[Squidward]

Originally Posted by steve25

Don’t kid yourself. It is possible that once the stat opens to move coolant thru the motor too fast for it to pick up heat as it should and on the other side of the system coolant can move too fast thru the rad for it dump the heat that it has picked up.

Moving coolant thru the rad too fast makes the rad area seem smaller then what it’s .

Respectfully, I don't buy that. More flow is always better heat transfer, whether it's air flow or coolant flow.

[zippy]

Originally Posted by Squidward

Respectfully, I don't buy that. More flow is always better heat transfer, whether it's air flow or coolant flow.

It's true. DeltaT time constant. Many years ago I tested that with my TA. And many others have too. Easy test. Take out thermostat completely. Max flow ytour cooling sys will get that way. Yup, take forever to warm up. And in town, slow stop and go driving, sure prob run cooler, as flow is cooler with lower RPM and engine power/throttle level

Now go on highway, go for a long hard rip. and keep in her for a while
Logic would suggest that then we have
More airflow due to speed
More coolant flow due to much higher RPM

But you will start having climbing temps. They will start creeping up and up and up.
You slow down and the temps go up even more before they start to come down

Why? The coolant was going so fast through the radiator that it had no time to remove enough of it's retained heat. Engine to coolant DeltaT is greater than the coolant to air DeltaT
Meaning, needs more time in rad to remove the heat than it does in block to pick up heat.

Scenario above, Put T stat back in and engine is stable at same high rpm load. Verifying flow speed matters

[srmmmm]

I cannot speak to the performance/reliability of the CVF water pump. I do have the polished CVF serpentine conversion on my 1970 Bird and can say it works perfectly with the exception of the power steering pump. I went through three of the power steering pumps in 2600 miles. There is something wrong in the manufacturing process of the polished pumps that contributes to leaks between the pump and reservoir and significant noise during operation. All were replaced under warranty, but pump number 4 was a black finish pump that the House of Hotrods said has been a trouble free version. I only have about 100 miles on the new pump but it is definitely much quieter than the polished versions I had earlier.
I originally had an Edelbrock Victor water pump installed on the engine build. The seal gave way after 1600 miles and the engine was prone to very high running temps at freeway speeds as well. I had not examined the pump prior to installation, but saw it after it came off the engine and was very surprised to measure the vane heights at an average of just 5/16". Edelbrock furnishes a new backer plate with the pump, but I fail to see how it could push enough coolant through the engine under high load conditions. Extremely disappointing for a $300 water pump.
I went to the PRW pump and have not had any overheating situations since.

[Squidward]

Originally Posted by zippy

It's true. DeltaT time constant. Many years ago I tested that with my TA. And many others have too. Easy test. Take out thermostat completely. Max flow ytour cooling sys will get that way. Yup, take forever to warm up. And in town, slow stop and go driving, sure prob run cooler, as flow is cooler with lower RPM and engine power/throttle level

Now go on highway, go for a long hard rip. and keep in her for a while
Logic would suggest that then we have
More airflow due to speed
More coolant flow due to much higher RPM

But you will start having climbing temps. They will start creeping up and up and up.
You slow down and the temps go up even more before they start to come down

Why? The coolant was going so fast through the radiator that it had no time to remove enough of it's retained heat. Engine to coolant DeltaT is greater than the coolant to air DeltaT
Meaning, needs more time in rad to remove the heat than it does in block to pick up heat.

Scenario above, Put T stat back in and engine is stable at same high rpm load. Verifying flow speed matters

Except that when you do your highway speed rip at higher rpm you not only increase coolant and air flow, but you increase heat generated by engine. So is your increase in temps due to coolant flow, or does the rate of heat generation now exceed rate of heat removal?

Your thermostat shuts to increase coolant temp, and opens to decrease it. Less flow equals increase temp, more flow equals decrease temp. From the factory, hd cooling/ac got smaller diameter pulleys for more flow. Engineers designing these systems knew more flow is better. More coolant flow, more air flow, more surface area, reduced ambient - all are factors to help cooling.

Good stuff, tho.

[65 Lamnas]

Originally Posted by zippy

It's true. DeltaT time constant. Many years ago I tested that with my TA. And many others have too. Easy test. Take out thermostat completely. Max flow ytour cooling sys will get that way. Yup, take forever to warm up. And in town, slow stop and go driving, sure prob run cooler, as flow is cooler with lower RPM and engine power/throttle level

Now go on highway, go for a long hard rip. and keep in her for a while
Logic would suggest that then we have
More airflow due to speed
More coolant flow due to much higher RPM

But you will start having climbing temps. They will start creeping up and up and up.
You slow down and the temps go up even more before they start to come down

Why? The coolant was going so fast through the radiator that it had no time to remove enough of it's retained heat. Engine to coolant DeltaT is greater than the coolant to air DeltaT
Meaning, needs more time in rad to remove the heat than it does in block to pick up heat.

Scenario above, Put T stat back in and engine is stable at same high rpm load. Verifying flow speed matters

Flow velocity DOES matter, but not for the reasons (and testing) you state.

If you stay within the design limits of the systems Pontiac designed over the years, then you CANNOT move to coolant too quickly to cool.

Removing the stat and allowing "full flow" of the system doesn't really "prove" anything, other than bad things happen when you don't utilize the system as designed. So the coolant travels too fast to reject heat with no thermostat....so what? Who drives around like that?

The stat is there to regulate temp, restrict flow, create system backpressure, and reduce or eliminate aeration of the fluid. Aerated fluid does s *****y job of cooling as heat doesn't transfer to air. The first rule of flow dynamics 101 is that velocity is your friend.

Your testing "back in the day" was invalid.