Quote:
|
Originally Posted by cnavarro
We ran the 160F low temp thermostat all winter in my Boxster with no ill effect as to warm-up. You receive the same amount of heat and just as fast as the stock 186F thermostat, even in sub zero weather.
If you're stuck in traffic or low speed operation, the coolant temp will creep up as with the stock thermostat until the fans go. Once in motion, the coolant temp will drop quickly. In the winter, it would stabilize at 172F. Last week with ambient air temp approaching 80F, it was hovering around 176F.
One of the main reasons to run the low temp t-stat is to lower the oil temperatures, which already run too hot for my liking.
As a side note, I had an owner of a GT3 call and want a low temp thermostat. I asked what he runs for coolant temps and he said it stabilizes at 176F in mid-70s ambient air temps, so it would appear Porsche already has a low temp t-stat standard in the gt3, gt2, and turbo. He also said his oil temps ran about 190F, showing an oil temp 10-15F above coolant temp, which I have observed before in cars with laminar flow oil to water coolers, like our cars have.
|
Good info. Charles thanks!
I'm sometimes a little slow on the up-take, so let me ask some additional questions.
Essentially, the importance of what you are describing isn't the opening temperature of the T'stat, but the closing temp?
IIRC, pretty much all T'stats work the same way: a cylinder w/ a wax pellet on the engine side of the T'stat has a piston on it attached by a rod to the valve. When the heat from the engine heats the wax pellet, it expands (both from the heat and from the phase change of a solid to a liquid - liquids are more voluminous than a solid of equal mass), pushing the piston and opening the valve allowing coolant to now flow to the radiator. Different opening temps are achieved by differing wax compounds and/or return spring pressure.
But, once open, they're all the same.
What you're saying (if I read you correctly) is that the temperature sensitivity is such that even a 4 degree difference (180° vs your observed 176°) is sufficient for the wax to start to contract and allow the return spring pressure to overcome the piston pressure and close (or partially close) the valve and reduce coolant flow to the radiators? Are they that sensitive?
And, if so, once closed and the temp rises 4° (back to 180°), the valve reopens, and the process starts all over again. To me then, it seems that the 180° T'stat is just more cyclic than the 160° one.
But does that really significantly effect overall operating temp? And, if so, by how much - what is the avg. running temp using the 180° T'stat? And what does that temp difference affect adversely? I mean as far as I can see, we're only talking about 4° here.
If we're looking to decrease the overall operating temp as a goal, would it be more effective (albeit more costly) to increase the capacity of the system by adding say the center radiator on non-S cars? Or by taking the oil cooling out of the loop and routing the oil to a conventional oil-to-air cooler? TIA
