Lower Temp Thermostat
01-11-2015, 06:16 PM
#46
Burning Brakes
Macster,
If I agreed with all of what you said, unfortunately, we'd both be wrong.
You didn't answer my question about personal experience with Thermostats?
I have personally carried out the development of the LN Tstat, starting prior to 2007. In that period of time we have ran street engines with stock thermostats on the street and then exclusively on the track, then torn them down, measure taper and ovality, then installed a Lo temp unit and done the same thing. I have also swapped the roles and started a fresh engine off with a low temp stat, then swapped it later for a stock one, and watched the values both ways.
Any engine I create will have a Lo temp LN unit (not any other) and will get that from day one, if it is removed, my warranty is void. Thats how strongly I feel, based on direct experience. Lots of the hot weather test work was done here, and we ran an engine for as much as 160 hours straight without shutting it down. The cold weather testing was done at LN, and Charles and I tackled it together, most of that was done in -10F temperatures, with some done at -27. Last year we took advantage of the super cold weather to prove the Cayenne low temp Tstat.
That even goes for my customer in Russia, who has been running one since 2009.
Lots of reasons why the Tstat is set the way it is at the factory, primarily for the hot restart emissions testing, as its very important to keep the coolant hot for as long as possible. This is why aircooled engines failed so horribly, because they cooled down too fast when shut down (after a brief temp spike just after shut down). My hypothesis is this period after shut down, is when lots of deformation issues occur.
Nothing has proven to keep cylinders straight and more round than reducing coolant operating temps by a few degrees. This is especially true for cylinders 2 and 5, where they are situated between cylinders, and see the hottest coolant, for the longest period of time.
Its not just the overall temperature of a Tstat that matters when developing a better mouse trap. How much the unit will bypass when cold, how soon it starts to open, and the temperature that it is fully open are all what required special attention.
I see factory engines with bores .010" oval by 100K miles, which is ridiculous. This is our normal findings, as Charles measures every block that goes to LN before machining, and notes mileage. Generally bore will gain .001 ovality and .0005" taper per 10K miles.
When developing the low temp Tstat we faced lots of ridicule, but we've never seen someone remove the low temp unit and go back the other way. The general consensus of "if the factory didn't do it" is the biggest wall that a developer has to face. Quite frankly, I don't give a damn what the factory did, or why they did it.
Yes, coolant temp matters in regard to enrichment, as well.. There's a point where the CLT can make serious power, I have observed a 15 degree window where the engine makes the most power, and coincidentally, the engine moves to a different fuel map for this window. You learn this from having to chase maps while developing ECU flashes from scratch. When Beth was Land Speed Racing her 996 I would work very hard to keep the car at an exact temp, around 4-6 degrees below the sweet spot while we were in line to make her run. That meant foreign the car up, shutting it off and doing what we could to keep the engine where I wanted it to be. When she'd launch, the entire run would usually complete before the temp was out of the sweet spot, netting the most power. It took me about 6 trips to the track to figure this out, and hours of studying datalogger and dyno plots.
All that said, still trying to be on my behavior around here and trying to help. Its kind of hard to be neutral when you developed the part that people are slamming; even though they have zero direct experience with it. This Tstat was another product that was developed first for my engine program, then began to be sold individually.
If I agreed with all of what you said, unfortunately, we'd both be wrong.
You didn't answer my question about personal experience with Thermostats?
I have personally carried out the development of the LN Tstat, starting prior to 2007. In that period of time we have ran street engines with stock thermostats on the street and then exclusively on the track, then torn them down, measure taper and ovality, then installed a Lo temp unit and done the same thing. I have also swapped the roles and started a fresh engine off with a low temp stat, then swapped it later for a stock one, and watched the values both ways.
Any engine I create will have a Lo temp LN unit (not any other) and will get that from day one, if it is removed, my warranty is void. Thats how strongly I feel, based on direct experience. Lots of the hot weather test work was done here, and we ran an engine for as much as 160 hours straight without shutting it down. The cold weather testing was done at LN, and Charles and I tackled it together, most of that was done in -10F temperatures, with some done at -27. Last year we took advantage of the super cold weather to prove the Cayenne low temp Tstat.
That even goes for my customer in Russia, who has been running one since 2009.
Lots of reasons why the Tstat is set the way it is at the factory, primarily for the hot restart emissions testing, as its very important to keep the coolant hot for as long as possible. This is why aircooled engines failed so horribly, because they cooled down too fast when shut down (after a brief temp spike just after shut down). My hypothesis is this period after shut down, is when lots of deformation issues occur.
Nothing has proven to keep cylinders straight and more round than reducing coolant operating temps by a few degrees. This is especially true for cylinders 2 and 5, where they are situated between cylinders, and see the hottest coolant, for the longest period of time.
Its not just the overall temperature of a Tstat that matters when developing a better mouse trap. How much the unit will bypass when cold, how soon it starts to open, and the temperature that it is fully open are all what required special attention.
I see factory engines with bores .010" oval by 100K miles, which is ridiculous. This is our normal findings, as Charles measures every block that goes to LN before machining, and notes mileage. Generally bore will gain .001 ovality and .0005" taper per 10K miles.
When developing the low temp Tstat we faced lots of ridicule, but we've never seen someone remove the low temp unit and go back the other way. The general consensus of "if the factory didn't do it" is the biggest wall that a developer has to face. Quite frankly, I don't give a damn what the factory did, or why they did it.
Yes, coolant temp matters in regard to enrichment, as well.. There's a point where the CLT can make serious power, I have observed a 15 degree window where the engine makes the most power, and coincidentally, the engine moves to a different fuel map for this window. You learn this from having to chase maps while developing ECU flashes from scratch. When Beth was Land Speed Racing her 996 I would work very hard to keep the car at an exact temp, around 4-6 degrees below the sweet spot while we were in line to make her run. That meant foreign the car up, shutting it off and doing what we could to keep the engine where I wanted it to be. When she'd launch, the entire run would usually complete before the temp was out of the sweet spot, netting the most power. It took me about 6 trips to the track to figure this out, and hours of studying datalogger and dyno plots.
All that said, still trying to be on my behavior around here and trying to help. Its kind of hard to be neutral when you developed the part that people are slamming; even though they have zero direct experience with it. This Tstat was another product that was developed first for my engine program, then began to be sold individually.
01-11-2015, 10:54 PM
#47
Rennlist Member
Macster,
If I agreed with all of what you said, unfortunately, we'd both be wrong.
You didn't answer my question about personal experience with Thermostats?
I have personally carried out the development of the LN Tstat, starting prior to 2007. In that period of time we have ran street engines with stock thermostats on the street and then exclusively on the track, then torn them down, measure taper and ovality, then installed a Lo temp unit and done the same thing. I have also swapped the roles and started a fresh engine off with a low temp stat, then swapped it later for a stock one, and watched the values both ways.
Any engine I create will have a Lo temp LN unit (not any other) and will get that from day one, if it is removed, my warranty is void. Thats how strongly I feel, based on direct experience. Lots of the hot weather test work was done here, and we ran an engine for as much as 160 hours straight without shutting it down. The cold weather testing was done at LN, and Charles and I tackled it together, most of that was done in -10F temperatures, with some done at -27. Last year we took advantage of the super cold weather to prove the Cayenne low temp Tstat.
That even goes for my customer in Russia, who has been running one since 2009.
Lots of reasons why the Tstat is set the way it is at the factory, primarily for the hot restart emissions testing, as its very important to keep the coolant hot for as long as possible. This is why aircooled engines failed so horribly, because they cooled down too fast when shut down (after a brief temp spike just after shut down). My hypothesis is this period after shut down, is when lots of deformation issues occur.
Nothing has proven to keep cylinders straight and more round than reducing coolant operating temps by a few degrees. This is especially true for cylinders 2 and 5, where they are situated between cylinders, and see the hottest coolant, for the longest period of time.
Its not just the overall temperature of a Tstat that matters when developing a better mouse trap. How much the unit will bypass when cold, how soon it starts to open, and the temperature that it is fully open are all what required special attention.
I see factory engines with bores .010" oval by 100K miles, which is ridiculous. This is our normal findings, as Charles measures every block that goes to LN before machining, and notes mileage. Generally bore will gain .001 ovality and .0005" taper per 10K miles.
When developing the low temp Tstat we faced lots of ridicule, but we've never seen someone remove the low temp unit and go back the other way. The general consensus of "if the factory didn't do it" is the biggest wall that a developer has to face. Quite frankly, I don't give a damn what the factory did, or why they did it.
Yes, coolant temp matters in regard to enrichment, as well.. There's a point where the CLT can make serious power, I have observed a 15 degree window where the engine makes the most power, and coincidentally, the engine moves to a different fuel map for this window. You learn this from having to chase maps while developing ECU flashes from scratch. When Beth was Land Speed Racing her 996 I would work very hard to keep the car at an exact temp, around 4-6 degrees below the sweet spot while we were in line to make her run. That meant foreign the car up, shutting it off and doing what we could to keep the engine where I wanted it to be. When she'd launch, the entire run would usually complete before the temp was out of the sweet spot, netting the most power. It took me about 6 trips to the track to figure this out, and hours of studying datalogger and dyno plots.
All that said, still trying to be on my behavior around here and trying to help. Its kind of hard to be neutral when you developed the part that people are slamming; even though they have zero direct experience with it. This Tstat was another product that was developed first for my engine program, then began to be sold individually.
If I agreed with all of what you said, unfortunately, we'd both be wrong.
You didn't answer my question about personal experience with Thermostats?
I have personally carried out the development of the LN Tstat, starting prior to 2007. In that period of time we have ran street engines with stock thermostats on the street and then exclusively on the track, then torn them down, measure taper and ovality, then installed a Lo temp unit and done the same thing. I have also swapped the roles and started a fresh engine off with a low temp stat, then swapped it later for a stock one, and watched the values both ways.
Any engine I create will have a Lo temp LN unit (not any other) and will get that from day one, if it is removed, my warranty is void. Thats how strongly I feel, based on direct experience. Lots of the hot weather test work was done here, and we ran an engine for as much as 160 hours straight without shutting it down. The cold weather testing was done at LN, and Charles and I tackled it together, most of that was done in -10F temperatures, with some done at -27. Last year we took advantage of the super cold weather to prove the Cayenne low temp Tstat.
That even goes for my customer in Russia, who has been running one since 2009.
Lots of reasons why the Tstat is set the way it is at the factory, primarily for the hot restart emissions testing, as its very important to keep the coolant hot for as long as possible. This is why aircooled engines failed so horribly, because they cooled down too fast when shut down (after a brief temp spike just after shut down). My hypothesis is this period after shut down, is when lots of deformation issues occur.
Nothing has proven to keep cylinders straight and more round than reducing coolant operating temps by a few degrees. This is especially true for cylinders 2 and 5, where they are situated between cylinders, and see the hottest coolant, for the longest period of time.
Its not just the overall temperature of a Tstat that matters when developing a better mouse trap. How much the unit will bypass when cold, how soon it starts to open, and the temperature that it is fully open are all what required special attention.
I see factory engines with bores .010" oval by 100K miles, which is ridiculous. This is our normal findings, as Charles measures every block that goes to LN before machining, and notes mileage. Generally bore will gain .001 ovality and .0005" taper per 10K miles.
When developing the low temp Tstat we faced lots of ridicule, but we've never seen someone remove the low temp unit and go back the other way. The general consensus of "if the factory didn't do it" is the biggest wall that a developer has to face. Quite frankly, I don't give a damn what the factory did, or why they did it.
Yes, coolant temp matters in regard to enrichment, as well.. There's a point where the CLT can make serious power, I have observed a 15 degree window where the engine makes the most power, and coincidentally, the engine moves to a different fuel map for this window. You learn this from having to chase maps while developing ECU flashes from scratch. When Beth was Land Speed Racing her 996 I would work very hard to keep the car at an exact temp, around 4-6 degrees below the sweet spot while we were in line to make her run. That meant foreign the car up, shutting it off and doing what we could to keep the engine where I wanted it to be. When she'd launch, the entire run would usually complete before the temp was out of the sweet spot, netting the most power. It took me about 6 trips to the track to figure this out, and hours of studying datalogger and dyno plots.
All that said, still trying to be on my behavior around here and trying to help. Its kind of hard to be neutral when you developed the part that people are slamming; even though they have zero direct experience with it. This Tstat was another product that was developed first for my engine program, then began to be sold individually.
01-11-2015, 11:59 PM
#48
Burning Brakes
One of the things that Porsche worked hard join with the 987/ 997 was running temperatures. I am sure that they saw the impacts that these things were having on engines when they were returned as cores. The way the cooling system is routed in the two models is drastically improved.
The result is cooler peak temperatures, especially on the track. I do not gain this data from OBDII or the factory gauge, I install 28 channel data loggers to gather the data, and they are driven by stand alone sensors. What the factory wants us to see through calculated CLT values, in the gauges, are different than actual, raw values.
Here are some examples of how the cooling sub- system was altered through the 9X6 and 9X7 models, as a comparative. These came from my M96/ M97 Engine Mechanical Class Presentations. There's a teaser in there too..
The result is cooler peak temperatures, especially on the track. I do not gain this data from OBDII or the factory gauge, I install 28 channel data loggers to gather the data, and they are driven by stand alone sensors. What the factory wants us to see through calculated CLT values, in the gauges, are different than actual, raw values.
Here are some examples of how the cooling sub- system was altered through the 9X6 and 9X7 models, as a comparative. These came from my M96/ M97 Engine Mechanical Class Presentations. There's a teaser in there too..
01-12-2015, 10:20 AM
#49
Race Director
Understand that all of that "expert" engineering about engine cooling done by Porsche is motivated primarily to comply with federal emmissiions. If Porsche doesn't comply with emmisions, they can't put a single car on the market, Cars that run hotter have less emmisions so its a no brainer Porsches are engineered to run hot.
Hottter running is not best for engine longevity, but engine longevity is not first on Porsche's list, emmisions are since engine longevity doesn't prevent Porsche from putting a car on the market, but emmisions will.
So its all a question of priorities. Porsche rocket surgeons have designed a fantastic cooling system that assures it complies with emmision standards, not necessarily engine longevity. The first thing Porsche has to do is get a car to market, they can deal with longevity problems later.
Hottter running is not best for engine longevity, but engine longevity is not first on Porsche's list, emmisions are since engine longevity doesn't prevent Porsche from putting a car on the market, but emmisions will.
So its all a question of priorities. Porsche rocket surgeons have designed a fantastic cooling system that assures it complies with emmision standards, not necessarily engine longevity. The first thing Porsche has to do is get a car to market, they can deal with longevity problems later.
As I have covered before testing has found engine wear increases with lower operating temperatures. It is not like these engines are operating at extremely high temperatures. They are operating at temperatures that have been found over time to deliver good engine life and performance.
While emissions compliance plays a large role in engine design Porsche -- and all other auto makers -- must still deliver satisfactory engine reliability. I note the Chevy Vega with its horrible engine reliability died a quick death. No sane car owner is going to turn around and buy another car from the same automaker if the first car suffered a premature engine failure.
The rest of your comments on engine longevity are simply nonsense and deserve no further comment.
01-12-2015, 04:23 PM
#50
This sounds like one of those discussions that needs to simply come to an end. I have a lot of respect for the primary participants, and would really like to keep it that way.
Thanks for everyone's opinions, but can we stop now?
Thanks for everyone's opinions, but can we stop now?
01-12-2015, 05:31 PM
#51
[B]I READ this exact same thread 10 years ago....except it was on HTT...a former motorcycle thread for Harley's. Oil coolers or not for Harley's!?? I-fecking-dentical to this whole steam of conversation, experts all over the country saying DO and others yelling DON'T! Absolutely hilarious! Just like a group from my last homeowners meeting deciding which paint to use on the fences, and the gravity and in depth analysis of opinions as to why choose A or B. I have no skin in this game, but @ 40K INSTALLED a new water pump & cooler T stat and installed an oil cooler on my bike @ 1K. AM I GOING STRAIGHT TO HELL!!! [/B
01-12-2015, 07:49 PM
#52
[B]I READ this exact same thread 10 years ago....except it was on HTT...a former motorcycle thread for Harley's. Oil coolers or not for Harley's!?? I-fecking-dentical to this whole steam of conversation, experts all over the country saying DO and others yelling DON'T! Absolutely hilarious! Just like a group from my last homeowners meeting deciding which paint to use on the fences, and the gravity and in depth analysis of opinions as to why choose A or B. I have no skin in this game, but @ 40K INSTALLED a new water pump & cooler T stat and installed an oil cooler on my bike @ 1K. AM I GOING STRAIGHT TO HELL!!! [/B
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hollywood1053 (02-08-2023)
01-14-2015, 04:43 PM
#54
Rennlist Member
For me, my car is and will remain stock, and parts replaced are oem. I really don't pretend to know better than those who built and designed the car and all of it's systems.
01-14-2015, 06:43 PM
#55
Yes, it is. Installing a LTTS in one of these engines -- any engine -- is about the dumbest move one can make.
Testing has found engine wear increases quite dramatically as engine oil temperature goes down. This is not at engine start but after engine start while the engine is just running, doing its job.
The t-stat is there to ensure the engine warms up within a reasonable time. Once up to temperature the air flow through the radiators controls the coolant temperature.
At some point this is helped by the radiator fans.
If you are uncomfortable with the max. coolant temperature and oil temperature your engine is manifesting under hard usage you need to consider more/better cooling. Adding a 3rd radiator and implementing a more aggressive radiator fan regime is what Porsche does when a car needs more cooling.
'course, the above is more difficult to do while installing a LTTS is relatively easy.
Testing has found engine wear increases quite dramatically as engine oil temperature goes down. This is not at engine start but after engine start while the engine is just running, doing its job.
The t-stat is there to ensure the engine warms up within a reasonable time. Once up to temperature the air flow through the radiators controls the coolant temperature.
At some point this is helped by the radiator fans.
If you are uncomfortable with the max. coolant temperature and oil temperature your engine is manifesting under hard usage you need to consider more/better cooling. Adding a 3rd radiator and implementing a more aggressive radiator fan regime is what Porsche does when a car needs more cooling.
'course, the above is more difficult to do while installing a LTTS is relatively easy.
Oh dear another one who thinks the thermostat doesn't control temperature...
01-16-2015, 01:45 PM
#56
Race Director
If you can't agree with what I posted then apparently the laws of physics are being violated in Porsche engines.
Personal experience, beyond just replacing them, with T-stats? No. But as I pointed out I'm not the one advising owners to switch away from what the factory installed to what is believed to be, pardon the expression, the hot setup, a lower temp T-stat.
The problem with testing is that it is impossible to cover all scenarios. While running an engine constantly with a lower T-stat in place didn't turn up any issues, there are a number of different usage scenarios that could result in a different outcome.
To make a blanket statement that all engines of a specific model require a different/lower temp T-stat is to assume all owners will use the car in the I think obviously optimum manner in which you tested the T-stat.
I think this is a dangerous assumption to make.
I guess what it boils down to is when you have been in business for a long time and have sold thousands of cars/engines and have stood behind these over the years for 50K or even 100K miles I would be more comfortable with your recommendation regarding installing a lower temp T-stat (although I have to wonder if doing so could in some regions of the USA run afoul of emissions regulations?).
Frankly, I have to say that if I believed I had to make such a change in the engine from any manufacturer I would simply avoid buying the car in the first place.
I am way beyond the desire to have to customize/mod an engine from which I expect to obtain what I believe to be satisfactory performance/service life in order to get this satisfactory performance and service life.
I prefer my cars deliver this out of the box, so to speak, rather than require extra work on my part.
Personal experience, beyond just replacing them, with T-stats? No. But as I pointed out I'm not the one advising owners to switch away from what the factory installed to what is believed to be, pardon the expression, the hot setup, a lower temp T-stat.
The problem with testing is that it is impossible to cover all scenarios. While running an engine constantly with a lower T-stat in place didn't turn up any issues, there are a number of different usage scenarios that could result in a different outcome.
To make a blanket statement that all engines of a specific model require a different/lower temp T-stat is to assume all owners will use the car in the I think obviously optimum manner in which you tested the T-stat.
I think this is a dangerous assumption to make.
I guess what it boils down to is when you have been in business for a long time and have sold thousands of cars/engines and have stood behind these over the years for 50K or even 100K miles I would be more comfortable with your recommendation regarding installing a lower temp T-stat (although I have to wonder if doing so could in some regions of the USA run afoul of emissions regulations?).
Frankly, I have to say that if I believed I had to make such a change in the engine from any manufacturer I would simply avoid buying the car in the first place.
I am way beyond the desire to have to customize/mod an engine from which I expect to obtain what I believe to be satisfactory performance/service life in order to get this satisfactory performance and service life.
I prefer my cars deliver this out of the box, so to speak, rather than require extra work on my part.
02-04-2015, 02:45 PM
#57
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02-05-2015, 12:46 PM
#59
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There is another way to look at the question of a low temp thermostat vs. an OEM thermostat for M97 engines, and that is to look at what Porsche has done for the 981. In those cars, there is a map-controlled thermostat (probably made by Wahler) as part of the Thermal Management System. This thermostat has two settings, a normal setting resulting in opening at a higher temperature, and a lower temperature opening (when the sport mode is activated as I recall). In the sport mode a small electric current will "pre-heat" the thermostat so it opens at a lower coolant temperature resulting in a decrease of about 20F under “normal” conditions (for example see http://www.planet-9.com/981-chat/897...nterlocks.html).
From a Wahler brochure (http://wahler.de/fileadmin/wahler/Do...schuere_en.pdf) “Electrical heating opens the coolant circuit earlier in situations of very increased performance requirements. Depending on the preset the engine can be operated hotter than previously usual, for instance at approximately 100 ̊C to 110 ºC in partial load conditions. This results in a consumption advantage of 1 % to 2 %. Under full load the temperature is reduced to approximately 80 ºC, which allows the performance – especially the torque – to be measurably increased by approximately 2 % to 3 %.” It should be noted that the temperatures mentioned above are examples and may not directly apply to 981s.
In 987 Caymans, the choice is either a low temp. thermostat or an OEM thermostat, but not both. It seems reasonable for choose the low temp. thermostat for its better performance and for the reasons well described by Hartech and Flat 6 Innovations.
It should also be noted that Porsche places the thermostat on the coolant return line and not on the outflow line. One way to think about this is that Porsche is more interested in keeping the engine temperature from becoming too low (perhaps at the cost of performance, bore scoring and cylinder roundness) while thermostats on the outflow are more focused on not letting the engines become too hot.
From a Wahler brochure (http://wahler.de/fileadmin/wahler/Do...schuere_en.pdf) “Electrical heating opens the coolant circuit earlier in situations of very increased performance requirements. Depending on the preset the engine can be operated hotter than previously usual, for instance at approximately 100 ̊C to 110 ºC in partial load conditions. This results in a consumption advantage of 1 % to 2 %. Under full load the temperature is reduced to approximately 80 ºC, which allows the performance – especially the torque – to be measurably increased by approximately 2 % to 3 %.” It should be noted that the temperatures mentioned above are examples and may not directly apply to 981s.
In 987 Caymans, the choice is either a low temp. thermostat or an OEM thermostat, but not both. It seems reasonable for choose the low temp. thermostat for its better performance and for the reasons well described by Hartech and Flat 6 Innovations.
It should also be noted that Porsche places the thermostat on the coolant return line and not on the outflow line. One way to think about this is that Porsche is more interested in keeping the engine temperature from becoming too low (perhaps at the cost of performance, bore scoring and cylinder roundness) while thermostats on the outflow are more focused on not letting the engines become too hot.
02-05-2015, 01:44 PM
#60
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I have a LN low temp Thermostat. I do not track my car, but I do run it's legs out. My issue with the OEM thermostat and the cooling system as a whole in my 996 was that after spirited drives, if I was stuck in traffic for any amount of time, my temp gauge would climb to higher than one would like levels. My options were to add a third radiator (which I still might do) or change out the thermostat when I was having my engine rebuilt. I chose the thermostat and my car does not get nearly as hot as it had previously. Yes my radiators are good and yes my fans work. This really seems like a silly argument, but on this forum, it doesn't surprise me one bit. As they say, opinions are like ********, and everyone has one.. including me.