The Medieval Thermostat and Ideal Temps
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Joined: Oct 1999
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From: Portales, NM USA
Car: 86 T/A
Engine: 5.0 TPI
Transmission: 700R4
The Medieval Thermostat and Ideal Temps
I still see questions like "I put in a 160° Thermostat why is my car running 180°?
Maybe this will help cooling issues or erroneous choices or diagnostics.
How It Works: The thermostat is a very archaic devise but it gets the job done. That little rod poking down in your engine block is filled with wax. That wax has a melting point. That melting point is the rating or temperature of the stat you just purchased. On a 195° thermostat the wax begins to melt at 195° and thereby expands pushing open a spring loaded valve allowing water to pass.
Here is where all the myths start. That thermostat doesn't snap open and shut like a relay. It has a range of operation. From fully open to fully closed. Typically on a 195° stat it will BEGIN to open at 195° and be fully open at 206° and when cooled will be fully shut at 188°. There is also a +/- 3° margin of error on the best of thermostats. So your stat has 3 important temps and a very wide range of operation.
Ideal Temp: A constant source of frustration that is very simple, yet complex. Simple: 195° is the ideal operating temp, actually 90° C at 1000 RPM idle which converted is 194° F. Exactly why we have a 195° thermostat.
Which Begs the Question Ideal for Who?: Every calibration in your cars computer is designed around this temp by GM to give a BALANCE of power, coolness, emissions, longevity and efficiency (MPG). You can alter this and get a little more power a little more cooling but you give up emissions and MPG. GM chose this temp as a BALANCE that yes has tradeoffs.
Problem: One size does not fill all. Engine temp is not the same in the Arctic Circle vs Death Valley even though both cars have the same 195° stat and GM IS NOT going to fine tune this depending on region.
Climate and conditions: dictate different circumstances and this is the ONE AND ONLY reason we even have a choice of stats with a different operating temperature. To fine tune our "operating range" to function the majority of time at the ideal operating temp of 195°.
It would be ideal to NOT need a fan - but it's there as an emergency device.
It would be ideal to NOT need a stat - but it's there to bring the fluids quickly to op temp and provide heat to keep your juevos from freezing off.
It is not there to solve overheating problems that are being caused by something else nor is it there to give the illusion of increased power via colder engines.
When ALL things are correct: timing, air dam(s), clear passage, good coolant mix, proper air/fuel ratio and you are operating at an undesired higher temp then you should lower your stat rating to bring the "range" down to give you optimal temp the majority of the time.
This is a formula whereas one size does not fit all and every single persons magic formula will be different. Mine happened with a 170 stat to keep my car at just under 200°. This info is for stock or near stock desires and it doesn't apply to race cars where power is the priority without regard to longevity, emissions or fuel economy.
Maybe this will help cooling issues or erroneous choices or diagnostics.
How It Works: The thermostat is a very archaic devise but it gets the job done. That little rod poking down in your engine block is filled with wax. That wax has a melting point. That melting point is the rating or temperature of the stat you just purchased. On a 195° thermostat the wax begins to melt at 195° and thereby expands pushing open a spring loaded valve allowing water to pass.
Here is where all the myths start. That thermostat doesn't snap open and shut like a relay. It has a range of operation. From fully open to fully closed. Typically on a 195° stat it will BEGIN to open at 195° and be fully open at 206° and when cooled will be fully shut at 188°. There is also a +/- 3° margin of error on the best of thermostats. So your stat has 3 important temps and a very wide range of operation.
Ideal Temp: A constant source of frustration that is very simple, yet complex. Simple: 195° is the ideal operating temp, actually 90° C at 1000 RPM idle which converted is 194° F. Exactly why we have a 195° thermostat.
Which Begs the Question Ideal for Who?: Every calibration in your cars computer is designed around this temp by GM to give a BALANCE of power, coolness, emissions, longevity and efficiency (MPG). You can alter this and get a little more power a little more cooling but you give up emissions and MPG. GM chose this temp as a BALANCE that yes has tradeoffs.
Problem: One size does not fill all. Engine temp is not the same in the Arctic Circle vs Death Valley even though both cars have the same 195° stat and GM IS NOT going to fine tune this depending on region.
Climate and conditions: dictate different circumstances and this is the ONE AND ONLY reason we even have a choice of stats with a different operating temperature. To fine tune our "operating range" to function the majority of time at the ideal operating temp of 195°.
It would be ideal to NOT need a fan - but it's there as an emergency device.
It would be ideal to NOT need a stat - but it's there to bring the fluids quickly to op temp and provide heat to keep your juevos from freezing off.
It is not there to solve overheating problems that are being caused by something else nor is it there to give the illusion of increased power via colder engines.
When ALL things are correct: timing, air dam(s), clear passage, good coolant mix, proper air/fuel ratio and you are operating at an undesired higher temp then you should lower your stat rating to bring the "range" down to give you optimal temp the majority of the time.
This is a formula whereas one size does not fit all and every single persons magic formula will be different. Mine happened with a 170 stat to keep my car at just under 200°. This info is for stock or near stock desires and it doesn't apply to race cars where power is the priority without regard to longevity, emissions or fuel economy.
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