http://www.superstreetonline.com/how-to/engine/0304-turp-intercooler/
Tube And Fin
"A conventional tube-and-fin intercooler weighs less than a bar-and-plate design," says Wang. "Typical tube-and-fin units utilize extruded tubes with fins pressed into place. In order to achieve strength, a thick, extruded tube must be used.
"The tube-and-fin core is held together and its seal is created at the joints at the end of the plates, which is usually .125 inches thick. The width of the tubes is less than the width of the side plate. Space is lost where the joints for sealing are used. So a 3.5-inch core will have tubes only 2.87 inches wide."
Unable to maneuver around the machinery, Wang continued, "Also, fin design in the charge side, inside the extruded tubes, was limited by the extrusion machine, which impeded the design of charge side fin geometry to meet individual custom applications. While this design did allow varying ambient fin designs, the charge air shortcomings proved too much of a handicap.
"Tube and fin has a larger leakage rate compared to bar-and-plate cores. Furthermore, tube-and-fin cores are more susceptible to road damage from rocks and debris than bar-and-plate cores; big trouble in front-mount applications. The oval tubes are extruded from thin-wall material and any sort of extreme pressure can cause these tubes to 'balloon.' In today's high-performance industry, high boost levels are the key power."
Bar And Plate
Wang had a more upbeat tone when it came to bar-and-plate construction. "Spearco pioneered bar-and-plate core design. True, the bar-and-plate design is a bit heavier than tube and fin, but this is actually advantageous.
"The core acts as a heat sink. Its ability to soak up more heat is especially useful in stop-and-go traffic. It keeps the charge relatively cool, then is able to dissipate the heat once the vehicle is in motion. Tube-and-fin units can't pull this off.
"A bar-and-plate core can take the damage of front-mount life and endure high boost without flinching. Sealing is superior in bar-and-plate units because the bars and brazing sheets run the length of the unit, providing a 100-percent seal between the ambient and charge sides.
"A key advantage of bar and plate is its extraordinary variety of fin designs on both sides of the cooler. Further, the height of the passages can be changed by using taller bars and fins, which dramatically expands the possibilities for the intercooler designer. A 3.5-inch thick core gets a 3.5-inch row of fins, not the 2.87 inches found in tube-and-fin designs.
"Also, a tube-and-fin design has a lot of room between rows where a bar-and-plate unit can get more rows into a given area with more area per passage which means more cfm and a more efficient unit. As far as big boost goes, the ability of a bar-and-plate core to handle high boost is determined by the thickness of the braze sheets, fins, side bars and top plates."
Spearco produces both tube-and-fin and bar-and-plate intercoolers. With bar and plate being so superior, one has to wonder why. It's all about cost. The tube-and-fin core is much cheaper to produce and is often used in OE applications, which inherently run lower boost levels.
Spearco put a new twist on tube-and-fin cores with its extruded tube design that incorporated the fins as part of the extrusion. In this design, the overall weight was about equal to a bar-and-plate core. tube-and-fin units are cheaper to manufacture.