Neither.
Serpentine coil/tube and fin heat exchangers (Haden 401) are pretty inefficient.
Dishplate style coolers are more efficient (Hayden Rapid Cool) as they can expose more fluid to the walls of the tubes, and can then transfer more heat in a given face area.
The best design is something like Earls Temp-a-cure, Setrab, etc.
These are the only stle heat exchangers you will find on race cars and air craft.
I copied this from a PDF catlogue, so the charts haven't come out, but the text gives you the idea.
TEMP-A-CURE™ OIL COOLERS
The Difference: Superior Design, Materials & Construction
Transmission LIfe Expectancy Chart
High Heat = Short Mileage
(Seals, Clutches, Burn Out, Carbon Forms in Oil)
(Plates Slip)
(Seals Harden)
(Varnishes Form)
Low Heat = Long Mileage
2,000 15,000 50,000 240,000
4,000 25,000 120,000
Investment… OPERATING YOUR VEHICLE at the upper limits of its capabilities often overloads stock cooling sys- tems. A properly chosen and installed TEMP-A-CURE cooler will cure your fluid temperature prob- lems. The new downsized cars now operate at or near their upper temperature limits most of the time. The harder we work them, the hotter they get… meaning that to protect your investment— install a TEMP-A-CURE cooler.
Today’s high performance car packs a lot of power in a smaller package. In order to save both weight and space, the typical OEM cooling system is designed for “normal” driving conditions. When driven hard for extended peri- ods, the cooling system may prove less than adequate. Earl’s offers the solution to marginal cooling systems— race proven lightweight and efficient oil coolers designed to fit in the smallest practical space.
Any performance vehicle can benefit from the TEMP-A- CURE difference. Tow vehicles, motor homes, passenger cars and even motorcycles can realize extended engine and/or transmission efficiency and life with an Earl’s TEMP-A-CURE oil cooler.
Racing cars have always required oil coolers. Since World War II, most racing cars, world wide, have utilized brazed aluminum “modular” oil coolers. The basic design of the modular oil cooler dates back to the early 1930s when it was developed for use with the Rolls Royce Merlin engine that powered the Spitfires and Hurricanes that won the Battle of Britain. This type of cooler with its internal tur- bulator plates and dense air fins provides maximum liquid side and air side surface area. The large collector tanks ensure minimum flow restriction. The fully brazed con- struction results in the most efficient possible thermal transfer path between liquid and air. All of this adds up to the most thermally efficient liquid-to-air heat exchanger available.
EARL’S TEMP-A-CURE OIL COOLERS OFFER THE FOLLOWING ADVANTAGES:
1. Manufactured in the U.S.A. from aircraft spec aluminum alloy, using the latest vacuum brazing technology.
2. Corrugated screen internal turbulator plates increase both thermal efficiency and mechanical strength resulting in the most efficient, smallest and lightest practical package.
3. Manufactured from thin aluminum plates for fastest possible heat transfer.
4. Inlet and outlet fittings o-ring to the top plate assembly for maximum joint strength.
5. Designed for the range of oil flows and air speeds encountered in high performance automobiles.
6. Available in four widths with a variety of inlet and outlet fittings including male AN, female NPT or male BSP, and hose barb.
7. Every cooler is pressure checked to 175 psi. Periodic samples are burst tested to 350 psi.
TEMP-A-CURE™ OIL COOLERS
Earl’s Design
For many years, professional racers have been using modular style oil coolers almost exclusively. Virtually every Formula One, Indy and GTP or Trans-Am car depends on these type units for engine and transaxle cooling. Temp-A- Cure coolers have been developed specifically for use in all types of engines and transmissions subjected to tempera- ture extremes, including competition and high performance uses. They are designed for the range of air speeds and oil flows normally encountered in automotive use, but built to aircraft standards of quality. They are constructed of high grade aluminum and are completely furnace brazed to insure the most thermally efficient joint possible between the oil tubes and air fins. The internal design of the oil tubes and the large area collector tanks provide maximum surface area with minimum pressure drop. The highly concentrated air fins offer maximum heat transfer to the outside air.
Typical Tube & Fin Design
The tube and fin cooler has little to offer in the way of efficient oil cooling. Its typical serpentine design has a large pressure drop due to the tube length and to the restricted bends. The tube and fin cooler cannot approach the cooling efficiency of Earl’s Fin density and oil side to air side mechanical bond. If the tube and fin serpentine style were the most efficient in terms of cooling, wouldn’t you expect to see this design used for radiators on OEM installations and racing cars?
Air Velocity: The Critical Factor in Heat Dissipation
EARL’S TEMP-A-CURE OIL COOLERS are designed to efficiently use all of the air that passes through them. The center chart below shows that a Temp-A-Cure cooler of comparable size is between two and three times more efficient in terms of heat rejection as a typical tube and fin type cooler. (“B”)
Cooler “A” in our chart below is of a popular stamped dish plate design; where the dish plates are the only components—no fins and no corrugated screen. This design, while extremely attractive to the manufacturer, sacrifices efficiency of heat transfer for ease of assem- bly.
The right hand chart below represents testing to determine pressure drop. It shows that the Temp-A-Cure cooler can handle a larger vol- ume of oil (four times the volume!) with less than half the pressure
drop of a typical tube and fin style oil cooler.
Earl’s Temp-A-Cure oil coolers are properly termed “air to liquid heat exchangers”. In order to operate efficiently, they must be mounted in a stream of moving air at ambient tem- perature. It is not a good idea to mount the oil cooler behind the water radiator where it will receive only heated air. It is not enough to lead air to the cooler—the heated air must have somewhere to go after it passes through the core. Remember, air always obeys the immutable laws of fluid dynamics. Simply put, air will only flow from a region of rel- atively high pressure to a region of relatively low pressure. Any attempt on our part to convince it to do otherwise is doomed to failure.
To obtain the heat rejection rate for a given Earl’s Cooler, multiply the dissipation value from the chart by the number of tubes in the cooler.
Based on 100º F Temp. Difference
Heat rejection rate per tube in B.T.U. / minute
40
30
20
10
Comparable heat rejection rates based on SAE 10 weight oil at 200° F. inlet tempera- ture and 7 square inches of matrix area. Contact Earl’s for specific comparison data.
Heat rejection in B.T.U. /
minute
60
50
40
30
20
10
12
10
8
6
4
2
Comparable oil pressure drop across matrix with SAE 10 oil at 200° F. inlet temperature.
Oil pressure drop in
P.S.I.
0 20 40 60 80 100
Matrix Air Velocity in f.p.s.
0 .5 1 1.5 2
Oil Flow in g.p.m.
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Oil Flow in g.p.m.
