Thoughts on installing a 'cooler' thermostat...???
08-30-2009, 10:16 AM
#166
Drifting
Thread Starter
Didn't think you would answer.
Hey 1999, what do you do for a living please?
Hey 1999, what do you do for a living please?
Last edited by Marlon; 08-30-2009 at 04:14 PM.
08-31-2009, 01:10 PM
#167
Racer
This is an awfully deep pool -- aww what the heck -- let's dive in and see whether we can swim.
Many years ago when I was a trainee automotive technician I was taught the following:
The vehicle manufacturer designs a thermostat to suit the thermodynamics of the particular motor vehicle including the efficiency/performance of the radiator and the engine design and so on -- so as to keep the engine at the designer's optimum temperature.
If everything is working okay the thermostat should be able to adjust to suit ambient temperatures and driving speeds and different loads so as to keep the engine running more or less at the designer's optimum temperature.
In some engines (we were told almost all engines) if you remove the thermostat altogether the engine will run very cold because the water goes around so fast that it never gets time to heat up meaning that most vehicles have radiator capacity beyond the need of the engine.
The thermostat is nothing more than an adjustable choke to try and keep the engine temperature at the designer's optimum temperature.
In this thread some people say there is a temperature that is more desirable than the engine designer's optimum temperature.
Jake Raby seems to be saying that he would prefer to see a lower temperature -- he says his experience with water cooled Porsche engines leads him to believe that the designer's optimum temperature is a bit too high.
Jake Raby may well be correct in what he says but I don't have anything by way of evidence to prove that but I can say that modern engines are designed to run a bit hotter than engines of previous decades so as to promote lower emissions (and if I'm wrong on this please let me know).
So on one hand we can say Jake Raby thinks it's a good idea to lower engine temperatures a little too perhaps try and get a bit more performance at the expense of slightly higher emissions and also to try and get a lower engine failure rate.
The question then is quite simply -- can a thermostat be used to just a little bit lower than the average operating temperature of a 996 engine?
And here -- for the purpose of this thread -- we have to use a dose of common sense -- as follows -- if the Porsche engine design department has used a thermostat that tries to maintain temperature (aka water flow) to achieve operating temperature 5 on a scale of 1 to 10 then you must be able to have a thermostat that will achieve an operating temperature of 4 on that scale and you must be able to have a thermostat that will achieve an operating temperature of 6 on that scale.
There will of course be a point where the temperature gets "out of whack" because it is beyond the design capacity of the engine and cooling system -- such as when you remove the thermostat altogether making the engine run very cold or when you put in a blocking plate with say a quarter inch hole in it (aka a superhot thermostat) which would make the engine boil very quickly.
So although some people seem to be saying that a colder thermostat can't make an engine run colder I think those people don't have a proper understanding of how thermostats throttle the water flow on an almost constant basis and that opening temperature is simply the temperature when the thermostat opens up and starts its real work of maintaining an acceptable coolant temperature in a wide variety of operating circumstances.
The temperature marked on a thermostat is the opening temperature only and is the reference temperature that the automotive technician users to test the thermostat to see whether or not it is opening at the correct temperature.
You can have two thermostats with the same opening temperature but with different design characteristics (aka flow potential).
So two thermostats with the same opening temperature can end up giving a different operating temperature -- one of them can have a smaller choke (aka hotter) and the other can have a larger choke (aka colder).
Truckers use radiator shutters (and most modern designs have are thermostat controlled) so as to reduce the airflow to the radiator because in very cold weather that airflow can stop the truck from ever getting hot enough to run properly. The point that the previous poster seemed to miss is that in such a truck the thermostat still opens at the required temperature because until the thermostat does open very little water leaves the engine meaning very little water gets to the radiator. It is only when the thermostat is open that the radiator shutters come into play because without those radiator shutters the water temperature coming out of the radiator would be too low thereby quickly taking the engine back to a very low temperature which would close the thermostat altogether and not allow the thermostat to operate as it should and stay open and move backwards and forwards within its range throttling the water but not shutting it off altogether.
Constructive comment eagerly sought.
And finally,
If you don't understand that a soap box is both a privilege and a responsibility it's certain that the short step up will see you fall a long way down.
Amateurs don't build skyscrapers -- entrepreneurs do.
Don't doubt a man just because he's got a financial interest -- remember he's got a profit motive to get it right and that is perhaps a better guarantee than an amateur with an automotive ego motive.
Michael Gibney
Many years ago when I was a trainee automotive technician I was taught the following:
The vehicle manufacturer designs a thermostat to suit the thermodynamics of the particular motor vehicle including the efficiency/performance of the radiator and the engine design and so on -- so as to keep the engine at the designer's optimum temperature.
If everything is working okay the thermostat should be able to adjust to suit ambient temperatures and driving speeds and different loads so as to keep the engine running more or less at the designer's optimum temperature.
In some engines (we were told almost all engines) if you remove the thermostat altogether the engine will run very cold because the water goes around so fast that it never gets time to heat up meaning that most vehicles have radiator capacity beyond the need of the engine.
The thermostat is nothing more than an adjustable choke to try and keep the engine temperature at the designer's optimum temperature.
In this thread some people say there is a temperature that is more desirable than the engine designer's optimum temperature.
Jake Raby seems to be saying that he would prefer to see a lower temperature -- he says his experience with water cooled Porsche engines leads him to believe that the designer's optimum temperature is a bit too high.
Jake Raby may well be correct in what he says but I don't have anything by way of evidence to prove that but I can say that modern engines are designed to run a bit hotter than engines of previous decades so as to promote lower emissions (and if I'm wrong on this please let me know).
So on one hand we can say Jake Raby thinks it's a good idea to lower engine temperatures a little too perhaps try and get a bit more performance at the expense of slightly higher emissions and also to try and get a lower engine failure rate.
The question then is quite simply -- can a thermostat be used to just a little bit lower than the average operating temperature of a 996 engine?
And here -- for the purpose of this thread -- we have to use a dose of common sense -- as follows -- if the Porsche engine design department has used a thermostat that tries to maintain temperature (aka water flow) to achieve operating temperature 5 on a scale of 1 to 10 then you must be able to have a thermostat that will achieve an operating temperature of 4 on that scale and you must be able to have a thermostat that will achieve an operating temperature of 6 on that scale.
There will of course be a point where the temperature gets "out of whack" because it is beyond the design capacity of the engine and cooling system -- such as when you remove the thermostat altogether making the engine run very cold or when you put in a blocking plate with say a quarter inch hole in it (aka a superhot thermostat) which would make the engine boil very quickly.
So although some people seem to be saying that a colder thermostat can't make an engine run colder I think those people don't have a proper understanding of how thermostats throttle the water flow on an almost constant basis and that opening temperature is simply the temperature when the thermostat opens up and starts its real work of maintaining an acceptable coolant temperature in a wide variety of operating circumstances.
The temperature marked on a thermostat is the opening temperature only and is the reference temperature that the automotive technician users to test the thermostat to see whether or not it is opening at the correct temperature.
You can have two thermostats with the same opening temperature but with different design characteristics (aka flow potential).
So two thermostats with the same opening temperature can end up giving a different operating temperature -- one of them can have a smaller choke (aka hotter) and the other can have a larger choke (aka colder).
Truckers use radiator shutters (and most modern designs have are thermostat controlled) so as to reduce the airflow to the radiator because in very cold weather that airflow can stop the truck from ever getting hot enough to run properly. The point that the previous poster seemed to miss is that in such a truck the thermostat still opens at the required temperature because until the thermostat does open very little water leaves the engine meaning very little water gets to the radiator. It is only when the thermostat is open that the radiator shutters come into play because without those radiator shutters the water temperature coming out of the radiator would be too low thereby quickly taking the engine back to a very low temperature which would close the thermostat altogether and not allow the thermostat to operate as it should and stay open and move backwards and forwards within its range throttling the water but not shutting it off altogether.
Constructive comment eagerly sought.
And finally,
If you don't understand that a soap box is both a privilege and a responsibility it's certain that the short step up will see you fall a long way down.
Amateurs don't build skyscrapers -- entrepreneurs do.
Don't doubt a man just because he's got a financial interest -- remember he's got a profit motive to get it right and that is perhaps a better guarantee than an amateur with an automotive ego motive.
Michael Gibney
08-31-2009, 03:11 PM
#168
Race Car
This is an awfully deep pool -- aww what the heck -- let's dive in and see whether we can swim.
Many years ago when I was a trainee automotive technician I was taught the following:
The vehicle manufacturer designs a thermostat to suit the thermodynamics of the particular motor vehicle including the efficiency/performance of the radiator and the engine design and so on -- so as to keep the engine at the designer's optimum temperature.
If everything is working okay the thermostat should be able to adjust to suit ambient temperatures and driving speeds and different loads so as to keep the engine running more or less at the designer's optimum temperature.
In some engines (we were told almost all engines) if you remove the thermostat altogether the engine will run very cold because the water goes around so fast that it never gets time to heat up meaning that most vehicles have radiator capacity beyond the need of the engine.
The thermostat is nothing more than an adjustable choke to try and keep the engine temperature at the designer's optimum temperature.
In this thread some people say there is a temperature that is more desirable than the engine designer's optimum temperature.
Jake Raby seems to be saying that he would prefer to see a lower temperature -- he says his experience with water cooled Porsche engines leads him to believe that the designer's optimum temperature is a bit too high.
Jake Raby may well be correct in what he says but I don't have anything by way of evidence to prove that but I can say that modern engines are designed to run a bit hotter than engines of previous decades so as to promote lower emissions (and if I'm wrong on this please let me know).
So on one hand we can say Jake Raby thinks it's a good idea to lower engine temperatures a little too perhaps try and get a bit more performance at the expense of slightly higher emissions and also to try and get a lower engine failure rate.
The question then is quite simply -- can a thermostat be used to just a little bit lower than the average operating temperature of a 996 engine?
And here -- for the purpose of this thread -- we have to use a dose of common sense -- as follows -- if the Porsche engine design department has used a thermostat that tries to maintain temperature (aka water flow) to achieve operating temperature 5 on a scale of 1 to 10 then you must be able to have a thermostat that will achieve an operating temperature of 4 on that scale and you must be able to have a thermostat that will achieve an operating temperature of 6 on that scale.
There will of course be a point where the temperature gets "out of whack" because it is beyond the design capacity of the engine and cooling system -- such as when you remove the thermostat altogether making the engine run very cold or when you put in a blocking plate with say a quarter inch hole in it (aka a superhot thermostat) which would make the engine boil very quickly.
So although some people seem to be saying that a colder thermostat can't make an engine run colder I think those people don't have a proper understanding of how thermostats throttle the water flow on an almost constant basis and that opening temperature is simply the temperature when the thermostat opens up and starts its real work of maintaining an acceptable coolant temperature in a wide variety of operating circumstances.
The temperature marked on a thermostat is the opening temperature only and is the reference temperature that the automotive technician users to test the thermostat to see whether or not it is opening at the correct temperature.
You can have two thermostats with the same opening temperature but with different design characteristics (aka flow potential).
So two thermostats with the same opening temperature can end up giving a different operating temperature -- one of them can have a smaller choke (aka hotter) and the other can have a larger choke (aka colder).
Truckers use radiator shutters (and most modern designs have are thermostat controlled) so as to reduce the airflow to the radiator because in very cold weather that airflow can stop the truck from ever getting hot enough to run properly. The point that the previous poster seemed to miss is that in such a truck the thermostat still opens at the required temperature because until the thermostat does open very little water leaves the engine meaning very little water gets to the radiator. It is only when the thermostat is open that the radiator shutters come into play because without those radiator shutters the water temperature coming out of the radiator would be too low thereby quickly taking the engine back to a very low temperature which would close the thermostat altogether and not allow the thermostat to operate as it should and stay open and move backwards and forwards within its range throttling the water but not shutting it off altogether.
Constructive comment eagerly sought.
And finally,
If you don't understand that a soap box is both a privilege and a responsibility it's certain that the short step up will see you fall a long way down.
Amateurs don't build skyscrapers -- entrepreneurs do.
Don't doubt a man just because he's got a financial interest -- remember he's got a profit motive to get it right and that is perhaps a better guarantee than an amateur with an automotive ego motive.
Michael Gibney
Many years ago when I was a trainee automotive technician I was taught the following:
The vehicle manufacturer designs a thermostat to suit the thermodynamics of the particular motor vehicle including the efficiency/performance of the radiator and the engine design and so on -- so as to keep the engine at the designer's optimum temperature.
If everything is working okay the thermostat should be able to adjust to suit ambient temperatures and driving speeds and different loads so as to keep the engine running more or less at the designer's optimum temperature.
In some engines (we were told almost all engines) if you remove the thermostat altogether the engine will run very cold because the water goes around so fast that it never gets time to heat up meaning that most vehicles have radiator capacity beyond the need of the engine.
The thermostat is nothing more than an adjustable choke to try and keep the engine temperature at the designer's optimum temperature.
In this thread some people say there is a temperature that is more desirable than the engine designer's optimum temperature.
Jake Raby seems to be saying that he would prefer to see a lower temperature -- he says his experience with water cooled Porsche engines leads him to believe that the designer's optimum temperature is a bit too high.
Jake Raby may well be correct in what he says but I don't have anything by way of evidence to prove that but I can say that modern engines are designed to run a bit hotter than engines of previous decades so as to promote lower emissions (and if I'm wrong on this please let me know).
So on one hand we can say Jake Raby thinks it's a good idea to lower engine temperatures a little too perhaps try and get a bit more performance at the expense of slightly higher emissions and also to try and get a lower engine failure rate.
The question then is quite simply -- can a thermostat be used to just a little bit lower than the average operating temperature of a 996 engine?
And here -- for the purpose of this thread -- we have to use a dose of common sense -- as follows -- if the Porsche engine design department has used a thermostat that tries to maintain temperature (aka water flow) to achieve operating temperature 5 on a scale of 1 to 10 then you must be able to have a thermostat that will achieve an operating temperature of 4 on that scale and you must be able to have a thermostat that will achieve an operating temperature of 6 on that scale.
There will of course be a point where the temperature gets "out of whack" because it is beyond the design capacity of the engine and cooling system -- such as when you remove the thermostat altogether making the engine run very cold or when you put in a blocking plate with say a quarter inch hole in it (aka a superhot thermostat) which would make the engine boil very quickly.
So although some people seem to be saying that a colder thermostat can't make an engine run colder I think those people don't have a proper understanding of how thermostats throttle the water flow on an almost constant basis and that opening temperature is simply the temperature when the thermostat opens up and starts its real work of maintaining an acceptable coolant temperature in a wide variety of operating circumstances.
The temperature marked on a thermostat is the opening temperature only and is the reference temperature that the automotive technician users to test the thermostat to see whether or not it is opening at the correct temperature.
You can have two thermostats with the same opening temperature but with different design characteristics (aka flow potential).
So two thermostats with the same opening temperature can end up giving a different operating temperature -- one of them can have a smaller choke (aka hotter) and the other can have a larger choke (aka colder).
Truckers use radiator shutters (and most modern designs have are thermostat controlled) so as to reduce the airflow to the radiator because in very cold weather that airflow can stop the truck from ever getting hot enough to run properly. The point that the previous poster seemed to miss is that in such a truck the thermostat still opens at the required temperature because until the thermostat does open very little water leaves the engine meaning very little water gets to the radiator. It is only when the thermostat is open that the radiator shutters come into play because without those radiator shutters the water temperature coming out of the radiator would be too low thereby quickly taking the engine back to a very low temperature which would close the thermostat altogether and not allow the thermostat to operate as it should and stay open and move backwards and forwards within its range throttling the water but not shutting it off altogether.
Constructive comment eagerly sought.
And finally,
If you don't understand that a soap box is both a privilege and a responsibility it's certain that the short step up will see you fall a long way down.
Amateurs don't build skyscrapers -- entrepreneurs do.
Don't doubt a man just because he's got a financial interest -- remember he's got a profit motive to get it right and that is perhaps a better guarantee than an amateur with an automotive ego motive.
Michael Gibney
A couple of comments:
First of all, the flow of the coolant in all 996’s was not designed optimally. The water pump and restrictions in the system do not flow the coolant where maximum efficiency of the radiators are achieved. If the system was designed correctly, increasing coolant flow would actually increase coolant temperatures in most cases and not decrease them as is the case in the 996.
The 996 engines are designed to operate at a 194F minimum temperature, yet due to coolant flow and insufficient air flow, coolant temperatures regularly reach 215+F just driving around town. Part of the cause is insufficient air flow and the design of the front bumper as well as the placement of the AC evaporators and their size relative to the radiators.
Without a thermostat in the system, the 996 engines run slightly cooler around town due to increase coolant flow and coolant temperatures can drop down to slightly less than 190F on the open road, depending on road surface and temperature and wether the AC is running.
This is not theory, speculation or anything else but factual information that has been exhaustively tested. The easiest and by far, the most efficient way to decrease your coolant temperatures in the 996 engines and to eliminate the huge swings in engine temperatures is to increase airflow through the radiators. This can most easily be achieved by running the fans during slow driving. An undersized water pump pulley has also shown a slight decrease in temperatures as does keeping the engine compartments cooler than the commonly 150+ F temperatures it reaches driving around town on sunny days.
As for your statement:
In some engines (we were told almost all engines) if you remove the thermostat altogether the engine will run very cold because the water goes around so fast that it never gets time to heat up meaning that most vehicles have radiator capacity beyond the need of the engine.
That is not correct.
08-31-2009, 06:30 PM
#170
Burning Brakes
In some engines (we were told almost all engines) if you remove the thermostat altogether the engine will run very cold because the water goes around so fast that it never gets time to heat up meaning that most vehicles have radiator capacity beyond the need of the engine.
I agree that this is not correct.
The fastest way to elevate an engine's temperature is to remove the thermostat altogether.
I also agree that an under drive pulley helps to reduce temps.. I have proven this on the street and track with my 996 running a 4" UD pulley that I have been testing.
WOW, we agreed on something.. COOL!
08-31-2009, 09:34 PM
#171
Nordschleife Master
04-21-2010, 02:38 PM
#172
Track Day
Join Date: Feb 2010
Location: Bronxville, NY
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I installed an Inengineering 160 degree thermostat in a 2001 C4. On the highway at greater than 60 reasonably steady state MPH, my temp gauge needle is on the right edge of the 180 degree post. That has not happened before and it is now consistent. When I slow down well under 60 MPH - traffic jam or lots of town stop and start driving - the temp gauge shows that the C4 heats up to where it always did under those conditions - right of the 190 post. I asked the owner of Inengineering why this is so. He replied that for so long as a lot of air is being rammed into the radiators the cooling fluid is flowing through the engine at an earlier temperature than the factory version. Next, I will install the Dakota digital temperature controller and start the fans at a lower temp and start up high speed at a lower temp and let the fans stay on for a programmed period after the car stops if the temp is at a programmed level when I turn the ignition off. Cicerosecundus
