Stock Thermostat

[JWoj3540]

I'm thinking about throwing a lower temp thermostat in my SS. Does anyone know what the stock one is rated at? I've been watching my coolant temp on the DIC lately and it seems to stay steady a few degrees over 200 so I'm assuming its rated at 200 degF?

If running a slightly colder (160-180?) themostat is better for the engine then why doesn't GM put these in stock? I'm concerned that there is a reason they want it to heat up to 200 degF or so?

[scottyvegas]

Originally Posted by JWoj3540

I'm thinking about throwing a lower temp thermostat in my SS. Does anyone know what the stock one is rated at? I've been watching my coolant temp on the DIC lately and it seems to stay steady a few degrees over 200 so I'm assuming its rated at 200 degF?

If running a slightly colder (160-180?) themostat is better for the engine then why doesn't GM put these in stock? I'm concerned that there is a reason they want it to heat up to 200 degF or so?

I just had some work done on my car (header,cats,tune,etc..). They did change the thermostat. I believe there is some tune work that needs to be done so the fans come on @ the correct temp w/ new thermo. I may be wrong though...

[SUX2BU]

Originally Posted by JWoj3540

I'm thinking about throwing a lower temp thermostat in my SS. Does anyone know what the stock one is rated at? I've been watching my coolant temp on the DIC lately and it seems to stay steady a few degrees over 200 so I'm assuming its rated at 200 degF?

If running a slightly colder (160-180?) themostat is better for the engine then why doesn't GM put these in stock? I'm concerned that there is a reason they want it to heat up to 200 degF or so?

That's not the way thermostats work. The degree rating on a thermostat is when it begins to open, NOT at what temperature the car will run at. Many, many people make this mistake and that is why they don't like 160* thermostats. They say 160* is too low of an operating temp (I agree) but that DOES noyt mean the car will run at 160*.

The stock thermostat is 186.8*. GM puts hotter thermostats in the car for better fuel emissions.

Originally Posted by scottyvegas

I just had some work done on my car (header,cats,tune,etc..). They did change the thermostat. I believe there is some tune work that needs to be done so the fans come on @ the correct temp w/ new thermo. I may be wrong though...

You don't have to tune with a thermostat, but you won't get the full benefits. I would still rather run a 160* thermostat with no tuning than a stock one.

[Russell James]

You won't like the 160 on cool mornings, increases the heater warm up time.

If your running 200ish on a 186 stat, the car will also run 200 on a 160 stat. They both will be open at those temps.

The performance difference comes in if you alter the fan settings in the calibration to work the fans at higher speeds at lower temps. Maybe then there is a hair of performance to be gained. But on the downside, you just killed your 100K powertrain warranty.

For me, I'll keep the warranty vs messing with something that really isn't a problem and might be some slight performance gain.

Then you also have the risk of an aftermarket stat sticking and stranding you who knows where without a warranty to cover the problems. Food for thought if you travel. The fewer possible problems the better in my opinion. If I have a problem, I just like to take it to any dealer and say fix it, no problems.

They don't do it stock, because they engineer the correct temp stat for a number of criteria - eng longevity, mpgs, emissions, oil change interval, heater performance... 186 is the perfect one for all that criteria.

[SUX2BU]

Originally Posted by Russell James

You won't like the 160 on cool mornings, increases the heater warm up time.

Just saw he is up north, that isn't a problem down here in Texas. Actually I don't know if my heater even works, I've never tried it. LOL. Down here 160* thermostats are mandatory.

[Texas2SS]

Originally Posted by SUX2BU

Just saw he is up north, that isn't a problem down here in Texas. Actually I don't know if my heater even works, I've never tried it. LOL. Down here 160* thermostats are mandatory.

160 stat was included with my first few mods. It's a must.

[Nvincent4708]

Originally Posted by Russell James

You won't like the 160 on cool mornings, increases the heater warm up time.

If your running 200ish on a 186 stat, the car will also run 200 on a 160 stat. They both will be open at those temps.

The performance difference comes in if you alter the fan settings in the calibration to work the fans at higher speeds at lower temps. Maybe then there is a hair of performance to be gained. But on the downside, you just killed your 100K powertrain warranty.

For me, I'll keep the warranty vs messing with something that really isn't a problem and might be some slight performance gain.

Then you also have the risk of an aftermarket stat sticking and stranding you who knows where without a warranty to cover the problems. Food for thought if you travel. The fewer possible problems the better in my opinion. If I have a problem, I just like to take it to any dealer and say fix it, no problems.

They don't do it stock, because they engineer the correct temp stat for a number of criteria - eng longevity, mpgs, emissions, oil change interval, heater performance... 186 is the perfect one for all that criteria.

Not necessarily true!

I typically notice this from a SBC.. a 180 thermo will operate at 195 and a 160 thermo will operate at 175. these are my round-a-bout numbers

While driving this will be the case.. However to fully benefit you will need the fan turn on temps changed with a tune for when you are sitting still. when you are driving.. the thermo will stay lower just because air is moving.

[JWoj3540]

Really good points here guys, thanks. I think the takeaway is that to get the full effect of a lower temp t-stat, you should tune the cooling fans.

That said, it is really interesting to think about what's really going on here, I hear two trains of thoughts:

1. Thermostat will open at a lower temp and therefore will keep the mean temp of the engine cooler...otherwise, what would be the point?

2. Thermostat will open at a lower temp, however, your engine will still run up to 200 degF or so cause that is just the temp it gets to when it's fully warmed up? Even if you're stat opens at a lower temp, that won't stop the engine from heating to its operating temp.

[SUX2BU]

Originally Posted by JWoj3540

Really good points here guys, thanks. I think the takeaway is that to get the full effect of a lower temp t-stat, you should tune the cooling fans.

That said, it is really interesting to think about what's really going on here, I hear two trains of thoughts:

1. Thermostat will open at a lower temp and therefore will keep the mean temp of the engine cooler...otherwise, what would be the point?

2. Thermostat will open at a lower temp, however, your engine will still run up to 200 degF or so cause that is just the temp it gets to when it's fully warmed up? Even if you're stat opens at a lower temp, that won't stop the engine from heating to its operating temp.

# 1 is true, # 2 is half true. The engine doesn't have a set temp it gets to when it is fully warmed up. The temp goes up and down depending on what thermostat is in it and when the cooling fans come on.

If you have a 160* thermostat and don't change the fan setting the fans will still come on at the designated temperature, BUT when the fans do come on there will be MORE coolant circulating through the system because the lower thermostat will be open bigger. So, the car will cool down faster.

[BluegraSS]

I have a 160 degree thermostat in my 2012 L99 SS. With the stock thermostat my car's normal operating temp. was around 193-194. Now it's 182 or so.

[ackeight]

I've heard a lot of arguments for both sides. They both seem like they have valid points. One of the points I heard from a very reputable builder was that GM built the tollerances/peak power for around 195 degrees. That's where you want to run the car at. I know 10 degrees cooler may not make a difference, but I'm deciding on sticking with the stocker.

[Higgs Boson]

tuning the fans won't do anything with an aftermarket stat. why? because the lowest you can program them to come on is 192. the 160 stat runs in the 180s. the fans never come on unless you are sitting around not moving.

the fans are programmed to come on much hotter, like 210 in the stock program, so you can program them to come on earlier, but it is moot.

[Bo White]

Another big reason GM has higher stat temps is for engine wear. A colder engine wears at a higher rate than a warmer one.

[Higgs Boson]

I wonder what the engine wear differences are between 180 and 210. I also wonder what the power differences are. Any studies completed on this?