Copper or AluminumIs one better than the other?
It’s no surprise that the majority of aftermarket performance radiators feature aluminum construction, though copper and brass construction is often favoured for a vintage or period-correct appearance.
Copper is a great heat conductor, but tube wall thickness needs to be thin for best heat dissipation.
When the wall is thin, tube diameter needs to be kept rather small (about 0.500 inches) to prevent it from ballooning under pressure.
Aluminum is a stronger material, so tube size can be larger (up to as much as 1.50 inches in some cases) and wall thickness can be greater, while producing a lighter-weight radiator at the same time.
Remember, aluminum is about 60 percent lighter than copper or brass.
The larger tube size also provides more coolant volume, which means more coolant is exposed to the heat exchange process, and the stronger aluminum material can take more abuse (i.e., heat and pressure).
To help illustrate the heat-dissipation capabilities, a two-row aluminum radiator featuring 1-inch tubes will dissipate heat roughly equivalent to a five-row copper radiator that features 0.500-inch tubes.
Copper requires brazing, and the lead tends to insulate the heat dissipation, while aluminum is welded.
However, a copper radiator is easier to repair than an aluminum radiator.
Pros and Cons?
You’ll have to weigh the pros and cons of each material before deciding what’s best for your build.
The lighter weight of an aluminum radiator (for street use) is a by-product that provides some bragging rights but, in reality, the lighter weight really only becomes a benefit in a competition car, where every ounce counts.
In short, an aluminum radiator is likely the better choice for a high-performance engine, an aluminum radiator will probably be more suitable for a custom rod where appearance matters and a copper or brass radiator will remain the better choice for restoration or period-correct applications.
Copper or aluminum radiators both have their place, depending on the application.
As I mentioned earlier, depending on available installation space, there’s no such thing as having a radiator that’s too big. You’ll want as much surface area as possible, with as many fins per inch as possible.
Depending on the choice between a downflow and crossflow (largely dependent on available space), you’ll want to maximize the core surface area. If the dimensions call for a radiator that’s wider than it is tall, a crossflow is the best choice.
While we’re focusing on the radiator aspect of the cooling system report, remember that the radiator alone can’t be held responsible for proper engine cooling. Airflow is critical, and that means proper fan selection and mounting. Always take advantage of a shroud in conjunction with either electric or mechanical fans.
The shroud should cover all of the core’s rear face except for the path needed at the fan (derivatives are available with flaps or louvers offset from the fan area to promote additional pass-through air at cruising speed).
A shroud directs the oncoming air to the fan’s air path, maximizing the fan’s performance. Aftermarket performance radiators are readily available with built-on shrouds and electric fan assemblies.
Rather than reinventing the wheel (unless you’re determined to fabricate your own custom shroud), it just makes sense to take advantage of these ready-built, fully assembled radiator/shroud/fan systems.