Radiators and Cooling 101

[fabr]

This is an EXCELLENT article on radiator/cooling tech. Long read but some very,very important info we all should educate ourselves on. Well worth the fricken hour or so it takes to read.

http://www.pirate4x4.com/tech/billavista/Cooling/

[dsrace]

very good info!!

[Nutz4sand]

I do not agree  with it all.

I know Bill Avista does know a lot about a lot of things but he cannot admit when he is wrong. I have seen it a good few times. He DOES make mistakes.

But because he calls his books of info "bibles" many worship the ground he walks on.

I refer mostly to his "myth" section in this coolant article.

He claims that you cannot run coolant through a radiator too fast. I call WRONG on that.

I AM interested to hear others inputs on his "theory" of faster is better no matter what else on coolant flow. I fall to the "heat takes time" to transfer and it can go through so fast it goes back into the engine TOO HOT.

Also his if you do not run a thermostat you should not run a restrictor. This would only work if the radiator was far to large. Heat up time would take forever.

His train metaphore for heat removal is pretty lame and it tears his theory apart as much or more than it helps it. 

He leaves to much to a guess. His "theories" do not work with every system. 


I also tend to think he is paid to push certain items anymore. Griffon radiators in this case.

[fabr]

You may well be correct.I have no idea,I am not well studied in the least on it but , what he says seems to be inline with my thinking.My biggest question that comes to mind ,in line with what you wrote above,is the truth or not of the patented tubes Griffin rads have that he claims are what?,100% more effecient than plain tubes? WHat's your opinion on that regardless of anything else he wrote?

[Nutz4sand]

I have bought tranny oil coolers specifically that had tube shapes and inserts inside the tubes to make the oil more turbulent and I do see how that can aid the oil (or antifreeze) in making the fluid inside contact the edge more so thus one would guess it WOULD have better cooling.


But I also know we have ran clear fluid thru clear  tubes with what amounted to glitter in it and we NEVER saw lanier flow.

Add in in a radiator the coolant is not being fed smoothly in the end and then forced down a oval tube its gonna be going nuts to a great degree.

I dunno if I would say the Griffin ones are that much better (100% more efficient... dunno to nah not quite). But are likely better to some degree.

One might say a test of that would be if the griffins were 100% more efficent one you found the smallest radiator you could live with to cool your engine with a normal radiator you could get a Griffin in half that size and be OK.

If I had nothing but time and money I might try it just to see. I WILL NEVER take his word for it.

I consider Bill-Avista a Ok source of info but one that needs to be double checked to be safe. When he can walk on water and turn my water into wine AND smite the dark one I will take his works as bibles.   

[fabr]

  I agree on the turbulence . Everything I have read has indicated it to be true.How true,in terms of % is debatable.
    I don't agree with you on the water speed through the engine though. I believe what he was really saying was that most engines have enough natural restriction in the cooling system(total head) to not be able with any conventional water pump push too much water through even if unrestricted  keeping engine at below optimal temps. Since we all use conventional electric or mechanical water pumps on our engines I see no way for there to be such a thing as too much flow considering the delta t stuff when using a proper thermostat. There is such a thing as too little flow for sure. If I have to make a choice I see only one option. USE a thermostat as the correct "restrictor".
  Just curious,it seems you have real issues with the author and I have no problem with that but,is there anything else inaccurate in your opinion with the article? It ,to me,seemed to be pretty spot on.

[Carlriddle]

Fabr must been reading my mind, but after readin i may be more confused.  I'm thinking I have more issue with pump flow or T-stat.  But will add that a functioning T-stat, cant have too much flow or even too big of a rad and fans.  Rare to hear anyone complaining their car is too cool.  Atleast in what we do.  Maybe if you haul ice cubes across canada in winter.

[dsrace]

well to be honest i read in about 3 pages and what i read seemed to be informative, and for the most part i still believe it is and with any article you always take it with a grain of salt.

 I do believe there is a lot of design work that goes into the cooling systems, but when we take motors out of the units they were designed for, the stock radiators just are not enough. now the radiator is part of the cooling system but not the cooling system as a whole, so a lot of the design work is done for us. on the bike motors there are several places to buy water pumps with a diff rake on the impellor to change the flow rate a little bit for diff purposes.   even if one wasn't going to use a thermostat you still have to use the restrictor ring off it to or in otherwords cut the core out of the stat. imo       as far as too fast and too slow through the system or radiator goes, this would all be determined by a number of factors per build. what i mean by that is a build running no stat or rest ring with a higher velocity pump over stock and a single pass rad 3 times the factory could have high flow problem to some extent.  i doubt that's what he was talking about but that would be 1 instance it's possible. 
i do know that there is a point where you have too big a radiator and too small but that grey area between those two points is huge!   

[BDKW1]

I refer mostly to his "myth" section in this coolant article.

He claims that you cannot run coolant through a radiator too fast. I call WRONG on that.

I AM interested to hear others inputs on his "theory" of faster is better no matter what else on coolant flow. I fall to the "heat takes time" to transfer and it can go through so fast it goes back into the engine TOO HOT.

Also his if you do not run a thermostat you should not run a restrictor. This would only work if the radiator was far to large. Heat up time would take forever.

He is 100% correct on this. Restrictors are complete crap and should never be used. If the fluid is staying in the radiator longer it is also staying in the block longer collecting more heat. This can lead to hotspots and boiling/steam pockets. Once you get a steam pocket your heat transfer goes to zero and things go down hill very quickly.
 
With higher flow, your temp rise may not be as much, but you flow rate is much higher effectively removing the same amount of heat without the risk of steam pockets.
 
What I have used for years on race trucks is an umbrella style thermostat with 3-3/16" bleed holes in it and no bypass hose. This allows for some flow restriction to aid with warm up but still allows for full flow at race temps. 100% of the coolant needs to go through the radiator on a desert truck. This may not be ideal for colder climates...........
 
You can actually buy these thermostats from Stewart racing components. They were originally developed by Robert Shaw. They had a very comprehensive online help section that covered everything in the "Bible" plus touched a little more on airflow around the radiator. Unfortunately, there website seems to be down at the moment..........
 
Also very important is the DC readings in the coolant. If you are using water wetter and have to much DC through the cooling system it will develop white chalky formations in the water passages. Bad news.........

[fabr]

+1 IMO

[Nutz4sand]

My biggest issue with billavista is to many take his word as gospel (hell he calls his books bibles it MUST be gospel) and they think nothing else can matter and when billavista makes a mistake they will defend it to the ends of the earth.

That said I do not believe that most engines have enough natural restriction flow to allow the coolant to cool in the radiator in most cases. Let run free the coolant will not cool enough in the radiator UNLESS its way way to big. You can EASILY put a temp gauge in the infeed and exit hoses and watch the temps climb till she boils over on most any unit out there with no thermostat (or restrictor) that is not sporting far to big of a radiator.

In those cases a restrictor could help.

Those with that too big a radiator will often not get to operating temp often if ever.


Restrictors and thermostats also make for higher pressure in the block. Besides the temps in a sealed system raising the pressure the pump pumping against the restrictor or thermostat will raise the pressure a few more psi in the block area. This is pretty easy to measure if you get a jones too. A restrictor would be more consistent as it does not vary (This does not mean its better!) but when a thermostat closes the pressure in a block on the pressure side of the pump will jump very noticably.

Bottom line I feel there are as many variables to this as there are vehicles and unless you are purposely duplicating a vehicle with an identical clone it will not be the same and even the clone will have SOME differences that could come into play in the cooling system. 

A LOT of this discrepancy comes from comparing a stock system thats built by the manufacturer to be as cheap as possible VS a guy building a toy with the best of the best parts to answer a problem.

Billavista often suggests better parts but does not always state when one thing that will work with a high dollar radiator is different that a stock radiator of some type. Its that kind of thing that is crap.  He DOES often say ones better but his theories are not clear to all for all parts and this often causes confusion among his "followers".

Who then try to spread the misinterpreted info as more gospel across the entire web. Yah I don't care for that.

[Nutz4sand]

He is 100% correct on this. Restrictors are complete crap and should never be used.

I would not say never.

  If the fluid is staying in the radiator longer it is also staying in the block longer collecting more heat. This can lead to hotspots and boiling/steam pockets. Once you get a steam pocket your heat transfer goes to zero and things go down hill very quickly.

I do agree that this can and does happen but thats to much of a blanket statement as some designs are VERY prone to this and some others are not. Without testing and researching whats going on in YOUR system you cannot say it needs to move faster or slow down more. WAY to many variables to say its one way and one way only.
 

With higher flow, your temp rise may not be as much, but you flow rate is much higher effectively removing the same amount of heat without the risk of steam pockets.

Higher flow rate removing the same amount of heat???  Not sure I follow that. Care to elaborate?
 

What I have used for years on race trucks is an umbrella style thermostat with 3-3/16" bleed holes in it and no bypass hose. This allows for some flow restriction to aid with warm up but still allows for full flow at race temps. 

Now this above sound suspiciously like a restrictor once the vehicle has warmed up. Does it not?
 

[BDKW1]

It's only a restrictor till you reach operating temp. Then it opens and you have full flow. The radiators we run are huge. The TT had 2 34 X 16 radiators in it. Would hold a constant 170 or so with a 180 drilled T-stat until you got on it. Never saw over 220 in it even flogging through a silt bed in 110* weather. Would hold 170 with the fans off in 30* weather in Nevada. I have been doing this for a long time and never seen a restrictor solve a problem. I have however solved many issues replacing them. Upping block pressure with a restrictor is a ban-aid. Pressure should be fairly consistent system wide. 25-30# cap and be done with it. If you restrict it so much that your block pressure prevents boiling in the block, as soon as it goes through the restrictor and the pressure drops it will boil. Poor combo.
 
The newer LS motors with the recirculating systems are the way to go. Zero restriction ever and full flow once up to temp. Unfortunately, a little hard to replicate on a SBC. I have been looking into making a billet housing with a return using a LS T-stat that would work on manifolds lacking in water passages and T-stat housings like the Edelbrock Victor SB2's.

[BDKW1]

Higher flow rate removing the same amount of heat? ??  Not sure I follow that. Care to elaborate?

Say you double your flow rate but your temp rise is only half as much, you are still removing the same amount of heat. Plus you do not have the pump loss that goes with the restrictor plate. HP loss due to these is huge. What would take 5HP to run turns into 20HP with a restrictor plate. Not only are you creating more load on the motor, but everything attached to the front of it.
 
One of the race shops I worked at had a flow rig for SBC mechanical water pumps. We were making billet housing and checking the flow side to side. It also had a heating element and pressure sensors. There was an electric motor to drive the pump. It revealed some really eye opening data.

[fabr]

Ok guys,here's a question for you. On my Brodix CV265 heads there is no water crossover passage. There are only 3  - 3/8" NPT outlets in each head allowing for a -8AN fitting each. The passageway in the tube is .375 ID . This comes to a total of  .663 square inches area. The commonly used restrictors that have been used are .625,.75 and 1.0" ID sizes. The 1" size is .785 sq. in.  and the .75 size is .442 sq.in.. At first thought I was thinking that the head outlets would be inadequate  but when looking at the numbers it seems the head outlet sizes are plenty adequate even offroad.  Opinions?  Does anyone have info on the Stewart thermostat that bdkw referred to about what it's total square inch flow area is?