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rear mount radiator water line sizes

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#21 ·
reddman said:
edit: Wait, after quoting you, did you delete your last post, or am I losing it? :confused:

I'm in no way a cooling expert or a motor expert, nor am I trying to swing a big dick around :D, I am just posting up my experience and what I believe to be true. I'm curious what part sounds contradictory. I'm not in this to argue, merely to increase my own and others knowledge.

If it is slowing the flow rate to increase thermal transfer, then here is a quote of Billa Vista's article about the rate of thermal transfer: "The rate at which this transfer occurs depends primarily on the difference in temperature between the two (the delta-T). When the difference is great, the transfer occurs extremely rapidly. As the temperature difference decreases - the rate of heat transfer decreases exponentially." I read this to back up what my own research has also showed, a marginal temperature difference between the water temp and block or air temp won't transfer heat very efficiently, high rate of water flow can cause this situation.
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Yes, I deleted it because I didn't want you to take offense and argue when I didn't really have any standpoint that I was trying to make in the first place. But I see you didn't take offense so I probably should have just left it.

I don't have time right now to read through the entire bible again but I do distinctly recall there being something about there being no such thing as too much velocity and that was mainly all I was referring to about my understanding of the bible. If my recollection is incorrect it wouldn't be the first time. :)

J. J.
 
#22 ·
patooyee said:
Yes, I deleted it because I didn't want you to take offense and argue when I didn't really have any standpoint that I was trying to make in the first place. But I see you didn't take offense so I probably should have just left it.

I don't have time right now to read through the entire bible again but I do distinctly recall there being something about there being no such thing as too much velocity and that was mainly all I was referring to about my understanding of the bible. If my recollection is incorrect it wouldn't be the first time. :)

J. J.
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Here we go, I knew I wasn't crazy:

"For those that cling tenaciously to myths, I am going to take one last crack at forever dispelling the Granddaddy of them all when it comes to cooling systems.

The myth is stated as either:

Coolant can be pumped too fast through the engine for it to absorb enough heat, or
Coolant can be pumped too fast through the radiator for it to cool properly, or
Cooling can be improved by slowing the flow of coolant through the radiator so it cools more completely.
NONE of these is true. The simple truth is that higher coolant flow will ALWAYS result in higher heat transfer and improved cooling system performance. "

J. J.
 
#23 ·
patooyee said:
Here we go, I knew I wasn't crazy:

"For those that cling tenaciously to myths, I am going to take one last crack at forever dispelling the Granddaddy of them all when it comes to cooling systems.

The myth is stated as either:

Coolant can be pumped too fast through the engine for it to absorb enough heat, or
Coolant can be pumped too fast through the radiator for it to cool properly, or
Cooling can be improved by slowing the flow of coolant through the radiator so it cools more completely.
NONE of these is true. The simple truth is that higher coolant flow will ALWAYS result in higher heat transfer and improved cooling system performance. "

J. J.
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That's an awfully general blanket statement to hold true in all cases.... In other words, there are a lot of variables that havent been accounted for.

I'm going to do some digging.... I'll post up what I find.
 
#24 ·
95geo said:
That's an awfully general blanket statement to hold true in all cases.... In other words, there are a lot of variables that havent been accounted for.

I'm going to do some digging.... I'll post up what I find.
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To me it makes it makes sense though because the longer coolant hangs out the less heat transfers out of it as time goes on. Thus, it is better to pass the same coolant through a cooler 10 times over the course of 10 minutes than to have it hang out there once for 10 minutes.

J. J.
 
#25 · (Edited)
patooyee said:
Here we go, I knew I wasn't crazy:

"For those that cling tenaciously to myths, I am going to take one last crack at forever dispelling the Granddaddy of them all when it comes to cooling systems.

The myth is stated as either:

Coolant can be pumped too fast through the engine for it to absorb enough heat, or
Coolant can be pumped too fast through the radiator for it to cool properly, or
Cooling can be improved by slowing the flow of coolant through the radiator so it cools more completely.
NONE of these is true. The simple truth is that higher coolant flow will ALWAYS result in higher heat transfer and improved cooling system performance. "

J. J.
Click to expand...
Wow, that seems to completely contradict the quote I grabbed. Hopefully Bill will see this and respond, because I disagree with that statement, not trying to argue, it just doesn't seem to be backed up by my own research.

Here is what Carroll Smith says in "Tune to Win" about heat exchangers: "Every transfer of heat between two fluids-and what we are trying to do is to transfer a percentage of the heat of combustion from the two cooling fluids to the airstream-is directly proportional to the mean temperature difference between the two fluids, to the area of interface between the two fluids and to the volume of the cooling fluid flow. In other words, in order to increase cooling we must increase the surface area of one or both sides of the heat exchanger or we must increase the volume of the airflow per unit time through the core."

I read the emphasized portion to also mean that slower water flow, to a point, will transfer more heat to the air at a set rate of airflow, than an extremely high rate of flow would. I'm curious what Billa Vista and experts in the field have to say about the subject.
 
#26 ·
reddman said:
Wow, that seems to completely contradict the quote I grabbed. Hopefully Bill will see this and respond, because I disagree with that statement, not trying to argue, it just doesn't seem to be backed up by my own research.

Here is what Carroll Smith says in "Tune to Win" about heat exchangers: "Every transfer of heat between two fluids-and what we are trying to do is to transfer a percentage of the heat of combustion from the two cooling fluids to the airstream-is directly proportional to the mean temperature difference between the two fluids, to the area of interface between the two fluids and to the volume of the cooling fluid flow. In other words, in order to increase cooling we must increase the surface area of one or both sides of the heat exchanger or we must increase the volume of the airflow per unit time through the core."

I read the emphasized portion to also mean that slower water flow, to a point, will transfer more heat to the air at a set rate of airflow, than an extremely high rate of flow would. I'm curious what Billa Vista and experts in the field have to say about the subject.
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Haha, I don't think my billavista quote contrasts yours at all and I think your quote from Tune to Win supports my theory thus far also.

Your quote from billavista states that max heat transfer occurs when there is the largest difference in temp between the fluid being cooled and and cooler. However, as billavista states in his bible, this heat transfer rate drops exponentially over time as the two temps come closer together. Thus, you loose a lot more heat in the first instants of contact than you dot he last, just like when you cool a red hot piece of metal under a faucet. Thus, by increasing the speed at which the coolant flows you are increasing the instances of high heat transfer and decreasing those of the exponentially lower heat transfer that occurs later on if the coolant were to hang out longer.

The quote you bolded above states that you must increase volume per unit of time. What is velocity if not volume/time? Thus, your bolded quote also agrees with billavista's statement IMO.

Finally, why are the coolant passages through the engine so small when compared to those outside the engine? If cooling capacity increased over time exposed, you would want to keep the internal passages huge, like 1.5" or above, in order to decrease velocity. Yet they are very small, most smaller than 1". I suspect GM does this to increase velocity and therefore increase cooling capacity.

I will admit that "heat pockets" are a mystery to me. I would venture a guess that a heat pocket would occur either when there is an air bubble where coolant is not flowing or when there is an expansion in chamber size to as in one spot coolant flows slower than others.

J. J.
 
#27 ·
Also, on an LS water pump by replacing the t-stat with a restrictor plate you are restricting flow INTO the engine, not out. It was the oppsite on the old SBC's. On a SBC, replacing the t-stat with a restrictor plate restricts coolant LEAVING the engine. Thus, the restrictor plate is doing completely the opposite on an LS than it is doing on a SBC, I'm 80% certain. :)

J. J.
 
#28 ·
patooyee said:
Haha, I don't think my billavista quote contrasts yours at all and I think your quote from Tune to Win supports my theory thus far also.

Your quote from billavista states that max heat transfer occurs when there is the largest difference in temp between the fluid being cooled and and cooler. However, as billavista states in his bible, this heat transfer rate drops exponentially over time as the two temps come closer together. Thus, you loose a lot more heat in the first instants of contact than you dot he last, just like when you cool a red hot piece of metal under a faucet. Thus, by increasing the speed at which the coolant flows you are increasing the instances of high heat transfer and decreasing those of the exponentially lower heat transfer that occurs later on if the coolant were to hang out longer.

The quote you bolded above states that you must increase volume per unit of time. What is velocity if not volume/time? Thus, your bolded quote also agrees with billavista's statement IMO.
It says for the same amount of airflow, a higher per unit time of water flowing through the core will transfer more heat than a lower per unit time. Higher per unit time means the same gallon of water spends more time per pass through the radiator, right? That is slower flow, faster flow would mean decreased airflow per unit time of water in the radiator.

Finally, why are the coolant passages through the engine so small when compared to those outside the engine? If cooling capacity increased over time exposed, you would want to keep the internal passages huge, like 1.5" or above. Yet they are very small, most smaller than 1". I suspect GM does this to increase velocity and therefore increase cooling capacity.
They are small because there are dozens of parallel paths that the water is taking, and the effective diameter is huge, meaning a slow flow rate.

I will admit that "heat pockets" are a mystery to me. I would venture a guess that a heat pocket would occur either when there is an air bubble where coolant is not flowing or when there is an expansion in chamber size to as in one spot coolant flows slower than others.

J. J.
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Heat pockets were also created by our flow problems. The pockets were superheating and boiling the coolant, causing it to burp out water, and we were low and hot every time we would check it. If the water flows too quickly (like when running at high RPM for extended periods with large diameter cooling lines), the flow can be turbulent inside the heads/block and vortices will form, and since they stay in a certain spot rather than flow with the rest of the fluid, hot spots develop. Or at least that's my understanding of it.
 
#29 ·
patooyee said:
Also, on an LS water pump by replacing the t-stat with a restrictor plate you are restricting flow INTO the engine, not out. It was the oppsite on the old SBC's. On a SBC, replacing the t-stat with a restrictor plate restricts coolant LEAVING the engine. Thus, the restrictor plate is doing completely the opposite on an LS than it is doing on a SBC, I'm 80% certain. :)

J. J.
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Yes, LS pumps flow "backwards", but the location of the flow limiter isn't the key. The current is the same at any point in the system, reducing it here or there still has the exact same effect. ;)
 
#30 ·
reddman said:
Higher per unit time means the same gallon of water spends more time per pass through the radiator, right?
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I don't think so. I think it means higher VOLUME per unit time, which would mean more has to flow through in the same amount of time. That's my semantic interpretation at least. :) I will try to refrain from more comments until someone can shed some more light on it though as I think you and I are just arguing our two semantic interpretations at this point and we need someone else to set us straight on terms. :)

J. J.
 
#31 ·
You're reading it wrong. "...in order to increase cooling... we must increase the volume of airflow per unit time through the core." Replace the word "unit" with the unit of your choice, for this example, lets use one gallon. Unit is the volume, he's just saying that it doesn't matter which unit you've decided to measure with, more airflow per unit translates to more heat transfer.

"In order to increase cooling, we must increase the volume of airflow per gallon's time through the core." :)
 
#32 ·
I'm saying you're reading it wrong. I say "unit time" can be replaced with anything. IE minute, hours, day.

So the way I read it it says, "In order to increase cooling, we must increase the volume of airflow per minute through the core." :)

Hence me wanting someone else to set us straight. Because the way you read it contradicts what billavista says. The way I read it doesn't. If you're interpretation was correct we would all want the smallest CFM electric fans possible so that the passing air would move slowly and absorb more heat. SPAL would be out of business.

That's it, I'm PMing billa ... :)

J. J.
 
#35 · (Edited)
From what i've learned in my Heat and Mass Transfer class in engineering...it really depends of several things mentioned somewhat above.

Heat flux (in Watts/Meter^2) = mass flow rate x specific heat x Difference in Temp

The mass flow rate is equal to = density x effective area x velocity.

So, in essence from those equations:

-If you increase the velocity OR the effective area (which area doesn't really apply so much here), you increase the mass flow rate.

-Increasing the mass flow rate in essence does increase the heat flux out of the system...so "yes" the greater the velocity of the fluid, the more it cools.

-But you also can have a greater heat flux out of the system by having a greater difference in temperatures. So the closer the temperatures of your fluid and say radiator are, you do in essence transfer less heat out of the system

Now...with that said, there ARE things besides that, that must be taken into account for the heat transfer. If you increase the velocity too much, you make the fluid too turbulent and risk superheating the fluid due to small air pockets created by eddy's (vortices basically) in the fluid.

So (as I've learned) it really comes down to a balance between velocity of the fluid, and making sure the fluid doesn't become overly turbulent causing you system to blow a hose :D
 
#36 ·
More flow rate is always better.

Higher airflow transfers more heat and higher coolant flow also transfers more heat. Why would we fight for all the airflow we can get but restrict the medium on the other side of the heat exchanger?

Restricting flow through the block will build a little pressure to help keep water from boiling in certain areas. This can help but it's not because the flow rate is lower. heat exchange and the related formulas are pretty simple and high flow is always good. There are other problems being solved if your cooling system works better with a flow restriction.

fwiw, our lines match the fittings griffin installed at 1.5 & 1.25 and it cools great. we used exhaust tube and silicone hose.
 
#38 · (Edited)
freerider15 said:
From what i've learned in my Heat and Mass Transfer class in engineering...it really depends of several things mentioned somewhat above.

Heat flux (in Watts/Meter^2) = mass flow rate x specific heat x Difference in Temp

The mass flow rate is equal to = density x effective area x velocity.

So, in essence from those equations:

-If you increase the velocity OR the effective area (which area doesn't really apply so much here), you increase the mass flow rate.

-Increasing the mass flow rate in essence does increase the heat flux out of the system...so "yes" the greater the velocity of the fluid, the more it cools.

-But you also can have a greater heat flux out of the system by having a greater difference in temperatures. So the closer the temperatures of your fluid and say radiator are, you do in essence transfer less heat out of the system

Now...with that said, there ARE things besides that, that must be taken into account for the heat transfer. If you increase the velocity too much, you make the fluid too turbulent and risk superheating the fluid due to small air pockets created by eddy's (vortices basically) in the fluid.

So (as I've learned) it really comes down to a balance between velocity of the fluid, and making sure the fluid doesn't become overly turbulent causing you system to blow a hose :D
Click to expand...
what he said

The more of those little mater molecules that QUICKLY touch the metal molecules, the more heat will be transfered. going fast alone does not transfer heat if all those speedy water molecules dont get to touch the metal and dont get mixed up. turbulence is key. fast linear flow is not as helpfull

but too much turbulence makes air pockets and you get decreased flow by overrestricting in an attemp to make the water move faster.

the reason you stir your kids soup is not to let that cooled soup at the top of the bowl touch the hot soup down below. you stir the soup because you want the hotter soup at the bottom to come in contact with the cooler air at the top. more heat is shed when the hotter soup touches the cooler air. the faster you can stir the better. the same thing is happening with the turbulance in the radiator. keep it mixed and keep it flowing.

this process has little to do with the size of the tube connecting the motor to the radiator
 
Discussion starter · #39 ·
talked to a few diiferent engine builders, every one told me run -16 for both lines, remove t-stat, freeze plug with 1/4" hole use one port for water temp and one blocked off.

glad i didnt spend a whole bunch of cash and tie on 1.75 and 1.5 aluminum tubing. mst likely would have been too much
 
#40 ·
gobigorgohome said:
alright so has anybody here ran -16/ -20 lines on a somewhat supped up ls1 with decent size dual pass, rear mount radiator. so how did it work? comments / suggestions?
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our last cars engine wasnt stock by any means, we ran a rear mounted ron davis 34x19, -24 AN with staeinless braided lines. It was way over kill, the reason I ran that was 1.5" aluminum tubing cooled the car perfect before we switched to the AN fittings and the -24 hose was 1.5". car never got hot. many people run the -16 an -20 an dont have any problems.
 
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