Macster

And subjects the circulating coolant to cooling. These engines already run pretty cool under moderate use especially if the weather's a bit cool. A low temp T-stat must means the engine's running "cold" most of the time.

Macster

Your car will be fine. While temps creep up in traffic as long as the cooling system is pressure tight and the radiator fans are working properly the engine coolant temperature will be just fine. It may rise some but the engine can easily tolerate the bit of increase in temperature.

Be sure to keep the trash cleaned out of the radiator ducts. While my experience is this does not affect the cooling the trash can lead to corrosion and premature failure of the radiator or A/C condenser.

As I have mentioned before with my Boxster with just 2 radiators I encountered 116F heat in southern AZ one summer on a drive through the southwest area and while the coolant temperature climbed to 226F and stayed there -- even with both radiator fans running at high speed -- the engine was just fine. And with (fresh) 0w-40 oil in the engine, too.

Because the car was rather new to me way back then when I got home I spoke to the SM about the elevated coolant temperature, and asked was it a sign of a problem, and he contacted the factory with all the telemetry I had gathered. The word from the factory was as long as there was no warning light on there was no problem.

That was over 275K miles ago and the engine's just fine and currently has 308K miles on it.

More recently my 996 Turbo lost a radiator fan in 90F+ heat (this in the Fresno CA area) and I didn't even know it until I got out of the car while the engine was idling to get something from the trunk and could tell by the lack of noise a radiator fan was not running. Feeling about and sure enough no air flowing through one radiator fan while the other side was blowing a mini hurricane. (A fan motor shaft had snapped was the diagnosis when I had this lookedi into after I drove the car around 150 miles to home.)

Even with just one radiator fan the coolant temperature was just fine and even the A/C worked with no problem.

Porsche does fit a 3rd radiator in some cars. Tip or PDK equipped cars get a 3rd radiator. So too do the Turbo models. But if your car came from the factory with 2 radiators it can handle anything Mother Nature can throw at it, even 116F (or higher: The Turbo has been in 119F) summer heat.

slicky rick

I would go wi a third rad. Looks good, added safety, cheap. How can you go wrong with that. I think it's a no brainier mod for me. You may not need it but an engine that has been taken cared of relative to heat tends to last longer. Agree with those who posted thermostat stays the same . It will heat up as fast and open when the temp is reached.

Flat6 Innovations

The low temp unit just doesn't start to open sooner, but it is also fully open sooner as well. This is often not considered by folks, and it is the most important aspect of the development. This is why every engine I have built since I developed this in 2007 has used one. The earlier full opening increases coolant volume to the engine. Thats the key.

beetleything

Yep - i get it. Better to have the flow going on these cars from what i have read - the passage ways are narrow thru the block and spikes in heat can happen and thus bore scoring and other calamities....

It seems you either get the idea of the LTT or you do not.

How you could think it makes your engine run at a lower operating temperature once it has been running 10 - 15 mins and is fully operational after initial warm up, even in cooler climates, is beyond me - but there you go....


Que Sera....

Bruce In Philly

FWIW, I spoke directly to a guy in Ohio that preps these engines for racing/hard track use and he swears by a lower temp thermostat in a 997.1, actually all models with this engine platform. (I spoke to him a few years ago before the .2/9A1 was out).

There is a question of the need for the 997.2.... some say yes, others say the 9A1 platform is robust enough that you don't need it....... I am keeping my eye out for more data here and I am leaning to installing one for my 2009..... when I need a more major service done such as a new water pump.

Overall, the issue as I understand it, is flow, not how soon it opens.

Another data point from my engineer friend at Ford.... I need to give him a ring on this one again..... 180 degrees is some magical number for temperature that balances part expansion, engine efficiency (fuel burning), and emissions. If you can make your engine run at a lower temp through a combo of higher flow, more radiator area, lower ambient temps etc. etc., you are costing gas mileage...... I need to confirm all of this again..... Anyone with more data?

BTW: I always try to get information from "reliable" sources, but even then, I am always amazed at how these experts can disagree.....

Peace
Bruce in Philly

utkinpol

i think it is a murky territory as i have heard exactly opposite from an another racing engine builder who told me that you need to keep block as original temperature level and not to deviate it down to ensure all proper gaps.

anyway, my motor is now close to 80k miles with all original internals, knock on wood.

177mph

The 3rd radiator is NOT a must for any 997.

It depends on your car, your intended use, and your location.

stronbl

Just as a point of reference and a bit of history, when Porsche initially brought out the revised X51 package for 997-2 in late 2009, they did not include the 3rd radiator. There was some question initially if a 3rd radiator was helpful with the PDK option - the concern was it may run a bit too cool under normal driving conditions. A 3rd radiator was available to purchase separately though. With the 997-2 GTS, Porsche had decided to include the 3rd radiator as part of the GTS package (also included the X51 option package). The 997-2 GTS also had a slightly revised PDK software setup.

My 2010 997-2 has the X51 option but not the 3rd radiator. After a couple track seasons in CA, I added the 3rd radiator as my max oil temp was approaching >250degF at times. By the way, the front bumper even had the template cut-outs needed for the 3rd radiator on my 2010 car. I have found that my oil temp from oil gauge has been about 15-20 degF lower for normal around town driving post 3rd radiator.

Derek Zoolander

I have a brand new in box OEM 3rd radiator kit for sale. I bought it from Suncoast with the intention of installing it when I did my water pump, but decided against it. If anyone local to DC/VA/MD/PA/NJ is interested, I'll save you shipping cost by picking it up.

Giorginetto

Silly question but don't all 996/997 Tiptronic have a 3rd radiator ?

lurchphil

I added the third radiator to my 2008 911S and then to my 2012 911S. Probably unnecessary but a little added cooling capacity is cheaper than visiting a shrink. I installed the 160 degree thermostat in the 2008 but I couldn't really tell much of a difference. Keeping the radiators clean is probably more important. Removing the front bumper is relatively easy and gives the access to do the job properly. An 8 gallon cooling system is probably adequate for all of us with the exception of those who live in very hot climates and/or do track time. I highly recommend the Zunnsport grills. 10 minute install. They keep rocks and other flying objects from impacting your A/C and radiator components.

captainbaker

Oh my......what is better for the common man? Third Rad, lower temp thermostat or both?

Im actually flummoxed as both are cheap and easy to install.

Lower engine temps is better for the engines health over time is my motto.

RennPart

as promised, in stock ready for immediate shipment

https://rennpart.com/product/third-radiator-kit/

Iceter

Well, you got one thing right, you either get it or you don't.

I can't speak for others in the thread, but I never said a LTT lowers operating temperature. In fact, I correctly pointed out that the upper temperature of your coolant is dictated by the cooling system as a whole and is unaffected by your Tstat.

An LTT does extend warm-up time, which extends the time that your car runs at a suboptimal temperature. You, on the other hand, said a LTT shortens warm-up time. This defies some pretty well-established laws of thermodynamics.

If you think that a LTT prevents temperature spikes in the block, consider that a fully open stock Tstat and a fully open LTT flow the same amount of the same temperature coolant to the same places in the block. A LTT doesn't do anything to ameliorate a poor design that doesn't flow enough coolant to one area of the block or heads. If Porsche designed the block in a way that doesn't get enough coolant to one of the cylinders, that will always be the case, no matter what Tstat you use.

If you want to increase engine wear, one of the best ways to do it is to lengthen the time it takes to warm up your engine. For an extra couple of minutes on every start up, you'll get colder oil temperatures, increased plug, sensor and cat fouling and a richer air/fuel mix that is great for washing away that cold lubricating oil. Sounds great to me.

I can't argue against a line of reasoning that doesn't make sense.

http://auto.howstuffworks.com/question248.htm