Cooling an internal combustion engine is a complex subject. In this article we will direct our efforts to those short-track, primarily dirt, race cars that run on quarter- to 3/8-mile tracks. Keep in mind, some things contained here do not apply to long-track, high-speed race cars.
The copper/brass stock-type radiator (left) will, when unpainted,actually transfer heat better than the aluminum one. The aluminumradiator (right), where legal, is both lighter and better for racingsince it is designed for higher flow rates.
There are many ways for a race engine to have cooling problems. The air/fuel mixture has a definite bearing on engine heat. A lean mixture will burn hotter. The type of fuel is important, too. Alcohol runs cooler than gasoline. Retarded ignition timing will build heat in an engine. It is often hard to trace this problem. Water flow through the cooling system is important. The engine needs high water flow rates. Manufacturers make high-volume water pumps for a reason. Head gaskets leaking combustion heat and pressure into the cooling system will lead to dramatic heating problems.
An old radiator may not leak, but it may have internal corrosion that can insulate the heat in. Air must move through the fins of a radiator. This requires a tight-fitting fan shroud with an efficient fan. Lastly, the radiator must be of sufficient size to cool the engine. This size is determined by engine horsepower, water flow, radiator condition, airflow, and radiator design. Steve Davis of Performance Distributors points out that low battery voltage can cause a weak spark, resulting in higher engine temperatures.
These two fans are frequently the choice for racing applications. Thesix-blade model and the four blade have close to the same airflow atracing speeds. The six blade has a higher air flow at lower speeds(yellow flag laps) and surprisingly uses slightly less power.
The point of all this is that there is not one thing that cools an engine. The cooling of an internal combustion engine is a cooperative effort on the part of many items. They must all work together as a team.
The Radiator
There are two choices of material for a radiator, copper/brass or aluminum. Unpainted, the copper/brass material transfers heat better than aluminum. This does not necessarily make it better for race car radiators. The copper/brass radiator is heavier than aluminum and is designed for all kinds of street use. It is not designed to work on a dirt circle track car. Yes, I have used them many times on stock cars in this application and they work well enough most of the time.