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Re: Science behind Mopar cooling?? [Re: Pacnorthcuda] #2866578
12/30/20 04:23 PM
12/30/20 04:23 PM
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Is it a 2 row core radiator? If so, why not just go with a 3 row core? I did that on my Charger and I had no more issues.

Re: Science behind Mopar cooling?? [Re: mopars4ever] #2866583
12/30/20 04:33 PM
12/30/20 04:33 PM
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Montclaire Offline OP
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Originally Posted by mopars4ever
Is it a 2 row core radiator? Is so, why not just go with a 3 row core? I did that on my Charger and I had no more issues.


To be honest I haven't checked yet. I know the rad is newer and doesn't have a lot of miles on it so I was going to try all of the basics before swapping radiators. The engine has a mix-match of parts on it (pulleys, brackets, etc) so I am going back to all stock pieces and assess from there. Can I ask where you bought yours? Thanks

Last edited by Montclaire; 12/30/20 04:34 PM.
Re: Science behind Mopar cooling?? [Re: Montclaire] #2866586
12/30/20 04:39 PM
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Can`t help with that as I had my original re cored.

Re: Science behind Mopar cooling?? [Re: mopars4ever] #2866589
12/30/20 04:44 PM
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Ah, ok. Another reason I wasn't looking to swap rads just yet - I know the chicom jobbers have smaller tubes than original so it might have to end up being a factory 22" rad with a new, proper dia core.

Re: Science behind Mopar cooling?? [Re: Montclaire] #2866596
12/30/20 04:59 PM
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Mine was re cored about 15 years ago so maybe they were different then.

Re: Science behind Mopar cooling?? [Re: mopars4ever] #2866616
12/30/20 05:49 PM
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As an example: OER makes a 22", 3-row radiator for 70-72 small block E-body (I have the later style water pump housing with the pass side discharge). It's listed as 1/2" tubes on 9/16" centers. Compare this to factory rads which are 9/16" tubes on 9/16" centers. Max cooling was even bigger - 5/8" tubes on 7/16" centers.

From Glen Ray:

coretypes.jpg
Last edited by Montclaire; 12/30/20 05:58 PM.
Re: Science behind Mopar cooling?? [Re: Pacnorthcuda] #2866729
12/30/20 09:27 PM
12/30/20 09:27 PM
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Originally Posted by Pacnorthcuda
Originally Posted by GODSCOUNTRY340
Chrysler used the 6 vain pumps on AC cars for this reason, remember there was an AC condenser in front of the radiator that isn't there with non AC cars. The condenser is not only restricting airflow through the radiator but it's transferring it's heat to the radiator so, Chrysler slowed the flow through the radiator to give the fluid more time to cool.

Nope. As Kunkel stated above, it’s to increase airflow while not increasing the opportunity for cavitation.


Come on now, the number of vanes on the pump have absolutely NOTHING to do with airflow. The water pump is pushing coolant, not air. Dirt track racers discovered many years ago that removing the thermostat actually caused engines to quickly overheat, the remedy was and still is, install a restrictor plate in place of the thermostat to SLOW DOWN coolant flow giving the radiator more time to cool the fluid.


I love the smell of Deer guts in the morning, it smells like... VICTORY!
Re: Science behind Mopar cooling?? [Re: Montclaire] #2866760
12/30/20 10:34 PM
12/30/20 10:34 PM
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Originally Posted by Montclaire
Hello, I have a 74 Barracuda with a transplanted 440. This is a factory non-AC car so it has a 22" radiator (newer stock-style replacement for the 1974 factory 19" unit). I'm going through the cooling system and will be replacing the water pump. As I understand it, non-AC cars got a 22" radiator, the larger pulley and an 8 blade pump. AC cars got a larger radiator, the smaller pulley and 6 blade pump. The net effect was a slightly under-driven pump on the non-AC cars and an over-driven pump with AC (around 140%).

I have both pulleys to choose from but haven't decided on a pump yet. I am not running AC, just want to cool the 440. Now, some subscribe to the theory that a faster pump is always better but I can't see how that would be accurate. The factory obviously had a reason for two different setups. My guess would be to give the coolant enough time to properly do its job with the smaller radiator. The AC cars probably got a 6 blade pump to reduce cavitation and the smaller pulley to increase pressure in the system. What did non-AC police package cars use?

Thanks in advance
its really simple . the thermostat is what gives "time to cool" ..... you need good speed/flow from -both- the pump and fan/ air at no- to slow speeds....

Re: Science behind Mopar cooling?? [Re: Montclaire] #2866811
12/31/20 01:02 AM
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Originally Posted by Montclaire
As an example: OER makes a 22", 3-row radiator for 70-72 small block E-body (I have the later style water pump housing with the pass side discharge). It's listed as 1/2" tubes on 9/16" centers. Compare this to factory rads which are 9/16" tubes on 9/16" centers. Max cooling was even bigger - 5/8" tubes on 7/16" centers.

From Glen Ray:


Yeah the internal construction of the radiator can make a big difference in how well it works. Cheap radiators look just like expensive ones on the outside but they don't flow as much so they don't cool as much. The more water you can flow thru the radiator the more heat you can pull out of the engine.

Re: Science behind Mopar cooling?? [Re: AndyF] #2866815
12/31/20 01:18 AM
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AC cars have smaller pulley, turning the fan and water pump faster, water pump have fewer blades to ensure no cavitation at high speeds. At idle, fan spins faster and the water stays in radiator longer...more cooling. And don't forget the shroud is required to be sure the fan is efficient.

Re: Science behind Mopar cooling?? [Re: Montclaire] #2866837
12/31/20 06:08 AM
12/31/20 06:08 AM
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The disagreements here are at root about cavitation, and the root of cavitation understanding is that the boiling point of water depends on BOTH temperature and pressure. The next important point is that the design of the pump impellor affects where on the blades a steam bubble meets a high enough pressure to suddenly collapse back into liquid water in an extremely violent event that human beings have a hard time imagining because it is the opposite of an explosion.


Re: Science behind Mopar cooling?? [Re: 360view] #2866865
12/31/20 09:46 AM
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One thing to keep in mind about all pumps is how close the impeller is to the housing surface.
I've tried a few pumps that had too much clearance for optimum water flow.

The flow rate is something I never could figure out how to measure,
but I would imagine the closer the impeller is to the housing surface, the better.

Joe

Re: Science behind Mopar cooling?? [Re: 360view] #2866866
12/31/20 09:47 AM
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This is a more complex issue then just flow or cavitation. Misapplication of principles. What does radiator flow mean? Water flow or air flow? Flow alone does not control heat transfer rate. Surface area, material, Temp difference of air and water, design all factor in for radiator heat transfer coefficient to maximize the cooling of the water at the radiator. Contact time in both the radiator and the engine do matter. Cavitation is not only the material damage to the impeller, it changes the efficiency of the pump and you lose flow volume. Capacity of the system matter too, with regard to equilibrium of the system.

Time matters. Take a frozen radiator, and 200 degree water and push it through the radiator in 1sec. What is outlet temp of water. How about after 5 sec, one minute? Same with the block.

If the radiator was cooling incoming 210 degree water and dropping it to 150 at outlet what would happen as the water temp in the engine started to drop to 175. The thermostat would close and reduce the flow to help keep the motor water temp at the optimum temp so the block would be at the correct temp for combustion and operating design. At that point, what good would this high capacity radiator, fan, and water pump do if the system is causing the thermostat to cycle closed trying to keep the the motor at the correct operating temperature. North Dakota in the winter with no thermostat. What would max engine temp be under those conditions.

Look at service manual, race manual, and the Chrysler training material, and everything was a trade off. The hemi and the small impeller was a performance move to save HP loss. Same with the centrifical fan for hemi versus thermostatic one for AC cars. I think Superbirds where having cooling issues and the recommendation was to go to a fixed fan blade. This would be a HP loss at high speed though. Look at all the combinations of fan types, blade lengths and pitch, impeller types and your head will spin.

If you are have a cooling issue, I would look at the block and head cleanliness and your radiator. A good cleaning flush. You can use a temp sensor gun to see if you have hot spot on the engine, head, manifold causing excess heat generation. A good solid fan will maximize air flow at idle. I think the pump impeller would be the last thing I would look at unless some thing wrong internally with the housing and the water is not flowing properly.

That test the RV guys did was interesting reading as it was hard to come to solid conclusions on what is best for cooling if I remember right. Which impeller do you want to use? Notice the orientation and size difference, and this doesn't even include the turbine style plastic and cast blades used in the mid 60s.

20171230_161021A.jpg
Re: Science behind Mopar cooling?? [Re: dragon slayer] #2866907
12/31/20 11:25 AM
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Originally Posted by dragon slayer


Time matters. Take a frozen radiator, and 200 degree water and push it through the radiator in 1sec. What is outlet temp of water. How about after 5 sec, one minute? Same with the block.



In a closed system like an engine, the time in the radiator spent cooling is also the time in the engine spent getting hotter, then microboiling starts to happen and your plan to spend more time in the radiator cooling the water off just got it's butt handed to it. Last thing you want to do is slow water flow. Max flow short of cavitation works best. Same with air flow. No one ever says " we need to slow the flow of air thru the radiator so the air has more time to cool it" wonder why?

Re: Science behind Mopar cooling?? [Re: Sniper] #2867043
12/31/20 03:40 PM
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several times it has been stated a .040 distance needs to be kept from the pump to the housing to prevent cavitation.
that is from the blade tips to the housing casting, correct ?
beer

Re: Science behind Mopar cooling?? [Re: Sniper] #2867046
12/31/20 03:44 PM
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Originally Posted by Sniper
Originally Posted by dragon slayer


Time matters. Take a frozen radiator, and 200 degree water and push it through the radiator in 1sec. What is outlet temp of water. How about after 5 sec, one minute? Same with the block.



In a closed system like an engine, the time in the radiator spent cooling is also the time in the engine spent getting hotter, then microboiling starts to happen and your plan to spend more time in the radiator cooling the water off just got it's butt handed to it. Last thing you want to do is slow water flow. Max flow short of cavitation works best. Same with air flow. No one ever says " we need to slow the flow of air thru the radiator so the air has more time to cool it" wonder why?


There is an optimum flow point in any system. The water is a confined unit, the air is not. It is an unlimited source so of course you want to cycle it through as fast as possible. If the air was part of a closed system and getting hotter each cycle you would rethink air flow velocity.

Re: Science behind Mopar cooling?? [Re: dragon slayer] #2867068
12/31/20 04:17 PM
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The big takeaway from the RV pump comparison is the difference in flow at low rpm between the impeller designs. The first pump with the large 8-blade impeller seems to move the most coolant at idle or near idle. Since I apparently need to increase either or both coolant and air flow at low speed I will be using a remanned 8-blade iron pump with the large pulley, unless I find an 8-blade pump already on the engine, in which case I will swap to the smaller AC pulley. There is also a “compromise” Hemi pulley that falls around 120%.

If these changes do not work I will look deeper - radiator upgrade, internal blockage, etc. I had the car out for a while in November on a 50’ day and it stayed reasonably cool so I am optimistic that putting some things back to stock will get me where I have to go. The crank pulley is not stock so it could just be a drastically under driven 6-blade pump providing poor coolant flow combined with a lack of shroud and aftermarket fan causing poor air flow.

Re: Science behind Mopar cooling?? [Re: Montclaire] #2867083
12/31/20 04:42 PM
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You are on the correct path. For you application you want to move as much water as possible thru the system. Other applications have different requirements but your application is going to work best with a lot of water flow. You'll also want to have a shroud and a clutch fan and then just keep an eye on the radiator. The one you have might be fine, if not you might need to get a 3 core or one with bigger tubes.

Re: Science behind Mopar cooling?? [Re: AndyF] #2867098
12/31/20 05:28 PM
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That’s the plan. I bought a reproduction 22” shroud and a Mopar 5-blade fan with clutch. I also have a factory 7-blade fan to try if the 5-blade doesn’t move enough air, assuming it clears the shroud. It’s off a 1973 small block AC car.

Last edited by Montclaire; 12/31/20 05:28 PM.
Re: Science behind Mopar cooling?? [Re: Montclaire] #2867284
01/01/21 06:31 AM
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Happy New Year to all who care about Mopars and cooling lol...

If Wingcar owners can keep their Mighty Mopars cool with the 'airflow' they have, then there is hope for all Mopar owners.
Modern cars work on very tight cooling margins, small rad, small hoses, high power efficient electric fans and everything working as good as poss!

Mopars with 22 inch rads, built from old copper/tin/brass combo's are always gonna be at a loss.
My Moparmate runs a 512ci motor in his 66 Polara, and it still has overheating problems after 3 different rads and 25-pumps... fan

It started out as a 'never hot' 383ci engine with a 22 inch original rad. and working Air CON!
Once we put a 440ci motor in the rad would not keep up in heavy traffic.
So we got a new rebuilt 26 inch Fury rad from a 71 car and tried that.
Better but still not right in the summer months...

On to the new 512ci with Edelbrocks and TTI full 2.5 system

Eventually we removed the Air-con system (that was still working fine) and it made very little difference at ALL!
Next on the list was all the possible water pumps available from 'Tom, Dick and Harry', the worst being '440 source'... panic
The housing has very small and restricted waterways and the impeller was deffo Chevy! spank

So he took the plunge and bought a new 'two row' extra cooling 26 inch ALI rad (same width as a 4 row) and guess what?
It was worse... help

Just in case you was wondering, yep it always had a rad specific 'fan shroud' and clutch fan.
We think the opening in the 'rad support area' is a little small for a Bigblock car, but cutting is Not an option...

The Polara ran 13.20secs 'in drive' at Santa pod raceway, she did get a little hot, but nothing horrendous... drive
Not bad for a 'stock car' in full trim with street tyres 'weighing in' (with driver and passenger) @ TWO TONS... drinking

The plan is to run a 12sec pass (in drive) and put the 383 back in, how boring... fury
Covid has a lot to answer for... ozbbq

Last edited by Gtxxjon; 01/01/21 06:46 AM.

Carpe diem, quam minimum credula postero, thanx Horace!

There’s no point trying to fix stuff that ain’t broke,,, 'but if ain’t broke',,, you is not trying hard enough...
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