Considering a lower temp t-stat.

[Terry Posten]

Looks like we can get 160, 170, 180, 192, and OEM temp.

I only drive my car during spring, summer, and fall. It NEVER sees winter driving. Anything under 50 deg it will not come out of the garage.

Currently my car runs between 205-215 and want to lower that a little bit so that maybe the under hood temps will be a tad lower.

What is the general consensus on running a 170 t-stat?

 

[Barnes]

I guess I finding myself asking this question every time someone mentions a lower temp thermostat: why?

If your car does not overheat, what is the point? Does it have an effect on knock? I doubt it. Does it increase oil life? Maybe. Does it add an extra gadget to your mod list? Yes.

But seriously, I've never seen it explained what purpose this mod has on a 4g63.

 

[Brunoboy]

I have a 160 failsafe , its nice because my last 170 failed and would never blow hot on the heater

 

[Street Surgeon]

For posterity, why don't we include the pn's for all the above referenced thermostats /ubbthreads/images/graemlins/smile.gif

 

[vtecds1]

I have a 160 degree Beck/Arnley Thermostat Part No. 143-0687 .

 

[HHIVR4]

Ive been running a 160 for years..It gets really hot here and gives me some leeway if I get stuck in traffic and forget to turn on fans.

 

[belize1334]

The stock unit is fully open by 205*. I run a 180* unit which is fully open at about 199*. It's a slight improvement but I like it. I wouldn't advise going lower than that or you'll have issues with your fuel trims which won't update below 195*.

 

[turbowop]

I'm pretty sure the fuel trims update once the temps are over 180, not 195.

 

[grocery_getter]

ECU cold start routine ends at 176deg. If you can change when cold start routine ends to a lower temperature, like maybe 160deg and adjust the fuel map values then a lower temp thermostat that is lower than 176deg is a viable choice. Otherwise your car will be running in cold start mode all the time OR bouncing between cold start and normal running mode when the coolant temperature swings just to the left or to the right of 176deg.

I would advise to go with 180deg thermostat at the lowest with a stock ecu.

 

[jepherz]

Both posts from Mark and Andre beat my comments. But basically your car won't ever enter closed loop operation if it's that cold.

 

[Brunoboy]

I got better gas mileage with the thermostat . Went from 220 gas liight to 280 still no gas light aha

 

[jepherz]

Yeah, but you're probably comparing it to your broken 170 thermostat...

 

[Terry Posten]

I ordered the $7 170 deg unit.

I am also getting a 10"x10"x1.5" oil cooler with spal fan w/shoud to get some extra oil colling.

My goal is keep the temp gauge under 200F even in 90+ deg weather.

I will let you all know how it works out.

 

[4thStroke]

I don't know which t-stat is in my car (I haven't touched it since I got it), but the only thing that's different from last summer is now I use 20-50 synthetic oil vs the 1-30 or 10-40 conventional. My gauge starts creeping when I sit in traffic now with one fan on full time and the other switching on and off with the heater.

 

Here's my THEORY. The thermostat in normal operation will open and close and open and close, etc. The radiator has to be sized appropriately so that after the t-stat has opened and reclosed, the coolant that is stuck in the radiator gets cooled enough before the t-stat opens again. Think of it like swapping two batches of coolant, while one batch is being heated by the motor, the other is being cooled by the radiator, then they switch. Let's say that you're running that low temp t-stat, and its a real hot day. It would be possible to create more heat faster than you can get rid of it, a problem that is increased on cars that are heavily modified. Once you've reached the point that the t-stat is open and stays open(because the coolant in both the engine and radiator are hotter than the t-stat temp) the coolant never has any time to cool off, as it is just constantly circulating, there is the potential for an increased likelihood of overheating. My opinion: just get awesome fans and at the most, only go one step colder on the t-stat.

 

[iceman69510]

Quoting brunoboy:
I got better gas mileage with the thermostat . Went from 220 gas liight to 280 still no gas light aha



Very unlikely, as efficiency actually improves with warmer temps.

Terry, the temps you are seeing are not too hot. As long as you can maintain them, there really is not a problem.

 

[belize1334]

^^ But the t-stat isn't an on-off switch. Realistically it will open/close slowly and eventually find a fixed point somewhere in it's operation and stay there unless conditions change. Essentially you've got a differential equation for heat dissipation and one of the key parameters is the t-stat position which affects fluid flow. When you first kick things off you get a "transient response" which is what you're referring to with the open/close behavior. This eventually "rings down" and you're left with the steady state solution which for this kind of system should be stable... no on/off cycling but rather just a "partially open" configuration.

Of course if you're too cold or too hot then you saturate the response of the t-stat and then it's either closed or wide-open.

 

[Brunoboy]

Quoting iceman69510:
Quoting brunoboy:
I got better gas mileage with the thermostat . Went from 220 gas liight to 280 still no gas light aha



Very unlikely, as efficiency actually improves with warmer temps.

Terry, the temps you are seeing are not too hot. As long as you can maintain them, there really is not a problem.


then explain why it happened like this? maybe because I replaced the Coolant temp sensor that goes to the ECU?

 

[iceman69510]

Well there you go. Maybe now your engine actually knows what the temp is.

Still think that is too cool.