Why the 160 degree thermostat?

[mwiteck01@gmail.com]

So after all of this, what is the optimum running temp for a LS3. I like to run under 200*F
Any thoughts? Thanks

[Leadsled]

I have the 180° thermostat, CSF aluminum Radiator and the Z/28 hood vent. I see 175° cruising speeds never gets over 195-205 idle in South Carolina 105° weather

[acammer]

Originally Posted by mwiteck01@gmail.com

So after all of this, what is the optimum running temp for a LS3. I like to run under 200*F
Any thoughts? Thanks

160*F. Occasionally you see oddball behavior like ledsleds car running below the threshold, but for the most part at highway cruising or with the fans on high you'll typically see temps stabilize 15-25*F over the rated thermostat rated temperature. So, a 160*F stat will give you 175-185*F cruising. 175*F is about as low as you want to operate at continuously, but the closer you can stick to that point then the more thermal overhead you have build into the system to absorb extra heat when you apply high loads.

I used to be a big fan of the Mishimoto 169*F thermostat as a perfect option to get the baseline operating temp up just over 180*F, but ultimately I saw problems with a few of those T-Stats and abandoned them. The cheapie 160*F stat from Summit that was originally in the car before all that testing went back in and has been flawless for years. I did collect a lot of thoughts for additional reading if you're interested:

https://www.camaro5.com/forums/showt...oogle_vignette

[1JEWLDSSRS]

Originally Posted by acammer

It was interesting to look through this 11 year old thread and observe the painful amounts of mis-information. Just remember kids, you can't believe everything you read.

High level overview:

• Coolant still gets to the same temp with a lower temp thermostat . No, if the car has adequate cooling (ie is moving, and/or the fans are properly configured) it will run cooler.
• Low temp thermostats make the car slower to warm up. No, it changes nothing about warm up time, just where the thermostat opens and temps settle at.
• Stock thermostat is 180*F. No, it's 187*F
• 20* of coolant temperate doesn't matter. No, it matters a bunch. There are several tables within the OEM ECU that actually begin altering enrichment and spark advance based on coolant and intake air temperature - and those can have a profound effect on power output. Thermal management is critical on any vehicle, but much more so on a performance vehicle.
• Tuning is required to prevent a code. No - a 160*F thermostat that functions correctly will meet the minimum threshold for "warmed up" by the ECU. Tuning is highly recommended to match fan on/off points for the lower temperature thermostat.

As always, Andrew to the rescue!! Great info sir!! Thanks for all your wisdom and knowledge. We all appreciate you and what you do for our Camaro family!! Cheers..

[Leadsled]

[QUOTE=acammer;11439212]160*F. Occasionally you see oddball behavior like ledsleds car running below the threshold, but for the most part at highway cruising or with the fans on high you'll typically see temps stabilize 15-25*F over the rated thermostat rated temperature. So, a 160*F stat will give you 175-185*F cruising. 175*F is about as low as you want to operate at continuously, but the closer you can stick to that point then the more thermal overhead you have build into the system to absorb extra heat when you apply high loads.[QUOTE=acammer;11439212]

I’m sorry, I just looked. I do have the 160°

[1JEWLDSSRS]

[QUOTE=Leadsled;11439298][QUOTE=acammer;11439212]160*F. Occasionally you see oddball behavior like ledsleds car running below the threshold, but for the most part at highway cruising or with the fans on high you'll typically see temps stabilize 15-25*F over the rated thermostat rated temperature. So, a 160*F stat will give you 175-185*F cruising. 175*F is about as low as you want to operate at continuously, but the closer you can stick to that point then the more thermal overhead you have build into the system to absorb extra heat when you apply high loads.

Originally Posted by acammer

I’m sorry, I just looked. I do have the 160°

I have a 160 in my engine, and on any normal cruising day at 55 or above, this is where mine runs. I have seen the temp go down to around 170-172 on cold winter days on the highway. But normally it right at 175-185..

[Leo72793]

[QUOTE=1JEWLDSSRS;11439314][QUOTE=Leadsled;11439298]

Originally Posted by acammer

160*F. Occasionally you see oddball behavior like ledsleds car running below the threshold, but for the most part at highway cruising or with the fans on high you'll typically see temps stabilize 15-25*F over the rated thermostat rated temperature. So, a 160*F stat will give you 175-185*F cruising. 175*F is about as low as you want to operate at continuously, but the closer you can stick to that point then the more thermal overhead you have build into the system to absorb extra heat when you apply high loads.

I have a 160 in my engine, and on any normal cruising day at 55 or above, this is where mine runs. I have seen the temp go down to around 170-172 on cold winter days on the highway. But normally it right at 175-185..

im... considering this since im having temps in the city go up to 223 than randomly drop to 203. then climb up. debating on amsoil Ethelyn glycol coolant too.

[el ess A]

I don't care if you believe me or not, but I'm going to put this here.

Your engine is designed to have X amount of clearances at normal operating temperature. Those clearances are "off" at startup, so it benefits the engine to warm up to N.O.T. as quickly as possible. Emission and wear-wise. You know because you've heard it most of your life- engines suffer the most wear at cold startup. Engines in good shape, at N.O.T., suffers the least amount of wear.

A closed, stock rated thermostat will help raise temps faster in the block than a 160 T-stat. So instead of just warming up the coolant in the block, at 160 degrees it starts to open and now has to warm up the "new, cooler" coolant from the radiator entering the block, too. More volume to warm up than what it started with. So yeah, it's minimal time difference, but it actually does increase warmup time slightly. A minute here and there of extra wear on your engine adds up over time. If people are throwing codes due to this, the anectdotal evidence shows.

The 187 or 160 thermostat does nothing for normal operating temperature. It only determines minimum temperature for opening. That's it. From the beginning of thermostat use, GM designed the systems for the T-stat to begin to open at a certain temp, then be fully open up to a certain temperature above that setpoint. Like around 200-ish. The coolant system components takes it from there. And when cooling down, the t-stat was designed to be fully closed a few degrees below the opening setpoint. I'm not following the logic that temperatures "settling" anywhere, as they'll settle where they will, regardless of which thermostat you choose since it'll be above those T-stat opening temps anyway. Running 220 or so on the street is NOT a problem for a closed, pressurized cooling system in good shape. I think GM considers anything under 240 deg F ok. Obviously not pushing it at those temps, but the engine can survive.

Once it's open, the T-stat's job is done and heat transfer is now totally controlled by the cooling system components like radiator, pump, fans, and air flow through the radiator. If the system is sized and maintained properly, you'll have no overheating issues.

Keep in mind, more power adds heat. And who doesn't like more power? But adding stuff like dual turbos, et al, could alter the sizing and flow requirements of the cooling system and then you may need to start changing out or adding components to compensate if you go outside GM's designed capacity. You now become the "new" cooling system's design engineer. If you know what you're doing, no problems. Most problems are caused by poor airflow across the radiator. Obviously, system dirt, clogs, corrosion, etc., can have an effect too.

There's also a wive's tale about residence time in the radiator. Something like "You can't remove your thermostat because the coolant needs to spend more time in the radiator to cool down so you don't run a high operating temp." Malarky. If that was the case, then the coolant spends less time in the block heating up, too. So it cancels each other out. So whatever tricks you might think you can do to change time in the radiator also changes time in the block the same amount. One adds the heat, one takes it away. It's a closed system, and can't be escaped. It will find its own equilibrium for system conditions. It's all about the heat transfer equations in fluid thermodynamics.

If you know Q dot equations, apply them here. Mass flow rate is your friend. Higher delta T (difference between temperatures) is your friend. If you apply them to the coolant systems, you'd find there's no real need to use 160 degree thermostats in a stock system. Use them if you want to, if it makes you sleep better. I know there are some people that flat-out refuse to believe in the equations, but that's not my problem. There may be a need somewhere off-road you may can see a benefit of the 160 thermostats. Not sure where that would be. But for the normal, everyday driving on the roads, it's a waste of $$ and time, IMO.

[chevy pilot]

In my opinion 195 F is a ideal temperature.

[Trawz]

Originally Posted by acammer

I used to be a big fan of the Mishimoto 169*F thermostat as a perfect option to get the baseline operating temp up just over 180*F, but ultimately I saw problems with a few of those T-Stats and abandoned them.

What sort of problems did you encounter with the Mishi T-stat?
I have been running the 169* t-stat for over a year now and have been good thus far, but I have heard others also have had bad luck with the Mishi t-stat.

[Bluebagger06]

I did a 160 thermostat also and run right at 180 at operating temps!

[acammer]

Originally Posted by Leadsled

I’m sorry, I just looked. I do have the 160°

No worries - that makes a lot more sense!

[acammer]

Originally Posted by Trawz

What sort of problems did you encounter with the Mishi T-stat?
I have been running the 169* t-stat for over a year now and have been good thus far, but I have heard others also have had bad luck with the Mishi t-stat.

I had not one, but two of them have the rubber stopper material begin to disintegrate and prevent the thermostat from fully closing. It's the only time I've had any sort of warm up code set with the car - that small leak, especially if you drove the car right away and keep the rad cool, was just enough to tip it over the threshold.

I like the temp set-point a lot with a bolt-on car. A cammed car is so much more inefficient in those lower RPMs that it'll keep itself warm enough with a 160 in all but the coldest of ambient temps, but the 160 with a bolt on car would see temps dip lower than I was comfortable with.

I shared a lot of details in my review here on Camaro5.com if you want more details and information.

[acammer]

We're aligned on some of this, with a few places we see it differently. I'm a big fan of friendly discourse, so by all means lets continue to hash it out.

Originally Posted by el ess A

I don't care if you believe me or not, but I'm going to put this here.

Your engine is designed to have X amount of clearances at normal operating temperature. Those clearances are "off" at startup, so it benefits the engine to warm up to N.O.T. as quickly as possible. Emission and wear-wise. You know because you've heard it most of your life- engines suffer the most wear at cold startup. Engines in good shape, at N.O.T., suffers the least amount of wear.

Agreed. I suspect we may disagree on what acceptable normal operating temperature should be. I did a whole deep dive on this years ago and essentially came away from that exercise with the understanding that 175*F of engine/coolant temperature is about the point at which wear stabilizes. Operating below that risks increased wear, unless of course the engine is designed for it, which our modern emissions compliant cars certainly are not. So, there is a point at which "too cold" could be problematic.

A closed, stock rated thermostat will help raise temps faster in the block than a 160 T-stat. So instead of just warming up the coolant in the block, at 160 degrees it starts to open and now has to warm up the "new, cooler" coolant from the radiator entering the block, too. More volume to warm up than what it started with. So yeah, it's minimal time difference, but it actually does increase warmup time slightly. A minute here and there of extra wear on your engine adds up over time. If people are throwing codes due to this, the anectdotal evidence shows.

I think we see this from different angles, because I think we hold a difference of opinion on what "up to temperature" is. We'll get into that more on your next point, but essentially I would say "up to temp" means that the system has stabilized at whatever temperature it will operate at under sustained cruising speed. With a 160*F stat, that's somewhere around 178*F, with the factory 187 its more like 205*F. Warm-up should look exactly the same between a 187 and a 160 degree thermostat until they hit their respective opening points.

I have run several different 160 and 169 thermostats over the years - and the ONLY time I've had a failure to warm up code was when a thermostat failed to close fully due to degrading material on the stopper. I live in upstate NY, and as you can imagine in our spring and fall months I will operate the car at near freezing temps - no issues whatsoever.

The 187 or 160 thermostat does nothing for normal operating temperature. It only determines minimum temperature for opening. That's it. From the beginning of thermostat use, GM designed the systems for the T-stat to begin to open at a certain temp, then be fully open up to a certain temperature above that setpoint. Like around 200-ish. The coolant system components takes it from there. And when cooling down, the t-stat was designed to be fully closed a few degrees below the opening setpoint. I'm not following the logic that temperatures "settling" anywhere, as they'll settle where they will, regardless of which thermostat you choose since it'll be above those T-stat opening temps anyway. Running 220 or so on the street is NOT a problem for a closed, pressurized cooling system in good shape. I think GM considers anything under 240 deg F ok. Obviously not pushing it at those temps, but the engine can survive.

Once it's open, the T-stat's job is done and heat transfer is now totally controlled by the cooling system components like radiator, pump, fans, and air flow through the radiator. If the system is sized and maintained properly, you'll have no overheating issues.

This is where we are pretty far apart on things - the thermostat absolutely plays an ongoing, significant roll in operating temperature after reaching it's opening temperature during initial warm up. Having used a multitude of thermostats from OEM, to the Mishimoto 169*F stat, and the old reliable 160*F stats from Summit I can tell you that each has a distinct influence on normal operating temperature.

The fundamental flaw in your explanation and understanding (in bold and italics in your quote) is that you're not allowing for the fact that the cooling system has more than enough capacity to cool the engine back down to temperatures at which the thermostat will begin to close and regulate temperature. This absolutely DOES happen, and is the fundamental principal behind using a cooler thermostat. If this was not true, I would agree, what's the point?

But it's absolutely a fact that at light load cruising speed (55+mph) in ambient air (at least under 100*F) the cooling system will pull the temperature in the system down to the point where the thermostat begins to close to regulate temperatures. It's also a fact that with manual control of the cooling fans and moderate ambient air temps you can even cool the system to the point of the thermostat being to close while standing at idle.

In the late fall with sub 70*F ambient air temps I can run the fans on high while idling in the staging lanes at the drag strip and drag the temperature from 200+*F down to 178*F where my 160 stat starts closing up. Proper fan tuning in the ECU allows my car to almost never exceed 200*F in ambient temps up to 100*F. I just don't have a hot enough environment to offer input on what happens when it gets even hotter outside than that, but I'm sure it reaches a point where you can only cool it so much.

I've achieved similar results with other cars that I tune or help out on - this is no one-off fluke, but something I've repeated on several different 5th gen Camaro's, from bolt-on setups to 800+whp blower cars. I agree completely that really anything less than ~235*F of water temperature is no big deal, and is common with modern vehicles including the Camaro. That doesn't in any way make it optimal from a performance standpoint, for reasons I've already described in posts above.

Keep in mind, more power adds heat. And who doesn't like more power? But adding stuff like dual turbos, et al, could alter the sizing and flow requirements of the cooling system and then you may need to start changing out or adding components to compensate if you go outside GM's designed capacity. You now become the "new" cooling system's design engineer. If you know what you're doing, no problems. Most problems are caused by poor airflow across the radiator. Obviously, system dirt, clogs, corrosion, etc., can have an effect too.

There's also a wive's tale about residence time in the radiator. Something like "You can't remove your thermostat because the coolant needs to spend more time in the radiator to cool down so you don't run a high operating temp." Malarky. If that was the case, then the coolant spends less time in the block heating up, too. So it cancels each other out. So whatever tricks you might think you can do to change time in the radiator also changes time in the block the same amount. One adds the heat, one takes it away. It's a closed system, and can't be escaped. It will find its own equilibrium for system conditions. It's all about the heat transfer equations in fluid thermodynamics.

Agreed completely about adding power typically adds heat - basic physics, and there needs to be appropriate steps taken to mitigate that. Also agreed on the whole "coolant needs dwell time in the radiator" is a bunch of crap as well. The opposite is actually true, the more you cycle the system, the bigger the differential you get between the radiator temp and the outside air, and the more heat it can shed.

If you know Q dot equations, apply them here. Mass flow rate is your friend. Higher delta T (difference between temperatures) is your friend. If you apply them to the coolant systems, you'd find there's no real need to use 160 degree thermostats in a stock system. Use them if you want to, if it makes you sleep better. I know there are some people that flat-out refuse to believe in the equations, but that's not my problem. There may be a need somewhere off-road you may can see a benefit of the 160 thermostats. Not sure where that would be. But for the normal, everyday driving on the roads, it's a waste of $$ and time, IMO.

Your position stands on the fundamental flaw in understand that once the thermostat's opening point is exceeded it's "out of the equation". That's just not the case - the cooling system, especially on mild to moderately modified cars, has more than enough capacity to bring the coolant right back down to point where the thermostat begins closing and regulating the "minimum" system temperature. If the car is at cruising speed, or the fans have been calibrated to target a lower temperature, then the lower temperature thermostat absolutely produces a lower operating temperature.