Can the 911 run too cold?

[RichHawk]

I have two thermostats, one opens a lot earlier than the other.

Probably 160 deg starts opening on one, and it's fully open at 180 deg.

The other doesn't start opening until 180 deg

Should I install the cool opening one or warm opening one?

Different Temperature range thermostats?

Richard

[safe]

176f (80 c) and above is considered operating temperature. All engines, not only air cooled Porsches, tries to regulate the temperature at around 190f.

My engine I runs with an aftermarket EFI and doesn't want to work at 100% until it reaches at least 160f. Under that and I have to compensate with more fuel.

[RichHawk]

We need to standardize on Oil Temperature as the variable under discussion, as it is the thing the Thermostat can effect.

I'm running the stock Motronics injection system, Which I ASS-ume has the ability to measure outside air temp, as well as engine temp, and make mapping corrections.

With this base line, and knowing that the two thermostats in question differ by about 20 degrees opening temperature, which is the lesser of the two evils?

1) run the cold thermostat: Take longer to come up to proper operating temp. and potentially worry about condensation buildup in the crankcase. (Is condensation an actual problem? Does anyone have an actual verified case if it?)

2) run the Hotter 180 deg thermostat: Have the engine oil at nearly 220deg (100c) before the thermostat is fully open and the engine mounted oil cooler is fully used.

Richard

[stownsen914]

Running around with the oil < 180 degrees all the time probably wouldn't be good for the engine. Condensation wouldn't ever burn off (sorry no documentation on this) properly.

For the hotter one, does it really not open completely until 220F? Even if so, I might opt for the hotter thermostat. Assuming that this car sees primarily street use, I'm thinking that running around too cool all the time would be worse than running closer to 220F on a regular basis. Keep in mind that some additional cooling happens as soon as the thermostat starts to open, so even with the hotter thermostat I wouldn't assume that your oil temp will always reach 220.

Others' opinions may vary

Scott

[RichHawk]

So here's the converse opinion. (I'm being devil's advocate, and really looking for the "right" opinion chime in if you have some experience. So far we are lacking any.)

Running the cooler thermostat may slow the condensation vaporization out of the oil. But you don't have to have 220 deg to make water vaporize off. If that were the case the water sitting in a glass my kitchen table would never evaporate. But we know it does. And we know the warmer something is the quicker water will evaporate off. Will condensation burn out of 160 deg oil? I'm confident it will. It might take 5 minutes rather than 3 minutes, but it's going to vaporize.

So baring any definitive data, or hell even any first hand opinions, I'm going to run the cooler thermostat.

Richard

[longhornchris04]

Assuming you aren't starting, running it just to say 160 - 180 then shutting down, then you should be able to "burn out" the water.

Remember, the oil temp is the oil temp at the sensor, not the peak peak oil temp. If you run the engine for a reasonable amount of time (10+Q... I have no idea what "reasonable" is) then you should cook off the oil.

You should be ok with the cooler thermostat, but I would avoid the short trips (well duh) and just make sure the oil gets to the operating temp and stays there for ~15-20min to make sure the water cooks out.