Radiator Core Styles

Radiator Core Styles

Core Types

The radiators that Cool Craft Components sell come in 3 different base core designs along with add-on options to offer the most comprehensive line of drop-in replacement radiators on the market.
Standard Automotive Core
Similar to the OEM style radiator of the 60’s its constructed using 1/2″ fins and is available in 2, 3 or 4 rows. If you are looking for the same cooling as found in your original 50’s – 70’s car, then this is core for you.
High Efficiency Core
Our High Efficiency core is available in copper/brass or aluminum construction. The copper/brass High Efficiency cores are available with 2, 3 or 4 rows of 1/2″ tubes. The aluminum High Efficiency core is available with 2 rows of 1″ tubes.Our 4 row copper/brass and 2 row aluminum cores cool the same with a slight edge going to the copper/brass core. How is this possible? Its simple. The 4 row copper/brass core is constructed with 1/2″ in-line tubes giving you 2 inch thick core. The 2 row aluminum core is constructed with 1″ tubes, again giving you a 2 inch think core. Both cores use similar size serpentine fins giving you similar amounts of heat transfer points. For more information on the cooling efficiency of aluminum vs. copper/brass cores, please refer to “Aluminum or Copper/Brass” section.
Optima Core
For most applications, we suggest using a Standard Automotive core or a High Efficiency core in either Copper/Brass or Aluminum. There are some of you horsepower junkies out there that have blown their engines and need the cooling power of our Optima core. Constructed using an in-line tube design with 1/4″ serpentine fins we are able to put more tubes in the core which increases the amount of heat transfer points. Our 4 row Optima core has as many rows as a 6 row Standard Automotive core. Couple this core type with the Tripleflow add-on option and you will get the greatest temperature reduction from inlet to outlet in a drop-in replacement radiator available.
Tripleflow Option
Our Tripleflow option is an inexpensive way to add up-to 15 degrees more temperature drop from inlet to outlet to any of our radiators. By building internal walls into the tanks, the coolant is re-routed to pass through the radiator three times (top to bottom or side to side) resulting in three separate exposures to temperature dropping airflow, with little to no adverse flow restriction.

NOTE: Due to the internal walls we are unable to include a transmission cooler in radiators ordered with the Tripleflow option. We do offer auxillary coolers that look and work great. This option is not available for flathead (4 connection) radiators and requires that the inlet and outlet are located on opposite sides.

Aluminum or Copper

The thermal conductivity or heat transfer rate of copper is 92% versus aluminum which is approximately 49%. However, the copper fin bonded to the tubes, or water passages, using lead solder is very inefficient and slows the heat transfer rate to just slightly better than that of aluminum. This can be a disadvantage of copper if the bonding process does not allow the copper fin to touch the brass tube, and why not all copper/brass cores of similar design, but different manufactures, transfer heat equally.

Copper/brass radiators, because of their weight and durability, have been around a long time and can be easily disassembled and reassembled for cleaning purposes. Not the case with aluminum, unless speaking of the O.E. version that comes with crimp mounted plastic tanks. As a result the life expectancy of the aftermarket aluminum radiators will be far less than that of copper/brass.

To better understand the function and performance of any given radiator it helps to understand the “cooling” process and think of it in a way that allows for comparison. The words cooling, or better cooling, or efficient cooling are thrown around a lot in advertising and promotional terms but for the most part un-quantifiable at best without a reference or yardstick to measure by.

To measure and control the cooling processes you have to take several variables into consideration. Variables include engine temperature production at different rpm’s, or engine operating btu output, coolant absorption rates, coolant flow rates, or gpm’s, and coolant temperature reduction rates that will vary with the size of the radiator and the amount of (cfm’s), speed, and temperature of the air flowing through the radiator. The only device to actually compare one radiator vs. another with absolute control is to have a wind-tunnel that can duplicate actual driving conditions under various specified conditions. U.S. Radiator built radiator dyno or test stand in 1999 and tested every core design and manufacture, in both copper/brass and aluminum, for plain and simple temperature drop, inlet to outlet, at specific and controlled parameters.

So what did US Radiator learn? First and foremost, they discovered that where the radiator is concerned core design and NOT material had the greatest effect on temperature drop. While all radiator cores might look the same they perform differently based on tube spacing and fins per inch. Heat transfer points where temperature is actually allowed to leave the radiator are where the fin is bonded to the tube. The more transfer points, the greater the temperature drop. A 60’s core for example had a 1/2” tube spacing (ie, 1/2” fin between the tubes) and by going from a two row radiator to a four row core design they were able to double the heat transfer points which resulted in a 15-20% increase in temperature drop without changing the other variables (air flow, coolant flow). In the 80’s the Japanese came out with a core design in response to the need to down size, which has become the standard, and was efficient enough to allow the re-introduction of aluminum (a less efficient heat transfer material) at the O.E. level. By changing the tube spacing to 3/8″, a design referred to as High Efficiency in the industry, more tubes or water passages and fins were allowed across the face of a core with a specific width in inches. The design was simple enough but proved to be very efficient in that more heat transfer points created greater temperature drop inlet to outlet. At this point the move to aluminum construction was purely financial in that raw materials are purchased “by the pound” and a finished aluminum radiator weighs about 25% of a copper/brass unit (dollars per pound being almost equal at that time) and resulted in huge savings to the O.E.’s . This is why we’ve seen most copper/brass manufactures either switch to aluminum or fold up their tents permanently. It is important to note that this decision was based solely on financial savings and should not be confused with more efficient.

In fact, the tests that US Radiator conducted, resulted in almost exact temperature drops, aluminum vs. copper/brass, at all operating ranges where the core design was the same with a slight advantage going to the copper/brass unit (even against their own aluminum units).

Do you need a new radiator?

Lets face it, radiators are expensive. It’s in your best interest to exhaust every option before investing in a new radiator unless of course your existing radiator has obvious damage or is older than dirt.

There are many reason why a car may be overheating. Some are auto make/model specific which won’t be covered here. The web is a great resource to turn to to find out what others have done to cure their overheating autos. Its probably not a stretch to say that most automotive magazines have tech articles on cooling in their spring issues every year.

Airflow, let me say it again, AIRFLOW, or lack-there-of, is one of the major contributors to overheating problems. Lack of airflow can be a result of an un-shrouded radiator, fan installed backwards (rotating in the wrong direction) or a manual fan not sitting at the proper angle in the shroud. We highly recommend a shroud properly fitted to the fan and radiator. The only time you really depend on a fan is at idle or low speed where there is little or no air flowing through the grille. Shrouds are necessary to maximize the amount of ambient air being pulled through the grille and radiator.

Proper fan and shroud alignment should be leading edge 1/3 in and trailing edge of fan 2/3 out. The air flow off the back of the fan deflects at about a 45 degree angle when set this way. When the blade extends further into the shroud the air off the back of the blade flows straight back into the block and decreases the airflow efficiency by about 15%.

If an electrical fan is the only way to go then by all means place it on a shroud that covers the entire core. We often see an electric fan attached directly to the core and the only thing this does is waste the rest of the core surface when you need it the most. A 16” electric fan attached to a core only cools a 16” circular section of that core. Where space is an issue we offer 3/4″ deep custom aluminum shroud that enables adequate air flow over the entire core and when combined with a thin-line electric fan results in a total depth of 2 3/4 “.

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