Engine Cooling System - Keeping Your Cool

A short track stock car will often need a fan to make sure as much air as possible is drawn through the radiator. This is because the car will not be traveling at 100-plus mph on a regular basis. Many times, the speed range for a short track car running on a quarter-mile or 3/8-mile track may run from 35 mph to 85 mph. These lower speeds mean that it is necessary to run a fan to make sure that enough cool air goes through the radiator. If you are running a fan, you will need to develop a good fan shroud to make sure the fan is able to really do its job. The fan shroud needs to cover the fan with no more than 3/4-inch clearance around the OD of the fan. And the fan should not stick into or out of the end of the shroud by more than 1/2 inch. This will ensure the fan will actually move air and help cool the engine.

The OEM water pump will most likely work up to the 500hp level. Once you start to get power levels above this mark, it is a good idea to start looking into some of the aftermarket water pumps. As you get into the elevated horsepower levels, you will need the pumps that have impellers designed to work at the higher rpm levels that these higher horsepower engines develop. Aftermarket water pumps also have larger shafts and stronger bearings than the OEM pumps. Just like the rest of the engine, the water pump needs a higher level of strength as you start to place greater demands on it.

There are other pitfalls to avoid with cooling systems. It is important to make sure the system is properly filled to avoid capturing any air in the block. This requires checking the coolant level after the engine has been fired for the first time. It is possible to capture air in the block, so you need to "burp" the system to make sure that no air is captured in the block or any of the hoses. It is a very good idea to run a coolant recovery system.

Some tracks do not allow the use of ethylene glycol-based coolants because they can be very slippery if spilled on the racing surface. If this is the case, you will not be able to add antifreeze to the system and you will be forced to use only water for a coolant. This means you will have to use some other means of preventing corrosion in the cooling system. There are some products on the market that improve the water in the cooling system. Red Line markets a product called Water Wetter, a wetting agent for cooling systems. It can be used in cooling systems that are running only water to help prevent corrosion and rust. It also helps heat transfer and can improve cooling. If you are forced to run a water-only coolant, this product is a big help.

The way a radiator is mounted is critical to the cooling system and its longevity. Remember, the radiator is not a stressed member of the chassis and will not take a great deal of abuse. The radiator should be mounted so it can flex and move just a bit. Most OEM mounts cradle the radiator. Your mounting system should try to mimic this mounting method. Bolting the radiator solid to the chassis is a sure recipe for cooling system disaster.

Many racers remove the thermostat from the cooling system and think they have avoided a potential failure. Often, the thermostat is replaced with an orifice, or worse, nothing at all. While this removes any problem that may occur due to a stuck or broken thermostat, there still may be some issues. Without a thermostat, it is very difficult to get an engine to warm up properly, which is a bad thing. A method that is very popular is to drill some 3/16-inch holes in the thermostat to keep it from ever being completely closed. This will ensure constant coolant flow, and you will still get the benefit of having a thermostat.

Checking a thermostat as a part of your regular maintenance program is not that big of a deal. Just place the thermostat in a pan of water with a thermometer. Then, place the pan on the stove. You can see when the thermostat opens and check the opening point on the thermometer. Just remember to wash the pan to promote domestic tranquility.