I think drilling holes helps. Also with burping the system quicker of air bubbles when doing a flush. Some guys who lived in Arizona didn't run a T-stat.

 

I think that nearly everyone who posts about overheating issues in the summer, has a degraded condition radiator. People don't change their coolant. Cooling system gets all sludged up. Heat transfer and water flow goes down. They post here.

 

The water moving too fast through the radiator myth is an old one that got its roots from the old low pressure cooling systems from 70-100 years ago or from removing the tstat on a modern high pressure system and the cooling issue getting worse. Because to the layman the solution was to slow down the water flow with a restrictor or putting the tstat back in... then the water must have been moving too fast. The real reason those solutions worked is increasing the block pressure. A lot of people don't realize that the coolant pressure in the block is double (or more) of that seen in the radiator in modern systems. That added pressure can add 25°+ of boiling/steaming protection over the radiator cap pressure rating. Reduce that pressure by pulling a tstat for example causes steaming which creates hot spots and reduces absorption.

So, if a high flow tstat can maintain adequate block pressure and flow more water, they can and do work well.

A few months back I read in a similar debate on a different forum that a new trend with these extreme performance drag engines is to install a block coolant pressure sensor. They log the data and can get early detection on head gasket issues or figure out at what boost levels they actually start to push water. A few of those guys stated that they were really surprised to see ~30-35lbs in the block while only running 12-18lb radiator caps.

 

That's what bugs me. I want a stable temp through all operating conditions, not this fluctuation. PO had a 160 tstat and temps would be 160 on highway and 225 in traffic, up and down all day long. no thanks.

I'm now stable with a dewitts single row, 195 acdelco hiflow tstat, and tuned fan1 for on 98c off 92c.
My temp gauge sticks right in the middle at around 92c, and confirmed on the digital readout, brings me peace

 

Here and every car forum in existence.Or they change their coolant but it's too late for the radiator . Same with all other fluids it drives me nuts when I see black brake fluid in reservoirs ha,ha....but that is how a hard lesson is learned...

 

The car can run fine at any of those temps. Having a "stable" temp is fixing a psychological problem, not an actual one. I "get it", why you wanted to do that...but it's not necessary.

You could have likely achieved the same results with the "tuned fan1 for on 98c off 92c." -as that is really the controlling factor; the fan on temp.

 

On the L 98 cars the rear water passages on the the factory intake gasket has a partial blockage in it to restrict flow by design for a hotter running car for emissions reasons. I switch to the 1204 gaskets for an older sbc.

 

I'd love to know who taught your fluid thermal dynamics class. You can increase flow to the point that it does not effectively absorb the heat from the metal it is passing over. Can you build a small block chevy water pump that can reach that point? Maybe, maybe not.

 

Wait. You mean that I have to follow scheduled intervals for fluid changes? WTF!! Salesman never said anything about it.

 

Not.

Water will absorb heat from a material it's touching, regardless of how fast it's going. The water could be going 300 mph but if the block is 200*F and you're pushing 30*F water through that block at 300 mph...that block ain't going to over heat. Right? RIGHT. So where did that heat go? Into the water.

 

Fixed.

Re-read your "fluid thermal dynamics" class literature.

 

It's a misconception. Yes, the faster water will absorb less heat in its time in the block, meaning a lower Delta T and lower temps entering the radiator. That much is true. Slower moving water will have a larger Delta T from entering the block and exiting as well as entering the radiator and exiting. This is where the "giving it time" to absorb heat comes from.

That's all fine and well but...

It's not about Temps and it is about Q or energy transfer. The more water you put through will transfer more energy without getting as hot (T) because the molecules move through each area in less time but go between the absorbing area (block) and rejection area (radiator) at a faster pace. In the end, it is about Q rejected. Which is what @Tom400CFI is trying to explain.

Think about a pot of boiling water sitting beside the stove.
You put it on and let it sit, it will eventually boil
Now lets say you have two pots and every 10 minutes you switch them... both will boil and then not when taken off
Now do 4 pots and switch them in rotation every 5 minutes... goign to take a lot of rotations to reach a boiling point
Now do 8 pots every 2.5 minutes... they will probably never boil.

But given the pots are the same material, same water level in each and so forth... in a 20-40-60-80... how ever long of a period you want to go, the same energy was put out by the burner, the same energy was absorbed by the water in the pots, but by changing it over faster none of them ever got too hot as they were rejecting heat while waiting.

Now just replace the multiple pots with a pump and a heat exchanger (radiator) in place of the waiting period.

If you were running a small pump that would move water between the radiator and the pot and rejecting the heat, it would take a longer time to reach boiling point, the faster you run the pump, the lower the ultimate temperature would be, but the pot isn't going to melt down because the water is moving "too fast".

The faster it turns over, the lower the temps will ever reach... still the same energy. - Thermodynamics... energy can't be created or destroyed, only converted.

 

You just taught the entire first week of my thermo 1 class in a single post. Can we do mixing and molar properties next?

I tried this with a certain member who shall not be named... he claimed an aluminum headed engine takes longer to warm up than an iron headed one... I laid out all the thermal conductivity stuff and he just brushed it off. And then he really brushed off resistance models.

 

Fantastic post, Kyle. Thanks for clarifying, what I was struggling to convey!

 

Don't forget if things move too fast, surface friction will start to add to the heat issue. SR-71!!!!

On a smaller scale, things like Laminar and turbulent flow will come into effect as well. However, this isn't rocket science and we are not talking about going to a 4000gph pump on the front of the engine. Do keep in mind, all of this is not free. The more GPM you move, the more power it will consume, less to the tires. More power produced, more heat that needs to be extracted. Diminishing returns start to apply because of back pressure (head), flow characteristics changing, and etc.

A properly designed cooling system will take surface area contact, flow rate, volume, fluid's heat transfer properties, the heat source material's heat transfer properties, heat exchanger efficiency all into account. And with a street car, has to account for various scenarios. Hence why thermostats progressively open, water pumps speed up with rpm, and dual fans can be off, one on, or both on.

I think this will help everyone, not a car but a baseboard style heating... which you should easily see an engine would be the boiler and the radiator the baseboard heaters here

 

They way I have had it explained to me is a molecule of water/coolant on a single pass through the system. The cooling potential outweighs the heating potential in a proper system. So if you heat 1 degree and cool 1.2 degrees from a single pass and you speed that up, you would get greater cooling over a specific period of time. Lots of other factors involved but that is the simple math explanation of why more flow is better before you get into friction and cavatation and whatnot.

The HVAC stuff for conditioning air works the same way but homes/buildings aren't truly closed loop and removing moisture from the air for example is reduced with too fast of a blower speed.

 

Another great example. I've thought of using that one too; you're cold, huddled over the base board for heat. Is the base board going to keep you warmer if the water is flow quickly through it? Or slowly, yet "removing more heat" from that slow moving water? I want the fast moving water! I hate being cold!

 

Also a good way to look at the "efficiency" of the radiator. As fluid gets contaminated and passages get restricted the efficiency goes down and those numbers will change. Even in the block itself, if you have scale or rust build up, it will prevent heat absorption.

True HVAC in a house is not a closed system, but the heating example I gave only looked at the closed boiler loop and how it can give off heat at the radiators, not how it contained the heat in the house. Homes must breath to prevent stale air, but our cooling systems need to be void of air.

 

Yea, I wasn't trying to dismantle your boiler example. Just when people here about HVAC stuff coming into this argument sometimes they bring up a too fast of an airflow over the evap coil causing issues. Don't really know why I really went off on that tangent.

Great posts Kyle.

 

I would stick with the stock thermostat temperature of 180F, get the whole cooling system in proper working order (if not already), then simply keep up with maintenance. I do a flush & fill every 4 years, only drive it about 5-7k miles per year. Also, no way would I program the fans to come on at 200F, that is way too low. I've thought about this and decided not to change my settings, but if I did... I would pick 215F, that is a much more reasonable range and still way below the factory fan temps.