Quick tranny cooling question, 727
11-22-2008, 02:27 AM
#16
Administrator
Well, I reckon I'll be the stick in the mud and vote for the cooler.
(NOTE: The following numbers are off the top of my head therefore out of reach of the digits on my hands and feet).
- Having simply more fluid does not equate to more cooling effect.
When it comes to heat transfer between two things, in this case, hot fluid to cooler air (heat always moves to the cooler object), of the numerous facets effecting such, . . .
- The difference between a standard pan, and say a unit with four quarts additional capacity, amounts to the additional metal involved in making the pan deeper. For our discussion let's imagine the pan is 12" square. For our discussion let's say we can accomplish the additional capacity by making the pan 2" deeper.
- The four 12" sides adds up to 48". Making it 2" deeper means we're adding 96 square inches of surface area to the pan.
Now let's consider what might be the more commonly seen remote cooler with a fan. For the sake of our discussion, let's say it is a six-pass cooler using 1/2" OD pipe in an 8" x 10" x 1" finned assembly.
- If one were to straighten all the pipe, split it down one side, and unroll the pipe so as to make a single strip of metal we might have (again for the sake of easy discussion) a 1" wide strip that's about 70" long (six at 10" plus five U-bends at a conservative 2" long)
With comparing the surfaces areas thus far, we have approx 96sq/in for the pan vs the 70sq/in of the cooler's pipe.
Now add all the added surface area afforded the cooler with the addition of the fins. Figure perhaps 10 fins per inch of cooler. that's about 10" at 10 fins per inch or 800 sq/in.
That comes to roughly 870sq/in of surface area (8" x 10" x 1" finned assembly) compared to the 96sq/in of the pan.
That's a BIG difference in the world of thermal dynamics as the exchange of heat is by way of the surface area..
Also consider that the thickness of the metal effects the heat transfer rate. The typical aluminum pan is much thicker at the point of fluid to air transfer as compared to the thinner pipe. This is skewed even more by the fact that most of the coolers run copper pipe which thermally conducts heat better than a comparable unit of aluminum.
IMO, you'll get a much better bang for the buck with a cooler.
So say the voices.
Yes, I've been drinking tonight.
(NOTE: The following numbers are off the top of my head therefore out of reach of the digits on my hands and feet).
- Having simply more fluid does not equate to more cooling effect.
When it comes to heat transfer between two things, in this case, hot fluid to cooler air (heat always moves to the cooler object), of the numerous facets effecting such, . . .
- The difference between a standard pan, and say a unit with four quarts additional capacity, amounts to the additional metal involved in making the pan deeper. For our discussion let's imagine the pan is 12" square. For our discussion let's say we can accomplish the additional capacity by making the pan 2" deeper.
- The four 12" sides adds up to 48". Making it 2" deeper means we're adding 96 square inches of surface area to the pan.
Now let's consider what might be the more commonly seen remote cooler with a fan. For the sake of our discussion, let's say it is a six-pass cooler using 1/2" OD pipe in an 8" x 10" x 1" finned assembly.
- If one were to straighten all the pipe, split it down one side, and unroll the pipe so as to make a single strip of metal we might have (again for the sake of easy discussion) a 1" wide strip that's about 70" long (six at 10" plus five U-bends at a conservative 2" long)
With comparing the surfaces areas thus far, we have approx 96sq/in for the pan vs the 70sq/in of the cooler's pipe.
Now add all the added surface area afforded the cooler with the addition of the fins. Figure perhaps 10 fins per inch of cooler. that's about 10" at 10 fins per inch or 800 sq/in.
That comes to roughly 870sq/in of surface area (8" x 10" x 1" finned assembly) compared to the 96sq/in of the pan.
That's a BIG difference in the world of thermal dynamics as the exchange of heat is by way of the surface area..
Also consider that the thickness of the metal effects the heat transfer rate. The typical aluminum pan is much thicker at the point of fluid to air transfer as compared to the thinner pipe. This is skewed even more by the fact that most of the coolers run copper pipe which thermally conducts heat better than a comparable unit of aluminum.
IMO, you'll get a much better bang for the buck with a cooler.
So say the voices.
Yes, I've been drinking tonight.
This scares me the way you think.
Sometimes I think you have the other half of my brain.
Jim
11-22-2008, 05:18 AM
#17
Registered User
Go with the cooler, Chrysler didn't put a deep pan on it because they knew that for harsh use more was needed. If they could've got away with a bigger pan they would've cheaped out and done it. That's my perspective on the matter.
11-22-2008, 06:20 AM
#18
Registered User
You think the cooler on the block really heats it up more than it cools? Obviously, the best setup would be a deep trans pan and a extra cooler, but this is supposed to be a budget build for weekend fun. So I'm thinking of going with one or the other. I do plan to install a converter before I go really run it hard, as I know the stocker really heats things up being loose as it is. I figure that would be about the best $300ish bucks I can spend related to the tranny.
Jason
Jason
The exchanger on the right side of the block is to WARM up the fluid. The exchanger at the radiator is to cool it down. For towing/hauling Dodge offered an under bed exchanger with fan.
When I was doing my searching to decide between $$ for a pan or a cooler/fan I settled on the underbed exchanger with fan. So far so good.
11-22-2008, 07:13 AM
#19
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Well sounds like a cooler and fan... Thanks for the thoughts and suggestions. Now the question is how should I set it up? Are you guys plumbing it inline to go through the fan/cooler last, just before the fluid runs back into the trans? How high of pressure are those lines?
Jason
Jason
11-22-2008, 07:20 AM
#20
Registered User
I routed mine just like the factory did them basically.
I used 1/2" hydraulic line. I'll have to crawl under the truck to look and see exactly where I tee'd in.
Make sure your cooler is 1/2" lines.
I used 1/2" hydraulic line. I'll have to crawl under the truck to look and see exactly where I tee'd in.
Make sure your cooler is 1/2" lines.
11-22-2008, 08:05 AM
#21
1st Generation Admin
The stock/OEM transmission fluid flow is . . .
- The fluid leaves the transmission on the driver's side, just behind where the bell-housing connects to the gear-box.
- A few inches out of the trans the fluid flows past the in-line temperature sensor for the OD control.
- From there, the fluid flows to the tube & shell type heat exchanger mounted under the exhaust manifold. There, the fluid is warmed to a minimum temperature, or cooled if the fluid is warmer than the engine coolant circulating in the heat exchanger.
- Now the transmission fluid flows to the little radiator (also a heat exchanger) mounted up front next to the driver's side headlight where the fluid can be cooled even more.
STOP!
If it's the dead of winter, how is cooling the fluid of help after trying to keep the fluid at a minimum operating temperature? How do the two heat exchangers work together?
- If you look in the engine bay, between the battery and the main radiator, you'll see the two transmission fluid lines going to and from the little transmission fluid radiator. Notice the little things that appear to be spacers between the two lines. My initial thoughts were that they were some kind of support for the hoses. Nope, not even close.
They are actually pipes that basically short-circuit the transmission fluid flow. Here's the way it works ~
In the winter . ..
- The warm fluid flows to the little radiator where it's cooled.
- In cooling the fluid, that fluid in the little radiator gets thicker. As such, it takes more work to push it through the little radiator. Hold that thought . . .
- The warm fluid coming from the transmission, like anything else, will take the path of least resistance. With the cold, thick fluid sorta blocking the flow through the little radiator, the warmer fluid will now tend to flow more-so through the little by-pass tubes effectively by-passing the little radiator.
Pretty slick.
- From there, the transmission fluid flows back the the transmission itself.
As we add supplemental coolers to help dump the higher heat added to the fluid by heavily working the truck, Dodge offered the supplemental remote cooler (W/thermostatically controlled fan) mounted back on the frame rail, up under the driver's side. As far as the transmission fluid flow goes, and in keeping with dumping the work added heat, it's the best location (fluid flow wise) to put the remote cooler.
So say the voices.
- The fluid leaves the transmission on the driver's side, just behind where the bell-housing connects to the gear-box.
- A few inches out of the trans the fluid flows past the in-line temperature sensor for the OD control.
- From there, the fluid flows to the tube & shell type heat exchanger mounted under the exhaust manifold. There, the fluid is warmed to a minimum temperature, or cooled if the fluid is warmer than the engine coolant circulating in the heat exchanger.
- Now the transmission fluid flows to the little radiator (also a heat exchanger) mounted up front next to the driver's side headlight where the fluid can be cooled even more.
STOP!
If it's the dead of winter, how is cooling the fluid of help after trying to keep the fluid at a minimum operating temperature? How do the two heat exchangers work together?
- If you look in the engine bay, between the battery and the main radiator, you'll see the two transmission fluid lines going to and from the little transmission fluid radiator. Notice the little things that appear to be spacers between the two lines. My initial thoughts were that they were some kind of support for the hoses. Nope, not even close.
They are actually pipes that basically short-circuit the transmission fluid flow. Here's the way it works ~
In the winter . ..
- The warm fluid flows to the little radiator where it's cooled.
- In cooling the fluid, that fluid in the little radiator gets thicker. As such, it takes more work to push it through the little radiator. Hold that thought . . .
- The warm fluid coming from the transmission, like anything else, will take the path of least resistance. With the cold, thick fluid sorta blocking the flow through the little radiator, the warmer fluid will now tend to flow more-so through the little by-pass tubes effectively by-passing the little radiator.
Pretty slick.
- From there, the transmission fluid flows back the the transmission itself.
As we add supplemental coolers to help dump the higher heat added to the fluid by heavily working the truck, Dodge offered the supplemental remote cooler (W/thermostatically controlled fan) mounted back on the frame rail, up under the driver's side. As far as the transmission fluid flow goes, and in keeping with dumping the work added heat, it's the best location (fluid flow wise) to put the remote cooler.
So say the voices.
11-22-2008, 11:38 AM
#22
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Thanks for all the info! So good quality 1/2" oil hose would work? We cary Areoquip oil hose here at the shop, its good for 250 psi. I'm thinking of using that.
Jason
Jason
11-22-2008, 02:32 PM
#23
Registered User
I cut in right past the OD sensor to run to my cooler.
Now that I didn't know but wondered how the two opposing elements worked. I'll have to go out and look at that now...
- If you look in the engine bay, between the battery and the main radiator, you'll see the two transmission fluid lines going to and from the little transmission fluid radiator. Notice the little things that appear to be spacers between the two lines. My initial thoughts were that they were some kind of support for the hoses. Nope, not even close.
They are actually pipes that basically short-circuit the transmission fluid flow. Here's the way it works ~
In the winter . ..
- The warm fluid flows to the little radiator where it's cooled.
- In cooling the fluid, that fluid in the little radiator gets thicker. As such, it takes more work to push it through the little radiator. Hold that thought . . .
- The warm fluid coming from the transmission, like anything else, will take the path of least resistance. With the cold, thick fluid sorta blocking the flow through the little radiator, the warmer fluid will now tend to flow more-so through the little by-pass tubes effectively by-passing the little radiator.
Pretty slick.
- From there, the transmission fluid flows back the the transmission itself.
They are actually pipes that basically short-circuit the transmission fluid flow. Here's the way it works ~
In the winter . ..
- The warm fluid flows to the little radiator where it's cooled.
- In cooling the fluid, that fluid in the little radiator gets thicker. As such, it takes more work to push it through the little radiator. Hold that thought . . .
- The warm fluid coming from the transmission, like anything else, will take the path of least resistance. With the cold, thick fluid sorta blocking the flow through the little radiator, the warmer fluid will now tend to flow more-so through the little by-pass tubes effectively by-passing the little radiator.
Pretty slick.
- From there, the transmission fluid flows back the the transmission itself.
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