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

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Phreakish said:
I remember a little while back reading about how audi had done years of research to come up with a little plastic baffle that preferentially sent the cooled water from the water pump to the higher side of the bores first in an effort to reduce temperature differences from the top of the bore to the bottom. In so doing, they increased their MPG's by something like 1.2% which yeilded far more in emissions credits than the program cost and also cost far-far-far less than developing a new block with improved coolant flow paths.
The main benefit of keeping the bore evenly cooled was improved ring sealing that accounted for lower fuel consumption and less blow-by which help with oil consumption and keeps key parts of the exhaust alive longer. The original temperature difference was in the mid double-digits from what I recall, and the baffle got them into single digit territory.
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Similarly, HD passed all the Euro emissions standards with the air cooled engines until just recently, the last few years. I would love to understand the mechanics of that. It's amazing how a little tweak can bring things into line
 
Newbomb Turk said:
I can. If your engine speed is below 8k speed the pump up.

The only reason to slow the pump down is if you can’t keep the belt on.

At some point the fan, ANY fan will become less effective and will fail.

That’s why you slow a pump down.

For the drive through idle guys and the rest of us not turning that kind of rpm need to speed the pump up.

The fact that this is still being discussed is proof positive old myths never die.
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So you typed all that just to admit that speeding a pump up or down is still situation dependent?

You gettin' paid by the word, or what?
 
Of course the WP produces pressure. When the WP is not turning there is no flow....& no pressure.
The t'stat is the smallest opening in the engine cooling system, & it creates the pressure build up in the engine. Purposely designed to produce this pressure which helps subdue/eliminate nucleate boiling in hot spots.
 
jos51700 said:
So you typed all that just to admit that speeding a pump up or down is still situation dependent?

You gettin' paid by the word, or what?
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Not at all. I explained what you didn't.

In most cases the water pump is turning too slow. Simple as that.
 
Bewy said:
When the WP is not turning there is no flow....& no pressure.
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Dunno about this one. The point made earlier about pressure being created by heat in the engine by heating the coolant made sense (to me).

If there was no flow (let’s just say no pump inline) pressure would still be created by the heating of the liquid, kind of like a steam engine? No?
 
About 15 years ago, I had a radiator recored by a guy that ran his rad shop for probably 60 years. I admit I do not remember how the subject came up, but he mentioned sometimes using a lower pressure radiator CAP. Of all the yap yap I have read on FABO about cooling over the years, I do not ever remember such being discussed.
 
barbee6043 said:
using a lower pressure radiator CAP.
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I am unsure of the exact numbers of lbs of pressure (cap) to boiling point, but having the cap the weakest part of the system makes sense to me. Next in line of the cap, of too high of pressure, is a hose or the heater core. 13 lb cap seems to be the weapon of choice on that front.

How much pressure does a heater core solder joint take, and for how long, and how many cycles? I feel like a lower pressure system that flows well and uses area (rad dimensions) and air flow is a good ticket.

Saying that, i am currently using a 1” smaller WP pulley on a flowkooler, 2 core (1” tubes) 24.5” wide aluminum rad with 3400 cfm worth of air. (13 lb cap).

187* all day. Might see a spike to 192* under certain conditions.

383 with a cam (250/250@50)
4 speed
AC not hooked up yet. (Big azz condenser is in place though)

This is a significant drop in temp from previous setup. I can bore you with that setup if prompted.

Pay me :lol:
 
"Centrifugal pumps work on the simple principle of imparting kinetic energy to the liquid. The pump consists of an impeller that is generally situated on a rotating shaft and turns inside of the pump casing[^1^]. When the impeller rotates, it creates a vacuum, sucking the fluid into the pump casing. This movement of the impeller adds kinetic energy to the fluid, increasing its velocity."
 
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barbee6043 said:
About 15 years ago, I had a radiator recored by a guy that ran his rad shop for probably 60 years. I admit I do not remember how the subject came up, but he mentioned sometimes using a lower pressure radiator CAP. Of all the yap yap I have read on FABO about cooling over the years, I do not ever remember such being discussed.
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I think rrr commented on that a while back , he said in some instances a lower thermostat would help overall temps ...??
 
A lower-than-spec pressure cap is a band-aid for a fragile, leak-prone system. When a radiator builder says something like "Run a 7-pound cap", that translates into English as "I do crummy work; get your radiator somewhere else".

Lower pressure = more localized nucleate boiling at internal hot spots = poorer heat transfer out of the engine and into the coolant.

That is unless you are running waterless coolant, which has a very high boil point and so won't boil at hot spots even at atmospheric pressure.
 
slantsixdan said:
A lower-than-spec pressure cap is a band-aid for a fragile, leak-prone system.
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For sure. I used to have a 62 Falcon with a 200 cid six cylinder. After I got it I drove it around for a few months without any issues. It never got hot, but I noticed the seal on the rad cap was gone, and had probably been gone for years. I'm sure it was not putting the system under any pressure at all.

I put a new rad cap on and promptly blew the upper rad hose off the next time I drove the car any significant distance. Weakness found! Turns out it was just a worm clamp that wouldn't tighten up anymore.
 
slantsixdan said:
A lower-than-spec pressure cap is a band-aid for a fragile, leak-prone system. When a radiator builder says something like "Run a 7-pound cap", that translates into English as "I do crummy work; get your radiator somewhere else".

Lower pressure = more localized nucleate boiling at internal hot spots = poorer heat transfer out of the engine and into the coolant.

That is unless you are running waterless coolant, which has a very high boil point and so won't boil at hot spots even at atmospheric pressure.
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I always try to run whatever is stock. Normally, that's "around" a 13 pound cap.
 
slantsixdan said:
False. It does no such thing (even tho you found this claim on the internet, and usually they don't let stuff on the internet that's not true).
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Far as I know the impeller moves water and that's it.
 
slantsixdan said:
False. It does no such thing (even tho you found this claim on the internet, and usually they don't let stuff on the internet that's not true).
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I tried to avoid the use of the word "vacuum", but I maintain low pressure area created by "centrifugal" force, and the terms "single suction, dual suction pumps" seems to support what I was taught, well before the interweb, lol
 
RustyRatRod said:
I always try to run whatever is stock. Normally, that's "around" a 13 pound cap.
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13, 14, or 16, depending on whether the car had a standard or heavy-duty cooling system, had A/C, etc. There might've been 15-pound caps in there, too. Different kinds of seals and pressure valves on 'em, too; article here.
 
Post #264.
Slantsixdan,
You are incorrect & my comment was correct: the WP does produce pressure. If there was no pressure, the water would just be churned up.....but not moved through the engine.

This is from the Stewart Water Pump catalog, says it all.....

img420.jpg
 
For flow to exist there has to be a difference in pressure in the system between inlet and outlet of the pump....
Doesn't matter how it is created or the type of pump. It's all about pump induced pressure at the inlet and outlet being different, lower at inlet than the outlet means we can assign one of them as an outlet, and expect a flow OUT. A flow that occurs regardless of a low or high ambient pressure across the whole system, its about a difference.

Then the coolant is biased to flow in the correct direction.
If it flows, and there are restrictions to the flow between block and head or from head through thermostat, you will have some pressure in the system that can be recognised as being generated by the pump and not the heat energy.

we also need hot coolant to travel down the radiator, hot stuff rises, hot air rises, hot fluid rises, convection is a thing. So there has to be a pressure difference between inlet and outlet of the radiator in order to force the hot coolant down to get cooling benefit of the finned tubes, we are pushing it from the top tank against its nature, in order to be cooled and sucking it down as well by the low pressure at the inlet of the pump.

its a water/coolant "pump"

to make the coolant flow faster
1) reduce restrictions ....bigger pipes bigger holes between head and block bigger thermostat housing fewer bends bigger or more pipes in the radiator
2) A more efficient pump, not necessarily a faster spinning pump, that creates a bigger pressure difference between inlet and outlet, it tries to move a bigger volume per minute

Dave
 
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