Quote Originally Posted by DmaxMaverick View Post
The ideal engine temperature to achieve optimal thermal efficiency, power and economy far exceeds the abilities of traditional engine cooling system components, coolant fluid, and engine components. Essentially, the coolant medium is the limiting factor at the lowest level. The use of NPG coolant removes this factor, and steps the process to the next level: the components. 240°F is about the maximum with EG/water coolant at 15 PSI. The ~200°F operating temperature standard for almost all passenger vehicles allows for a bit of flexibility to keep the temperature at a safe level, with a buffer for overheat conditions. Above that, components such as hoses and seals become vulnerable to heat damage.

The problem isn't so much what temperature can be withstood, but what temperature can be maintained and/or managed. Lowering an engine's operating temperature (by installing lower rated thermostats, for example) to address a frequent overheat condition is most often a band-aid to mask a problem of a less than optimal cooling system, or exceeded mechanical/physical limits (too much power). The lower operating temperature only increases the range of the buffer. In most cases, the problem isn't the maximum temperature, but the ability to control the temperature once it reaches a point of no return. This is why we hear of some trucks that can do a job without ever overheating, while others boil over, all else being equal. Heat generated by burning fuel is used in two ways, either by converting it to forward motion, or shedding it to the environment (cooling system). A 100% efficient powerplant would remain at ambient temperature, all the time, always have power limited only by the fuel consumed, and be absolutely silent. Unfortunately, we can't achieve that, so we have to settle for a middle ground. Some heat energy is used to move you down the road, and the rest is returned to the environment, one way or another.
So then our issue is not so much the operating temp as it is the control of that temp (temp range) as it relates to the flow rate and quantity of coolant on reserve(rad). This is an easily solved problem in a constant load environment where stationary power is needed but more challenging in variable load environment like motor vehicle applications. So upsizing the coolant reserve(rad) and flow rate, when possible, is always a good idea as well as the air flow across the rad. Thanks for the info again.