low temp thermostat

[sambb]

When I do my radiator, I'm going to fit the 82 degree (rather than 90 degree stock) thermostat. My question relates to the interplay of this thermostat with the fan switch. There is a 91/100 degree stock one and an aftermarket 85/90 degree one.
The guys at Awesome GTi said that on our Polo the fan control actually looks at the engine temp and the radiator temp as seen by the fan switch.
So to my mind if I change to the lower temp thermostat, I'd pretty much have to be running the lower temp radiator fan switch too wouldn't I so that the two marry up?
anyone gone down this path??

any advice welcome as I need to get onto ordering bits before my radiator has a haemorrhage

sam

[Eddy]

Hoyhoy.

Interesting subject Sam.

[louis19]

I believe Sean's car runs a 71C thermostat. Might be worth a chat with him or Gav as he might know a bit more info on the subject

[sambb]

Just got a return email from Awesome. He thought that running the one step cooler thermostat would be effective at keeping the engine temps more consistent with the standard fan switch retained. I'll have to clarify again but he seemed to intimate that doing the switch too might be a bridge too far and cause the ECU to enrichen the fuel trims.
All I want is to smooth out any big temp differentials between the engine and radiator and the existing thermostat doing big temp dumps in and out of the engine. The whole sequence of events at hilllclimbs absolutely cooks the engine - sitting in the line, launching hot and then having to shut it down hot with no cool down possible. I've learnt a few tricks like turning the A/C on to keep the radiator fans running which may help but I'm afraid I'm going to warp/blow something that I can't afford to fix. I'm not keen on any detrimental effects on trims though

[Martin]

When you say the track guys, you mean hill climbs?
At race tracks we have great airflow through the radiator

I do agree with the commuter cooling design, and combined with hill climbs you're in a tricky situation
The conventional approach to not being able to manage engine/water temperature is to increase the capacity of the cooling system
Is there a larger radiator available for your car?
It would be the single most effective change you can make

Water injection into the inlet and over the radiator would be worth looking into
(MCM did a crude water over the radiator setup and got positive benefits)

Will a 70 degree thermostat solve the problem, starting from a lower base?
It's possible it will have limited effect
Without adequate airflow through the radiator (short hill climb),
in a car that is struggling to control temperature
does it mater what temperature the thermostat opens?
I mean, once the temperature goes north, you're back to the original problem
Maybe your second run will be cooler, but eventually the fundamental problem will occur

The oil cooler will only cool oil - not the engine - and only with airflow

By all means use the +30% thermostat - they will work fine
My only point was ignore the +30% claim
(I think I have one in my Pulsar race car! LOL )

[h100vw]

The oil cooler will only cool oil - not the engine - and only with airflow

The current oil cooling is assisted by the heat exchanger, that is part of the oil filter mount. The purpose being that the heat in the water warms the oil as the engine heats up from a cold start. Perfect logic for colder climates than Australia.

When the oil goes over 90degrees the heat transfer is in the opposite direction. Heat transfers to the coolant.

If an external oil cooler is fitted as Eddy has, including a thermostat, then much of the thermal load of cooling the oil with the coolant is removed. Consequently, the water temps will be way down. Far enough that it may be possible to run a smaller radiator.

Especially true if the heat exchanger is deleted.

[Martin]

The current oil cooling is assisted by the heat exchanger, that is part of the oil filter mount. The purpose being that the heat in the water warms the oil as the engine heats up from a cold start. Perfect logic for colder climates than Australia.

Good point

I deleted that item in my Nissan 350Z

[Martin]

All I want is to smooth out any big temp differentials between the engine and radiator and the existing thermostat doing big temp dumps in and out of the engine.

This won't be happening - the thermostat opens and closes slowly

[sambb]

Yeah I'm just not sure how it will play out if I run the cooler thermostat but retain the standard fan switch. Awesome thought that the ECU would probably prioritise the engine temp sensor reading and override the fan control even though the switch should theoretically only turn on at 100 degrees and back off at 91. I'd just hate for it to not work out that way and the fans end up hardly being on.
I was surprised that the our fan switch could input to the ECU but apparently its not a dumb/local switch like in the golf mk3/4 & bora. Actually after re reading their return email I'm going to have to get clarification on whether it may be more than just incompatible with the fan control system - I'll have to check if the 85/90 fan switch will even fit!

[Stuwey]

Why do you want it to run cooler?