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RAPID RADIATION Radiators And Heat Exchangers For The Off-Road Environment By Dan Sanchez Modern engine compartments in trucks, SUVs, and UTVs are limited in space, so one of the only ways to upgrade your vehicle’s cooling capabilities for off-roading is to improve cooling efficiency. In some situations, more efficient radiators, adding heat exchangers, as well as oil and transmission coolers can improve cooling capacity and efficiency, but it’s important to know how they work. Aluminum vs Copper Radiators A big debate among cooling experts is the efficiency of modern aluminum radiators versus older style copper units. Most radiator manufacturers agree that copper is more conductive than aluminum but the fact is that copper is also much more expensive than it was in the past. “Aluminum is less expensive and easier to manufacture,” says Mike Murphy, Performance Division Product Manager at US Motor Works LLC. “They are made differently than the older copper radiators that we soldered with lead, which is very inefficient. By modern standards, radiator manufacturers can make aluminum radiators that are just as efficient as the old copper ones.” “A custom aluminum radiator can be made to maximize all the available space in a vehicle,” says Jack Anderson C&R Racing Engineering Manager. “Larger core areas combined with maximum airflow provide greater cooling efficiency.” In some vehicles, custom radiators can be made with more rows of tubing to increase cooling capacity within the basic dimensions of the factory radiator. Environmental Factors Driving on the highway with occasional off-roading is very different from a pre-runner or race vehicle that encounters much more dirt and dust that is thrown at it. “When you’re driving alone or out in front while off-road, there’s lots of clean air for adequate airflow to radiators,” says Anderson. “When you’re stuck for miles behind another race car, however, dirt and dust can clog radiators. That’s why many are tucked behind front shrouding or in the bed. This presents another problem of restricted airflow so pusher fans are required to compensate.” Since these areas get less airflow, it’s one of the reasons why radiators and coolers that are mounted in the back, are much larger than what stock vehicles use. The idea is also to move as much water as possible, but the limiting factor is always airflow, so electric fans are often needed,” he added. Fins And Plates Radiators and coolers are manufactured in a variety of ways to fit small spaces and for efficiency. Heat Sinks are the least efficient and are often a simple tube with cooling fins extended around the outside body. Plate and Fin style coolers are how most radiators are designed where the fins are tightly configured within the tubes for higher airflow and to displace heat. Stacked Plate coolers are the most efficient and have internal fins and extra heat sinking inside the tubes. They also have wider heat dissipation fins. These are most commonly used for oil cooling. “In race applications and in heavy dirt environments, you may want to choose a stack plate core or extruded plate core,” says Murphy. “Fin configurations are wider on these types of coolers to allow for dust and silt to pass through much easier. Tighter fin configurations may clog up easier and when it does, heat dissipation drops dramatically.” Heat Exchangers While coolers and radiators use airflow to drop fluid temperatures, heat exchangers use coolant to lower fluid temperatures. “Heat exchangers are a great way to lower fluid temperatures when done correctly,” says Jeff Howe, President at Howe Performance. “Many would fail but that’s because they weren’t properly sealed.” Howe has a new heat exchanger that he believes is solid and uses O-rings to separate oil from coolant. “We’ve seen 30-degree temperature drops on oil from our heat exchanger used on the hot water side of an off-road racing team’s engine,” says Howe. While many heat exchangers should be used on the cool-side of the vehicle’s radiator coolant system, industry experts agree that if heat exchangers were used with a stand-along cooling system, they would be much more effective in off-road racing applications. “The trend with more efficient radiators and cooling systems is the move towards thinner and lighter units,” says Anderson. “The large three-foot-wide and three-foot-tall radiators we used to see on race cars were affecting the dynamics of the vehicle, the smaller cores are reducing weight and improving aerodynamics, while also providing efficient cooling.” SJ C&R Racing Howe Performance US Motor Works LLC

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