By Ron Ceridono & Rob Fortier – Images by Rob Fortier
According to Johnson’s Radiator Works, “Copper has been, and will be for the foreseeable future, the ultimate material for heat transfer, long-lasting durability, and easy repairability.”
There has been an ongoing debate comparing the effectiveness of copper/brass radiators (copper is used for the fins and brass is used for the tanks) and all-aluminum radiators. The bottom line is this: When comparing the thermal conductivity of the two materials, copper is rated at 398 W/m-K; on the same scale, aluminum is rated at 235. That simply means copper conducts heat much better than aluminum. So why do OEMs use aluminum? The primary reasons are that aluminum is cheaper and lighter than copper.
While copper/brass radiators are known to be efficient and long-lasting, aluminum radiator manufacturers will point out that the solder used to attach the copper fins to the tubes is a very poor conductor of heat. That means the critical balance is to use enough solder to ensure the fins are securely bonded to the tubes while not disrupting the transfer of heat from the tubes to the fins and ultimately to the air. To that end, Johnson’s Radiator Works limits the solder applied to the tubes as close to 0.0006 inch thick as possible, providing the necessary strength while maintaining the utmost efficiency.
With the exception of the petcocks and bungs, every part of Johnson’s radiators are manufactured and assembled in-house. The cores are made from 0.125×0.5-inch brass tubes with proprietary brass fins and small louvers that create turbulence in the airflow. With over 600,000 louvers in each radiator, these fins dissipate heat more effectively than smooth fins. The assembled cores are attached to holes punched in the headers and secured by dipping the assembled components in a solder bath. The tanks are stamped from 0.040-inch brass; automatic transmission coolers are an available option, as are steam vents for LS applications.
A common question when installing a new radiator is what type of antifreeze to use. At one time that decision was simple enough; there was basically one choice and it was green. There are a variety of products to choose from and they are identified by their color. Johnson’s suggests that selecting antifreeze should be based on the combination of engine components being used. For those with an iron block, heads, and water pump, original green antifreeze is recommended. Iron blocks with aluminum heads and/or aluminum water pumps use blue. With orange suggested for when using an aluminum block, heads, and water pump.
Another decision to be made when installing a new radiator is the type of fan to use. In this case a 19-inch Vintage Air brushless fan for 1966-77 Broncos was chosen. Equipped with SPAL’s latest motor technology, the brushless design extends the lifespan of the fan motor and also improves its reliability. Another advantage to Vintage Air’s brushless fans is the integrated variable speed controller, which eliminate the need for relays. The sophisticated controller provides a “soft start,” which eliminates the amp spike from the large initial electrical draw when a brushed fan starts. The controller then slowly ramps-up the fan speed, running it only hard enough to cool the engine.
Installing an electric fan often requires drilling holes in the radiators side straps for mounting brackets, which can be a scary thing to do on a new radiator. However, Johnson’s Radiator Works eliminates the potential for problems by using a last row of “dead tubes” on either side of the core.
We combined the best of both worlds—copper/brass Johnson’s Radiator Works radiator and Vintage Air’s all-new 19-inch/850-watt CustomFit brushless fan kit—in our ’48 Chevy, now with its compact Eddie Motorsports V Drive installed, and without exaggeration, could not be happier with the cooling results. Follow along, then give Johnson’s and Vintage Air a call and get your truck running COOLER than ever!
But, a quality radiator alone won’t keep your engine properly cooled—your airflow and, more specifically, its management, are equally important. At higher freeway speeds, unrestricted air flowing through the radiator can typically keep things relatively cool. But how often are we not on the open highway when we drive our trucks?! Not only is an efficient fan crucial to keeping your engine cool, so too is a proper fan shroud.
Check out this story in our digital edition here.
More 3100 pickup features and tech here.
