For the record, a V-8's cooling system is the most forgotten and neglected part of any hot rod. We speak from firsthand experience. It used to be that you could replace a factory 195 degree thermostat with a 160, then swap the factory four-blade steel fan for an aftermarket 5-, 6- or 7-blade aluminum or fiberglass fan and be done with it.
While these tricks may help some, the times have changed and the available power levels have increased immensely. We're thinking mainly of the larger and more powerful crate engines that are oh-so-popular, but more and more people are building 700-, 800- and 900-horse street cars. And, not only do they want them to go fast, but they also want them to idle in summer traffic without overheating. Much of this story is meant to be a wake-up call to all of you who plan to install a new, more powerful engine to your otherwise stock Chevrolet.
Think about this: Your stock and high-performance gas-powered V-8 engines create combustion-chamber temperatures of 5,000 degrees Fahrenheit. It gets there faster when it's supercharged, or when the high-performance engine is at full-throttle. The cylinder's "heat energy" produced can be subdivided into 25 percent usable horsepower, 35 percent unusable that goes out the exhaust, and another 10 percent absorbed by the engine oil. The remaining 30 percent of the heat is absorbed by the cooling system-which we have some control over. By controlling the overall design of the cooling system, we are simply attempting to control the "working temperature" of the engine to suit our means.
For the record, your gas engine will also generate about 150,000 BTU of internal heat at 2,500 rpm. Less the emissions particulates, this is enough heat to keep a six-room house a comfy 70 degrees while the outside temperature is 0 degrees. All things considered, the hotter your street engine runs, the more efficient it will be, the more horsepower it will develop, and the less overall emissions it will emit. If your street engine runs too cool, it will eventually create an excessive amount of emissions followed by sludge (from raw gas, exhaust blow-by, crankcase moisture/condensation and related deposits).
Excessive cylinder wall taper (from the top half of the engine block being warm from combustion heat, while the lower half is cooler) causes the cylinder walls to wear at different rates, resulting in uneven cylinder wear, and thus decreased efficiency and output.
Water has been proven to be the best disperser of heat. Its molecular structure is spaced far apart, which allows large amounts of heat to be absorbed quickly. Unfortunately, water is also highly corrosive to all of the metals within the cooling system. Additives (antifreeze) are therefore mixed in to help correct the water's pH balance to make it non-acidic. Now, the cooling system's metals aren't slowly eaten up and rust is not created. Experts agree that a 50/50 mix of antifreeze and water works best, all things considered. Various manufacturers have introduced extended-life antifreeze. Texaco Havoline's Dex Cool is good for five years or 150,000 miles. Not to be confused with regular green antifreeze, it's colored orange. It might be just the thing for race and show car tow vehicles and for people always on the go.
TIP: Cooling system inhibitors and additives (just like engine oil additives) wear out over time and need to be replaced. It's recommended that the stock coolant be replaced and the system flushed every two to four years, depending on mileage and wear. If the antifreeze is allowed to "wear out" and is not replaced, serious damage to the cooling system and engine will result from rust and corrosion. In addition, the radiator and cooling system can become plugged with depleted additives and inhibitors, resulting in engine overheating and possible serious damage.
Another common problem with all cooling systems, no matter how custom, is electrochemical degradation. ECD, as it is known, takes place whenever a conductive fluid (water, in this case) comes in contact with different types of metals that make up the cooling system. This reaction is caused by the pH balance of the coolant having a higher than normal acidic balance. When the pH balance slips to the acidic side, the acids begin attacking and destroying the parts of the cooling system including the radiator, heater core, water pump, head gaskets, freeze plugs and coolant hoses. This is yet another major reason to replace the engine coolant at least every four years.
TIP: One of the biggest misconceptions about antifreeze is that if some is good, more is better. On the contrary, antifreeze itself does not provide any direct engine cooling benefit; the water does most of that. The antifreeze is there primarily to correct the pH of the water, eliminate freezing and to internally maintain a clean cooling system by preventing the formation of rust, scale and hard water deposits. Because today's factory cooling systems are designed with very small margins of error, even a slightly dirty cooling system will cause overheating. A 10 percent loss of cooling system capacity because of deposits is enough to cause modern engines to overheat, as most have a 195 degree thermostat.