jaetee

So, apparently Porsche recommends a 180 degree thermostat for the 3.4... Is that with Central/northern European climates in mind?

Engine is out getting IMSB, clutch and such done... should I put in a 180 or 160 degree thermostat?

kromdom

what did your shop/mechanic recommend?

Slakker

Definitely a good upgrade. These engines don't do a good job of cooling evenly. So it's the hot spots that don't show up on the coolant temp guage that you are worried about.

From Pelican:
http://www.pelicanparts.com/techarti...eplacement.htm

The factory thermostat starts to open at about 187 degrees F (86 degrees C) and only fully opens at almost 210 degrees F (99 degrees C). This means that the engine needs to get very hot before it starts sending its coolant to the front radiators. For this reason, I recommend installing a low-temperature thermostat in place of the factory one. LN Engineering has developed a thermostat that starts opening at 160 degrees F (71 degrees C) and is fully open at about 180 degrees F (82 degrees C). Lower coolant temperatures translate into lower oil temperatures, and the dyno tests that LN Engineering has performed on the cars with the low-temp thermostat installed have revealed a small increase in horsepower (typically about 5 horsepower). It is my guess that Porsche designed the thermostat to open a bit later in order to help the cars run a bit hotter, which typically helps with emissions testing and the burning off of water out of the oil, which can then lead to longer oil change intervals. Installing the low-temp thermostat is a smart idea for engine longevity--it's available for about $175 from PelicanParts.com.

Macster

Use the factory T-stat. If you are worried about engine cooling install a 3rd radiator.

Frankly, it doesn't get that hot in Florida. Up until a day or two ago it had reached 100F 6 or 7 days a row here where live in CA. Both cars have the factory T-stat and both run just fine.

Both cars have been in much higher ambient temperatures -- from 116F to 119F -- and have not had any problems. That's with over 303K miles on the Boxster and over 145K miles on the Turbo.

Remember the oil, 0w-40 or 5w-40, the "40" is the oil's viscosity rating at 212F so the oil is designed to run at what we might consider "hot" but not to the oil.

kromdom

as soon as the rest of RL wakes up, stand by for a healthy debate about this old/recurring topic

DBJoe996

Oh yeah! Almost as good a debate as what type/weight oil should I use...

perryinva

I installed the 160F Tstat. My Porsche mechanic strongly recommends it on the 996 base don his experience. They can be found for WAY less than $175. I think with the housing I paid around $80. IIRC, the 997 cars have 160F tstats?

Ahsai

Read this document and decide it for yourself. This is the most comprehensive analysis by engineers to date that's in publication I've seen.

http://www.hartech.org/images/downlo...0(interim).pdf

I'm tired of explaining it.

jaetee

I found a shiny new 160 detree tstat not terribly far away, it's en route to the shop.

My mechanic said that in FL climate, going this route will help reduce chance of heat soak. Sounds pretty much on par with most of what I'm seeing in these responses. Thanks for posting the literature links. Very interesting reading.

Ahsai

I think we should put that link as a sticky.

kromdom

perryinva

I agree. Especially since on most cars, the thermostat is on the hot side exiting the engine, to the radiator. On the Porsche it is on the cold side, leaving the radiator, mixed with the engine discharge that circulates through the heater core. Makes no engineering sense that the same high temp (185F) is correct for the hot side and the cold side. Read that Hartech article many years ago, and convinced me for sure.

Ahsai

One of the great things about that article is it also explains the corresponding design in the air-cooled and even 944 engines and how they are different than the m96 and why these problems are only unique to the m96 series.

Even with the m96, 3.4 and 3.6 are very different too and it explains why the 3.6 is more prone to scoring.

It's really great that they share what they found and their methods to support their theories, which I must say make a lot of sense when you put everything together.

Ben Z

I have an RN replacement engine in mine. Those come with the LN lower temp thermostat (as well as Nickies cylinder liners and some other improvements). Previously I was sure a lower temp thermostat would not affect the upper operating temp once the stat was fully open, but I have noticed it's a bit lower according to the guages. Although I can't say for certain it's due to the thermostat vs some other modification(s).

perryinva

In an absolute sense, you are correct. A full open 165F Tstat passes the exact same amount of coolant as a 185F Tstat. The problem is that under normal driving conditions, the 165F is full open and the 185F is not. SO when you decide to push the engine the hot spots that may (or may not) exist in ones particular engine example, will get too hot before the Tstat sees the increase in temp, and enable potential scoring. The 165F is already at full open and full flow and can prevent the hotspot from ever occurring. When I switched to the 165F Tstat at around 40k miles, I noticed immediately that the indicated temperature on the gauge was a full roughly 12 degrees cooler just cruising down the interstate. During spirited driving it would rise less than it did with the older tstat, but more importantly, once back to normal driving, the 165F unit quickly brought the temp back to it's previous level, indicating that the temperature was under control. The old one used to stay elevated, indicating the cooling rate at the tstats current position was significantly less than the 165F. It was not equally full open. For a few bucks, it is one less contributing factor I have to worry about.