Opinions: Lowering Temps - 3rd Radiator? Clean it?
07-07-2022 | 08:05 PM
#31
Rennlist Member
Joined: Sep 2019
Posts: 822
Likes: 474
From: Ventura CA
You are good to go. Maybe YOU "need" a third radiator , but the car does not and it has spoken with results that are well within the original design parameters. Leave it alone and both of you will be happy. With many years as a professional engineer in air conditioning systems and designer of heat transfer systems and heat exchangers just like the radiators and condensers that are used on automobiles, we sometimes get it right. Prairiedawg is a technician in the A/C world so he sees all the real world scenarios of stuff that went wrong and he has to fix it.
The cooling system is not an uncontrolled system. The heat rejection load of the engine is well known and documented by the design engineers at Porsche for every engine speed and power output. The cooling system is designed to carry this load all the way up to the max outside air temperature that the car will be operatered in. This may be 125 Degrees F. but I am not sure At idle engine speeds the heat load is low but the airflow thru the heat exchangers is also low ,hence forced fan cooling. At high power output (going fast) the heat load is greater but the forced convection of air flow thru the radiators is enough to keep the engine within operating parameters and will achieve a steady state temperature. In design of the cooling system, we acknowledge that dirt and crude inside the water side of the radiator will degrade performance over time. This is called "fouling factor" and the whole system is "overdesigned " by 10 to 20% to address this. In you case with the dirt and flattened fins, you were up to 40% loss.
The heat load of the PDK transmission (a big number) was enough to overwhelm the system at max conditions so the addition of the third radiator was added (late) to bring things back to steady state conditions. Stick shift cars don't need it and did not get it.
The cooling system is not an uncontrolled system. The heat rejection load of the engine is well known and documented by the design engineers at Porsche for every engine speed and power output. The cooling system is designed to carry this load all the way up to the max outside air temperature that the car will be operatered in. This may be 125 Degrees F. but I am not sure At idle engine speeds the heat load is low but the airflow thru the heat exchangers is also low ,hence forced fan cooling. At high power output (going fast) the heat load is greater but the forced convection of air flow thru the radiators is enough to keep the engine within operating parameters and will achieve a steady state temperature. In design of the cooling system, we acknowledge that dirt and crude inside the water side of the radiator will degrade performance over time. This is called "fouling factor" and the whole system is "overdesigned " by 10 to 20% to address this. In you case with the dirt and flattened fins, you were up to 40% loss.
The heat load of the PDK transmission (a big number) was enough to overwhelm the system at max conditions so the addition of the third radiator was added (late) to bring things back to steady state conditions. Stick shift cars don't need it and did not get it.
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07-11-2022 | 07:58 PM
#33
Rennlist Member
Joined: Oct 2014
Posts: 5,279
Likes: 1,292
FWIW I don't know what an over lubricated bearing looks like. Also, assuming it is the thermostat's job to control engine temperature, I'm not sure what too much cooling capacity in the form of an extra radiator looks like either.
