one from the car, it is a 2785-942, 26", which supposed to be from a '67 C-body.
From what i found is that mine should have a 2949-054. (also 26")
The radiator currently installed is a single row with a core thickness of around 1-9/16", what type of core does a 2949-054 radiator have?
I read someone "guessing" it would be a 3-row core and then it should be quite thicker as well compared to the 1-9/16" i have now.
I want to see if i can find the right replacement core for this, probably aftermarket as i am not willing to pay $1400 for a factory correct radiator.
Just looking for some improved capacity.

It's for a '69 Coronet R/T with 440, auto, non ac, 4.10 ratio rear axle with sure grip.

I found this on a "local" parts store here in Europe, to me this one would be a good upgrade, right? (3-row, 2" thick)
https://www.moparshop.com/en/Online...diator-B-Body-26-66-69-BBM-Standard-A/T?c=585
Not sure what you guys have on experience in regards to single row and 3-row types radiators.

Edit: What would the difference be between factory ac and no ac?

Any info or suggestions would be welcome.
 
Last edited:
Maybe it's not the radiator. Have you made any modifications to the engine?
 
Maybe it's not the radiator. Have you made any modifications to the engine?

The engine is not stock, upgraded with some cam and Holley Sniper EFI but nothing extreme.
Bear in mind it has a track type rear axle which always added a 26" radiator for a reason, it just needs more cooling.
To me this single row radiator is already under rated for a stock engine, therefore i would expect a 3-row would only improve things but i have no experience in going from one type radiator to the other and what the differences are.
What i know if that with a 185* thermostat the coolant should be just above that in normal circumstances, 200* just shows a lack of efficiency with a full open thermostat.
 
I bought the 170 ebay special aluminum radiator, fits and works great
 
After some communication with the parts shop they advised to go with the high efficiency 4-row radiator.
A 3-row would probably do as well but for a bit more i could get one that should be well capable and probably never have to look at the temperature gauge anymore with any concerns.

Once installed and tested will post the results for anyone interested.
 
Do some web research on the effectiveness off 2 core vs 3 core vs 4 core and vs tube size. Lots of tests have been done and is very informative.
 
When i looked through the radiator yesterday i could only see 1 row as i was not straight in front of it, but today i removed the cap and looked inside and it actually has 2 rows. My bad...

Anyway the one on order is a 4 row, which could only improve things i believe.
I am not expecting it would need much more compared to now but it is never a bad thing to have a radiator with some over kill.
Since there is also a aftermarket oil cooler in front for the transmission which would take some efficiency i guess as well.
Hopefully i can install it in 1-2 weeks and still test it out with some hot days to come.
 
Do some web research on the effectiveness off 2 core vs 3 core vs 4 core and vs tube size. Lots of tests have been done and is very informative.

The effectiveness of a 4 tube vs 3 tube core is dubious. The 4th tube is being cooled with air coming off the third tube (and subsequently the third tube being cooled from air coming off the 2nd tube). It has everything to do with the APPROACH temperature difference. Like trying to cool 190°F coolant with 180°air. Depending on the VOLUME of air and its temperature and volume of coolant (and its temperature), very LITTLE heat is being exchanged in terms of Btu's transferring from one media (liquid) to the other media (air). The coolant traveling thru the tubes (temperature) remains relatively the same (parallel flow...top to bottom), but the air temperature increases as it travels thru the radiator. By the time the hot air reaches the 4th tube row, its almost the same temperature as the coolant....no or very heat is transferred. What's important is the fins between the tube rows. The higher the fins/inch count (18-20 fins/lineal inch) the more SURFACE AREA is available to transfer the entrained heat in the tubes to the fins to the air stream passing thru the fins. In addition, VELOCITY of both media streams is important....the higher the velocity the more heat is transferred....from the heat source (engine) to the heat exchanger (radiator) to the air stream passing thru the radiator's fins. This is a fundamental principle of thermodynamics.
BOB RENTON
 
Thx all for your input.

Obviously the thicker core will come with more fin area compared to the old one.
I can not fully agree with you Bob, velocity and turbulence are important factors for heat exchangers, though velocity is more for the cooling medium (in this case the air) as you want a maximum of this infinite cooling medium to pass through to get a high as possible delta-T between air and coolant.
This is what does good for the 4th row still getting relative cold air.
Turbulence is more important for the coolant inside the radiator core to continue mixing while it cools.
With more tubes to flow through the coolant velocity inside the core will reduce, GPM of flow produced by the pump could slightly increase (due to less back pressure) but remains same as a minimum.
This should provide more time for the coolant to cool down inside the core with more surface area to give it off to.
The air velocity remains same as i will not change the radiator fan setup, restriction will become higher due to the denser core but i have faith that the flex-fan will manage to pull sufficient air through.
I really like the way they work, at low rpm they are at full pitch on the blades and shove heaps of air.
Therefore i suspect the core to be not sufficient, after all it was designed to cool a C-body 383 engine.

I have put my faith on a 4-row core now, for sure it will improve things but it is always nice to hear if someone has some experience with a swap like that.
 
The effectiveness of a 4 tube vs 3 tube core is dubious. The 4th tube is being cooled with air coming off the third tube (and subsequently the third tube being cooled from air coming off the 2nd tube). It has everything to do with the APPROACH temperature difference. Like trying to cool 190°F coolant with 180°air. Depending on the VOLUME of air and its temperature and volume of coolant (and its temperature), very LITTLE heat is being exchanged in terms of Btu's transferring from one media (liquid) to the other media (air). The coolant traveling thru the tubes (temperature) remains relatively the same (parallel flow...top to bottom), but the air temperature increases as it travels thru the radiator. By the time the hot air reaches the 4th tube row, its almost the same temperature as the coolant....no or very heat is transferred. What's important is the fins between the tube rows. The higher the fins/inch count (18-20 fins/lineal inch) the more SURFACE AREA is available to transfer the entrained heat in the tubes to the fins to the air stream passing thru the fins. In addition, VELOCITY of both media streams is important....the higher the velocity the more heat is transferred....from the heat source (engine) to the heat exchanger (radiator) to the air stream passing thru the radiator's fins. This is a fundamental principle of thermodynamics.
BOB RENTON
Well said. Thanks for the explanation.
 
Thx all for your input.

Obviously the thicker core will come with more fin area compared to the old one.
I can not fully agree with you Bob, velocity and turbulence are important factors for heat exchangers, though velocity is more for the cooling medium (in this case the air) as you want a maximum of this infinite cooling medium to pass through to get a high as possible delta-T between air and coolant.
This is what does good for the 4th row still getting relative cold air.
Turbulence is more important for the coolant inside the radiator core to continue mixing while it cools.
With more tubes to flow through the coolant velocity inside the core will reduce, GPM of flow produced by the pump could slightly increase (due to less back pressure) but remains same as a minimum.
This should provide more time for the coolant to cool down inside the core with more surface area to give it off to.
The air velocity remains same as i will not change the radiator fan setup, restriction will become higher due to the denser core but i have faith that the flex-fan will manage to pull sufficient air through.
I really like the way they work, at low rpm they are at full pitch on the blades and shove heaps of air.
Therefore i suspect the core to be not sufficient, after all it was designed to cool a C-body 383 engine.

I have put my faith on a 4-row core now, for sure it will improve things but it is always nice to hear if someone has some experience with a swap like that.

Incorrect assumption.... as the air passes thru the fins, the velocity slows down, due to turbulence, while the temperature increases, reducing the temperature DIFFERENCE or the approach temperature between the relative media streams. Efficient heat transfer can only be accomplished WHEN the two fluid streams are at maximum differences...cold air vs hot coolant. As one temperature approaches the other, little, if any, heat transfer occurs. This is the argument against the 4th tube row, closest to the fan, as it receives the hottest air against the same high temp coolant as the first row or the air INLET to the radiator.
You need to define the terms such as: "sufficient air flow" or "GPM of the flow increases as back pressure decreases. GPM is a function of impeller size and RPM", and possibility NPSHr (aka back pressure) and as velocity thru the core is refuced....conversely it is also is reduced in the heat source (engine) allowing the coolant to absorb more heat only to be conveyed to radiator....catch 22....the two fluid streams are the same....it cannot be slowed down in the radiator but not in the heat source (engine) as the two are mutually inclusive....with only ONE pump, providing the system motivation. Coolant flows and temperatures and the quantities of heat exchanged (Btu/hr) can only be expressed as real numbers....not "heaps of air" or "infinite cooling media (CFM or GPM?)". IF real numbers are known, then they could be inserted into equations to prove or disprove their influence on overall system performance...not just feelings..... Just my opinion of course.....
BOB RENTON
 
Incorrect assumption.... as the air passes thru the fins, the velocity slows down, due to turbulence, while the temperature increases, reducing the temperature DIFFERENCE or the approach temperature between the relative media streams. Efficient heat transfer can only be accomplished WHEN the two fluid streams are at maximum differences...cold air vs hot coolant. As one temperature approaches the other, little, if any, heat transfer occurs. This is the argument against the 4th tube row, closest to the fan, as it receives the hottest air against the same high temp coolant as the first row or the air INLET to the radiator.
The air temperature inside the radiator will not reach the coolant temperature, velocity slows down indeed so the higher the better to begin with especially to ensure that the 4th tube also gets good cooling but the air out of the radiator will not reach the coolant temperature in any case.
Even if that 4th tube reduces the coolant temperature from 190* to 180* is sufficient as this is still acceptable as it will mix with the coolant from the front tubes which will be much lower and only slightly affects the total temperature after the radiator.

You need to define the terms such as: "sufficient air flow" or "GPM of the flow increases as back pressure decreases. GPM is a function of impeller size and RPM", and possibility NPSHr (aka back pressure) (this is a fact, every pump performance curve shows less flow at higher back pressure/head) and as velocity thru the core is refuced....conversely it is also is reduced in the heat source (engine) allowing the coolant to absorb more heat only to be conveyed to radiator....catch 22....the two fluid streams are the same....it cannot be slowed down in the radiator but not in the heat source (engine) as the two are mutually inclusive....with only ONE pump, providing the system motivation.
That theory would be fully true if ALL coolant always passes through the radiator, but in reality there is only a partial water flow that passes through the radiator and the remaining amount is directly returned to the pump suction side where it mixes with the cold water returning from the radiator. (This is controlled by the thermostat, the hotter it gets, the more it opens.)
So your pump could push 20 GPM, yet only 5GPM could flow through the radiator and the remaining 15 gallon goes directly back in the engine, mixed with the 5GPM cooled water from the radiator.
The coolant flow on the engine side remains quite steady at a given rpm, the hotter it gets, the more the thermostat opens and the more flow of coolant start to pass through the radiator to maintain the set point.

Coolant flows and temperatures and the quantities of heat exchanged (Btu/hr) can only be expressed as real numbers....not "heaps of air" or "infinite cooling media (CFM or GPM?)". IF real numbers are known, then they could be inserted into equations to prove or disprove their influence on overall system performance...not just feelings.....
I do not have any measuring equipment for flow or velocity so running numbers is difficult, yet i am sure one can understand that if the same amount of coolant needs to pass through, say 60 cooling tubes or 120 cooling tubes, that the overall velocity in the 120 tubes is lower as there is more space to pass through which gives the coolant more time for heat transfer.
 
The air temperature inside the radiator will not reach the coolant temperature, velocity slows down indeed so the higher the better to begin with especially to ensure that the 4th tube also gets good cooling but the air out of the radiator will not reach the coolant temperature in any case.
Not necessarily true...air velocity does not slow down appreciably as it passes thru the radiator
Even if that 4th tube reduces the coolant temperature from 190* to 180* is sufficient as this is still acceptable as it will mix with the coolant from the front tubes which will be much lower and only slightly affects the total temperature after the radiator. YES....the blend temperature of the combined coolant will depend on the TOTAL volume circulated and it will depend on uniform air volume passing thru the radiator.


So your pump could push 20 GPM, yet only 5GPM could flow through the radiator and the remaining 15 gallon goes directly back in the engine, mixed with the 5GPM cooled water from the radiator.
The coolant flow on the engine side remains quite steady at a given rpm, the hotter it gets, the more the thermostat opens and the more flow of coolant start to pass through the radiator to maintain the set point.

Not necessarily true.....you're assuming that the t-stat is closed. Under actual operation, after the engine reaches opersting temp, the t-stat will be open, directing the bulk of the coolant (for argumentative purposes 98% of the coolant is directed to the radiator), and given the total number of tubes in the radiator, you're assuming that flow in each tube is uniform (highly unlikely) and its velocity thru the tubes remains constant and the engine's operating RPM, insuring that the pump RPM and cooling fan RPM remain constant, the system will acieve a steady state condition, which in an automotive application would be unusual. For a industrial application with the pump (operating at a fixed RPM with a fixed set of conditions: discharge pressure, in ft head and suction pressure, NPSHr at a constant temperature and viscosity) the statment would be true. You're assuming some unproven values of, 20 gpm snd 5 gpm, once the t-stat is open, circulated volume of both air flow across the radiator and coolant flow thru the block and radiator is subject to operating conditions. The blend temperature of the coolant exiting the radiator is a variable quantity depending on both air flow velocity and its entering and exiting temperature as well as coolant flow volumes and velocities depending on RPM.
To this end, we'll just have to agree to disagree on the stated premise. In another lifetime, I use to design high temperature gas to gas heat exchangers/heat recovery systems and also liquid to liquid process heat exchangers and liquid to gas heat exchangers, and in my experiences, gas to gas (and liquid) heat exchangers velocity, volume, metal temperatures, fouling factors, are important design parameters and consideration aspects. I maintain that the Laws of Thermodynamics are irrefutable and should be followed with hard numbers and not unproven suppositions.....including the "my buddy said......."
BOB RENTON
 
for argumentative purposes 98%

So you are allowed to put numbers for argumentative purposes but if i do that you blame me for not giving calculations and unproven arguments.....
I just put a number for the ease of understanding as well, i did not say anything about these are actual numbers.

I guess the function of a thermostat is unclear to you, a thermostat is not an open-close valve but starts to open at the given temperature and only opens more as the temperature continues to rise.
Until its piston reached its full stroke, which commonly is 15-20* higher then the opening temperature.
The more its open, the more coolant is getting by-passed through the radiator and thus more coolant gets cooled while the remaining coolant flow still is able to return directly to the pump suction side in an uncooled state but mixes with the cold coolant flow from the radiator before re-entering the engine.
There are applications where a thermostat is used that actually closes the direct return to the pump to push all coolant through its heat exchanger, but not in automotive applications.

And yes, this way the process works, at any engine rpm and at any flow in GPM that the pump puts out.
It does not matter if i say 20GPM or 2000GPM, a part of that flow gets cooled and a part of it returns to the pump directly depending on the variables mentioned above.

Down the line, if my 180* thermostat is fully open at 195* and my cooling system reaches temperatures above that said 195* (i've seen 205*) it simply means the cooling system is not capable, it lost control of cooling the engine. (only in summer temperatures)
Since i have the right radiator shroud and a good fixed mechanical fan i can't improve much there so the last option is the radiator core itself.
Since this is an "incorrect" 2-row radiator designed to work with a 383 engine it is easy to say this one would not be fit for purpose for a modified 440 with a 4.10 ratio rear axle in a 85* outside temperature.
So i am in need of an upgrade, hoping someone here had some good results with a 4-row core radiator.

Bob, you are very known here for your lecturing in theoreticals, but the fact is that likely the only guys who did the math on this cooling systems were the guys at Chrysler in the '60's and '70's.
We are here now without all the test equipment and calculations and share experiences of what works and what not.
The route to Aluminium radiators with shrouds and electric fan show many issues, with only some that had good succes so i don't like to choose that route.
Instead sticking with the OEM type brass cores with OEM shroud and mechanical fan, keeping it simple as built, gives me more confidence as most have good succes with that setup.
 
So you are allowed to put numbers for argumentative purposes but if i do that you blame me for not giving calculations and unproven arguments.....
I just put a number for the ease of understanding as well, i did not say anything about these are actual numbers.

I guess the function of a thermostat is unclear to you, a thermostat is not an open-close valve but starts to open at the given temperature and only opens more as the temperature continues to rise.
Until its piston reached its full stroke, which commonly is 15-20* higher then the opening temperature.
The more its open, the more coolant is getting by-passed through the radiator and thus more coolant gets cooled while the remaining coolant flow still is able to return directly to the pump suction side in an uncooled state but mixes with the cold coolant flow from the radiator before re-entering the engine.
There are applications where a thermostat is used that actually closes the direct return to the pump to push all coolant through its heat exchanger, but not in automotive applications.

And yes, this way the process works, at any engine rpm and at any flow in GPM that the pump puts out.
It does not matter if i say 20GPM or 2000GPM, a part of that flow gets cooled and a part of it returns to the pump directly depending on the variables mentioned above.

Down the line, if my 180* thermostat is fully open at 195* and my cooling system reaches temperatures above that said 195* (i've seen 205*) it simply means the cooling system is not capable, it lost control of cooling the engine. (only in summer temperatures)
Since i have the right radiator shroud and a good fixed mechanical fan i can't improve much there so the last option is the radiator core itself.
Since this is an "incorrect" 2-row radiator designed to work with a 383 engine it is easy to say this one would not be fit for purpose for a modified 440 with a 4.10 ratio rear axle in a 85* outside temperature.
So i am in need of an upgrade, hoping someone here had some good results with a 4-row core radiator.

Bob, you are very known here for
We are here now without all the test equipment and calculations and share experiences of what works and what not.
The route to Aluminium radiators with shrouds and electric fan show many issues, with only some that had good succes so i don't like to choose that route.
Instead sticking with the OEM type brass cores with OEM shroud and mechanical fan, keeping it simple as built, gives me more confidence as most have good succes with that setup.

"your lecturing in theoreticals, but the fact is that likely the only guys who did the math on this cooling systems were the guys at Chrysler in the '60's and '70's".
I've always believed that theoretical values formed the basis for facts.....whether you believe the theories (or understand them) or how to apply them, is somewhat moot. I'm not going to argue your understanding of thermodynamics or the ability to do the calculations to prove or disprove your point of view....suffice to say we have different viewpoints of what is acceptable or not.....so....who is right or wrong? It depends on one's overall objective and understanding of the concept.....and leave it go at that.......
BOB RENTON
 
I am not saying who is right and who is wrong, of course is a theory supported by some numbers and calculations the exact science, but i (and many here, including yourself probably) do not have any equipment to do the tests and run the numbers to calculate exact.
I only state we do not have to go that far, people with some hands on experience in the usage/swap of a said type of radiator/engine combo would already provide good info on the facts and could share their experiences.
Claiming numbers and facts that nobody here has and likely will never have does not help any of us as we simply do not keep flow meters for air/water systems and the likes in our toolbox.
 
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