May 24, 2023

Let’s Vent About Radiators

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Let’s Vent About Radiators

By Jefferson Bryant

Unless you are running a Beetle, Corvair, or a non-hybrid EV, the car in your driveway and every other driveway is water-cooled. This means that under the hood (in most cases), lives a large radiator the facilitates exchanging the heat from the engine coolant into the air that passes through the fins. Seems pretty simple, right? The reality is that while radiators might not be a flashy item, they are more complicated that just a couple tanks and some tubes. Technically they are simple, but the science and technology that goes into the designing and building these heat exchangers is certainly not.

Are All Radiators the Same?

In short, absolutely not. Even just but the effective cooling space of two identical radiators the differences can be vast. The size of the cooling fins and tubes, build materials, and core thickness all have an effect on the cooling capacity of the radiator. Radiators are solely responsible for cooling your vehicle’s engine, it is imperative that you get it right. From the factory, the OEM designers developed a radiator that was sufficient to cool the engine that was being installed by the factory. For instance, most GM muscle cars have thin 2-core copper radiators that can easily support a small-block chevy with a mechanical making 400 hp. Swap that SBC for 6.0 liter LS engine that is running AC and a 4-speed auto transmission, that factory 2-core radiator is going to struggle to keep up with the cooling demands of the engine.

Go back a little further to say a 1965 Mustang with a 200 ci straight six. These cars came with very small down-flow radiator that could cool the little 6-banger, but that same radiator is going to struggle with even a 302 swap, regardless of any band-aids you strap to it. An adequate cooling package is crucial for any car, and cooling is too often overlooked as a budget necessity instead of what it really is- insurance for your engine.

Outside the radiator, the capacity and functionality of a radiator is directly tied to the method of drawing more air through the core. Most vehicles older than the 1990s had mechanical fans. This has always been a cheap place for hot rodders to gain horsepower by swapping in lighter fans and fans that flex at higher speeds so they don’t have as much drag on the engine. Most hot rods these days should not be running mechanical fans, as electric fans are far superior in terms of flow, packaging, and parasitic power loss.

Just strapping a fan to the radiator is only going to get you so far. The correct installation of an electric fan necessitates a shroud that covers the entire core of the radiator and funnels air through the fan blades. While this might slightly reduce the air flow from at-speed flow (when the vehicle is moving about 40 mph) where the air speed of the air entering the radiator is higher than the fan, most vehicles struggle more to remain cool under 40. Stop and go traffic on hot days with the AC cranked is the worst possible condition for a radiator. Maximizing the efficiency of the cooling fans increases the efficiency of the entire system.

If your vehicle has additional heat exchangers installed, such as an external transmission cooler, oil cooler, AC condenser, turbo/blower intercooler, then you need even more efficiency. Every heat exchanger that is stacked in front of the engine’s radiator reduces air flow and it heats up the air more than the ambient temps because those exchangers are doing their jobs. So even if your old radiator was up to the task before, if you add more equipment, it may not be any more.

Copper Vs. Aluminum- Which Is Better?

Until the early 1970s, all vehicles had copper/brass radiators, this didn’t start to change until the mid-1980s when copper and brass started to become harder to find. By the late 1990s, most vehicles had aluminum core radiators. So that means that aluminum is better, right? Not quite. The reality is that copper is a much better heat exchanger than aluminum, though aluminum does well in this regard in its own right. Even though copper is more efficient at conducting heat, it needs a much larger space to do it. An aluminum radiator can dissipate heat in a smaller envelope than a copper and brass radiator simply due to construction. You can fit more fins and tubes in the same space with aluminum as you can with copper/brass.

Copper is not as strong as aluminum, and much less forgiving. Copper does not hold up against the strain like aluminum does. The tubing walls are thicker in copper because it has to be, even at the typical 15 psi cooling system pressures, a copper tube can blow out, especially with some age and corrosion. Additionally, copper tubes are soldered to core base, which insulates the copper, so the heat transfer is reduced. Copper/brass does however have another feather in their radiator cap- repairability. Unlike aluminum, copper/brass radiators can be serviced. While their numbers have dwindled, there are service shops that can rod-clean the tubes, straighten fins, and solder up leaks in any copper/brass radiator. Sprout a leak in an aluminum radiator, and you need a specialist who has the ability to weld soda cans together, but in the confines of a radiator, not exactly the average tire shop job.

In the end, copper/brass radiators are efficient and perfectly acceptable for OE restorations and stock applications where originality is key. If you can upgrade to aluminum, is it worth the expense, and if you have a high-performance engine, necessary.

Now that you know the dirty details of automotive radiators, how sure are you that your vehicle has the right radiator for the job? US Radiators can help sort out if your vehicle has the right amount of cooling capacity or not. If you don’t, their 50-plus years of experience in automotive radiator-ology will get you exactly the right cooling package that you need to ensure your engine will stay cool and running smooth for years to come. These guys don’t just make high-performance radiators, they have radiators for all the popular models, but they also have to earlier stuff that is nearly impossible to find, including Kaiser-Frazer, International Harvester, even 1963-84 Toyota Land Cruisers, and if you have something they don’t stock., they make custom radiators too. Establishing an efficient and effective cooling system in your hot rod, custom, or even daily driver is not that difficult, but there is no one-size fits all approach that works. Give US Radiators a call at 323-826-0965 to discuss your project so they can configure your cooling system to match.