If this was really an important thing (its not) then you should just run 100% water, maybe with a little corrosion inhibitor added. Thermodynamicly, the water outperforms the coolant. ... But that doesn't matter because the system is designed for the specified coolant mixture.


The thermostat controls the rate of heat transfer from the engine to the radiator, which is the only thing that matters. (My radiator doesn't spin my wheels.)

 

Wrong again. Water boils faster than coolant, period. Coolant also lubricates. Two things water cannot do. And in cold climates the water will freeze overnight.

You knew these two things......didn't you.....LOL.....



Without a radiator....you overheat in 15 minutes, every time, every car on planet earth.
Without a tstat the engine will be fine in almost all situations. Many people run without a tstat....MANY.

Get it......the only part on a car that transfers heat from the coolant to the ambient air is the RADIATOR. The tstat simply controls TIME......that coolant sits in the radiator.

Do you still think the part that we call the tstat is what cools the coolant in our engines.....LOL

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wssix99,

Do you think the thermostat in our homes actually cools the air that blows through the vents...?

Nope....it only tells the compressor when to turn on at a certain temp. Kind of like our tstat in our engines senses a certain temp....and opens the valve.

They both sense a predetermined set temperature....then they allow something to happen after that. In the engine it allows coolant to move......in the house it allows the compressor to start up.

Same - Same.

Now, for a little old lady in her house.....I'm sure she thinks that hitting that switch on her wall is what actually makes cold air come out of the vents in her bedroom......but thats ok, thats all she needs to know.



.

 

It was stated earlier that the water pump flow is not part of the heat removal process. That's incorrect. Heat exchanger heat removal is proportional to mass flow rates. Typically, the more flow rate the more heat is removed...up until the point of disturbing the radiator heat transfer equilibrium or causing pump cavitation. At that point the thermostat would close down some to reduce mass flow rates and restore the balance. Moving the coolant is critical. See how long before the engine overheats without a coolant pump in your thermostat/radiator system. Water flow is just as important as temperature differential and air flow. You don't want your coolant just "sitting" stagnant in the radiator.

Another issue with using the plain old green coolant is that it works by leaving a "protective" chemical deposit behind on the cooling system surfaces. That build up actually reduces heat transfer across from engine metal to bulk coolant. The OAT and HOAT coolants do not deposite chemical layers. One can easily have lousy heat transfer across your engine block due to clogged passages and chemical buildups....leading to lower coolant temps. In this case, low coolant temps on your instrument panel gauges aren't a good thing because your engine is overheating. Unless you have thermocouples in your engine hot spots, you'd never see it.

My '99 has used DexCool since day 1. In fact, the factory fluid was in there for 12K miles/13 yrs. It was a bit ugly. Surprisingly, the radiator was clean as a whistle. After 4 years of running fresh fluid I took some out this year. It was a perfect light and translucent pink....as if it were brand new. I changed out 2 gallons of a 50-50 mix but it didn't appear to need it.

In my old '68 GTX I had issues with it running hot in the summer. After a new coolant system and about every other fix I could dream up, I just went with 90% water and 10% glycol + water wetter. It ran 10 deg cooler since water is a better heat transfer agent than glycol. At the same time, I had less margin before the coolant would boil. It's a physics fact that water removes more heat than glycols. It's one of the reasons (besides safety) why track and drag cars run water. The glycol really doesn't lubricate anything these days because most water pumps have sealed bearings and mechanical seals....unlike 40-50 years ago.

https://books.google.com/books?id=06...ricant&f=false....then why do we have high flow water pumps for performance applications?

http://www.cliveyboy.com/2012/11/how...ooling-system/....water flow matters....more is usually better.

 

Water is da best coolant but antifreeze contains desirable anti-corrosive properties, so a slight mix of both is ideal. In places it does not freeze (here) I use less than 20% anti freeze. Use only distilled water. Flush maximally before final filling with expensive anti freeze mixtures. Tracks require 100% water so sometimes I just leave out the anti freeze for a couple months till I can hit the track.

 

Some misconceptions in here...

When it comes to heat removal there are three things that matter:
*heat capacity - the energy required to heat a gram of something 1 degree Celsius. Higher heat capacity is better for coolant.
*flow rate
*pressure

"Coolant" is not coolant. It is a liquid solute that has colligative properties. This means it raises the boiling point of water and depresses the freezing point. Just like salt does water. It's why salting ice makes the ice melt. It drops the freezing temperature as the salt reacts with the ice.

No matter the color, the antifreeze serves to REDUCE the heat capacity of the water. Kingtalon is correct on this point. But the designers make up for it with flow.

Boiling is the other thing that can kill a cooling system which is why you need pressure. Pressure prevents boiling, which maximizes heat transfer from the metal to the water. One of the main purposes of the water pump - beyond flow - is to provide pressure.

One thing glycol does is break up the surface tension of the water. You may have heard "soap makes the water wetter"? Technically this is called a surfactant. Oils have them added also to help get the liquid into smaller spaces. In this sense, the glycol does increase the lubricity of water, but this probably matters less than it used to. Still, it does aid in some way to heat transfer, but less so than the reduction in heat capacity due to the amount of water not in the system.

So what's the best coolant? Water with a small amount of very low molecular weight surfactant. Exactly what I run in the summer.

 

Boiling points aren't directly related to heat capacity. This is why school is so important, America...


Excellent post. A+++

 

If Flow = 0 then obviously the rad will stay cool and the engine will overheat.


What most miss is that as flow increases, the two become more identical in temp. At flow = infinity (or max) the water in the engine and radiator as close to temp as possible. I think this is why the tale "no thermostat overheats the engine" comes from, without a thermostat you get some max flow, which to the observer looks like the engine and radiator are the nearly the same temp all the time (it might lead to the incorrect conclusion that nothing is being cooled off, or that water needs to spend more time in the radiator to cool off).

 

While bulk boiling of the coolant is not desired, some nucleate boiling near the metal to water interface does improve the heat transfer....at least that's my recollection from HTFF classes from 40 yrs ago. That's where small bubbles are formed on the wall and quickly carried away by the coolant and popped.

 

That's where pressure comes into play. You can also get a steam jacket right at the interface, which acts as in insulator. It takes alot of heat to boil water to steam - true. But once it boils, it's a thermal insulator. Pressure breaks it up and keeps those bubbles small

 

So funny when all you guys try to pull physics out of the air......LOL

It doesn't matter how much flow you have
It doesn't matter if pressure is perfect
It does matter if you have special spaceship fluid from NASA in the system
It doesn't matter if you have a tstat or not have a tstst

WITHOUT THE RADIATOR OPERATING PROPERLY...AND NOT BLOCKED WHERE AIR CANNOT FLOW THROUGH IT....the engine over heats. All of the other parts can be super-duper NASA parts and fluid......200mph coolant speeds through the system, titanium computer controlled tstat built by NASA.......

The RADIATOR is the ONLY part of a cooling system that dissipates the heat out of coolant. The coolant temp flowing across the cylinder walls is going to be the same temp when its moved (flow) 6 inches away from the cylinder walls and is now somewhere else. FLOW DOES NOT COOL the coolant.....IN A CAR ENGINE.

The coolant starts to cool AFTER it reaches the radiator....and not before it reaches the radiator......IN A CAR ENGINE.

If a news paper gets stuck in front of the radiator or condenser (for guys with A/C still in the car).......WATER PUMP STILL WORKS (flow).....TSTAT WIDE OPEN BECAUSE ITS WORKING.......PRESSURE IS HIGH........

READY.....READY.........THE ENGINE WILL STILL OVERHEAT. Because in a car engine, FLOW and PRESSURE don't mean **** when it comes to keeping the coolant COOL. Thats the job of the RADIATOR and ONLY the RADIATOR.

YES....all parts must work properly and the system needs pressure........but the RADIATOR ALONE is the part of the system that is responsible for carrying heat away.

Funny fellas......

.

 

So, the type of coolant really doesn't matter then. Perfect.

 

It does matter how much flow you have
It does matter if pressure is perfect
It does matter if you have special spaceship fluid from NASA in the system
It does matter if you have a tstat or not have a tstst

Now that that's all cleared up.

Even with a NASA approved radiator working at 100%, if the other parts of the system have issues, you aren't going to be cooling very well or not at all. How does that NASA radiator work when the thermostat fails shut or the water pump dies?

The radiator is certainly not the only component dissipating heat. There is significant heat removal through the engine oil/oil cooler/oil sump, fuel spray/mixture vaporization, exhaust gases/piping and of course from heat radiating to the air from the engine block, especially as 65 mph air moves underneath the car and through the grille around the engine. Those are not negligible losses, in fact as much or more heat is removed via exhaust gases than through the cooling system. Mess up your car's timing, fuel injection, valve conditions, exhaust, etc. and that NASA radiator won't help you any more. It's a good thing our automotive engineers attended their HTFF and physics classes. Air-cooled engines have been around a long time. They didn't or don't need radiators. The original VW Beetle and some Porsches had air-cooled engines. On the coldest of winter days I could stick a newspaper across the radiator air side inlet and not overheat. Heat removal from the other methods could likely handle the job.

And just for sticklers, the radiator surely can't be the only heat sink in the coolant system. That's because many 1998-2002 F bodies came with a PS cooler in the radiator supply line. At times, that PS "cooler" was certainly removing heat from the coolant system.

 

Looks like we need to give out another A+++ grade in this thread, this time to Firebrian for his post above. All great and accurate points, but here is something interesting that might be overlooked by some:

Timing certainly can and does affect engine temps, and it does so without any changes to the radiator or ambient conditions.

Just to be clear, the radiator, and coolant which passes through it, is absolutely not the only means by which heat is removed from the engine (one should be careful to not overlook the heat removed by engine oil and the exhaust system, as pointed out by Firebrian above.)

Having said that, it would be accurate to state that the radiator is the primary means by which heat is removed from the coolant, but this still requires flow (water pump) to work properly in an automotive application. You can't really state that the radiator itself is more important for cooling the coolant than the water pump, since this type of system will fail if you remove or disable either component.