Click Here to Begin SlideshowLast issue we dug into copper versus aluminum radiators. In the big picture, it’s pretty clear that aluminum makes for a better rad, but there’s even more to the technology:
People often ask DeWitts if they can build a radiator with 1-¼-inch tubes. The answer is yes. Every model they build is available with 1-¼-inch tubes, and this option adds approximately 10% additional cooling. With that said, maybe a better question is, "Do I need to get 1-¼-inch tubes"? DeWitts notes that a double row core with 1.0-inch tubes is equal to a five (5) row copper unit and almost double the heat rejection of a single row aluminum unit. So in most cases, the larger tubes are not necessary.
Increasing tube size isn’t always possible with a copper-brass design because of tube wall thickness limitations. Today’s radiator technology (which typically uses wider tubes inside aluminum rads coupled with multi-louvered fins) has allowed the aluminum radiator to cool efficiently. Just as important, aluminum rads are now as strong, if not stronger than, their older copper-brass relatives.
So can you build a copper radiator the exact same way DeWitts makes the aluminum models? Yes, and it would likely work better than the aluminum. The downside is, it would also weigh about 90 pounds! Not exactly high performance friendly.
The truth is, today, an aluminum radiator in your high performance street car or racecar will simply cool better. Tests from various sources document a 28% increase in performance over a brass-copper equivalent, provided both radiators are identical in size. The reality is the use of aluminum in radiator construction can lower engine temperature by 30 degrees. Any vehicle will benefit from an aluminum radiator.
There’s a lot of confusion out there about what’s “hot” and what’s not when it comes to radiator technology. For example, one or more companies have been claiming they’ve come up with a “revolutionary advancement in cooling technology.” What is this breakthrough? DeWitts tells us this technology is actually Extruded Cooling Tubes (ECT), and it is not that revolutionary. In fact it’s not even new, as this technology has been around for many years. ECT has been popular in high-pressure oil systems and Charge Air Coolers (CAC) for more than a decade. Extruded cooling tubes are made by heating and pressing aluminum material through special dies to create a custom shape. It is very difficult to form these tubes with thin wall thicknesses. Typical wall thickness on this type of cooling tube runs between 0.020-0.040-inch, which is thick for cooling. The heavy tube wall thickness and internal trusses provides the strength that can hold higher pressures.
DeWitts adds: “Roll form tubes (RFT) are the gold standard in automotive cooling. Every major auto supplier today uses RFT because the thinner wall will transfer heat better and reduce unnecessary weight. The typical wall thickness range for RFT is 0.010-0.015-inch (obviously, much smaller than the 0.020-0.040-inch tubing mentioned above). This design will hold pressures as high as 45 psi without tube distortion, providing a pressure safety factor of 300% when pressurizing the cooling system to 15psi.”
One company is making a claim that their ECT technology offers “more than triple the burst pressure of any other performance aluminum radiator in the world!” DeWitts Radiator LLC, amongst others, has resisted the industry trend to use even thinner tubes and fin to save money on material. According to DeWitts: “We have stayed with proven (0.013-inch [26mm]) and (0.015-inch [32mm]) wall tubes when some companies are running 0.003-inch thinner material. We also continue with 0.005” fin material when others are using 0.003-0.004-inch fin. This may not sound like a big difference; however, our design will hold 60 psi without tube distortion and 100 psi without bursting.”
There’s more, too: “Another misleading item is the ‘55mm Core with Twelve (12) 4mm Wide Tubes’ feature. That statement is creative; however, they really only have one (1) tube that is 55mm wide. This tube is called a multi-port design with twelve 4mm paths for the coolant to flow. Due to the heavier tube wall thickness, the inside diameter is 25% smaller than a standard double row 26mm core.”
In comparison, a typical extruded cooling tube design will be heavier, run hotter and have a higher pressure drop than a standard double row 26mm design radiator. The only clear difference of an ECT is the higher burst pressure. Since all automotive applications run in the 10-20 psi range, there is really no advantage, while there are several disadvantages.
That’s a wrap for this segment. Keep your eyes peeled to these pages for more info on high performance aluminum radiators. We’ll dig into double and triple pass radiators, along with three row rads and even “four core” radiators. You might be surprised at what we’ve discovered.
Today’s modern, properly engineered aluminum radiators will easily out-cool yesteryear’s copper-brass radiators. And they will prove lighter too. This example tips the scales at a mere 20 pounds (empty).
These are roll-form radiator tubes. The typical wall thickness range for roll form radiator tubes is 0.010-0.015-inch. This design will hold pressures as high as 45 psi without tube distortion. See the text for more info.
Image courtesy DeWitts Radiator
DeWitts can build a radiator with two rows of 1.0-inch tubes or, in their HP Series, two rows with 1.25-inch tubes. This rad is an HP series for a first generation Camaro or a 1968-70 Nova with a big block.
Each radiator core is assembled and brazed in DeWitts’ state of the art aluminum-brazing furnace. All of their radiators are epoxy free.
