Aluminum Radiator Technical Information


Tubes are the primary source of cooling. A radiators cooling capacity is governed by a number of factors. Most important are the tubes, the primary source of cooling. Heat dissipates from the coolant (water and antifreeze) through the tube wall (primary), then through the fins (secondary). Air passing through the fins carries away heat, thereby allowing tubes and fins to absorb more heat from the coolant. In serpentine fin (VT) construction, the flat side of the oval tube is in direct contact with the fin, providing secondary cooling. The rounded ends of the tube are not in direct contact with the fin and therefore do not provide secondary cooling. On the other hand, the rounded ends of the tube provide strength to the tube keeping internal pressure from pushing the tube into a round shape (ballooning).
In the beginning, there was the copper brass radiator. Copper brass construction seemed the obvious choice for the first radiators because of superior heat conductivity, ease of forming and ease of repair. The earliest radiators used round tubes. Manufacturers moved to 1/2′ oval tubes in the late 1920′s which worked well with the low-powered engines of the day.
In the late 1940′s, Ford began using 5/8″ tubes. In 1958, GM followed suit using 314″ tube with a wall thickness of .005. This wall thickness worked fine on 1/2″ tubes but proved too weak for the wider tube thus GM ran into problems with ballooning. GM ultimately recognized the cooling advantages of the wider tube and forged ahead with a new tube with walls .007 thick.  GM also tried one other approach. They built a radiator that used 3/8″ tubes. By increasing the number of tubes in the radiator, GM was able to compensate for this smaller tube size. The smaller tube had virtually no dead spots. In other words, virtually all of the coolant came in direct contact with a tube wall. However, because the tubes were so tiny, even the smallest particle could cause them to clog thus decreasing the overall efficiency of the radiator.

In the 1980′s, Ford attempted to improve the cooling efficiency of their radiators by utilizing computer technology. What Ford learned was that improving the cooling efficiency would require utilizing wider tubes. This meant that still a greater tube wall thickness would be needed to prevent ballooning. For example a 1″ tube would require a wall thickness of .015″ which was over twice the thickness used on a 5/8″ tube.

At a time when auto manufacturers were trimming weight on all their vehicles, the increase in weight that resulted from the increased tube wall thickness was unacceptable.

The question that manufacturers were faced with was “How can a radiator be built with increased tube width, increased tube wall thickness and still end up being lightweight?”. The answer – ALUMINUM! An aluminum radiator built with 1″ wide tubes with a .016″ tube wall turned out to be approximately 60% lighter than the same copper brass radiator. The 1″ tube increased direct tube – to-fin contact and cooling capacity by roughly 25%. Therefore, a 2-row aluminum radiator with 1″
tubes is equivalent to a 5-row copper brass radiator with 1/2″ tubes. The state of the art engineering advantages of the increased tube-to-fin contact are far superior to the lead joint found on copper brass radiators. The welded aluminum construction also proved to be stronger than the lead – soldered copper brass radiator. Today all vehicle manufacturers incorporate aluminum radiators with wide tubes in their designs. GM, for instance, offers an aluminum radiator with 1-1/4″ tubes. Mercedes Benz uses 1 1/2″ tubes.

Copper is a good heat conductor, but solder required to bond the tubes to fin creates an insulation point that prevents some heat transfer. Aluminum tubes are welded rather than soldered to the aluminum tanks, providing a more efficient conductor for cooling efficiency.

The strength of the materials is one difference between aluminum and copper. The copper tubes carrying the coolant must be very thin to keep a copper brass radiator cooling efficiently. Since copper is relatively weak, the tubes must be narrow in order to prevent the internal pressure from swelling or exploding. Aluminum is much stronger, allowing the use of considerably wider tubes. Wider tubes allow more direct contact between the fins and the tube, increasing the radiator’s capacity to dissipate heat away from the engine.

Aluminum radiators are commonly recommended and preferred for the demands of high performance applications.

Another important benefit of aluminum is its resistance to damage. SCP goes the extra mile to supply the GRIFFIN rugged, durable, high performance radiators. Every GRIFFIN radiator is reinforced with a special high temperature epoxy, which provides additional tube to header strength and assists in the prevention of vibration failure. This process is Q1 approved by Ford Motor Company, one of the toughest quality standards in the industry.

The intercore structure is furnace brazed at temperatures in excess of 1100 degrees Fahrenheit. This unique GRIFFIN manufacturing process also anneals the tubing, making it flexible to resist puncture or split damage when assaulted by smaller debris found on a racetrack. Aluminum tubing tends to bend rather than tear or split. In many cases, the GRIFFIN manufacturing process is the difference between finishing a race and experiencing an expensive failure.

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