Anyone using an electric water pump?

[Jaydee]

I was told by my radiator guy that if the flow is to fast , then the coolant doesn't get a change to cool down, because it goes through the radiator to fast. So the thermostat serves as a restricter as well as regulating the temp.
JD

[scottj]

Originally Posted by Jaydee

I was told by my radiator guy that if the flow is to fast , then the coolant doesn't get a change to cool down, because it goes through the radiator to fast. So the thermostat serves as a restricter as well as regulating the temp.
JD

Yet no one ever recommends slowing down airflow through the radiator to give the air more time to absorb the heat... hmmm, strange.

[bobcowan]

Originally Posted by Jaydee

I was told by my radiator guy that if the flow is to fast , then the coolant doesn't get a change to cool down, because it goes through the radiator to fast. So the thermostat serves as a restricter as well as regulating the temp.
JD

This is true. For anything other than drag racing or autocross, never remove the thermostat and leave an open port.

Originally Posted by scottj

Yet no one ever recommends slowing down airflow through the radiator to give the air more time to absorb the heat... hmmm, strange.

You restrict water flow, not air flow.

[Jaydee]

I guess if you ran some boiling water over a piece of cold steel quickly it will still be hot, but if you ran it very slowly, it will get a chance to cool down. But if you cool down the steel with fast air it will just simple keep the steel cooler.

So how many drag cars don't use radiators? Top fuel rail don't seem to have a radiator?
JD

[jeffnolan]

Air is a poor conductor of heat, only the first layer of air touching the radiator fins has a cooling effect, the surrounding air doesn't get much tansfered to it. Convection by continuously replacing the contacting layer with fresh air increases the heat transfer to the bulk of the air in the vicinity of the radiator by conduction. Slowing down the air flow through the radiator quickly saturates the contacting layer of air to no effect on the surrounding layer, which is why no one recommends it.

Originally Posted by scottj

Yet no one ever recommends slowing down airflow through the radiator to give the air more time to absorb the heat... hmmm, strange.

[scottj]

Originally Posted by jeffnolan

Air is a poor conductor of heat, only the first layer of air touching the radiator fins has a cooling effect, the surrounding air doesn't get much tansfered to it. Convection by continuously replacing the contacting layer with fresh air increases the heat transfer to the bulk of the air in the vicinity of the radiator by conduction. Slowing down the air flow through the radiator quickly saturates the contacting layer of air to no effect on the surrounding layer, which is why no one recommends it.

Yes, I understand. The post you quoted was actually meant to be sarcasm. What most fail to understand is that the same applies to both air and water flow with regard to flow rate.

[GBowman]

Late to the party here...but...I have found a huge benefit in my elec water pump (Meziere) is that when I shut down I can turn the key on and have water pump & fan run for a couple of minutes with the engine turned off in order to mitigate heat soak. This is a huge up side if you do any restaurant hopping and only shut down for an hour or two at a time. I've had heat soak issues in the past and this has cured that problem 100%.

[monster7]

Originally Posted by Jaydee

I was told by my radiator guy that if the flow is to fast , then the coolant doesn't get a change to cool down, because it goes through the radiator to fast. So the thermostat serves as a restricter as well as regulating the temp.
JD

This is correct from a physical point of view, also true for water (heat transfer rate)! If the flow is too high, the heat transfer rate will decrease, also the efficiency will do so.

[cycleguy55]

Originally Posted by Jaydee

I was told by my radiator guy that if the flow is to fast , then the coolant doesn't get a change to cool down, because it goes through the radiator to fast. So the thermostat serves as a restricter as well as regulating the temp.
JD

Your radiator guy is giving you bad advice, probably based upon advice he got from someone who didn't know better. As scottj pointed out in post #22: "The longer coolant is in the radiator, the longer it's in the block gaining heat." That's almost a direct quote from what Stewart Components includes in their cooling Tech Tip #3. Stewart Components

More content from the same Tech Tip:

• "We strongly recommend NEVER using a restrictor; they decrease coolant flow and ultimately inhibit cooling."
• "Coolant in the engine will actually boil away from critical heat areas within the cooling system if not forced through the cooling system at a sufficiently high velocity. This situation is a common cause of so-called "hot spots", which can lead to failures."
• "Years ago, cars used low pressure radiator caps with upright-style radiators. At high RPM, the water pump pressure would over come the
  radiator cap's rating and force coolant out, resulting in an overheated engine. Many enthusiasts mistakenly believed that these situations
  were caused because the coolant was flowing through the radiator so quickly, that it did not have time to cool."