Some Insight To Cooling Systems In Race Cars

Photo:Attribution Some rights reserved by Jim & Rachel McArthur

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.

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.

he cooling system in a typical drag race car is marginal at best, yet we want the engine to be as cold as possible to produce maximum power. The colder the engine, the less likely it is to detonate. That’s why Pro Stock racers use chillers and refrigeration systems to lower the water temperature to below 50 degrees before a run. These systems also have enough pressure to purge air pockets effectively from the system. I realize that such systems are impractical for sportsman racers, but their use illustrates the importance of keeping an engine cool and its cooling system purged of air for maximum performance.

Filling the radiator doesn’t necessarily mean that the coolant is where you want it. It’s vitally important that the water completely fill the passages around the combustion chambers. Air is a much less effective heat conductor than liquid; efficient heat transfer demands that the coolant be in constant contact with the metal. Unfortunately, the water jackets must occupy the spaces between the ports, the head bolts, and the spark plug bosses. These convoluted passages are prone to capture air pockets and bubbles that prevent the coolant from fully contacting the metal surface.

The objective of any racing engine is to burn as much fuel as possible in the shortest amount of time. The energy that’s released is what propels the car to the finish line. The unavoidable consequence is that more heat is also released into the cooling system. Keeping this heat under control is essential to engine survival.

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