RACING RADIATORS DOS AND DON'TS
"Every transfer of heat between two fluids, like water to air, is directly proportional to the mean temperature difference between the two fluids, to the area of the interface (the cooler area) between the two fluids and the volume of the cooling fluid flow." Carroll Smith, Tune to Win
Here are some tips that can help in understanding cooling the water or oil of a racing engine.
- Pick up the air flow from the grill area where the highest air pressure location on a car or truck is located. With proper ducting to the radiator, it provides maximum performance.
Pick up the air flow from the grill area. There resides the highest air pressure location on a car or truck, and with the proper ducting to the radiator, it provides maximum performance. Without a duct, air pressure builds in front of the radiator, and it spills over into the engine area. This dynamic spoils the internal aerodynamics, increasing lift and drag, and it severely affects cooling.
Keep the fins of the radiator straight to avoid blocking the air flow. Fin combs are available from radiator shops or APPLIEDSPEED.COM.
Keep aluminum radiators unpainted and clean of debris and dirt for best results. The paint acts as a thermal barrier to heat. No, the color black does not help to dissipate heat.
- Keep the fins of the radiator straight to avoid blocking the air flow. Fin combs are available from radiator shops or APPLIEDSPEED.COM.
- In racing situations and with performance engines, it is best not to use any “antifreeze and summer coolant.” Antifreeze prevents the water from freezing, but as far as keeping water cool it does nothing. In fact, antifreeze increases the water temps. The product is very viscous, and it increases the surface tension of the cooling medium. The added viscosity reduces the flow of the coolant in the system
- Do not paint heat exchangers. The paint acts as a thermal barrier. No, the color black does not help to radiate heat.
- If you installed a new radiator and decided to remove it for storage, dry it off inside and out to prevent corrosion. Drops of water will attract the ions from the aluminum, and they can turn the radiator into a sprinkler.
Radiator fin combs come in a variety of shapes. They fit most fin spacing. A fin comb can make a great addition to the race tool box. This one is available from APPLIEDSPEED.COM.
- Always protect both sides of a radiator with thin plywood when not racing. Those planks also help to bring the temps up more rapidly before going out on the track. Of course, remember to remove the plywood before racing.
Stant Racing Division manufactures high-pressure radiator caps that go up to 31 PSI.
- It all works together. As such, the flow from the water pump must be up to the task. A purpose-built water pump, like those produced by Edelbrock, pump about twice the volume of water without cavitating. Heat rejection increases proportionately to the pressure and turbulation within the cooling system. Higher flow rates witness better heat rejection, particularly with double-pass core configuration radiators.
Edelbrock manufactures high performance and racing water pumps that improve flow and eliminate cavitation. Do not attempt to race with a stock water pump as those only lead to overheating and possibly other serious engine troubles.
For racing and performance use welded aluminum racing radiators like this one on the left from C&R Racing at APPLIEDSPEED.com. Plastic radiators are not made to hold the pressure seen in competition, and they tend to leak at the seams like the one in this photograph.
- Attempt to achieve the biggest difference in temperature possible between the water in the radiator and the ambient air. The radiator exchanges heat with the ambient air, the more significant the difference between the two, the more heat that it can reject.
- The radiator core must be fed with plenty of ambient air. See sections on radiator ducts and fans.
- To protect the engine from possible detonation, overheating, and catastrophic failure design a system that can allow the pressure to rise as high as necessary without the cap releasing pressure.
- Use the type of water suggested by the radiator manufacturer and when using antifreeze always follow manufacturer’s recommendation or use the pre-mix. Whether you run straight tap water or distilled always install a bottle of Redline’s “Water Wetter” as it contains minerals that prevent ionization of the aluminum in the radiator.
Always mount radiators and coolers on soft rubber. When solidly mounted the vibrations can cause cracks, and a failure can ensue.
Offroad vehicles can gather some interesting trophies on their radiators. Whether you are a full-on racer, you tow a trailer, or you just like Jeeping and camping, it is important to keep an eye on the radiator. Occasionally flush it out from the back with a spray of water. Avoid getting soap on the aluminum as the stuff will cause corrosion that creates a barrier to the incoming air flow.
- External corrosion can occur on aluminum radiators. This problem is usually caused by soap from car washes. Hose off the radiator fins with a low-pressure stream of water to flush out the fins from the inside.
- If you run straight water for racing make sure there is plenty of pressure in the system to avoid boiling and corrosion.
- Do not ground radiators. Instead make sure all the electrical components, the engine, transmission, and differential are grounded to avoid electrolysis and galvanization.
Ron Davis Radiators offer this Master Grounding kit. The kit is intended to ground all the electrical components as well as the transmission, differential and engine to prevent electrolysis which can lead to galvanization in the radiator.