Radiator cooling efficiency

Getting ready to purchase a replacement radiator for a 70 E-body 440 with A/C. This combo can test a cooling systems ability to maintain proper cooling. Already have a good fan clutch and fan shroud. 2 decisions to make. Which is better,
2 rows of 1" tubes?
3 rows of 5/8" tubes?
4 rows of 1/2" tubes?
Also what is the best material? Aluminum or Copper/Brass?

Thanks Group!!

Aluminum is good for saving weight, that's all I have to say about this topic. Give Glen-Ray Radiator and a call and ask for Bob, he has done the research...

An aluminum radiator is usually much, much cheaper than a copper/brass one.

When my 51 Plymouth's radiator sprung a leak I was looking at $1000 or so to get it restored. Having a honeycomb core didn't help. New three row Champion that bolted in was about $200. Since my ride is not a restoration type deal I save the money. Neither of them had a problem cooling he 97hp flathead six.

With the above being said there is only 1 place IMO, he is not cheap, but QUALITY never is. In addition resolving cooling problems can be a much more costly experience, in one case ~ 20X. That is right, 20 times the cost of his radiator and that is a conservative estimate

GLEN RAY RADIATORS

Takes a special kind of thinking to spend ~$28k to resolve a cooling system issue.

Four times the cooling area surfaces should be better than 1/4 the same area
Call U.S. Radiator in Los Angles to compare prices for the same one as others are quoting you

if you want additional cooling, consider multi pass radiators instead of a single pass.

I have a double pass, but I have seen a triple pass radiator as well.

Definitely Glen Ray

The double and triple pass radiators come from the circle track racing people. The concept is the coolant flows through the radiator like normal, but then passes through it a 2nd or a 3rd time, at about the same flow rate as a single pass. The process lowers the coolant temp leaving the radiator significantly without slowing the coolant flow.

If you really want to test a cooling system, test it in circle track racing.

In a 50 or 100 lap feature event, the motor runs wide open for 3/4 of each lap. The other 1/4 its either slowing down dramatically, or under its greatest load, lap after lap. Air flow through the radiator is always a challenge, often the "traffic" in front of you is right at your front bumper, and generally, the opining for the air flow is kept to the minimum to increase the aerodynamics if no one is in front of you. If that 100 lap feature event is held on a 1/4 mile track, the motor is running like that for 25 straight miles, if the track is bigger, its even more miles. Should the race be halted for any reason, the delay is probably worse for the cooling system, because the delay would be too short to cool anything down, and the delay may result in a total stop, sit and wait, to resume. It would be about the same as running down the highway at 100 mph pushing the car in front of you for 12 1/2 miles on a curvy road with 40 mph turns every 1/8 mile, then stopping at a long traffic light in some small town, the turn around on the same road resume the race at 100 mph speed on that same curvy road, pushing the car in front of you, for the rest of the 25 mile trip.

Any double or triple flow radiators I've seen were all aluminum. They will not look anywhere near OEM if that is a concern, and you may have to alter your inlet or outlet hose configuration.

If the OEM look is important, your options disappear quickly.

I run a two row Griffith, with my 440, 4 sp 500 hp,no A/C and no cooling issues ever. I run a stock fan shroud and clutch fan.

https://www.griffinrad.com/inc_results_ymm.php?year=1970&make=plymouth&model=Cuda

Chrysler made millions of cars back then that didn't have any trouble with cooling. Do you have a factory 7 blade fan and the correct water pump and is it a factory shroud? What is the engine tune like? Glen Ray uses cooling tubes which are similar to what big truck use, that is one reason they cost more. Bob is the best in the business.

U.S. Radiator relocated to Arkansas (from Calif) a few years ago.

I purchased a 22" "Triple Flow" aluminum radiator (with two 1.25" rows) from them... appears as a stock factory radiator (upper and lower tanks).... I have a 22" core opening.

I have no problems while regular driving, however, under ~20-30 minute road race lapping ... and extreme pylon autocross competition (lots of autocross runs at MOPARTY!), the engine runs hot... I intend to install one or two shrouded electric puller fans (replacing my aluminum 7-blade clutch fan and factory shroud)... hoping that will help... especially during long runs and in-between runs. I've tried running 160,180 and 195 thermostats... no difference with the hi-heat issues when racing long periods of time. I'll typically turn on the heater full-blast to reduce the heat when racing.

I'm also going to make and install an upper flat shroud.. grille-to-core-support... as I see on all road race cars at various tracks.

1. In general, more surface area cools better & you can "approximate" that by adding up the inches.....e.g. 2 rows of 1/2" cools about the same as 1 row of 1" tubes.... so 3 rows of 5/8" tubes is the best from your list
2. Brass cools slightly better than aluminum, but weighs A LOT more (costs more too)

Mr. Sniper,
It takes a special kind of person to make snide remarks without knowing the facts
I believe what I accomplished is referred to as TENACITY, PERSISTENCE, and a happy customer. I resolved an issue that unbeknownst to me at the time had plagued the car for over 10 years. I am known for resolving issues that others had not been able to, this was only ONE of many. Did the customer pay 28K? NO!. He paid what he could afford and I ate the rest.
Would you have done the same?

AGREED 100%,
So what's the difference? The efficiency of the majority of today's replacement cores. They are not ALL created equal as the bean counters and "improved" manufacturing processes over the years have slowly degraded the efficiency in the chase of profit.
While discussing 1-2-3-4 rows there are several other variables, IE: tube thickness. the number of fins per inch, the thickness of those fins, louvered fins, staggering the rows, the methods used to manufacture the cores. All of these and a few more affect the efficiency.

What would happen if you put (plumbed) a radiator, any material radiator, in a vacuum by itself? Of course, being a vacuum there is no air, so how would it cool or dissipate that heat? When we started water cooling off road/MX motorcycle engines the engineers reminded me that the engines are not necessarily "water cooled" as the water (coolant/anti-freeze) is just the "medium" for taking the heat from the engine (combustion, friction i.e, clutch friction) to a place that it can more efficiently dissipate that heat, by transferring it to a larger surface and then having it transferred to the air via airflow over the surface of a radiator as an example. So airflow is the key and not just the number of veins or surface area. We also stopped painting the radiators with black paint and found a somewhat clear coating that dissipated heat much better that paint. Most forget about airflow and if you still think airflow has not much to do with it, watch a NASCAR race sometime and watch how a hotdog wrapper will overheat a car in only lap or less. Then watch how a crew member will take and put a small piece of duct tape on the grill or air intake to get the temp back up or peel it off to cool it down. AIRFLOW. As mentioned the radiator shroud and the fan plays a bigger part on how the cooling system works IMO than the row layout, just me and my

Mike

The cooling system isn't magic. You want me to revise my comment, then give us the facts otherwise I have no basis other than your claim of what it cost to fix an issue that isn't rocket science.

2 rows of 1" tubes will keep the engine cool if the rest of the cooling system is correct, the others "can" dissipate more heat but there isn't any heat left for them to dissipate if the rest of the cooling system is right and the only thing they will dissipate is money from your wallet. The others will have more places that are likely to leak also. Now if you don't have good coolant circulation because your water pump is turning too slow or blades worn or not enough of them or the air under the hood is not managed properly by the shroud and things to block the air from circulating AROUND the radiator than the more expensive options may cover up those other issues.

Maybe one should inquire about the facts before making the snide comments you seem to enjoy posting. FYI the short version is within this recent post from last year
https://board.moparts.org/ubbthread...recore-a-26-hd-radiator.html#Post3095492

Another in which you were involved also lists a little bit of info on my background / experiences in this area
LINKY 2

I would like to ask that you read your comments as though they were directed at you and how you might take them. That also is not rocket science but rather something we should have been taught and all try to do. It's called being respectful to each other, EVEN IF WE DISAGREE. Our world world benefit from it. We are supposed to be here to help, not ridicule each other

One can debate about cooling efficiency but..
Mopar designed an adequate cooling system the challenges are when engine modifications are done..
We have found often the cooling problems are related to incorrect ignition timing and/or lean fuel mixture.
IMHO.. Today it is difficult to find an experienced mechanic that will take the time to diagnose and correct that doesn't cost major $$...

Just my $0.02...

You don't typically get to pick both tube size AND material. Larger tubes are almost always aluminum (stronger material), while the smaller tubes are typically the copper/brass. Aside from just comparing tube size, you need to look at tube spacing and number of tubes. At the end of the day, you can get a lot of heat to the radiator, but if the airflow isn't there, the heat doesn't come out (More tubes and less fin = more pressure drop on the air side for the fan to overcome).

Pick a product from a proven, quality supplier (Glen Ray, Griffin, etc) and you'll be fine. It all comes down to the look you want in the car too.

And don't forget camshaft selection.

Excellent point. "back in the day" it was very rare to find a Mopar performance car (or most any other brand performance or standard car) that had over heating issues in standard trim. They all knew about heat and thermal issues down to having power steering coolers, and transmission cooling etc., They were always on top of those potential issues to the point of even being on the over cautious point.

The other point is...
Today frequently guys will start bolting on these aftermarket electric fans schemes to address their overheating problems..
But..
Next then they fail to understand about the high current drains of the fans, often exceeding what their alternator and wiring can support..


Just my $0.02....

Yes, I went through this with the 383 in my 69 GTS. Typical .509 cam, Torker intake, Carter 650, MP electronic ignition on a stock bottom end. Had overheating problems like crazy, threw everything I could on it, radiator, fans, pulley's, shrouds, and it ended up being to lean and too much timing! This was in 1981, so these kinds of things have been going on for decades...

had a frein back in the mid 70's with a warmed over 383 in a 63 Plymouth. Always ran hot. Hid tried all kinds of things to no avail. When he swapped a 440 in he found the root cause. The water pump impeller was laying in the housing
We weere pretty young and didn't think to check for water movement at 2-3k RPM

A few years ago I had a street rod come in the shop with a new engine , trans, radiator etc. and a heating problem. had been to a couple of different places with no success. It had a 90° elbow on the top tank so you could not really see the coolant. A borescope showed little movement of the coolant at 2500 RPM. After checking pulley ratios, the thermostat etc, we found a red shop towel inside the lower radiator hose All was well after removing it

Use a radiator with the two biggest cores you can find. More smaller cores is not better.

Aluminum will cool whatever you can throw at it and weigh and cost less than other matériels.

Use a high flow water pump. The Milodon and Flowkooler pumps are both great and I’ve use both. Last time I looked the Milodon was cheaper than the Flowkooler. The both work equally the same.

Use a Stewart Components high flow thermostat.

Make sure your water pump is turning crank speed at the MINIMUM. If you can get the water pump turning 10-12% faster than the crank it’s even better. Even 6% overdriven is better than 1:1 and never underdrive the water pump.

It’s a system. You can’t neglect one area and expect the best cooling.

If the system is correct, your engine should rarely run hotter than your thermostat rating. In other words, when the cooling system is correct and you decide a 180 thermostat is what you want the engine even on the hottest days should never go above 190 degrees. And that should be at a stop light and as soon as you get rolling the temperature should go back to 180.

In the same example if your temperature is at say…195-200 degrees with a 180 thermostat then your cooling system capacity, coolant flow (which includes fan speed for slow driving conditions) or both are incorrect.

personally, i like to see around a 195 degree temperature.
that keeps contaminates in the crank case boiled off, as well as a tick better as mileage.
if all is well with the coolant system, even 200 doesn't bother me in stop and go traffic on a hot day.
however, your tuneup must be on target, as well as the total cooling system.
these cars when new came with a 185 thermostat, and that means it starts to open at that temperature, usually becoming fully open 10 or 15 degrees hotter.
also, the dash gauges were marked L to H with a line between for a reason. if the needle settled at halfway or a little less and stayed there, we were happy.
we then installed a mechanical temperature gauge and immediately had "overheating" issues because we saw 195-200 degrees, while the factory dash gauge still registered in the middle, or less. some of the factory gauges ran closer to the L position, and we REALLY freaked out when a mechanical gauge said 195 or so.

I think everybody scared the op away after the pissing match or throwing in their $.02 Copper/brass cool better than aluminum but it is used more often. Shouldn't be a factor unless you want 100% stock look. As mentioned a lot of factors go into getting the "correct" cooling. As a rule of thumb compare the original radiator that was used (engine/accessories(AC) etc) and compare it to a replacement. You can use this as guide or use this one.

Oh I'm still here. Not a sc sc scared. Just gathering all the info I can before the purchase. Consensus is, get two rows of biggest tubes you can, 1" - 1 1/4" compared to 3-4 rows of 1/2"- 5/8".

many, many years ago when replacement 4 core brass/copper radiators were introduced, sometimes they didn't solve cooling issues, and at the time, the consensus was the cores were too close together, not allowing the heat to fully transfer to the surrounding air.
today, i have no experience with one of those [4 cores] that are available, so i don't know if they work better or not.
i mainly get involved with modified vehicles or resto-mod ones, but i like to learn about new ways/things i don't know, or old ways/things i have forgotten about.
if i'm way off base, please correct me when you can !

I much prefer copper/ brass but impossible to find anymore

Things I have learned about performance engines and cooling systems are you need a lot of coolant flow and good clean airflow over the largest rad you can fit in the core support. I drive a Flowkooler pump 1-1 with the crank and an ECP 26" aluminum radiator with great results. https://speedcooling.com/product-category/radiators/mopar-radiators/page/2/

Gus

Can't disagree with the bolded part
But myself I have seen no change with the flow kooler or other similar pumps testing under as close to laboratory conditions as I could get and measuring with thermocouples and digital meters (laboratory grade again)

When I get a radiator done at glenray it is always 10lbs heavier than if I get it recored at a local shop, maybe the metal is thicker. All I know is Bob's stuff works.

those "flow kooler" water pumps are the ones with the "circular" vanes about 1/4" or so high, on a cast circle base ?
i always like to overdrive the pump some, but is there such a thing as being overdriven too much ? there are only so many pulleys to choose from.

Can't disagree with the bolded part
But myself I have seen no change with the flow kooler or other similar pumps testing under as close to laboratory conditions as I could get and measuring with thermocouples and digital meters (laboratory grade again) [/quoteI

I had an issue with scale clogging my rad over and over so I installed a filter in the upper hose and I could actually see the flow difference between the factory pump and a Flowkooler pump. The filter was a good tool to catch the scale from my block. I ended up filling it 3 times now it stays clean.

Gus

The thermostat serves another purpose, and that is to regulate the flow rate. Removing it will cause overheating but can help compensate for a crudded up radiator. Pushing the coolant through a good radiator too fast can also cause O/ heating as the coolant may not have enough time to exchange the heat. So I would say yes. remeber you are dealing with several variables. Flow rate, pressure driving the flow, pressure in the system, size of the radiator, air flow through the core, Ambient temps, BTU's being generated, and the the infamous core debate itself. Probably a few others as well but that's a kwik list

interesting on the flow and scale

The "coolant too fast" theory has been debunked dozens of times. Increased flow rate leads to turbulence, and turbulence within a pipe/tube encourages mixing (better contact with the walls to remove heat) and enhances heat transfer performance all the way to the point of physical tube erosion from the fluid velocity being too fast for the material. There have been some potential claimed issues with pumps cavitating, but that has nothing to do with coolant moving too fast in the radiator.

still wondering about those flow cooler pumps, are they the ones with the "circular" vanes about 1/4" tall on a cast round base ?

OK 💨

The originals had a flat plate on the engine side of the vanes. there were "KITS" with a plate and pop rivets available for awhile.

I consider them to be right up the with Slick 50. I was taught to ask if and idea is so good, are the major MFR's adopting it? Think of the warranty savings

This is the one I use

I'm assuming the OP is looking for a "new" radiator. Not sure if the old one needs replaced or just not doing the job. I once had an issue with overheating myself, but it was narrowed down to timing. One the timing issue was corrected, the overheating went away. I should add that the overheating was only at idle or very low RPM

thanks.
the one i'm thinking about might be the milodon pump. [i have not used the google to look, so i guess i need to]

I bought a Milodon HV water pump at Summit and opened it up at the counter and there was a GMB pump in the box Gave it back and they brought me the FlowKooler pump

Gus

This is a completely accurate and more detailed response than mine... there is more than just adding the inches....like dimpled tubes and these things mentioned. Somebody else mentioned air flow, which is also important. You need coolant flow and air flow to cool the engine

Yes. Being the original poster, I was wanting to replace the rotted out 26", 3 row radiator in my project car. It is a slightly modified, cruiser street 440 with air conditioning possibly in the future. My biggest concern was just having enough cooling for now with an all aluminum unit, plus any future plans I have for the car.

I have a 22" 3 core champion on my 600hp hemi and it cools great.

[size:11pt][/size] Well this will not be the first time, and absolutely not the last, that I over think something. About half of the cars we run around with, can go for hour and a half to two hour cruises to a show, but won't last 20 minutes in a parade.

A 4th of July parade will certainly test a cooling system, especially if your behind the HS band with the AC running, and the car was running with the AC cranked up, while you were waiting for them to set up the parade to get started.

That sir is not a radiator problem, but rather a lack of air flow through the radiator . A bigger radiator may help a bit, but the root cause is air flow,

Again

Somewhat related to this overall subject, when using an electric fan (puller, 1 or 2 fans), some fan shrouds are solid, while others have small venting slots or flappers around the otherwise solid shroud areas. I'm considering to get an electric fan (1 or 2), that would have a fan shroud. Any preference/suggestion on the design of the shroud? This would be for my aluminum triple-flow US Radiator, 22" wide (fitting my core opening)... runs hot while road racing/autocrossing, but cool in regular street or hwy driving. I've tried different thermostats... no difference when racing.

A shroud with the flappers would be the better option. When the air flow is low, it will still let the fan pull the air through the entire radiator, and at any point the air flow is higher, the flaps open so the fan can't block any air flow. The best of both worlds.

The OEM fan shroud on my 90 Dakota V6 5 speed had a belt driven fan and the shroud had the flappers. That one was the 1st OEM shroud with the flappers I'd ever seen (not that it was the 1st ever, but just the 1st I'd seen).

IMO, You have either an inefficient core for the BTU's being generated or an air flow issue. My bet is on the 1st .

So you seem to be quoting from discussions such as this https://www.eng-tips.com/viewthread.cfm?qid=262583
Not a single respondent to that stated that they were a -hands on- Chemical or Hx engineer and the info given reflects that. Top hit in google isn't necessarily correct.

Laminar flow can affect both the airflow and coolant.

There is a dwell time required for both the air and coolant to absorb or shed heat.

Despite what we observe in the top of a radiator, the coolant in an engine dose not achieve/maintain turbulent flow (exceeds its Reynalds rating) through the entirety of the system (if at all), there are many different flow rates occurring in the different sized passages.

This leaves laminar flow as the predominant effect, with much of the heat moving slowly on the edges and fast moving cold coolant channelling to the centre of flow.

Hence the balancing act of flow rates, volumes, materials in play, size of condensers and so on that every auto manufacturer has had to do for over a century now.

If it were as simple as "make the coolant flow faster", there would be only a few different smaller radiators in use and water pumps would be multistage jobbys flowing many multiples of the volume (and pressures?) in use now.

I use manually controlled heat exchangers on a regular basis and I can assure you if the coolant is too fast, performance can drop to the point of not working at all.

No, im not an engineer, just a tinkerer and a thinkerer

There is a HUGE issue with your thinking regarding how much time the coolant stays in the radiator. Thinking and saying the coolant has to stay longer in the radiator to absorb more heat is a circular logic. And a flawed one.

Any and by any I mean ANY restriction in the flow of coolant (or air) degrades the cooling systems ability to do its job. That’s a simple fact. Look in the Factory Service Manuals for different years of engines and you will see the performance engines had OVERdriven water pumps. Not UNDERdriven. UNDERdriven might work in a low performance application but where coolant temps are critical (this could be for any number of reasons but a couple would be making more horsepower requires more cooling and running higher compression on limited octane fuel such as pump gas requires engine temperature to be controlled and as such in my 11.77:1 pump gas engine I keep the coolant temp at 160 to control detonation) you overdrive the pump.

Under driving the pump was a 1990’s fad that should have died with the 90’s.

So while you are tinkering and thinkering, consider this. Every time you leave the coolant in the radiator longer, the coolant stays longer in the block. Where it picks up more temperature and that means you start taxing the cooling system harder.

An air to water cooler (thats what a radiator is) is limited in its ability to cool by whatever the ambient temperature is. That’s one reason a thermostat is needed, even though it’s a restriction. You have to set the MINIMUM coolant temperature with it so that on days where ambient temperatures are low you can get the required minimum temperature you need. For me, that’s 160 or the heater becomes less effective. And I’ve driven my junk in near zero weather.

Along those lines, let’s take a look at a 100 degree day and think it through. In this case, the lowest possible coolant temperature you can attain is 100 degrees. Of course, that doesn’t happen because you have a thermostat to regulate minimum temperatures AND because as the delta T decreases (thats the difference between ambient and coolant temperature) the ability of the coolant to drop the temperature becomes less effective.

In other words, let’s say you have a 190 degree thermostat and it’s 100 degrees ambient. You have a 90 degree difference. If we have an ambient temperature of say 60 degrees you’d have a 130 degree difference. That change in temperature differential between those two ambients means the lower ambient temperature has more cooling capability than the higher ambient. And those numbers are taking for granted the cooling system is good enough to maintain thermostat temperature on a 100 degree day. Most cooling systems aren’t well thought out enough to do that so you may be at 195 or even 200 degrees of engine temperature and that makes it even less efficient.

All this matters because the longer the coolant stays in the radiator the longer it stays in the block, picking up heat. If you have enough coolant flow that when the coolant temperature is at your thermostat rating, then it’s easier to keep the coolant at that temperature. But, if you don’t have enough coolant (and/or air) flow, the n forcing the coolant to stay in the block longer taxes the system harder.

You need the coolant speed to make the coolant take on as much heat as it can to reduce hot spots and to cause turbulence. Laminar flow (air there really is such a thing in a cooling system) might sound good on paper but it’s not.

When you see a cooling system that can’t maintain its thermostat rating you KNOW that the coolant is moving too slow thereby staying in the block too long, or you don’t have enough airflow or both.

It’s time to slay the wives tale that keeping coolant in the radiator longer is the correct way to do it. It’s not. It’s bad.

Do you even see the logical fallacy in your argument?

Actually Moroso was selling under drive crank pulleys at least 20 years before that. I think they were more interested in parasitic HP loss and high rpm pump cavitation than street car cooling. We used them mostly in drag cars.

What Mad science has said probably came from research at the University of Minnesota which has been leading in heat transfer study since 1887. They could be wrong, or the physics in some radiators is different than the rest of the universe. More/faster flow is good, slow is not. Some rumors are persistent through time, and this "too fast through the radiator" will come up again. But it won't be true then, either.

I have spent over 25 years in various engineering capacities several of which dealt with cooling.
The1st, 2nd, and 3rd bolded statements by 83 hurst IMO are correct. especially #3

The 1st statement by MS is not, an automotive radiator does not generate heat.
The 2nd Statement in is also misleading as the entire system design has to be considered many vehicles will overheat without a t/stat in place. Please see LINKY
The 3rd statement is true to a point, BUT if the radiator, fan and flow rates are correctly designed that heat will be dissipated
The 4th Statement if it moves too fast in the block or radiator it will not have enough time to absorb or shed the heat (See above link)
The 5th needs clarification on "maintain its thermostat rating you KNOW that the coolant is moving too slow thereby staying in the block too long, or you don’t have enough airflow or both." Too hot or too cold ?

The last statement "It’s time to slay the wives tale that keeping coolant in the radiator longer is the correct way to do it. It’s not. It’s bad." I also disagree with as once again, it goes back to the design of the entire system.
Not trying to start a p'ing contest just stating my experience's and opinion's

Go look at the formula for calculating thermal transfer efficiency. Guess which variable isn't in it? Time.

https://www.researchgate.net/publication/320490866_Performance_Analysis_of_Automobile_Radiator

So Sniper's link is about the construction of a cross flow radiator and its configurations. They are comparing radiator designs against each other, so everything is consistent. There is nothing considered concerning over heating. Yes, I read it.

TJP's linky is specifically referring to over heating, its primary concern is low air flow through the radiator. It appears to be an article in a news paper from a guy that had an over heating experience on an LA freeway, so it may well only be an opinion as well.
It does state "If for some reason the air flow rate through the radiator is too low, the radiator won't be able to do its job and the engine may overheat. At this point (after over heating) If the coolant flow rate is increased the engine will then transfer more heat to the coolant which will exacerbate the situation. I looked it up, exacerbate means to aggravate or irritate. Yes, I read it too.

The battle rages onward!

The battle rages on because of the myths perpetuated that will not die.

Think about it.

The longer the coolant stays in the radiator, it’s also staying in the block longer. Where it picks up more heat. That means the radiator has to dump more heat. So staying in the radiator is adding to the heat load the radiator has to eliminate.

We are working with limited temperature differentials. On a 100 degree day, the difference between that ambient temperature and your coolant temperature is less than it is if the ambient is say…60 degrees. That temperature differential is what makes cooling possible.

What your temperature gauge is telling you is the AVERAGE coolant temperature at the intake manifold. You can (and probably will) have localized coolant temperatures much higher than what the gauge says.

Getting the coolant out of the block quicker (more flow) will reduce local hot spot temperatures because the coolant is moving out of those areas so it’s not allowing the temperature to build up in those places.

You can always tell when a cooling system is inadequate. When the temperature on the gauge is higher than the rated temperature of the thermostat you’ve got issues. If you have a 180 thermostat then your gauge should stay between 180-185 in ANY weather conditions you may incur. On a very hot day, you may see an additional 10 degrees of temperature sitting at a LONG stop light or (alike happens to me if I’m not paying attention) if you get caught waiting for a long train to get out of the way. But as soon as you start moving the temperature should go back to where it normally runs.

If you have a 180 thermostat and your normal operating temperature is say…195 then your cooling system is inadequate. That then is a coolant and air flow issue. Too slow of coolant speed or not enough airflow or both.

The thermostat sets the MINIMUM operating temperature. That’s all it’s job is. It’s a restriction and that’s BAD, but it’s necessary. I have to run a thermostat. If I don’t, even on a 90 degree day my coolant temperature won’t go over 120 degrees or so. On a 50 degree day it won’t go over about 90 degrees. That’s because my cooling system is fully capable of controlling coolant temperature like it should so the thermostat does exactly what it should do, and that’s set the minimum temperature.

There is a reason why guys can go from a 190 to a 160 thermostat and the engine doesn’t stay any cooler. The cooling system is inadequate to deal with the heat load it has to deal with.

I run my water pump at 6% overdriven and if I could I’d double that or a bit more. We had some 108 degree days several years back and my engine temperature was at 160 even in that heat. At stop lights it would get to 175ish and then it would drop back down to 160 once I got moving again.

The backwards thinking that the coolant has to stay in the radiator longer to dump more heat is a fallacy, because the coolant stays in the block longer picking up more heat that the system has to deal with.

Mad Scientist, I don't think you can ever dispel this myth. There is some myths that will never go away. My favorite, besides this topic, is the Pennzoil myth. I'm not sure how to say this nicely, but both of us should maybe consider that the scientific principals of heat transfer apply evenly throughout the universe, with the exception of some radiators installed in mopar cars and trucks. Have a nice day guys......hang in there

Since you're interested in qualifications, I am an engineer that has done heat exchanger modeling, and have quite a bit of experience with air to water heat exchangers. You learn a lot when you learn to calculate things beyond just Reynolds Number... since you've been busy on google trying to find a place where I copied an argument from (and I didn't), I recommend you research Nusselt number and understand how it works.

Here's a simple explanation. Put your soup in the microwave to heat it. This represents a cross section of a tube in a heat exchanger. You run the microwave for 90 seconds, and you find that the edges are blazing hot and the center is cold. Why? The fluid is heating via conduction and not mixing (like laminar flow)... So what do you do? Stir it! Imagine if you could actually stir the liquid while microwaving - that would be efficient. Turbulent flow turns conductive heat transfer into convective heat transfer and greatly increases the heat transfer capacity of the system.

I may have missed it (this is a long thread) but no one has mentioned that the rate of heat transfer increases as the temperature differential between the hot object (engine in this case) and the cooling fluid increases. So that would support the postulation of not moving fluid slowly through the block if you want efficient heat removal. You wouldn’t run a small radiator fan(s) so that the air has more time to remove heat from the radiator because we all should know that would result in poor heat extraction and thus an overheated engine, so why would you reduce the flow of the water pump?

Not to go off-topic, but “Pennzoil myth”??? High paraffin base stock that leads to sludge/varnish under high heat???

Gee, that is a really nice write up.

Except, the thermostat temp (160, 180, 190) is the temp the thermostat starts to open, not the temp it is fully open. If you have a 180 thermostat and your coolant temp is 180, either your gauge is incorrect, or your thermostat is not operating correctly. Of course that also depends on the location of the gauge sender, in relation to the thermostat, and you are assuming the gauge sender is submerged in coolant and not in a trapped air pocket.

A cooling system that can maintain the coolant temperature within 10 degrees of the thermostat rating is functioning correctly.

I've been playing with cooling systems on cars & trucks for a very long time. There is very seldom (read that as almost never) one "fix" that works every time. Usually is a combination of "fixes" that have to be tested to determine which one(s) will cure the issue. Air flow that passes through the radiator traveling all the way through leaving the engine compartment, and obstructions and alterations that change coolant flow speed (fast or slow) from the original design are usually right after coolant leaks as the places to start. Outside of poor maintenance, modifications to the cooling system (or the motor) are usually the causes of cooling system failure.

Question if you take the radiator, water pump, thermostat, coolant or everything to do with liquid cooling out of the picture for engine cooling what would be the main component for cooling the engine?

Is this like that Schrodinger's cat question?

I think my answer is the state of the tune-up

Gus

Moparts: where you come to get lectured on the intimate Laws Of Thermodynamics, Boundary Layers, Air Flow; but you still haven't fixed your overheating dilemma.

Just trying to show how surface area, material, and air flow IMO have as much or more to do with engine cooling than flow rates and radiator cores. I've raced air cooled motorcycle engines for a long time and in the late '70's early '80's high performance motocross and off-road motorcycle engines became liquid cooled and we dealt with the overheating issues and mostly (but not exclusively) the problems were caused by lack or reduced air flow. On air cooled engines it relied on the surface area of the cylinder fins, the material (aluminum) and the air flow across and around the cylinder and cylinder head fins. When we went to liquid cooled engines all we were basically doing was using the coolant as a medium to take the primary source of heat engine combustion and taking it to one or two aluminum radiators and dissipating that heat to air. No real rocket science except in air flow with radiator side panels as scoops and our engineers even came with side panel or radiator "shrouds" that had opening that created a "chimney effect" that would help remove hot radiator air from behind the radiators at slow speeds or even at a standstill. Engines are still air cooled in my opinion they just use coolant to take that heat to a radiator or air cooling area. That's why I feel or know that air flow, surface area and material are most important. Check out this air cooled, 500cc single, hemi head, twin spark plug 60+ HP motocross bike from the early '80's. Lots of aluminum cooling fin area with lots of space for air flow. BTW most liquid cooled motocross bike still use the same basic size aluminum radiators to this day. Only a few things have changed like special radiator coating rather than black paint to better dissipate heat or small electric fans on the backside of the radiators for extreme slow moving conditions. AIR FLOW IMO is a key element.

CLARIFCATION The link is to an article, in a publication, by the California Institute of Technology also know as CalTech.

The article is in response to: Question of the Week: Why Does an Engine Cooling System Have a Thermostat, and How Does It Relate To the Coolant Flow Rate?

Submitted by Bill McLellan, Pasadena, California, and answered by Melany Hunt, Associate Professor of Mechanical Engineering, Caltech.

I'm going to go out on a limb here and say Ms. HUNT likely knows more than all of us on this subject

Yeah I get the airflow deal. All you have to do is look at the duct work on a cup car to see the science behind air flow to EVERY component on the car that generates heat.

Gus

And as I mentioned before, a small piece of duct tape added or removed or a hotdog wrapper and either overheating, too cool or just right.

Only if you buy cheap assed, low grade thermostats. Stewart Components makes the best thermostat. And they are FULLY OPEN at their rated temperature. So there is that.

So when I say the thermostat sets the MINIMUM OPERATING TEMPERATURE that means you can’t buy straight junk. You need to spend a bit of money on a quality thermostat.

"Not to go off-topic, but “Pennzoil myth”??? High paraffin base stock that leads to sludge/varnish under high heat???"

Kinda sounds like you're into it.

Note how many race oil companies come out of Pennsylvania. Pennsylvania crude has some of the best lubrication qualities of all crude on the planet. If it was actually bad, they would have fixed it decades ago.

Not going any further with this.

Another factor to consider, if you increase the fluid volume of the radiator (by adding extra size/square area, rows of fins, etc), then that extra volume should help to dissipate at least a little more heat.... my thoughts.

just like the "quaker state" myth..............
both of these myths were ultimately chased back to bad maintenance, [not changing the oil] and short trip driving, not allowing the oil to get up to proper operating temperature.
these myths were rampant in my junkyard ownership days [1972-1984/5], and we sold a lot of engines because of them. knowing several people well that bought engines from us, it quickly became apparent no matter what oil was used, not changing it and short trips did engines in.
remember now, back in those days, the machining process was totally different than today's, and if an engine lasted 100k, it was because of good maintenance and/or long drives getting everything up to proper operating temperature.
and as above, that's all the further i'm going with this.

If you haven't bought your radiator yet, check out Holleys winter sale. Here is a radiator for your car, I believe.... You won't beat this price.. https://www.holley.com/products/cooling/radiators_and_accessories/radiators/parts/FB706

that IS a good price !

Man that looks just like my champion???

Ok, so i went n read some more, chatted to some people and worked out what i had wrong with the other condenser i use and im happy to take my Spanking.

Please sir may i have another lols

So in my reading a couple of nuggets that popped out for me were...

No point having a radiator larger than the actual open area of your grill minus any mesh and so forth, seems like common sense and would point to where a smaller thicker radiator could work better than a wider 2 core one depending on the car.

One source stated that the ideal flow speed through a radiator tube is 6-7 feet per second with the errosion factor starting at 10fps - thoughts, comments, is it worth the math to work that out?

It would seem to me that an external electric pump like the Davies Craig ewp 40gpm with a diy pwm control for it and thermo fans would be a good street set up that would be traffic jam indifferent? No doubt insufficient for a serious engine with sustained rpm, thoughts?
https://www.summitracing.com/parts/dcw-dc-8160

Go to the Stewart Components web site and read their tech pages. They are experts.

That DC 40 GPM pump won’t cool much. You can bet it will flow half of that in an actual cooling system.