Making big power with today's high-performance parts is relatively easy. Just go online, choose the parts that match your performance target, andwait for the goodies to arrive. But after those extra horses are stabled under your hood, you may notice your temp gauge is running hotter than before. More-powerful engine combos, lower rearend ratios, and high-stall converters all contribute to greater engine heat. Without the proper cooling components, out-of-control engine heat can cause head gaskets to blow, parts to seize, and blocks to crack.
A better idea is to match the cooling system to your engine combo and vehicle use. This means installing a system complete with adequate frontal airflow, correct radiator sizing, a properly selected thermostat, a good water pump, a fan, and a shroud. Understanding which components you'll need and installing them properly will keep your engine running cool and your performance hot.
The Liquid System
Most modern passenger-car engines are cooled with a liquid, typically water and coolant (for street use). This circulates (powered by a water pump) inside the engine through water jackets and out through an upper radiator hose, where it enters the radiator core to be cooled. The radiator core's numerous passages, called rows or tubes, have cooling fins attached. As the hot liquid travels in one direction through the radiator core, moving air (drawn by the engine fan and vehicle movement) lowers the liquid's temperature dramatically by heat transfer, and it is cycled back into the engine.
Open & Shut Case
Thermostats regulate the flow of the cooling liquid after the engine's temperature has reached a set level. This is done largely to allow quicker warm-ups. For most engines, thermostats are available from 160 to 195 degrees F. Some newer thermostats are available in even higher ratings.
Switching from one thermostat rating to another may raise or lower the engine's operating temperature. For colder-weather operation, a thermostat with a higher rating of 195 is usually the best choice. If a colder thermostat, such as a 160, is used in a cold climate (below 60 degrees F), the vehicle's engine may never reach operating temperature and the heater may never produce warm air. Additionally, the condition may increase engine wear due to colder (and thicker) oil, the fuel not burning as completely, and possibly smaller engine clearances.
In warmer climates, a 160 or 180 thermostat may keep the engine temperature down by a few degrees as long as the cooling system is efficient enough to maintain the colder operation. If the cooling system's efficiency is marginal at best, the engine may run at the same higher temperature, in spite of the thermostat.