Drag race car9/12/2023 ![]() 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.įilling the radiator doesn’t necessarily mean that the coolant is where you want it. These systems also have enough pressure to purge air pockets effectively from the system. That’s why Pro Stock racers use chillers and refrigeration systems to lower the water temperature to below 50 degrees before a run. The colder the engine, the less likely it is to detonate. The 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. That’s why the temperature gauge in my Suburban quickly heads for “H” when I’m towing up a grade. Even the cooling systems in passenger cars and light trucks are rarely able to keep up with the heat gain when the engine is run at continuous peak power. Look at the size of the radiator that’s required to cool a 500-horsepower engine operating continuously in a diesel-powered commercial truck– it’s enormous. It’s more accurate to think of these components as “cool down” systems rather than cooling systems, since their chief purpose is to reduce coolant temperature after a run.Ī true cooling system would require a massive radiator, a high-volume water pump, and huge fan to balance the input and output of heat. Drag race cars typically use tiny radiators (or sometimes no radiator at all), low-volume electric water pumps, and inefficient fans that simply can’t cope. ![]() Most drag race cooling systems are utterly inadequate to dissipate such staggering heat. So if a drag race engine burns one gallon of gas in the course of staging, burnout, and a quarter-mile run, potentially more than 36,000 BTUs have been dumped into a cooling system with a capacity of only a few gallons of water. Approximately 30 percent of this waste heat must be dissipated by the engine’s cooling and lubrication systems. The rest is turned into waste heat or consumed by mechanical friction. A typical internal combustion engine converts only about 25 percent of the fuel’s energy into useful work (accelerating the car). One gallon of gasoline contains roughly 120,000 British Thermal Units (BTU) of heating value, enough energy to raise the temperature of 1,000 pounds of water by 120 degrees. And yet a dedicated drag race car probably wouldn’t last a minute under those conditions. At the Bonneville Salt Flats, land speed record racers run flat-out for miles at maximum power. Why are drag racing engines prone to meltdown? We’ve all watched NASCAR engines run 600 miles at wide-open throttle on a sweltering summer day without problems. It’s a blessing that an overheated engine is seldom run to catastrophic failure – usually it loses so much power that the driver realizes that something is wrong and shuts it down. ![]() Hot spots in the combustion chambers lead to preignition, which in turn leads to detonation, which initiates a chain of destruction. Excessive heat does bad things to good engines – head gaskets fail, decks turn blue, valves recede and tulip, pistons seize, and aluminum alloys lose strength. The results are unmistakable when an engine overtaxes its cooling system. In comparison, drag race cooling systems are almost an afterthought – and that’s a grave mistake. Racers typically devote a great deal of time and money to oiling systems, devising windage trays, baffles, deflector screens, and dry-sump systems to ensure continuous lubrication. “Most drag race cooling systems are utterly inadequate to dissipate such staggering heat.”Īn engine has two fundamental needs: lubrication and cooling. By David Reher, Reher-Morrison Racing Engines ![]()
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