I ordered an aluminum radiator from Auto City Classics. It’s stock appearing and has 1” tubes. The plan was to get the one that’s in the car flushed and rodded but the more I thought about it, it seemed like throwing good money after bad. The guy I bought the car from said it needed a shroud - not that it needed to be flushed, making me think that it’s always run hot.

Every traditional brass/copper replacement radiator on the market under $600 has 1/2” tubes (actually slightly less due to the metric/standard conversion). Combine that with today’s crappy chicom copper and aluminum just made more and more sense. The unit that was already in the car was a three row, better than what I could buy in copper for the same price as the aluminum.

Not sure if your comment is directed at me, or that we disagree much on this issue.

But now I have gone back and viewed EVERY reply here ( which I should have done at the onset), and which I had not done in my first reply when I first offhandedly mentioned cavitation. When others before me mention cavitation, it mostly seemed to be in reference to proper pump selection, design, and installation. All valid concerns. But it seems when pump based cavitation erupts, its hard for me to visualize any significant real flow increases, if any. Another member mentioned bubble formation on surfaces ( from heat?), but my cavitation concern was primarily from cavitation resulting from higher flows, or inertia cavitation, which is not a likely result with pump cavitation. High flow cavitation is for us likely extremely difficult to confirm or diagnose, other then if we make a change, that change explains all by itself the fix, an unscientific conclusion.

I guess we are out in left field now with some of these discussions and none of it really helps the original poster. One of the earlier quotes is kind of funny as it is lifted from a paragraph called Common Misconceptions. It is also very vague. With a statement that increased flow increases cooling. Cooling of what? And under what conditions? I did spend some time looking at some engineering papers, mostly from Auto field.

Coolant flow is the item they seem to look at the least other than warm up phase. First, the biggest concern is proper engine temperature to improve emissions and conserve fuel. All the strategies are around warm up, and idle with a cooling system that can handle worst cooling condition WOT full load. But all the emission and fuel economy problems are at start up (warmup) and idle. So for our problems with our cars take what Chrysler did for a car with AC. They increased coolant capacity and surface area of the radiator. 22" to 26". Sure a lot has to do with making the AC work, but it also had to make the engine work too. Then they increased the speed of the fan and water pump by about 40% via pulley ratio. Then they increased the diameter of the fan, then they increased the pitch of the fan all to really increase dramatically the air flow through the radiator at (low speeds and idle); this with a constant input air temp because it is an open system. Unlimited air. But what about that increase in water flow? Well, instead of leaving impeller alone, they reduced the blades from 8 to 6. They reduced the diameter from 4.4" to 3.65" all to reduce impeller surface area and reduce the flow. Prevent cavitation I am sure. Is flow higher or lower then no AC car? Don't know. But I know they chose to offset the increased rpm of the pump with a smaller impeller.

As far as the engineering, it is not just cavitation, but also aeration that can cause problems with cooling rate when flow is increase too much. It is not nucleate boiling that cause loss of heat transfer rate, nucleate boiling is the peak of heat transfer flux. It is the departure from it and film boiling that insulates the metal heat source and dramatically reduces the heat transfer rate. You have no evidence that increasing flow dramatically in the engine block can prevent this film or steam boiling in certain pockets of the block and heads.

If you have modified your engine and increased it's heat output, your best to go increase the coolant capacity and cooling area with improved airflow. Not concentrate on increasing water flow through the system.

Do you really think if you are sitting in traffic with a moderate load on the engine and high air temp, watching coolant and oil temp rise, that if you had a booster water pump and turned it on to increase water flow that some how the system temp would just go down? Where did the heat go?

What material is best for radiator construction for heat dissipation, is it aluminum?

Copper and brass are better thermo conducting. Given identical construction that would work better.
But aluminum can be built stronger and lighter, and cheaper, typically aluminum is built with a larger surface area to achieve better cooling.

When Howard Stewart was running his own Q&A board in the late 1990s it was the most informative source of automotive cooling information I have ever encountered.

I was just wondering if anyone who is limited on radiator area size and radiator depth
has disconnected the heater hoses
and connected them to a smaller “trans cooler” sized radiator for extra summer cooling?
Obviously this would be a Summer season only modification.

Along similar thinking,
does anyone make an air conditioning condenser that could be mounted in an alternative location that is not in front of the radiator?
All the condenser needs is an air flow.
One could pull cool air from a selected high pressure spot at the rear or side of the car and blow it through a condenser in an unconventional spot, even in the trunk.
Those “window-less” home air conditioners have condensers that are nothing like flat.

"Common metals ranked by thermal conductivity
Rank Metal Thermal Conductivity [BTU/(hr·ft⋅°F)]
1 Copper 223
2 Aluminum 118
3 Brass 64
4 Steel 17
5 Bronze"

https://www.metalsupermarkets.com/which-metals-conduct-heat-best/#:~:text=As%20you%20can%20see%2C%20out,use%20for%20a%20specific%20application.

Good deal - report back and let us know how it works for you.




Last page you blame nucleate boiling, now you're switching to film boiling. When you google "film boiling", here's the first result that pops up: Film boiling occurs when the pressure of a system drops or the flow decreases.

Yes, please keep blaming everyone else for lack of evidence. Stewart has no idea what they are doing as a company, either.




More misinformation here - increase the coolant capacity? That way, when someone follows your cooling system logic and slows the flow rate down so it boils in the block, they can make it 5 miles from home before overheating instead of 3 miles. Coolant volume doesn't help heat transfer.

In the last sentence, you defined a scenario where the system heat transfer rate is limited by the air cooling side, then asked someone to prove it's not. That's nonsensical.

I never said slow coolant down, my point was raising flow when everything else is constant does not have the effect your stating. The industry concentrates on capacity of the system, air flow. Clear Chrysler thought they had the WP size correctly for non ac cars, and when they add the heat load of AC they increase capacity and air flow. The increase air flow also increased water flow, and they then reduced that water flow with a smaller impeller surface area. Why if increased flow is beneficial.

Most studies are on tubes and flat surfaces, not winding path with obstructions inside the water jacket of a block. You don't know the pressure gradients inside the block. One study that was working on electric pumps and valves determined that to have an effect you would need to cool the block from the side with individual control valves for each cylinder.

Yes I misspoke about nb. It is the departure from it when heat flux falls off. Flow alone does not determine dnb other than on a flat plate or tube. But just because NB is maximum heat flux does not mean you want to operate there if you have the cooling capacity. Your at the limit and if you depart your in trouble in those areas localized or not.

Increase flow is increased parasitic loss of power, cavitation and aeration. The last two are not beneficial to flow and heat transfer.

Yup, and now look at an Emissivity table - how much an item can radiate the heat out - paint em black fellas, they both suck when shiny
https://www.engineeringtoolbox.com/emissivity-coefficients-d_447.html

Interesting chart. A big difference in polished aluminum (0.048) and black enamel paint at 0.8. But farther down the list there's "Paint" (non-specified) at 0.96.

I'd like to see actual coolant temps with a polished aluminum rad vs a black-painted one, all else being equal.