If you want to cool the steel and you're in a hurry, do you use a trickle or a firehose? The specific heat of water is 1BTU per F per pound. A cubic foot of water takes 62.3 BTUs to cool it just 1*F. Since we're worried about time, there's two ways to do it in a hurry.... You can hit it with something VERY VERY VERY cold (not an option with our setups) -or- you can hit it with a BUNCH of things that are slightly colder.
Would you go slow and get $15 an hour from now or a penny every second?
A radiator is a heat exchanger (technically it's a 'conductor/convector' as that's how it does most of it's cooling). The goal when keeping engine temps under control is to conduct heat from the engine into the coolant. Then a pump, pumps the coolant with the stored energy into the radiator. Coolant weighs over 62#'s per cubic foot and air weighs .08#'s per cubic foot. All things being equal (and 100% efficient), it takes a bunch of air just to average the temps of the two.
When it comes to heat rejection, the main factor is 'Delta T' which is a fancy way of saying 'difference in temperature' which is a fancy way of saying 'your cooling system works better in Antarctica'.
If the ambient air outside (or the back of the A/C condenser) is 100F and you desire 160F you only have a '60 degree Delta T' to work with. If it's 150F due to a front mount and running the A/C in a parking lot you only have a 10F Delta T. That's not a flow issue, that's a physics thing.
Now when it comes to cooling going so fast it can't lose heat, that's just wrong. It takes some abstract thought to wrap your mind around what's going on. If you want to lose the most amount of BTU's per unit of time the way to increase that is to make the coolant entering the radiator hotter!
When it exits the engine, it's as hot as it's going to get (assuming it's cooler than 180F outside ). The hot coolant enters the radiator on the DS and that's where Delta T is the greatest. That first inch leaving the tank will have the most amount of heat transfer as from it's point of view the air 'feels the coolest' going across it. As the coolant works it's way across the flues, it's getting cooled and getting closer to ambient. As the coolant cools down, the Delta T gets smaller and smaller so less heat gets moved into the airstream.
Let's say you slow the flow level down so that the coolant can crawl through the radiator so it can't 'go too fast to lose heat'. Lets say in this example when it's halfway across the fins, the coolant temp is the same as the outside air... You just wasted 1/2 the radiator.
At the same time in that example the #1 and #2 combustion chambers are boiling the crap out of the head and detonating like crazy because there's not replacement coolant flushing the heat away. Since the coolant is going so slow, it enters the engine 'cold as hell' and had the front cylinders ice cold.... as it absorbed buttloads of heat from the three cylinder walls, then each of the other 2 combustion chambers before getting to the front two cylinders. You have a severe mismatch in temps across the engine, localized boiling, and all kinds of interesting (very bad things) that water does when it's pressures and phases are dancing all over the place. To make things worse, the steam will act as an insulator for the iron and act as a physical buffer to keep the coolant from even touching the melting engine. (that's how firewalkers walk across coals. The steam layer keeps the heat source from setting fire to their feets)
Now lets at what happens when the coolant 'goes too fast to cool'... When it's comes out of the engine at full temp and enters the radiator, just like in the other example it has the same Delta T relative to ambient conditions. But since it's moving along at a good pace, the radiator gets to use the entire flue length to reject heat energy (the equivalent of doubling you radiator width/ doubling useable airflow). Plus with the added velocity and pressure there will be increased tumble and 'scrubbing' going on between the coolant and flues increasing efficiency.
The faster the coolant is going, the move even the temp is inside the engine. When the gauge reads '180F' for example, it's only that temp at the location of the sending unit. The temp is progressively cooler as you work your way backwards through the head and block towards the radiator outlet.
Now with the pump, velocity matters here too. For a pump to move mass you have two sides to consider... The high pressure side and the low pressure side. For a pump to be working right it needs a pressure head. When that fails you have cavitation and other nasties going on. (If you've ever seen a pump cavitate on the dyno, you'd wonder how the radiator hoses didn't disintegrate. They can go berzerk!)
For a pump to be loaded with the head it needs to do it's job it had to have a pressure differential. On a sealed cooling system like in a car it pulls from the bottom of a radiator through a rubber hose. (the hose needs to be meaty and/or have a spiral wound metal coil in it to keep it from collapsing or being a flow restriction). It then pumps the water into the block, to the back of the block, into the heads (series cooling in this example, not parallel cooling), through the heads and into the thermostat housing. Normally the thermostat itself is the orifice/restriction so that the block in under pressure to load the pump, raise the boiling point of the coolant, and minimize localized boiling and phase changes. With a normal GN/TTA if you remove the thermostat the radiator flues becomes the choke point, which is fine....
***historical data*** We've all heard the wives tales of how removing the thermostat will make your car overheat. This particular tale doesn't apply to us. On older SBC cars and cars with the radiator cap on the same tank at the top hose the extra velocity overwhelms the spring in the cap, slowly vents the coolant.... when the coolant mass isn't enough to keep up with heat rejection needs, overheating leads to phase change.... then it's all over.
Think putting your finger over the end of the garden hose. The house pressure is still the same but the extra velocity (force) will blast the bikini top off your houseguest.
On our cars, the cap is on the low pressure side of the radiator. It's basically just exposed to system pressure not pressure+velocity (PSIA .vs PSIT).
Moral of the story our hotrods make 'X' amount of waste heat (in the water jacket) which means with only have to get rid of exactly 'X' into the air stream. The faster the flow, the more even the temps across the combustion chambers ft to r.
Obsessing over certain flows or certain restrictions are usually just covering up a more basic issue that just isn't obvious.
Don't get me wrong, I love figuring out new and interesting ways to mess with stuff. You know, like figuring out how to survive without working, and talking nice young ladies into taking it up the exit pipe, and getting free hottubs off craigslist... but I've heat to figure out how to break the laws of physics.
Would you go slow and get $15 an hour from now or a penny every second?
A radiator is a heat exchanger (technically it's a 'conductor/convector' as that's how it does most of it's cooling). The goal when keeping engine temps under control is to conduct heat from the engine into the coolant. Then a pump, pumps the coolant with the stored energy into the radiator. Coolant weighs over 62#'s per cubic foot and air weighs .08#'s per cubic foot. All things being equal (and 100% efficient), it takes a bunch of air just to average the temps of the two.
When it comes to heat rejection, the main factor is 'Delta T' which is a fancy way of saying 'difference in temperature' which is a fancy way of saying 'your cooling system works better in Antarctica'.
If the ambient air outside (or the back of the A/C condenser) is 100F and you desire 160F you only have a '60 degree Delta T' to work with. If it's 150F due to a front mount and running the A/C in a parking lot you only have a 10F Delta T. That's not a flow issue, that's a physics thing.
Now when it comes to cooling going so fast it can't lose heat, that's just wrong. It takes some abstract thought to wrap your mind around what's going on. If you want to lose the most amount of BTU's per unit of time the way to increase that is to make the coolant entering the radiator hotter!
When it exits the engine, it's as hot as it's going to get (assuming it's cooler than 180F outside
). The hot coolant enters the radiator on the DS and that's where Delta T is the greatest. That first inch leaving the tank will have the most amount of heat transfer as from it's point of view the air 'feels the coolest' going across it. As the coolant works it's way across the flues, it's getting cooled and getting closer to ambient. As the coolant cools down, the Delta T gets smaller and smaller so less heat gets moved into the airstream.Let's say you slow the flow level down so that the coolant can crawl through the radiator so it can't 'go too fast to lose heat'. Lets say in this example when it's halfway across the fins, the coolant temp is the same as the outside air... You just wasted 1/2 the radiator.
At the same time in that example the #1 and #2 combustion chambers are boiling the crap out of the head and detonating like crazy because there's not replacement coolant flushing the heat away. Since the coolant is going so slow, it enters the engine 'cold as hell' and had the front cylinders ice cold.... as it absorbed buttloads of heat from the three cylinder walls, then each of the other 2 combustion chambers before getting to the front two cylinders. You have a severe mismatch in temps across the engine, localized boiling, and all kinds of interesting (very bad things) that water does when it's pressures and phases are dancing all over the place. To make things worse, the steam will act as an insulator for the iron and act as a physical buffer to keep the coolant from even touching the melting engine. (that's how firewalkers walk across coals. The steam layer keeps the heat source from setting fire to their feets)
Now lets at what happens when the coolant 'goes too fast to cool'... When it's comes out of the engine at full temp and enters the radiator, just like in the other example it has the same Delta T relative to ambient conditions. But since it's moving along at a good pace, the radiator gets to use the entire flue length to reject heat energy (the equivalent of doubling you radiator width/ doubling useable airflow). Plus with the added velocity and pressure there will be increased tumble and 'scrubbing' going on between the coolant and flues increasing efficiency.
The faster the coolant is going, the move even the temp is inside the engine. When the gauge reads '180F' for example, it's only that temp at the location of the sending unit. The temp is progressively cooler as you work your way backwards through the head and block towards the radiator outlet.
Now with the pump, velocity matters here too. For a pump to move mass you have two sides to consider... The high pressure side and the low pressure side. For a pump to be working right it needs a pressure head. When that fails you have cavitation and other nasties going on. (If you've ever seen a pump cavitate on the dyno, you'd wonder how the radiator hoses didn't disintegrate. They can go berzerk!)
For a pump to be loaded with the head it needs to do it's job it had to have a pressure differential. On a sealed cooling system like in a car it pulls from the bottom of a radiator through a rubber hose. (the hose needs to be meaty and/or have a spiral wound metal coil in it to keep it from collapsing or being a flow restriction). It then pumps the water into the block, to the back of the block, into the heads (series cooling in this example, not parallel cooling), through the heads and into the thermostat housing. Normally the thermostat itself is the orifice/restriction so that the block in under pressure to load the pump, raise the boiling point of the coolant, and minimize localized boiling and phase changes. With a normal GN/TTA if you remove the thermostat the radiator flues becomes the choke point, which is fine....
***historical data*** We've all heard the wives tales of how removing the thermostat will make your car overheat. This particular tale doesn't apply to us. On older SBC cars and cars with the radiator cap on the same tank at the top hose the extra velocity overwhelms the spring in the cap, slowly vents the coolant.... when the coolant mass isn't enough to keep up with heat rejection needs, overheating leads to phase change.... then it's all over.
Think putting your finger over the end of the garden hose. The house pressure is still the same but the extra velocity (force) will blast the bikini top off your houseguest.
On our cars, the cap is on the low pressure side of the radiator. It's basically just exposed to system pressure not pressure+velocity (PSIA .vs PSIT).
Moral of the story our hotrods make 'X' amount of waste heat (in the water jacket) which means with only have to get rid of exactly 'X' into the air stream. The faster the flow, the more even the temps across the combustion chambers ft to r.
Obsessing over certain flows or certain restrictions are usually just covering up a more basic issue that just isn't obvious.
Don't get me wrong, I love figuring out new and interesting ways to mess with stuff. You know, like figuring out how to survive without working, and talking nice young ladies into taking it up the exit pipe, and getting free hottubs off craigslist... but I've heat to figure out how to break the laws of physics.
