Adjustable thermostat discussion
03-04-2007, 01:46 PM
#22
The "cooling capacity" of the system is directly related to settings of the electric fans. When they are not on, and the vehicle is not moving, the cooling system is extremely inefficient, and the engine will overheat quickly. The cooling system depends on airflow through the radiator in order to do its job, I'm sure you know this. If car A has a 160 degree thermostat, and car B has a 190 degree thermostat, and both were left to sit and idle with no fans, both engines will overheat. However, since the thermostat in car A will open sooner, and thus starting the flow of coolant sooner, it will take longer to heat up, because heating 14L of coolant in the entire system takes more energy that heating just the few liters of coolant that are already in the block. Now, after coolant begins to flow in both cars, they will both overheat, unless you get some airflow through the radiator, which is where the fans come in. Assuming we are on the topic of F-bodies, we are using electric fans, which are preset to come on a specific water temperature. Stock, they are set to 226/219 for low, and 233/227 for high. So, back to my original point, the temperature of the engine depends on the efficiency of the cooling system, which in our case, is pretty much determined by the settings of the fans. This is why if you want an adjustable engine temperature, run a low or no thermostat, and then somehow have adjustable fan settings, which an SLP fan switch might work well for. To satisfy some people's claims that their lower thermostat reduced their running temp, here's one case in which it would. If you start your car, and then immediately get on the freeway before it fully warms up. In this case, there is airflow through the radiator, similar to if you lowered the fan settings, in conjunction with the lower thermostat. As soon as you get off the freeway, the airflow stops and the engine will continue to heat up until the fans come on.
Originally Posted by Steve Bryant
Ferocity02,
I disagree with you. If a vehicle has a radiator with more than adequate cooling capacity and adequate airflow through that radiator, the thermostat temperature set point will determine the temperature around which the engine coolant temperature will regulate. The set point determines both when the valve in the thermostat will begin to open and close again. What you say would be true only if the cooling capacity of the radiator were inadequate for the BTU production of the engine in given ambient temperatures and operating load of the engine.
If what you say were true, no truck diesel engine would ever come up to normal operating temperature in the colder months.
Steve
I disagree with you. If a vehicle has a radiator with more than adequate cooling capacity and adequate airflow through that radiator, the thermostat temperature set point will determine the temperature around which the engine coolant temperature will regulate. The set point determines both when the valve in the thermostat will begin to open and close again. What you say would be true only if the cooling capacity of the radiator were inadequate for the BTU production of the engine in given ambient temperatures and operating load of the engine.
If what you say were true, no truck diesel engine would ever come up to normal operating temperature in the colder months.
Steve
03-04-2007, 02:57 PM
#23
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Ferocity02,
I'm not excluding F Bodies, but this thread is on adjustable thermostats and the topic of thermostat operation has entered into the discussion. In discussing the operation of the thermostat, I qualified my statements to assume "a radiator with more than adequate cooling capacity and adequate airflow through that radiator". It doesn't matter how you get the airflow through the radiator (forced air from vehicle speed, mechanically driven fan, electrically driven fan), none of these issues change the basic function of the coolant thermostat. It opens and closes to control engine coolant temperature. It doesn't matter if the thermostat is installed in an F Body, a Corvette, a truck or a boat.
The control of electric fans is important whether due to rising coolant temperature operation of air conditioning, etc. But the electric fans have nothing to do with the operation of the thermostat. That's all I'm saying. Please give this a little thought.
Steve
I'm not excluding F Bodies, but this thread is on adjustable thermostats and the topic of thermostat operation has entered into the discussion. In discussing the operation of the thermostat, I qualified my statements to assume "a radiator with more than adequate cooling capacity and adequate airflow through that radiator". It doesn't matter how you get the airflow through the radiator (forced air from vehicle speed, mechanically driven fan, electrically driven fan), none of these issues change the basic function of the coolant thermostat. It opens and closes to control engine coolant temperature. It doesn't matter if the thermostat is installed in an F Body, a Corvette, a truck or a boat.
The control of electric fans is important whether due to rising coolant temperature operation of air conditioning, etc. But the electric fans have nothing to do with the operation of the thermostat. That's all I'm saying. Please give this a little thought.
Steve
03-05-2007, 11:22 AM
#24
The original post in this thread implied that simply by adjusting the opening and closing points of the thermostat that one could in turn control the running temperature of the engine, which is simply not true. If you still don't believe me, get a colder thermostat and install it and tell me it runs cooler. With this said, I'm done here.
03-05-2007, 01:03 PM
#25
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In my convoluted way of thinking the fans are just an artificial way to push the radiator through the air when the car is at low speed. Of course fan settings are going to have a major effect on what temperature the car runs in traffic. I suppose it matters what you consider the primary operating mode to be. Fans aren't going to be able to reduce coolant temp lower than the thermostat set point. For this reason I consider the thermostat as the primary temperature regulation device. The fans are an accessory. I do know of someone who built a 55 chevy with a massive Griffin radiator, like the 1.5" core tube stuff and he ran sans fan on the streets of California without much trouble.
03-05-2007, 02:56 PM
#26
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andereck,
You are right. If you are in a warm climate like Los Angeles, Phoenix, Houston or Miami; you might get the wrong idea of the function of the thermostat versus fans (mechanical or electrical). However, if you lived in Milwaukee, Detroit or Toronto only in the winter, you'd wonder if the fan had any function at all. You could cut the wires and you'd hardly notice any difference even in city driving.
Steve
You are right. If you are in a warm climate like Los Angeles, Phoenix, Houston or Miami; you might get the wrong idea of the function of the thermostat versus fans (mechanical or electrical). However, if you lived in Milwaukee, Detroit or Toronto only in the winter, you'd wonder if the fan had any function at all. You could cut the wires and you'd hardly notice any difference even in city driving.
Steve
03-05-2007, 03:14 PM
#27
Originally Posted by Steve Bryant
andereck,
You are right. If you are in a warm climate like Los Angeles, Phoenix, Houston or Miami; you might get the wrong idea of the function of the thermostat versus fans (mechanical or electrical). However, if you lived in Milwaukee, Detroit or Toronto only in the winter, you'd wonder if the fan had any function at all. You could cut the wires and you'd hardly notice any difference even in city driving.
Steve
You are right. If you are in a warm climate like Los Angeles, Phoenix, Houston or Miami; you might get the wrong idea of the function of the thermostat versus fans (mechanical or electrical). However, if you lived in Milwaukee, Detroit or Toronto only in the winter, you'd wonder if the fan had any function at all. You could cut the wires and you'd hardly notice any difference even in city driving.
Steve
03-08-2007, 05:14 AM
#28
Mine IS adjustable
http://www.cardomain.com/ride/460473/12
No leaks. I just have to wait until the engine has cooled down to change the calibrated screw.
http://www.cardomain.com/ride/460473/12
No leaks. I just have to wait until the engine has cooled down to change the calibrated screw.
03-11-2007, 02:09 PM
#29
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BMW has been using an electronically controlled t stat for a few years. It has a regular t stat with a wax pellet and a heating coil which is supplied a pulse with modulated 5v controlled by the pcm to control temp. If the pcm says that the t stat should open at this temp under this condition it sends the required amount of voltage to heat up the element whic open the t stat to which ever temp desired. This def could be manually controlled and is def something worth looking into.
Alex
Alex
