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Hello,

What is the impact of installing a 180 degree thermostat and dropping the engine's running temperatures ~20 degrees? How does it affect the computer and tuning if the car never reaches the (seemingly) high 210+ degree temp range?

My car is stock, no engine mods. But I live in Texas and our 100+ degree days are getting longer and much more frequent. I have historically put 180 degree thermostats in other performance vehicles I've owned, but I just wanted to see if any experts here had opinions one way or the other.

Thanks
 

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In stop and go traffic it won't affect ECT much. Your fan will still come on when it does now. It will help on interstate driving some.
Most people have no issues with a 180 deg. thermostat but if you use one on a very cold morning (freezing or so) it can take longer than the ECU thinks it should to reach operating temperature and it may set a fault.
 

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TrackDay , correct me if I'm wrong, but engine efficiency is optimized around block temperature, so if you're not "using" the 180deg for modifications, then you're losing some mileage/efficiency.

Also, engine materials have temperature ranges they want to be in for improved wear characteristics...
 

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If you run with the AC on while creeping through traffic, the fan will cycle on, keeping the coolant temperature lower than OEM. Highway / Freeway cruising, the coolant temperature will remain lower as well, since air flow speed is great.

The higher temp thermostats are strictly for emissions, e.g. higher operating temps are emissions friendly. No reason to run these motors as hot as they do from factory.

Keep in mind, the PCM monitors time to reach operating temperature (coolant), if there's latency (too long), a CEL will trigger, ODBII = P0128.
 

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So you would have to unlock the PCM and tune it to get the fans to come on for a 180• stat?
Ideally, it's the proper method to do, is to have the tune adjusted accordingly. My car always triggered a CEL, no matter how many times I reset the PCM, once it reached readiness state, the P0128 code would come up. Sure a 180 T-Stat alone would provide some benefit, but I had one installed while waiting for my tuning session.
 

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Probably doesn’t make sense to unlock and tune for just a t-stat? Might as well get a tune because warranty is no good after it being unlocked for t-stat?
 

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Oh well. On my first freeway drive it threw the P0128 code, the check engine light came on, and then Dodge emailed me :)

Reverting to the stock thermostat tonight...
Temps look better. By chance, did you enter the feeeway while the car was still warming up? If so, the CEL is expected.
 

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Hello,

What is the impact of installing a 180 degree thermostat and dropping the engine's running temperatures ~20 degrees? How does it affect the computer and tuning if the car never reaches the (seemingly) high 210+ degree temp range?

My car is stock, no engine mods. But I live in Texas and our 100+ degree days are getting longer and much more frequent. I have historically put 180 degree thermostats in other performance vehicles I've owned, but I just wanted to see if any experts here had opinions one way or the other.

Thanks
The engine runs at a colder than what is an ideal temperature. Tests have found wear goes up and fuel economy goes down when the engine temperature is reduced. Not what I would want to subject my Challenger's engine to.

The factory T-stat and cooling system capacity/water pump size and speed and fan staging will work to keep the engine coolant temperatures within reason.

With my Hellcat while the coolant temperature can climb to 212F and oil temperature to 230F when I drive car in city stop/go traffic, after just a few minutes on the freeway/highway the coolant temperature is down near 200F but doesn't appear to go below 199F. The oil temperature drops to but appears to remain above -- but not by much -- the coolant temperature. This on mild days. Have to mention I have driven the car in near 100F ambient temperature and the coolant temperature and oil temperature do not appear to get any higher. It would appear Dodge has the engine cooling well under control. Which makes sense. Can't image after the dyno run when all the factory big wigs are in attendance and high fives are exchanged from seeing the desired 707hp obtained someone brings up engine cooling and everybody looks away and someone says: "Oh well, at least the owner can install a lower temperature T-stat."

Remember the oil is designed to work best at 212F. (This the temperature at which the "40" in 0w40 viscosity is measured.) Obtaining this temperature also helps ensure any water the oil collected -- as a byproduct of combustion (and supercharged engines are notorious for high amounts of blowby which only makes water contamination of the oil an even a bigger problem) -- gets hot enough to be boiled away to keep the water content of the oil way down.

Really you are doing the wrong thing to fix something that is not broken.
 

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The engine runs at a colder than what is an ideal temperature. Tests have found wear goes up and fuel economy goes down when the engine temperature is reduced. Not what I would want to subject my Challenger's engine to.

The factory T-stat and cooling system capacity/water pump size and speed and fan staging will work to keep the engine coolant temperatures within reason.

With my Hellcat while the coolant temperature can climb to 212F and oil temperature to 230F when I drive car in city stop/go traffic, after just a few minutes on the freeway/highway the coolant temperature is down near 200F but doesn't appear to go below 199F. The oil temperature drops to but appears to remain above -- but not by much -- the coolant temperature. This on mild days. Have to mention I have driven the car in near 100F ambient temperature and the coolant temperature and oil temperature do not appear to get any higher. It would appear Dodge has the engine cooling well under control. Which makes sense. Can't image after the dyno run when all the factory big wigs are in attendance and high fives are exchanged from seeing the desired 707hp obtained someone brings up engine cooling and everybody looks away and someone says: "Oh well, at least the owner can install a lower temperature T-stat."

Remember the oil is designed to work best at 212F. (This the temperature at which the "40" in 0w40 viscosity is measured.) Obtaining this temperature also helps ensure any water the oil collected -- as a byproduct of combustion (and supercharged engines are notorious for high amounts of blowby which only makes water contamination of the oil an even a bigger problem) -- gets hot enough to be boiled away to keep the water content of the oil way down.

Really you are doing the wrong thing to fix something that is not broken.
So you think it’s harmful for your engine to run at 200F? But 230F is great? I thought the purpose of running the engine so hot was for EPA reasons? I don’t want my engine to run 230F and would rather run the risk of failure at 200F... in the olden days we always installed a 180 stat and I don’t remember mass failures from not being 230F? I will have to do some research I guess.. nice write up! I wonder how the oil protects during startup when it’s cold? Weird when you find out right is wrong and wrong is now right! I also think the oil being 212F contributes to the condensation or moisture or water.. I’m shore if my old thinking is flawed im going to hear about. Lol
 

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The engine runs at a colder than what is an ideal temperature. Tests have found wear goes up and fuel economy goes down when the engine temperature is reduced. Not what I would want to subject my Challenger's engine to.

The factory T-stat and cooling system capacity/water pump size and speed and fan staging will work to keep the engine coolant temperatures within reason.

With my Hellcat while the coolant temperature can climb to 212F and oil temperature to 230F when I drive car in city stop/go traffic, after just a few minutes on the freeway/highway the coolant temperature is down near 200F but doesn't appear to go below 199F. The oil temperature drops to but appears to remain above -- but not by much -- the coolant temperature. This on mild days. Have to mention I have driven the car in near 100F ambient temperature and the coolant temperature and oil temperature do not appear to get any higher. It would appear Dodge has the engine cooling well under control. Which makes sense. Can't image after the dyno run when all the factory big wigs are in attendance and high fives are exchanged from seeing the desired 707hp obtained someone brings up engine cooling and everybody looks away and someone says: "Oh well, at least the owner can install a lower temperature T-stat."

Remember the oil is designed to work best at 212F. (This the temperature at which the "40" in 0w40 viscosity is measured.) Obtaining this temperature also helps ensure any water the oil collected -- as a byproduct of combustion (and supercharged engines are notorious for high amounts of blowby which only makes water contamination of the oil an even a bigger problem) -- gets hot enough to be boiled away to keep the water content of the oil way down.

Really you are doing the wrong thing to fix something that is not broken.

I would have thought the engineers would have put a 212 degree stat in if they wanted 212, for some reason the Hellcat's got a 203 stat o_O.
 

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At tune time I will drop the thermostat to a 190 or 195 and have the tuner adjust the fan operation to work in the new range. Wouldn't go any lower than that. And I'm in the valley of the sun. It gets hot here. For quite a long time.

But I do make a point of using a thermostat that fails (and a lot of them do fail) in the OPEN position instead of the closed position.
Because I can still get home when it fails. When they fail in the closed position, you're screwed.

Fail-Safe Thermostats
 

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Don't do it. I have contributed in many threads listing the reasons to leave the thermostat alone, and what damage and the issues that occur when a lower stat is installed. You can search on my name. There are other owners with other horror stories as well. Suggest you leave it alone.
 

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Don't do it. I have contributed in many threads listing the reasons to leave the thermostat alone, and what damage and the issues that occur when a lower stat is installed. You can search on my name. There are other owners with other horror stories as well. Suggest you leave it alone.
Thanks for the info!
 

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Don't do it. I have contributed in many threads listing the reasons to leave the thermostat alone, and what damage and the issues that occur when a lower stat is installed. You can search on my name. There are other owners with other horror stories as well. Suggest you leave it alone.
Even with a pulley change and tune? Thx.
 
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