Coolant temperature has never run so low.
#16
Rennlist Member
LTT will do nothing for folks that have high temps due to not being able to exchange the heat properly (low airflow across rads, faulty fans, faulty pump, debris, scale, etc.). But those having that issue will have it regardless of LTT or not. So if all else is equal, might as well do LTT.
That said, any temps below 95C, in my opinion, are pretty darn good, considering so many of us already have temp well above that number - ranging from 95-105 - so for those situations, LTT probably won't help all that much. Even folks who perform flushes, rad cleanings, water pump replacements and adding a 3rd rad don't always help either.
Moral of the story: do what can to reduce the temps, and a LTT is just one of many items that appears to work just as well as any other attempt. Combinations are often what's required for some to make a dent in high temps
That said, any temps below 95C, in my opinion, are pretty darn good, considering so many of us already have temp well above that number - ranging from 95-105 - so for those situations, LTT probably won't help all that much. Even folks who perform flushes, rad cleanings, water pump replacements and adding a 3rd rad don't always help either.
Moral of the story: do what can to reduce the temps, and a LTT is just one of many items that appears to work just as well as any other attempt. Combinations are often what's required for some to make a dent in high temps
#17
Drifting
I have a OBD2 scanner/guage installed and it gives digital readouts which is more precise then the dash guages. Before LTT the dash needle would sit between "8" and "0" (which is 186F on digital). Now it sits just a hair left of the line mark above the "8" (which is 174F on digital).
There was also mention of improving the coolant routing .
#18
Drifting
its 65 degrees F in the summer where OP lives... He is the last person in the continental US that needs a LTT unless he is tracking it. Hell Id think hed need a HTT and a sweater.
#19
Drifting
The reason for a LTT has little to do with ambient temperatures.The damage occurs before the OEM thermostat opens completely.And at 65 deg F ambient, the thermostat will eventually open - but too late.
The LTT does not fix the defects in the design of the M96 Cooling System. It treats the symptoms, not the cause.
Some expert M96 Forum Members have rectified some of these design defects in their rebuilt engines but I believe they still use an LTT.
#20
Rennlist Member
If the previous Threads on this subject are reviewed, the same misunderstandings recur.
The reason for a LTT has little to do with ambient temperatures.The damage occurs before the OEM thermostat opens completely.And at 65 deg F ambient, the thermostat will eventually open - but too late.
The LTT does not fix the defects in the design of the M96 Cooling System. It treats the symptoms, not the cause.
Some expert M96 Forum Members have rectified some of these design defects in their rebuilt engines but I believe they still use an LTT.
The reason for a LTT has little to do with ambient temperatures.The damage occurs before the OEM thermostat opens completely.And at 65 deg F ambient, the thermostat will eventually open - but too late.
The LTT does not fix the defects in the design of the M96 Cooling System. It treats the symptoms, not the cause.
Some expert M96 Forum Members have rectified some of these design defects in their rebuilt engines but I believe they still use an LTT.
I mean, when it's cold outside, say 32F, the water in the rads is so cold, even a very tiny amount of fluid that escapes the regular themostat - which starts to open at 194F - still seems very safe, even if there are localized hot spots that are over 20F hotter in the hottest parts of the block.
#21
Drifting
If you read the Threads I mentioned it may help.Jake and Ahsai were notable contributors.I was not.
The location of the cooling system design problem in the M96 is a a long way from the thermostat and the circulation in the problem area is sub-optimal. So the OEM thermostat does not respond soon enough to a localized spike in temperature - among other things.
The LTT addresses only the cooling system design problem inside the engine. That is partially why we are not discussing more powerful fans for more airflow and related modifications.
It is all in the previous Threads on this subject. These are not my ideas but yes , I did fit a LTT based on those discussions we had years ago when I rebuilt the engine.
The location of the cooling system design problem in the M96 is a a long way from the thermostat and the circulation in the problem area is sub-optimal. So the OEM thermostat does not respond soon enough to a localized spike in temperature - among other things.
The LTT addresses only the cooling system design problem inside the engine. That is partially why we are not discussing more powerful fans for more airflow and related modifications.
It is all in the previous Threads on this subject. These are not my ideas but yes , I did fit a LTT based on those discussions we had years ago when I rebuilt the engine.
#22
Race Director
Thread Starter
Who knew there was so much controversy with a thermostat change(upgrade)? I'll be wary of any future posts concerning our 996s, and God forbid we install a non Porsche OEM device in our aged 911s. Didn't realize such complications existed.
#23
Drifting
The explanation of why it is good is just M96 geekdom stuff. Some people don't care to follow the geek stuff. That's O.K. The important part is to preserve the M96 engines - the rest of the car should last for ever.
There is an interesting list of M96 preservation projects like the LTT elsewhere.
#24
Racer
Join Date: Dec 2016
Location: Eindhoven, the Netherlands
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With the normal thermostat it would run above 200F.
Now if you are living in a place where temperatures are normally higher (>90F?) I can imagine both thermostats quickly go to "fully open" state and you won't notice much of a difference except that the LTT just opens up earlier.
I anyway think as it is designed that it makes sense to have always the airco on so the fans are always running at low speed. This greatly helps to keep temperature at reasonable levels. Also with a LTT without those fans running in city traffic temperatures will run up to 220F before the fans kick in.
#25
Drifting
If you think the temperature setting for switching the cooling fans on is an issue, I'll remind you of these ideas:
https://rennlist.com/forums/996-foru...-fan-hack.html
or
https://www.renntech.org/forums/topi.../?_fromLogin=1
http://pedrosboard.com/read.php?7,4382,4424
https://rennlist.com/forums/996-foru...-fan-hack.html
or
https://www.renntech.org/forums/topi.../?_fromLogin=1
http://pedrosboard.com/read.php?7,4382,4424
#26
Addict
Rennlist Member
Rennlist Member
#27
Drifting
Paul gets it.
The point of the LTT is not to make the temp gauge read lower - as discussed in previous threads.
The CTS(for the temp gauge) is located(on the side of the console) quite far in the coolant circulation routing from the hot-spots of the engine so the gauge may be misleading in that regard.
See post 369 Here for a color diagram of the coolant circulation and helpful comments by Jake:
https://rennlist.com/forums/996-foru...engine-25.html
The point of the LTT is not to make the temp gauge read lower - as discussed in previous threads.
The CTS(for the temp gauge) is located(on the side of the console) quite far in the coolant circulation routing from the hot-spots of the engine so the gauge may be misleading in that regard.
See post 369 Here for a color diagram of the coolant circulation and helpful comments by Jake:
https://rennlist.com/forums/996-foru...engine-25.html
Last edited by Schnell Gelb; 07-17-2017 at 12:59 PM.
#28
Racer
Join Date: Dec 2016
Location: Eindhoven, the Netherlands
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Paul gets it.
The point of the LTT is not to make the temp gauge read lower - as discussed in previous threads.
The CTS(for the temp gauge) is located(on the side of the console) quite far in the coolant circulation routing from the hot-spots of the engine so the gauge may be misleading in that regard.
The point of the LTT is not to make the temp gauge read lower - as discussed in previous threads.
The CTS(for the temp gauge) is located(on the side of the console) quite far in the coolant circulation routing from the hot-spots of the engine so the gauge may be misleading in that regard.
However, in not too high ambient temperatures while driving I do see an effect that the average temperature is lower then with the normal thermostat. The LTT is fully opened at 82C (180F); if the temperature drops below 82C the LTT will react by closing a bit. Then the temperature goes up again to 82C etc. So it maintains the temperature at the fully open stage. As intended. Once the heat produced by the engine is above the capacity of the cooling system with LTT fully open the temperature starts to creep up until it finds a new balance.
With the standard thermostat the engine will find its balance at a higher point. IIRC it is only fully open at 99C (210F) but normally it does not reach that point when driving normally. So the coolant flow is restricted by the thermostat during normal driving.
My car is running with the original rads but new airco condensors. Maybe they let through significant more air then old ones? All the rest of the cooling system is in good condition including a new waterpump.
Last edited by Volkert; 07-17-2017 at 03:37 AM. Reason: Typos
#29
The steady state running is not the issue. Might be even that in the conditions you describe your engine will be running too cold or too much warm/cold/warm fluctuations. Especially in winter with colder ambient temps. But probably that is less problematic then running too hot initially.
The LTT its main function is to open quick enough after a cold start.
The LTT its main function is to open quick enough after a cold start.
#30
Former Vendor
The low temp unit opens sooner, and becomes fully open faster. The fully open faster part is why it can reduce operating temperatures, as it creates more cooling volume, being fully open.
These have been tested in temperatures below -20F before they were ever sold to the public, over a decade ago. The units are proven- every engine I build receives one. This includes units fitted to vehicles with my engine in Canada. About 1/3 of our work is Canadian, about 1/2 of those are C4s and driven year round.
The stock temperature thermostat had considerations when meeting the tests set forth by Federal Emissions Regulations. The engine needed the extra cooling system temperature to help keep the engine hotter for the "shed test" portion of the certifications.
Lots goes into these vehicles aside from what works best for the engine.
These have been tested in temperatures below -20F before they were ever sold to the public, over a decade ago. The units are proven- every engine I build receives one. This includes units fitted to vehicles with my engine in Canada. About 1/3 of our work is Canadian, about 1/2 of those are C4s and driven year round.
The stock temperature thermostat had considerations when meeting the tests set forth by Federal Emissions Regulations. The engine needed the extra cooling system temperature to help keep the engine hotter for the "shed test" portion of the certifications.
Lots goes into these vehicles aside from what works best for the engine.