Anyone have high water & oil temps on track?
06-22-2021, 04:31 PM
#1
Rennlist Member
Thread Starter
Anyone have high water & oil temps on track?
I'm trying to figure out why my oil temps and water temps are so high. I am racing a Clubsport, but same engine/cooling as the street GT4... I am familiar with the Clubsport/Cup Director Scholz saying 290F oil in the Clubsport is normal, but I've touched 300 and triggered "back off" warnings. Others racing against me had oil temps a solid 20 degrees cooler or more in the same conditions running (almost 😉 ) the same lap times. I'm wondering if anyone has encountered these high oil temps in their GT4s and if you found a cause. If you did, what was the fix?
06-22-2021, 10:13 PM
#2
Rennlist Member
06-23-2021, 08:14 AM
#3
Rennlist Member
Thread Starter
Try the CS subforum https://rennlist.com/forums/gt4-clubsport-262/
06-23-2021, 09:42 AM
#4
Rennlist Member
06-23-2021, 09:44 AM
#5
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Thread Starter
Appreciated, but I was intentional: the engine and cooling system on a CS is the same as a street GT4 and there are a lot more GT4s running around than CS', particularly GT4s with AC.
06-23-2021, 10:47 AM
#6
Does the CS have a sport mode button like the regular GT4? The “sport mode” on the regular GT4, aside from the auto-blips, significantly lowers the water and oil temps when active (opens thermostat to 3rd radiator).
06-23-2021, 11:01 AM
#7
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Last edited by DrJupeman; 06-23-2021 at 11:04 AM.
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06-23-2021, 11:12 AM
#8
I am unsure about the 981 CS, but I noticed that for the 718 CS in the parts manual that the thermostat is not a Motorsports specific part so I think it is the same as the street car. I expect the DME programming that controls the thermostat differs.
I used to own a street GT4 and tracked it at COTA at high ambient temps. We had to run windows down and I shut off the AC and used sport mode. never had an issue with oil/water temps. I may have some AIM data somewhere.
06-23-2021, 11:38 AM
#9
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Thread Starter
All 3 radiators are always active. The street car uses a "map controlled" thermostat. it uses a heating element to vary the "map". This has been documented several times here.
I am unsure about the 981 CS, but I noticed that for the 718 CS in the parts manual that the thermostat is not a Motorsports specific part so I think it is the same as the street car. I expect the DME programming that controls the thermostat differs.
I used to own a street GT4 and tracked it at COTA at high ambient temps. We had to run windows down and I shut off the AC and used sport mode. never had an issue with oil/water temps. I may have some AIM data somewhere.
I am unsure about the 981 CS, but I noticed that for the 718 CS in the parts manual that the thermostat is not a Motorsports specific part so I think it is the same as the street car. I expect the DME programming that controls the thermostat differs.
I used to own a street GT4 and tracked it at COTA at high ambient temps. We had to run windows down and I shut off the AC and used sport mode. never had an issue with oil/water temps. I may have some AIM data somewhere.
The Clubsport does use the map controlled thermostat (from the 981 CS technical manual):
"Map-controlled thermostat
The map-controlled thermostat is an insertion map-controlled thermostat with a heating element. The electric heating element of the map-controlled thermostat can be energised via the DME control unit. The flow of current through the heating element (electric resistor) causes it to heat up, which in turn influences the expansion element in the thermostat
and enables it to be opened. Actuation by the DME control unit is performed by means of pulse width modulation (between 2.5 and 97.5%), which means that the coolant temperature level can be continuously controlled.
The usual coolant temperature is 105 °C when the engine of the Cayman GT4 Clubsport is at operating temperature; it is reduced to 85 °C if necessary by opening (energising) the thermostat. This supports a performance-oriented driving style.
The coolant temperature is measured by the engine coolant temperature sensor and the radiator outlet coolant temperature sensor and transmitted to the DME control unit."
The map-controlled thermostat is an insertion map-controlled thermostat with a heating element. The electric heating element of the map-controlled thermostat can be energised via the DME control unit. The flow of current through the heating element (electric resistor) causes it to heat up, which in turn influences the expansion element in the thermostat
and enables it to be opened. Actuation by the DME control unit is performed by means of pulse width modulation (between 2.5 and 97.5%), which means that the coolant temperature level can be continuously controlled.
The usual coolant temperature is 105 °C when the engine of the Cayman GT4 Clubsport is at operating temperature; it is reduced to 85 °C if necessary by opening (energising) the thermostat. This supports a performance-oriented driving style.
The coolant temperature is measured by the engine coolant temperature sensor and the radiator outlet coolant temperature sensor and transmitted to the DME control unit."
06-23-2021, 01:14 PM
#10
Yes, I will need to find the references here, I didn't find anything about overheating in my initial searches. Are these thermostats prone to failure? Is that why there is discussion here? My question about AC is less about it being on/off and more about the condensers just getting in the way of needed air flow.
The Clubsport does use the map controlled thermostat (from the 981 CS technical manual):
The Clubsport does use the map controlled thermostat (from the 981 CS technical manual):
Presume you've checked the side inlet fan etc. Any ideas from PMNA?
06-23-2021, 01:31 PM
#11
I honestly think that's hot.
Is it the oil temperature high? Water temperature? Or both? How's the transmission temperature? I'm asking because all cooling is done by the same circuity: both the transmission and engine oil have a oil to coolant heat exchanger so you can start to isolate the issue (i.e. is it general cooling with the air to coolant radiator up front or isolated to a particular heat exchanger?)
Do you have datalogs to share to take a look?
Has the system ever been drained and refill: has it been properly bleed? Or have you tried to repeat whatever is the official coolant bleeding procedure i.e. could it be an air pocket stuck in the oil heat exchanger)?
Also the "Sport" button discussion is irrelevant as the ECU goes into "cooler mode" once it sees sustained engine load regardless of the sport mode setting. When you keep it in Sport Mode it's just always in cooler mode
I do believe as a side note that the CS has a slightly large oil heat exchanger as Rick proposed it as an upgrade when he built my 4.5, but he also said he never had particular issues with oil temperature so I declined the offer...
Is it the oil temperature high? Water temperature? Or both? How's the transmission temperature? I'm asking because all cooling is done by the same circuity: both the transmission and engine oil have a oil to coolant heat exchanger so you can start to isolate the issue (i.e. is it general cooling with the air to coolant radiator up front or isolated to a particular heat exchanger?)
Do you have datalogs to share to take a look?
Has the system ever been drained and refill: has it been properly bleed? Or have you tried to repeat whatever is the official coolant bleeding procedure i.e. could it be an air pocket stuck in the oil heat exchanger)?
Also the "Sport" button discussion is irrelevant as the ECU goes into "cooler mode" once it sees sustained engine load regardless of the sport mode setting. When you keep it in Sport Mode it's just always in cooler mode
I do believe as a side note that the CS has a slightly large oil heat exchanger as Rick proposed it as an upgrade when he built my 4.5, but he also said he never had particular issues with oil temperature so I declined the offer...
Last edited by Luca Paindelli; 06-23-2021 at 01:32 PM.
06-23-2021, 09:10 PM
#12
Racer
Yes, I will need to find the references here, I didn't find anything about overheating in my initial searches. Are these thermostats prone to failure? Is that why there is discussion here? My question about AC is less about it being on/off and more about the condensers just getting in the way of needed air flow.
The Clubsport does use the map controlled thermostat (from the 981 CS technical manual):
The Clubsport does use the map controlled thermostat (from the 981 CS technical manual):
If either or both the sensors are faulty then I would think that the DME will not open the cooling thermostat. Maybe that could be your problem....
06-24-2021, 09:03 AM
#15
There is a vacuum pump. Facing the engine it is on the lower right driven off the cam. per Porsche: The vacuum pump provides the vacuum for the brake booster and various vacuum valves (thermal management and induction system tuning flaps). For the Clubsports the pump is a maintenance item to be replaced every 5k km/ annually