Thermostat question 180 or 160?

jlat

Greasemonkey
Jan 25, 2013
195
28
hello people: I have a 86T and I've been bouncing back and forth with a the stat question. The chip producer recommends 160 but when in the cooler months the coolant temp. doesn't get out of 160. I don't think that's good and I like what is said about consistency. I'm still going back and forth on what to do..
IBBY
 

melloelky

Comic Book Super Hero
Oct 22, 2017
3,157
113
mass
A Lot Power GIF by DreamWorks Trolls
 
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Supercharged111

Royal Smart Person
Oct 25, 2019
2,440
113
Colorado Springs, CO
Hot engines are rejecting less energy from a given amout of fuel burned as waste heat so more of it is available for work. In other words, hotter engines are more efficient at converting fuel to work and thus use less fuel for a given work output. Rejecting less waste heat causes the engine to run hotter. Running an engine colder means wasting more energy in the fuel as wastd heat rather than using it for work. Moreover, it is impossible to completely convert heat to work as there will always be some waste heat due to the second law of thermodyamics. Most ICE produce 2x waste heat compared to work.

Where's the point of diminishing returns on that? Somewhere in the 200 range because that's what everyone runs?

hello people: I have a 86T and I've been bouncing back and forth with a the stat question. The chip producer recommends 160 but when in the cooler months the coolant temp. doesn't get out of 160. I don't think that's good and I like what is said about consistency. I'm still going back and forth on what to do..
IBBY

Tuners love pushing 160 stats. I wouldn't do it on a street car. Make sure they know that. Unfortunately this sounds like a mail order tune.
 
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Clone TIE Pilot

Comic Book Super Hero
Aug 14, 2011
2,672
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Galaxy far far away
Where's the point of diminishing returns on that? Somewhere in the 200 range because that's what everyone runs?



Tuners love pushing 160 stats. I wouldn't do it on a street car. Make sure they know that. Unfortunately this sounds like a mail order tune.

The idea engine temp for combustion would be several thousand degrees, but that is impossible due to material limitations.
 

69hurstolds

Geezer
Supporting Member
Jan 2, 2006
5,646
113
I like my engines like I like my coffee- hot.

For one, the 160 T-stat thing, IMO, is a waste of money for the street. For one, hardly anyone does anything with the rest of their cooling systems to make the T-stat work in that range. They just pop it in thinking it's going to solve an over-heating issue. The cooling system does NOT care. It should open at or around the 160 deg F mark, and close if it's under that. What your engine does with that is up to how it's built and if you changed anything on the system to take advantage of it. If your system was running 200-210 before, tossing in a 160 T-stat by itself won't make any change in that except to be a flow restrictor because it will be open most of the time.

As previously mentioned, controlling the fan temp on/off is a big player in helping keeping things cooler when using that 160 because you're trying to move a cooling medium. But it's still not a panacea. And especially if you're running old-school and have a fan clutch instead of electric fans. Those things don't even engage until coolant temps start hitting the higher temps. There's so many variables that can affect combustion temps and coolant temps. From RPM changing to fuel mixtures to pump design, coolant flows, and air flow through the radiator (and also out of the engine compartment)- all that makes a difference. Couldn't tell you how many posts of frustrations I've read about someone changing out their radiator only to find out their cooling problem didn't go away. A lot of times, it's not just the radiator causing the issues.

Delta T and flow rates are the key. Over the years taking courses like heat transfer and fluid dynamics has opened a lot of eyes to how coolant systems actually work. I know it did mine. Additionally, working at a nuclear power plant gave me access to steam generator engineers who's entire life was about heat exchangers, cooling systems, and metallurgy. Talking to them was challenging because those guys lived on a different plane of life. But they always were happy to answer questions about stuff like that.

There's a reason GM chose 195 T-stats for most G-body applications and that's fuel efficiency and subsequently, lower emissions. They just put in bigger engines (I know, laughable) or added a turbo if they wanted more power. Faster warm ups, higher engine temps, CCC, thus lower emissions= happier Feds. Parts book doesn't even give you a choice. Darn near everything is 195 except the turbo Buick, which is 180. GM part number 3041390 for V6, and 3051139 for V8, 195. (3054228 for 84-85 Turbo V6, 3037745 for 86-up Turbo V6)

Can you get by with a 180? Sure. I had been using 180s in most everything since I started working on cars. The only real problems I had with 180s is when they didn't work right. That's why you should test them before installation regardless of which you choose. I've caught 2 in my life that were dead right out of the box. It's not fun changing a T-stat twice because you didn't check it first.

This is all JMO, so take it with a grain of salt.
 
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Cuse99

Greasemonkey
Thread starter
Dec 21, 2020
218
43
Wow - I didn't think this questions would get so much attention. I appreciate all the feedback.
 
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64nailhead

Goat Herder
Supporting Member
Dec 1, 2014
3,347
113
Upstate NY
Wow - I didn't think this questions would get so much attention. I appreciate all the feedback.
The coolant range is an old school myth that has been busted many times, kinda like ignition timing, roller rockers, 6AL boxes, and so on.

It’s a crutch on a crutch as explained earlier by Clone TIA imho.

I’ll go out in a limb and bet that if you were to spend a day of tuning your timing curve, that you’ll drop you around town and highway temps by 10 degrees and most likely gain 10-15hp in the process. But damn is that time consuming.

And yes, this is a great topic that applies to every liquid cooled motor built.
 
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83MonteCarloSS

Apprentice
Oct 5, 2015
86
33
The coolant range is an old school myth that has been busted many times, kinda like ignition timing, roller rockers, 6AL boxes, and so on.

It’s a crutch on a crutch as explained earlier by Clone TIA imho.

I’ll go out in a limb and bet that if you were to spend a day of tuning your timing curve, that you’ll drop you around town and highway temps by 10 degrees and most likely gain 10-15hp in the process. But damn is that time consuming.

And yes, this is a great topic that applies to every liquid cooled motor built.
I almost hate to ask but what is the ignition timing myth you mentioned?
 

melloelky

Comic Book Super Hero
Oct 22, 2017
3,157
113
mass
Wow - I didn't think this questions would get so much attention. I appreciate all the feedback.
something to keep in mind with this particular rabbit hole,temp sensor placement can dictate "different" temperatures.by that i mean GM located them in the head which is known to be a hot(er)spot.so if you run yours in the intake closer to said 'stat vs the head you might see a difference in your particular reading/application/set up etc etc.so with *** temp 'stat in either location it might be a different experience for you compared to the next cat.
 
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