Cooling system tips centering around the most overlooked component in the loop…
the Thermostat

Any internal combustion engine incorporating a closed liquid coolant system, needs a thermostat. This not only regulates the temperature, but also the water flow during the open cycle of the thermostat. Too much flow can pass the water too quickly over the radiant surfaces, thereby not allowing efficient heat transfer. Too little flow can overheat the coolant before it gets a chance to radiate it's heat stored in it's mass. If coolant stays too cool, as in the case of no thermostat being present, the coolant can create air

pockets in the nooks and crannies in the cylinder heads, thereby "superheating" into an expanding gas, which forces water out of the overflow even though the water leaving the engine appears to be well below it's boiling point. This is a dangerous situation leading to serious engine damage due to cracked heads and cylinder blocks, without warning.
     Some reasons racers have deleted the thermostat in favor of calibrated water neck restrictors, is the goal to eliminate potential thermostat failures, as well as preventing conventional thermostats from being forced closed under high rpm water flow. Even though these concerns are genuine, they do in fact make 'racing' thermostats, called "Balanced Thermostats" which eliminate these concerns...

Standard thermostats can be off as far as 10 to 20 degrees, in regard to their stated opening and closing points. Balanced styles can be as accurate within 2 degrees. Standard types are prone to failure, such as the one in the center. This results from the brass metal bridge over the plunger giving way, therefore closing the thermostat completely, restricting all water flow. Within minutes, total engine destruction is inevitable.

The balanced version uses a "wax pill" (yellow arrow), which is designed to melt at a predetermined point, thereby opening the thermostat at precisely the same temperature, every time. The 3-port construction (blue arrow) equalizes the water pressure from above the valve (radiator side) to the higher, pump pressure side. This allows the thermostat to open effortlessly and accurately no matter what the water flow, or engine RPM is at that particular time. Non-balanced designs are prone to be forced closed when the water flow abruptly increases, such as during sudden increases in engine RPM.

Also, note the increased water flow capability (red arrow) of the Balanced model compared to the relatively smaller standard style thermostat.

Tests have proven that by simply opening the thermostat precisely at the same temperature over and over again, the engine remains cooler on the average. Engines can warm up faster to normal operating temperature, and cool down quicker once the engine exceeds the set point. This results in longer cylinder wear, and consequently longer engine life. By opening the thermostat 'on time', every time, the temperature swing is reduced, allowing for more complete cooling. By getting the thermostat open as quickly and as wide as possible, allows the warm water to exit quickly, thereby getting it to the radiator to begin it's cool down cycle as fast as possible. As a result, getting the cool water into the engine and holding it there, extracts as much heat from the engine as efficiently possible, therefore enabling to radiator to work at it's maximum potential as well.

As you can see, there's a lot more to a thermostat than just 'making your gauge stop' at a certain point!

The graph to the right illustrates the importance of how critical optimum coolant temperature is to the longevity and performance of an internal combustion engine. Cool water makes good horsepower, to a point. Warm water minimizes engine cylinder wear, to a point also.

However, there is a "middle ground" where both optimum performance as well as minimal wear share similar characteristics. That "magic" number lies in the 175-180 degree range, which requires a 180 degree thermostat..

The all too commonly used 160 degree thermostat is way too low to be considered for performance or engine longevity. As the chart illustrates, engine wear increased by double at 160, than at 185 degrees. So then, why do the 160's exist in the first place? The 160's were commonly used in older, open loop cooling systems where only 6 pound radiator caps were used, and low 212 degree boiling points were experienced. In contrast, modern cooling systems can see upwards of 260 degrees in coolant temperature with radiator pressures exceeding 45 pounds. Many early hot rodders found the 160's to be better performing than the 190's, however, the in between "180" appears to satisfy both ends of the spectrum. The correct water temperature is required for the  cylinders to achieve a minimum specific temperature in order to allow a fully homogenized Air/Fuel mixture to combust efficiently. Guess what the minimum number is… right! 180 degrees. Even so, you might see some still recommending the lower 160's, for no other reason than to possibly get that last drop of horsepower out, at the high price of dramatically reducing the life of the engine and it's internal components.