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Old 04-01-2010, 07:24 PM   #1
Prochamro
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Default Dual Radiators: series or parallel?

I'm running a gear drive twin F1C Procharged SBC 406 street car. I have two 12 x12x2 aluminium radiators with 11" fans.
They have -12AN fittings, there is also a CSR electric water pump with heater outlet.
Which will be more efficient, the radiators connected one after the other in series. Or using a pair of Magnafuel -12AN y-blocks feeding them in parallel?

I need to idle in central London traffic, burnout, then idle again, for hours on end in summer heat!!!!
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Old 04-02-2010, 02:06 PM   #2
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Default Re: Dual Radiators: series or parallel?

Run them parallel as long as both are the same.
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Old 04-02-2010, 03:12 PM   #3
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Default Re: Dual Radiators: series or parallel?

How are they mounted? They aren't stacked are they? What kind of car? Those radiators are less than small, transcoolers are bigger than 12 X 12 (not trying to be negative or a smartass, just putting things into perspective). Can you put up some pics of your arraingement? oj
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Old 04-02-2010, 05:02 PM   #4
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Default Re: Dual Radiators: series or parallel?

im no expert but id have to say youd prolly get better cooling sending it through one, then into the second. i dont see how parallel would be better? nitrobully can you please explain, not doubting you one bit, just trying to understand
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Old 04-02-2010, 10:10 PM   #5
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Default Re: Dual Radiators: series or parallel?

PRESSURE DROP.
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Old 04-02-2010, 10:39 PM   #6
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Default Re: Dual Radiators: series or parallel?

You can control the temp better with parallel plumbing.
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Old 04-03-2010, 08:02 PM   #7
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Default Re: Dual Radiators: series or parallel?

if you run them in parallel watch out for flow differences from one core to the other.
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Old 04-04-2010, 03:49 AM   #8
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Default Re: Dual Radiators: series or parallel?

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Originally Posted by ojh View Post
How are they mounted? They aren't stacked are they? What kind of car? Those radiators are less than small, transcoolers are bigger than 12 X 12 (not trying to be negative or a smartass, just putting things into perspective). Can you put up some pics of your arraingement? oj
A bit like this but with twin F1C blowers and a 406 small block. I'm also not cutting the frame as mines a street car and we have a lot of corners in the UK. I think his are possibly Griffin custom 14 x 14 x 2's on a 565ci BBC with an F3R....



They went for series but is that the most efficient. Most of you say parallel.
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Old 04-04-2010, 12:25 PM   #9
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Default Re: Dual Radiators: series or parallel?

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Originally Posted by stangboy86 View Post
im no expert but id have to say youd prolly get better cooling sending it through one, then into the second. i dont see how parallel would be better? nitrobully can you please explain, not doubting you one bit, just trying to understand
Parallel would be better for heat transfer, with the higher delta-T across the cores.

As you lower the temperature of the coolant(bringing it closer to ambient), you lower the effectiveness of the radiator.


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Old 04-04-2010, 05:32 PM   #10
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Default Re: Dual Radiators: series or parallel?

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Originally Posted by frtlnrbuick View Post
Parallel would be better for heat transfer, with the higher delta-T across the cores.

As you lower the temperature of the coolant(bringing it closer to ambient), you lower the effectiveness of the radiator.


Jim
Thanks again, by the way the Magnafuel -12 AN Y blocks look great. Just I'll be using them for water....

That delta T theorem also explains why my Porsche 996 runs a pair of 8" x 10" x 1" radiators to cool a 320hp motor and still has the same small radiators on the 997 twin turbo at 550 hp!!!
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Old 04-04-2010, 05:37 PM   #11
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Default Re: Dual Radiators: series or parallel?

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Originally Posted by frtlnrbuick View Post
Parallel would be better for heat transfer, with the higher delta-T across the cores.

As you lower the temperature of the coolant(bringing it closer to ambient), you lower the effectiveness of the radiator.


Jim
This.

In series, the second radiator will be far less efficient.
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Old 04-04-2010, 05:59 PM   #12
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Default Re: Dual Radiators: series or parallel?

I believe i'd go series too, keep the water in the radiator as long as possible. I'd even consider doing a double pass arraingement. If you feed one radiator with say a -16 how many rows will equal the amount of flow of the -16? Say the hose flowed 1 gal a minute, i'd find out how many rows it took to equal the flow rate of the hose. Then i'd block and divert the water back thru the other portion of the radiator and zig-zag its' way across two radiators until it had enough surface area to give up the heat. I just finished turning a regular radiator into a triple pass, the water passes thru it 3 times befor exit.
Coolant engineers speak of an air saturation point, in brief a molecule or thimblefull of air will gather up just so much heat as it passes thru a radiator, be it 1" thick or many inches. To get the most effective cooling you need to get the heat into as much air as possible. Image a thimblefull of water going thru a parallel 12X12 radiator, that thimblefull will see 12" of air before returning to the motor. If you can do double pass-series that same thimblefull would see 48" of air.
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Old 04-04-2010, 09:48 PM   #13
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Default Re: Dual Radiators: series or parallel?

No disrespect ojh - your theories are very labour intensive and non productive.
KIS ,water molecules need to be "Shocked" into releasing their heat load- smaller radiators with minimun dead volume are the most efficient.
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Old 04-04-2010, 10:11 PM   #14
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Default Re: Dual Radiators: series or parallel?

They are not even correct for the most part Chukky.....

Externally they are constant flow devices, seeing a given amount of air for a given amount of time. Of course the exact amount is always changing but always independent of water flow. Whether the water goes 12" or 48" it is still going through the same amount of heat rejection. The consequence of a triple pass is each tube must flow three times as much water. Often this will result in more pumping losses, less total water flow and ultimately less heat rejection.

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Old 04-05-2010, 07:25 AM   #15
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Default Re: Dual Radiators: series or parallel?

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Originally Posted by Ryan Norton View Post
They are not even correct for the most part Chukky.....

Externally they are constant flow devices, seeing a given amount of air for a given amount of time. Of course the exact amount is always changing but always independent of water flow. Whether the water goes 12" or 48" it is still going through the same amount of heat rejection. The consequence of a triple pass is each tube must flow three times as much water. Often this will result in more pumping losses, less total water flow and ultimately less heat rejection.

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