2000StreetRod
Moderator Emeritus
- Joined
- May 26, 2009
- Messages
- 10,597
- Reaction score
- 334
- City, State
- Greenville, SC
- Year, Model & Trim Level
- 00 Sport FI, 03 Ltd V8
electric fan temp setting?
Al Franklin (aldive) promoted the use of an electric motor driven radiator cooling fan to improve fuel economy and performance. According to his thread he adjusted the temperature control to maintain an engine coolant temperature of 192 deg F with an installed 195 degree thermostat. I think the fan was wired to be on whenever the A/C compressor clutch was engaged. He stated that the fan seemed to run continuously probably because in Florida the A/C is normally running. He had no way to monitor the radiator temperature but could monitor the ECT. I noticed that his transmission (5R55E) temperature would sometimes reach 200 deg F.
It occurred to me that there is a trade off between fuel economy/performance gains with an electric fan and higher transmission temperatures. Available documentation states that the 5R55E external cooling loop opens when the ATF in the torque converter reaches 150 deg F. I assume some engineering was performed to decide that 150 deg is the optimum operating temperature. If the electric fan does not keep the temperature in the radiator internal ATF cooler less than 150 degrees then the ATF will be heated rather than cooled when passing thru the radiator. There will be some cooling provided by the auxiliary ATF cooler but air to air coolers are much less efficient than fluid to air coolers.
When installing custom radiator cooling, consideration should be given to the radiator coolant temperature (RCT) and its impact on ATF temperature. I may search for a way to monitor RCT while driving.
Al Franklin (aldive) promoted the use of an electric motor driven radiator cooling fan to improve fuel economy and performance. According to his thread he adjusted the temperature control to maintain an engine coolant temperature of 192 deg F with an installed 195 degree thermostat. I think the fan was wired to be on whenever the A/C compressor clutch was engaged. He stated that the fan seemed to run continuously probably because in Florida the A/C is normally running. He had no way to monitor the radiator temperature but could monitor the ECT. I noticed that his transmission (5R55E) temperature would sometimes reach 200 deg F.
It occurred to me that there is a trade off between fuel economy/performance gains with an electric fan and higher transmission temperatures. Available documentation states that the 5R55E external cooling loop opens when the ATF in the torque converter reaches 150 deg F. I assume some engineering was performed to decide that 150 deg is the optimum operating temperature. If the electric fan does not keep the temperature in the radiator internal ATF cooler less than 150 degrees then the ATF will be heated rather than cooled when passing thru the radiator. There will be some cooling provided by the auxiliary ATF cooler but air to air coolers are much less efficient than fluid to air coolers.
When installing custom radiator cooling, consideration should be given to the radiator coolant temperature (RCT) and its impact on ATF temperature. I may search for a way to monitor RCT while driving.