Does This Debunk the "Coolant Can Flow Through the Radiator Too Fast" Idea???

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The ONLY reason OEM's use aluminum and plastic is that it is exponentinally cheaper than brass/copper! My 2001 2500 Cummins split one side of the plastic tanks while on a transport a couple years ago, NEVER had that happen to a brass radiator. Sure the solder has split on the top tank but it was simple to fix in a matter of minutes while on the road while the aluminum POS had to be replaced by me in a gas station parking lot after taking an Uber to and from a parts store that had one in stock and I barely got it together and on the road before dark. I have never had an issue with a brass radiator but sure have with aluminum, so this old fart will always err to the side of decades of service...
I had the same issue. The plastic tanks swell and crack when heated. I tried to repair the tank withy JB Weld, but it would not work with the tank swelling. I installed a new radiator and used less torque on the mounting bolts, to relieve some pressor at the breaking site. Seven years and so far, so good.
 
I had the same issue. The plastic tanks swell and crack when heated. I tried to repair the tank withy JB Weld, but it would not work with the tank swelling. I installed a new radiator and used less torque on the mounting bolts, to relieve some pressor at the breaking site. Seven years and so far, so goo.
When the "aluminum core with crimped on plastic reservoirs" began in early 1980's, I thought "this will be a cluster-f", particularly since they rely on a rubber gasket to seal the plastic. I did see some early ones taken apart at radiator shop when getting my brass Mopar radiator repaired, so perhaps some early teething problems, but they have since been fairly reliable. Best thing is they are cheap to replace in most vehicles (<$100), so no more rodding out cores.

Never had a leak from one, but replaced several when the tubes plugged with debris. Once was when I made the long-life Dexcool mistake (orange coolant) and it formed brown solids. My googling found that isn't due to the oft-claimed "reacts with any residual green coolant" but rather because it reacts with atmospheric oxygen. Apparently, cars using Dexcool (mostly GM) have a different coolant design to keep air out of the coolant system.
 
The engineering explanation is that there are multiple variables involved in engine cooling - flowrate, coolant properties (conductivity and heat capacity), temperature difference between metal parts and coolant, temperature difference between coolant and radiator tubes, heat convection from radiator tubes/fins to airflow. The later is the major bottle-neck in the series of heat flows. Most public with no science education can only think in terms of one variable affecting one outcome.
Exactly. And of that list, flow rate is the variable that's probably the easiest to change.
 
I read that stock Mopar pumps flow about 15% more than stock Chev pumps. So by speeding up the pump you guys have discovered something that the Mopar and Gm engineers completely missed.Me, don't know but i've found using
aftermarket parts is a step backwards more times than not.
 
I read that stock Mopar pumps flow about 15% more than stock Chev pumps. So by speeding up the pump you guys have discovered something that the Mopar and Gm engineers completely missed.Me, don't know but i've found using
aftermarket parts is a step backwards more times than not.


Not exactly. Chrysler was overdriving pumps a long time ago.

A quick read of the FSM will show that.

The aftermarket stuff is junk because SOME engines turn enough RPM that you can over speed the pump and fight keeping the belts on.

But I'd bet everything the engineers know that limit and run slightly under that speed.

At 8500 RPM you may have to turn the pump slower to keep the top pump speed where it would be if the engine only turned 7k.

Circle track guys are the WORST about speeding the pump up. Its in all the books that under driving saves horsepower so it must be true.
 
Not buying what they're selling. Too much self contradiction.
I kind of thought that a little too as I read it. I mean, after all, they are going to do and say everything to push their product. However, from a scientific standpoint, what they are saying does make sense. I never really bought into the thought that you had to SLOW the flow down through the radiator to give the water time to properly lose its heat. That means that the water is also flowing slower through the hot engine, and that would only allow the water to get hotter. The basic laws of Thermodynamics are only going to allow water to absorb so much heat before boiling, even with a pressurized system and antifreeze. Overall, I have to agree with the article.
 
Not exactly. Chrysler was overdriving pumps a long time ago.

A quick read of the FSM will show that.

The aftermarket stuff is junk because SOME engines turn enough RPM that you can over speed the pump and fight keeping the belts on.

But I'd bet everything the engineers know that limit and run slightly under that speed.

At 8500 RPM you may have to turn the pump slower to keep the top pump speed where it would be if the engine only turned 7k.

Circle track guys are the WORST about speeding the pump up. Its in all the books that under driving saves horsepower so it must be true.
That brings up an interesting point I had not thought about before. Why not just put a very slightly larger pulley on the water pump. For instance, going from a 6" pulley to a 6 1/8" pulley gives you a circumference increase of 1.19" (a 4.2% increase). Wouldn't that make the pump spin a bit faster and, therefore, move the water a bit faster? I would think that the impeller design will eventually be maxed out and not allow an increase, but 4% over stock should not reach that maximum. What do you think, @Newbomb Turk?
 
That brings up an interesting point I had not thought about before. Why not just put a very slightly larger pulley on the water pump. For instance, going from a 6" pulley to a 6 1/8" pulley gives you a circumference increase of 1.19" (a 4.2% increase). Wouldn't that make the pump spin a bit faster and, therefore, move the water a bit faster? I would think that the impeller design will eventually be maxed out and not allow an increase, but 4% over stock should not reach that maximum. What do you think, @Newbomb Turk?
A larger pulley on the PUMP will slow the pump down, not speed it up.
 
That brings up an interesting point I had not thought about before. Why not just put a very slightly larger pulley on the water pump. For instance, going from a 6" pulley to a 6 1/8" pulley gives you a circumference increase of 1.19" (a 4.2% increase). Wouldn't that make the pump spin a bit faster and, therefore, move the water a bit faster? I would think that the impeller design will eventually be maxed out and not allow an increase, but 4% over stock should not reach that maximum. What do you think, @Newbomb Turk?


I believe it’s all RPM related. Just kinda like a Roots blower, you have a speed in which the blower doesn’t make any more pressure and just adds heat.

In the world of AA/GS legal stuff, the best we could do was about 54% over. Any more that that IAT went through the roof.

When they went to the 5 speed and started shifting at 9200 rather than the 8500 we were at, we had to slow the blower speed down some so that it still only turned the blower at 54% over.

The car went faster due to more gears and more rpm and the blower made the same boost. Or close to it. That was quite a bit of time ago.

I believe the water pump behaves the same. If you over speed it you can run into cavitation and probably some other bad things.

When I get a minute I may do some math to determine how fast you’d have to over drive a pump at 7k to keep it at the same speed that it sees at 5500.

One other thing. Like all things some of what else we can do is limited by what we have to work with.

There is a minimum diameter you can make the water pump pulley and a maximum you can make the crank pulley and get them to fit together.

If the minimum WP pulley diameter is say 5.75 inches and the crank pulley is 7 inches that’s only 22% over. But whatever those sizes are, that’s all the faster you can turn the pump unless you increase the rpm.

Somewhere in there is where the most effective cooling happens.

I don’t think you could even fit pulleys to go 30% over unless you spin the engine 10k.
 
I replaced my water pump yesterday and decreased my water pump pulley size and saw a decrease in temp of around 10-12 degrees.

Was it the pump?( flow cooler)

Or was it the pulley?

I figured the pumps efficiency (if truly more efficient) deserved an increase in speed as it was 1:1 before the swap. Crank is 6” water pump pulley is now 5”. Water pump previously was 6”.

Still too hot in my opinion at 195-197*
 
I replaced my water pump yesterday and decreased my water pump pulley size and saw a decrease in temp of around 10-12 degrees.

Was it the pump?( flow cooler)

Or was it the pulley?

I figured the pumps efficiency (if truly more efficient) deserved an increase in speed as it was 1:1 before the swap. Crank is 6” water pump pulley is now 5”. Water pump previously was 6”.

Still too hot in my opinion at 195-197*
I don't know how much clearance there is between the fins and the shroud as a restriction (some airflow across the core has to turn to exit through the fan assembly), but you could add vent holes to the corners and add flaps. They can be made out of thin, flexible rubber, overlap the holes all the way around behind the shroud, and are hung with washers, nyloc nuts, and two machine screws (#8 would be fine or rivets are an option) side by side and on one side. The flaps operate on differential pressure. At low speed, the pressure in front of the shroud is lower than behind it from the fan operation, so the flaps are closed. At higher speed, the pressure in front of the shroud is higher than behind it, so they open, increasing airflow through the core.
 
you could add vent holes to the corners and add flaps. They can be made out of thin, flexible rubber, overlap the holes all the way around behind the shroud, and are hung with washers, nyloc nuts, and two machine screws (#8 would be fine or rivets are an option)
Makes sense

I have leather.

But for science, I may come up with the scratch for a two core and go clutch factory but since I’m hard headed I’ll throw the baby out with dual fan. A set up from “Be cool”. Go big. I’ll keep watching the thread.
 
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Is the 30% you're referring to the ratio of the pullys

Yes, 30% over crank speed. Of course the pulley ratio to get that 30% will change with RPM.

I may call Stewart Components tomorrow and ask if they know (I’m sure they know at least about their own pumps) how fast you can drive the pump before it cavitates or any other bad thing happens.

If you know that and your max RPM you can adjust the pulley ratio to keep from running the pump into issues.
 
There is a thread on FABO now about a thermostat gasket leaking. One contributor mentioned that he installed a Flowcooler high flow water pump and his leak started then. I had never heard of Flowcooler High Flow water pumps, so I went to their website. I read the "Common Questions about High Flow pumps" section on their website. It was very interesting. It is a short read.

Considering how many comments/threads/problems we hear about engines running hot, I think this is a very good thing to read. My engine runs a little hotter than I would like. I think I might try one of their pumps. I am not easily convinced by high pressure, phony sales claims. The data in this short article make a lot of sense to me. One thing I found interest was this:

" Hold on...doesn't the coolant have to have more time in the radiator to cool? No. But a lot of people still think so. We have come up with some explanations for the Doubting Thomas."

What they said was very interesting. Please take a look at it.

Commons Questions about Hi Flow Pumps
It's low rpm/idle where they help.
Just use a 8 impeller water pump and a single row as big as the core support window is and you'll be good into the 550hp range given the tune is right.
 
Yes, 30% over crank speed. Of course the pulley ratio to get that 30% will change with RPM.
I don't see how the pully ratio changes with rpm. At a given engine rpm the pump rpm will change with different pully ratios.
 
I don't know what the fuss is about. I run an aluminum rad. because of the bigger tubes in my 66 Barracuda 360 magnum with no thermostat. I put in a restrictor plate instead. I run a 3/4-inch hole in it for flow control. I have used this in my dirt cars and paved oval race cars. I have no problems with heat or cooling. According to my temp. gauge it stays at 190 degrees. I 'm happy with that.
 
I don't see how the pully ratio changes with rpm. At a given engine rpm the pump rpm will change with different pully ratios.


But it’s always 30% (or whatever the pulley ratio is as I’m only using 30 over as an example.

30% over at 1000 rpm is 1300 rpm PUMP SPEED at idle.

At 6000 PUMP SPEED is 7800.

At 10,000 rpm the PUMP SPEED is 13,000 rpm.

At some rpm the pump will be spinning faster than it can handle. Is it 10,000 pump rpm or is it lower?

I don’t know but I do know you can over speed the pump.

Let’s say 8000 rpm is all the pump can do (pump speed). And you are shifting at 9500. And the pump is is even 10% over driven, you can see how you’d have to slow the pump down.

My point is you can over speed the pump.

My math comes from using the over drive numbers in the FSM and the max rpm that engine ran.

If you think I’m wrong, show the math. I get tired of explaining what simple math over and over.

I’ll say it again, the pump can be over driven but AFAIK it’s hard to do unless you are running a ton of rpm.

It’s not hard to grasp.

It’s no different than getting the overdrive of a blower to match engine rpm.
 
I don't know what the fuss is about. I run an aluminum rad. because of the bigger tubes in my 66 Barracuda 360 magnum with no thermostat. I put in a restrictor plate instead. I run a 3/4-inch hole in it for flow control. I have used this in my dirt cars and paved oval race cars. I have no problems with heat or cooling. According to my temp. gauge it stays at 190 degrees. I 'm happy with that.


IMO that too hot and a restrictor is a bad way to control coolant flow.

Without knowing the particulars of your build it’s hard to say if that’s cooling the engine properly.

Do you run a vacuum advance? If not you should be.

What’s it like on caution laps? Does it stay cool or warm up?

If it’s warming up then on restart until the temp comes back down you increase the likely hood of detonation.

Seen that many times. Seen the drivers in the car losing their minds because it’s a long caution and their **** is over heating.

I don’t tolerate garbage like that. No one should.
 
Yes, 30% over crank speed. Of course the pulley ratio to get that 30% will change with RPM.
It's the way you phrased this that is confusing. The first sentence is saying is that the waterpump is 30% over driven, a 30% ratio. I understand that. It's the second sentence that I don't agree with. You say the pulley ratio to get that 30% will change with rpm. I asked you if the 30% you were refering to was the pully ratio and you said yes. If 30% is the pully ratio how is that going to change with RPM? If the ratio is 30% it's still 30% regardless of the rpm. The math you outlayed in post #69 is fine which leads me to believe you have a understand how pully ratios work. I think maybe the 30% you were refering to in that second sentence isn't the pully ratio but rather something else?
 
It's the way you phrased this that is confusing. The first sentence is saying is that the waterpump is 30% over driven, a 30% ratio. I understand that. It's the second sentence that I don't agree with. You say the pulley ratio to get that 30% will change with rpm. I asked you if the 30% you were refering to was the pully ratio and you said yes. If 30% is the pully ratio how is that going to change with RPM? If the ratio is 30% it's still 30% regardless of the rpm. The math you outlayed in post #69 is fine which leads me to believe you have a understand how pully ratios work. I think maybe the 30% you were refering to in that second sentence isn't the pully ratio but rather something else?


I figured everyone would understand you can’t over speed the water pump at idle.

So that assumption means that you understand that to correctly get the pump to run at its most optimum or at least as fast as it can before it starts having issue is RPM related.

And not idle speed rpm related.

Isn’t the thread where I explained the same thing using a Roots blower?

Same exact thing.

Edit: along those lines I can’t find pulleys that get anywhere near 20% over.

And, since you are limited in how small and big you can go on the pulleys will also limit what the drive ratios can be.
 
Yes, 30% over crank speed. Of course the pulley ratio to get that 30% will change with RPM.
I agree with post #71. It seems you have a pretty good understanding that it is pump speed that is important. Not too fast as to cause cavitation not too slow as to cause heating problems. You got the math right in post #69. But When I read this quote "Of course the pully ratio to get to that 30% will change with rpm" to me it sounds like you think that pully ratios change with rpm.
 
I am running a 360 magnum, mechanical advance 727 tranny 8.75 rear w/742 case and 391 gears. Took 3,000 off heads running a comp camp flat tappet hydraulic lifters. I can't find the papers now but, its 1 cam smaller than the mother humper. I don't remember the duration and lift. This is in my 66 Barracuda. Sunday driver. I don't drive it to far only to local shows. I'm pushing about 470 horsepower. It stays between 185 and 195. I'm a old time car nut. At 69 this will be my last build. I'm running 15 inch wheels with M/T street and race tires. Stil have the 13s on the front. I'll change to 15s when I upgrade to disc brakes.

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@Newbomb Turk

How does one tell if cavitation is happening?

My gut would say that bringing it up to temp so thermostat is open and then bringing up the rpm and look for bubbles in the filter before it wants to over flow.
 
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