SCORE Journal - The Official Publication of SCORE Off-Road Racing
Issue link: https://read.uberflip.com/i/1539923
COOL UNDER PRESSURE Technologies That Keep Baja Race Vehicles Cool By Dan Sanchez Improving cooling efficiency is one way SCORE racers and off-road enthusiasts can run their vehicles in high heat for long distances across desert terrain. What makes all this possible are advancements in radiator and heat exchanger designs, fluids that improve heat dissipation, and smart fans that enhance efficiency and cooling. We spoke with several manufacturers of radiators, smart fans, and cooling fluids to learn how these individual components can be combined to optimize cooling. Radiator Designs And Selection Most radiators and fluid coolers are manufactured from aluminum. Although copper is more conductive, aluminum is less expensive, making it a popular choice among racers and as original equipment in trucks, motorcycles, UTVs, and other vehicles. The two types of air radiators that are used to cool fluids within them are tube-and-fin and bar-and-plate coolers. Each has its own benefit depending on where they are used. According to Hayden Lowe, PWR’s Motorsports Project Engineer, tube and fin style coolers work better in spaces without incoming debris from direct airflow, and with minimal chassis twist. For many vehicles, this is behind the cab or in the bed of a race truck. Bar and plate coolers are a stronger design, but are less efficient at cooling than the tube and fin designs. “PWR has developed Bar and plate cores to be within 1-2% of the performance of a standard tube and fin core at the cost of weight,” says Lowe. “They are vastly more robust and allow for more punishing and advantageous mounting locations. These we will also pair with SPAL brushless fans to achieve the best airflow possible.” Aside from systems that use airflow to cool fluids flowing within them, racers also have the option of using fluid-to-fluid heat exchangers to lower the temperatures of vital fluids. “Heat exchangers are a great way to lower fluid temperatures when done correctly,” says Jeff Howe, President at Howe Performance. “Many fail in an off-road racing environment because they aren’t properly sealed.” Howe has a heat exchanger design that 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.” The 3Ps In off-road racing situations, having a radiator or heat exchanger in front of the vehicle can become damaged from debris. So it’s common for builders to move the cooling systems to the rear of race vehicles. To provide proper airflow, brushless fans are preferred. Nevertheless, efficiency with electrical fans depends on the three Ps: Push, Pull, and Placement. Pull (or draw-through) fans are the most commonly used on engine cooling radiators as they won’t hinder incoming airflow when the vehicle is at speed. According to most fan manufacturers, pull fans are also the most efficient and provide the most amount of cooling capacity and airflow. For optimum efficiency, however, race fan manufacturers agree that teams should cover as much of the surface area as possible with a fan shroud. “Ideally, having a shroud is more effective than not,” says Andy Wagoner, president at Steele Racing Products. “That’s because airflow is much more productive when it’s being funneled in versus just in the open air.” Without a fan shroud, Wagoner says you can compromise the amount of power the fan has to output to cool down a radiator. “In SCORE Trophy Truck classes, for example, we’ve seen some teams figure out the ‘sweet spot’ to utilize fans with a shroud,” he said. “This level of understanding about placement can outperform larger systems. The biggest difference is having a shroud bolted to the radiator with the fan close to it. High-end builds often have a gap to compensate for the theory of airflow and dead space to pull air through. The thought is to add more, or higher power fans to make it better, but they are missing the fundamental point.” Smart Fans While brushless fans are considered optimum, due to their use of magnets instead of motors with brushes that wear and need replacing, they can also be “smart” too. According to race fan manufacturers, these brushless fans can have an integrated microprocessor that can take inputs from the vehicle’s racing computers. “We can program fans to act under certain conditions, even to operate at specific speed intervals,” says Wagoner. This allows fans to operate differently depending on temperature, engine operation, track conditions, vehicle speeds, and more. Smart fans also allow the capability of a “slow start” condition, allowing for less power draw upon vehicle start-up, preventing blown fuses and other problems from initial power drain. The fan microprocessors are typically encapsulated in high-temperature thermal potting to prevent any dust or water intrusion. Quality Is Everything Since electric fans are the main source of airflow for cooling in an off-road vehicle, it makes sense to use high-quality products. According to the various manufacturers, they recommend sticking with brands that you know and not by the lowest price fan with the highest CFM rating. “There’s no governing body for testing fan CFM,” says Greg Goeders, Marketing & Aftermarket Sales at SPAL. “What you often see advertised as CFM are free-air numbers, meaning the fan output is measured outside of the vehicle, not with a cooler or engine bay in front or behind it.” Smart fans like those available from Steele Racing Products or SPAL are made for race vehicles and have lots of testing behind them to prove their performance in a variety of racing conditions. “Steele now has a new brushless Pro Series line for racers,” says Wagoner. These have a greater deep-dish style setup that creates additional dynamic pressure but in a smaller package. That helps mitigate space issues, but when placed right, it can be far more efficient than a larger fan to cover more area.” Wagoner suggests placing fans like these as close to the radiator or heat exchanger as possible. “These new fans are self-contained, but they should be paired with a cool shroud to be as tight as can be.” Companies like Derale also have cooling combinations now available in what they call a Powerpack. “These new, dual 12-inch, high-performing brushless fans with integrated fan controller, combined with their high-performing shrouds, are a combination that just can’t be beat,” says Frank Scerbo, Marketing Manager at Derale. “Offering a total of 4400 CFM, this dual electric fan assembly generates the most real-world airflow in the smallest package on the market.” SPAL also has a new fan coming out, a single 800-watt brushless 18-19-inch fan that puts out 3800 cfm and also features a microprocessor. “Nothing even comes close to the output and possibilities of this fan,” says Tom Longo, North America Aftermarket Sales Manager at SPAL. “We believe this fan will conquer the off-road market. Additionally, all SPAL brushless fans are rated at 5g shock and vibration resistance and are more robust for off-road applications. Cooling Fluids When you combine the latest in radiator and fan systems with the latest advancements in coolants, you come up with a solid system that can win races. Coolants have also progressed to become a complex and critical under-hood product. Ethylene Glycol was originally introduced to prevent cooling fluids from freezing, offering a better solution over water. Eventually, more additives were mixed in to provide a variety of coolant formulas for specific applications. According to the engineers at Peak Anti-Freeze, modern engine coolant is diverse and engineered to protect the many different metals and gaskets that are in modern engines. Within the Peak line of coolants, as an example, there are some with Inorganic Additives used to protect older domestic engines, and Organic Acid Technology used in OE domestic and some import engines. Various Hybrid Organic Acid Technology formulations are also required in some domestic and imported engines. Some require Phosphate Salts, others require Silicates, and there are some coolant varieties with Extended Life and Heavy-Duty formulas. So it’s easy to see that there are a variety of coolant formulations that are available. The correct one to use depends on the engine, and in the case of racing engines, the builder will know what works best with the radiators, water pumps, and gaskets they are using. Off-Road Racing Specific Coolants Some companies manufacture high-end coolants specifically for off-road racing. These formulations are designed to control extreme heat, as well as prevent foaming and cavitation in high-rpm racing conditions. Maxima Racing’s Off-Road Coolant is an example of a proprietary mix of premium glycol, laboratory-grade deionized water, and an advanced additive system designed to protect against rust, corrosion, cavitation, and foaming, while providing water pump and seal lubrication for steel, aluminum, and magnesium engines. “Developed with top SCORE Trophy Truck and Class racers, Maxima’s Off-Road Coolant has been tested and proven in the harshest and most extreme environments,” said Chris Schell, West Coast Business Development at Maxima Racing Oils. In addition, Maxima Racing Oils also has its Cool-Aide product, a non-glycol-based formulation designed to lower the surface tension of water. “Cool-Aide allows for better heat transfer and prevents corrosion in cooling systems without the use of glycols,” adds Schell. “The difference is that our Off-Road Coolant utilizes the benefits of glycols that allow for higher boil temperatures and freeze protection.” Avoid Overheating Failures When approaching cooling for off-road use or racing, the most important aspect that many of the fan, radiator, and fluid companies want you to know is that the basics still apply. Use high-grade products in an efficient cooling system with a fan shroud. “Simplicity matters,” says Wagner. “It’s easy to overcomplicate an electric cooling fan setup, but from our experience, it always comes down to the three p’s. Start there and work outwards.” “Bigger isn’t always better,” adds Longo. “More distance between the radiator and the fan in a shroud is what creates more airflow. Straight blade fans create greater airflow and allow for tighter clearances for maximum performance. Puller fans are the most efficient space permitting.” “A good engine coolant used with the same brand high-performance engine, transmission, and gear oils will improve heat transfer,” says Schell. “Together, they can deliver lower and more stable operating temperatures than mixing various fluid brands. In testing here at Maxima, we’ve seen temperature drops in the order of 18-46 degrees F., depending on vehicle conditions.”