180 degree thermostat? Why?

AlanEdwards

Registered User
I've seen on here in some signatures that some guys use a 180 degree thermostat as a performance modification.

What's the factory, 190?

And, what will a 180 do for us as far as engine performance?
 
AlanEdwards said:
I've seen on here in some signatures that some guys use a 180 degree thermostat as a performance modification.

What's the factory, 190?

And, what will a 180 do for us as far as engine performance?
It just opens a valve when the temperature of the engine reachers 180 degrees F, instead of 210 (correct me if I am wrong) which allows coolant to run on the big loop anf cool down the engine. As you know, our cars run very hot due to the M90. Therefore, the lower the temperature the better performance of your car and better for the engine from the mechanical point of view! Just do it! :D
 
I appreciate the reply, but I know what a thermostat is and what it does, and what it's for. I was just wondering about the lower temp and what the factory temp is supposed to be. I think that 210 is way too hot for factory though. Maybe 190 or 195. Anyway, I also understand that a 180 will make the engine run richer as well, decreasing gas mileage. How much of a difference will it make in regards to this? I've also read that the factory thermostat and temp is best. What do you guys think?
 
well

well it's true a factory t staty is best, which is 197. switching to 180 without doing anything else wont do much without modifying when your fan comes on. think about it, when the coolant temp reaches the factory 197 degrees, thats when the t stat opens to allow coolant to move through the radiator to be cooled off. Now if you change t stats to the 180, now it opens when the coolant is at 180 even though the radiator is still cooling off the coolant at the same rate, so basically the coolant is flowing quicker and the radiator cannot cool off the coolant as fast so it can sometimes actually make the car run hotter. However if you connect your rad fan to a switch and have it on while running the 180 t stat it will help cool off the coolant as fast as it flows with the 180 stat helping lower temps of engine. I switched to a 180 and i live in the texas climate and i just put my AC on whenever i need a fan cycle and it helps, or unplug my AC and keep the AC switch on which runs the fan all the time under 45 mph. If you live more north though where the temps are pretty much below 75, switching to a 180 will probably help because the airflow to the rad from the atmosphere should be cool enough. One time in winter when it was 50 degrees here in texas i got on the highway and was going down a hill where i didnt need any gas and i actually SAW the temp gauge drop, it was nice. As far as running richer and stuff, it's true that the computer is thrown off a bit, but i dont think it's very much. id sacrifice a few mpg for keeping your headgaskets and engine cooler. I've been ok with my 180 now for over 2 years. So in my my own experience, id change it if u live in the cooler climates. good luck-
Damon
 
GREATWHITE666 said:
So in my my own experience, id change it if u live in the cooler climates. good luck-
Damon

Damon,

Thanks for all the info. I'm in TX now and will soon be going back to Atlanta then to Tampa, FL. I'll keep the OEM stat in for now. Take care.
 
This information has been both posted and discussed many times but often the answers get lost in the threads as I am sure this one will also.

Nonetheless....

The stock thermostat is 195 deg. The stock fan is set to come on at 220 deg. This was done for a couple of reasons. 1) the higher the coolant temp, the more efficient the radiator is and the more effective the coolant is at removing heat. This allows the use of an undersized radiator and assures more even heat distribution in the cylinder heads. This would be a good thing. 2) higher operating temperatures keep the oil cleaner, emissions lower, and combustion more complete. This is also a good thing.

However.

The problems are: 1) Extreme system pressure. With an overall system that is prone to leaks (rad cap, multitude of hoses, thermostat housing, headgaskets, etc, these pressures tend to cause problems. 2) at those high temperatures, there is little margin before the coolant boils. 3) increased operating temperatures reduce the opportunity for power production as the blower and IC get badly heat soaked from engine bay temps. 4) The EEC starts to pull timing very quickly if temps approach 220 deg. 5) There is a good reason for the EEC pulling timing at 220 deg. Detonation becomes a big problem due to the higher inlet air temperatures.

So.

1) People notice that their car run significantly better when cool than when fully warm. This is very true because by the time the fan comes on the EEC has pulled timing and performance will go down. Logic finds it to be silly for an engine to be going into "protective mode" when it is really just at normal operating temp.

2) The EEC goes into normal operating mode at 180 deg, so there is no fuel economy drawback to running cooler.

3) There is no significant emissions effect to running cooler for our purposes. The OEM has specific requirements for the time required from cold start to full emissions compliance. Once you own the car you are no longer tested on cold start emissions. Many parameters in the EEC (and in the hardware as well!) are pointless after the car rolls of the dealer's lot.

3) If you do run a cooler thermostat, you may find that the radiator is less effective at maintaining a set temperature. It was marginal in size in the first place, and with a cooler desired operating temperature, it may have difficulty keeping up, particularly if you have numerically higher rear end gears or live in an overly hot climate.

4) Note: stock thermostat - 195 - stock fan temp - 220. Desired aftermarket thermostat - 180 - aftermarket prefered fan setting - 195. The target temp for a 180 thermstat is 190-195 deg most of the time, 180 for racing/track conditions.


Bottom line is that your engine should have had a 180 thermostat in the first place. In a perfect world it would be practical to maintain 200+ deg operating temps, a supercharger, and your headgaskets. However, with the fact that the 3.8L engine has its limitations, the SC overall has some design flaws, and most of us would like to at least maximize whatever output our individual SC's have, it is in your best interest to run a 180 deg thermostat.

With a 180 deg thermostat, you will find that the cooling system rarely ever develops enough pressure to push any coolant past the stock 16psi cap. On my car the coolant level in the reservoir never fluctuates and the hoses never get particularly firm.

The best way to compliment the 180 thermostat is with a chip that controls both fan speeds and shuts the fans off on the highway. We also set the switching temp for the EEC down from 180 to 160 deg so you never have to worry about dipping into the startup fuel tables on a cold day.

If you do drop engine temps by 20-25 deg you will find the performance is much more predictable and consistent. It can easily mean a good .5 sec improvement in performance in the 1/4 mile.
 
Well Dave, with the risk of sounding fickle, you've talked me back into it. I guess I'll be getting a 180 again. Thanks for the extensive detail. Take care.
 
Where To Buy?

XR7 Dave said:
This information has been both posted and discussed many times but often the answers get lost in the threads as I am sure this one will also.

Nonetheless....

The stock thermostat is 195 deg. The stock fan is set to come on at 220 deg. This was done for a couple of reasons. 1) the higher the coolant temp, the more efficient the radiator is and the more effective the coolant is at removing heat. This allows the use of an undersized radiator and assures more even heat distribution in the cylinder heads. This would be a good thing. 2) higher operating temperatures keep the oil cleaner, emissions lower, and combustion more complete. This is also a good thing.

However.

The problems are: 1) Extreme system pressure. With an overall system that is prone to leaks (rad cap, multitude of hoses, thermostat housing, headgaskets, etc, these pressures tend to cause problems. 2) at those high temperatures, there is little margin before the coolant boils. 3) increased operating temperatures reduce the opportunity for power production as the blower and IC get badly heat soaked from engine bay temps. 4) The EEC starts to pull timing very quickly if temps approach 220 deg. 5) There is a good reason for the EEC pulling timing at 220 deg. Detonation becomes a big problem due to the higher inlet air temperatures.

So.

1) People notice that their car run significantly better when cool than when fully warm. This is very true because by the time the fan comes on the EEC has pulled timing and performance will go down. Logic finds it to be silly for an engine to be going into "protective mode" when it is really just at normal operating temp.

2) The EEC goes into normal operating mode at 180 deg, so there is no fuel economy drawback to running cooler.

3) There is no significant emissions effect to running cooler for our purposes. The OEM has specific requirements for the time required from cold start to full emissions compliance. Once you own the car you are no longer tested on cold start emissions. Many parameters in the EEC (and in the hardware as well!) are pointless after the car rolls of the dealer's lot.

3) If you do run a cooler thermostat, you may find that the radiator is less effective at maintaining a set temperature. It was marginal in size in the first place, and with a cooler desired operating temperature, it may have difficulty keeping up, particularly if you have numerically higher rear end gears or live in an overly hot climate.

4) Note: stock thermostat - 195 - stock fan temp - 220. Desired aftermarket thermostat - 180 - aftermarket prefered fan setting - 195. The target temp for a 180 thermstat is 190-195 deg most of the time, 180 for racing/track conditions.


Bottom line is that your engine should have had a 180 thermostat in the first place. In a perfect world it would be practical to maintain 200+ deg operating temps, a supercharger, and your headgaskets. However, with the fact that the 3.8L engine has its limitations, the SC overall has some design flaws, and most of us would like to at least maximize whatever output our individual SC's have, it is in your best interest to run a 180 deg thermostat.

With a 180 deg thermostat, you will find that the cooling system rarely ever develops enough pressure to push any coolant past the stock 16psi cap. On my car the coolant level in the reservoir never fluctuates and the hoses never get particularly firm.

The best way to compliment the 180 thermostat is with a chip that controls both fan speeds and shuts the fans off on the highway. We also set the switching temp for the EEC down from 180 to 160 deg so you never have to worry about dipping into the startup fuel tables on a cold day.

If you do drop engine temps by 20-25 deg you will find the performance is much more predictable and consistent. It can easily mean a good .5 sec improvement in performance in the 1/4 mile.

Is the 180 deg. thermostat something I can pick up at a local NAPA store, etc? I'm doing an I/C fan install this weekend, and am also going to change my coolant to 25% ethelyne glycol/75% distilled water, w/WaterWetter as an additive. It's an excellent opportunity to change my T/S also.

Questions:

Is there a particular brand/type of ethelyne glycol that is best?

Is there a slick way to get the water out of the heater core? I'm trying to get as much old coolant out of the system as possible since the radiator and block plugs will be out anyway.

What is the chip you mentioned to alter the fan function?

How is the switching temp on the EEC modified from 180 to 160? I assume it involves reprograming the box.

Thanks for the thorough and informative information on this subject!

Jerry Davis
(830) 237-6632
 
We are always learning things and looking for new answers to old problems. The information I have posted above has been gleaned from posts by many others as well as personal experience and information received directly from others. It is not meant to be a comprehensive open/shut case on thermostat and cooling choices. Use it to help you decide and understand what you want to do with your car.
 
txsc said:
What is the chip you mentioned to alter the fan function?

How is the switching temp on the EEC modified from 180 to 160? I assume it involves reprograming the box.

You would need to purchase a aftermarket chip that overrides the preset functions of the ECU. XR7 Dave sells the SCT chip. He can help you out.

There is another way to get the fan to start earlier, that involves a couple of relays and temperatures probes. I haven't done this yet, so I can't help with doing this.
 
Nice post Dave. Very informative stuff. However, when you say, "at those high temperatures, there is little margin before the coolant boils"....wouldn't increasing your pressure cap to a higher pressure increase your boiling point. If one were so inclined to keep their SC at "those high temperatures" without reducing their margin of error.

I don't know...which is why I'm asking. Just trying to confirm or deny stuff I've been told.

Micah
 
Micahdogg said:
Nice post Dave. Very informative stuff. However, when you say, "at those high temperatures, there is little margin before the coolant boils"....wouldn't increasing your pressure cap to a higher pressure increase your boiling point. If one were so inclined to keep their SC at "those high temperatures" without reducing their margin of error.

I don't know...which is why I'm asking. Just trying to confirm or deny stuff I've been told.

Micah

For example, I have a 180 degree thermostat and a rad cap rated for 16psi. When temps hit 210 I know something is wrong and have a margin of time to resolve it because the car won't boil over till 235 deg.

When you are running at 220, you don't have much margin. You can only increase the boiling point so far, and when you do run such high coolant pressures you open the door to more leaks/blown items. How many cracked radiators, blown heater cores, leaking thermostat housings, bypass hoses, etc (I'll leave headgaskes out of this ;) ) have we heard about here? Reducing cooling system pressure all but eliminates those problems.

This is the part of the above post that is my opinion, just so you know where the theory comes from.
 
On my 92 5-speed w/ 3.27 gears, I have a 160 degree thermostat and the #14 wire disconnected on my IRCM. Fan (low speed) runs any time key is on. In town the gauge stays around the N on NORM. On the highway though it gets up to the R on the gauge. I don't know if its because the water isn't getting time to dissapate the heat through the radiator since its constantly flowing. I thought the fan was blocking air flow at highway speed (70 mph) so I unplugged it and the damn car got even hotter.

It runs rich as hell and my gas mileage is terrible. Now I assume the stock gauge is just an "idea of temp" I do have a brand new sending unit in it. I assume the car always stays in warm up mode which dumps more fuel and causes my car to run rich. Keeping it extremely rich also must lower my horsepower output since I noticed leaning out a mixture will put out more power but there is a happy medium w/ the A/F ratio.

So I'm thinking I have two options, get a chip to reprogram my EEC to be warm at 160 degrees, or switch to a 180 or 195 t-stat.

I'm sort of leary of running a hotter stat because it may run hotter on the freeway. But if my theory about dissapating heat in the radiator is correct, having a warmer stat will make the radiator cool the coolant more effectively.

So should I go to a 195 or 180? I'd like my gas mileage back. I got 345 miles out of a full tank mixed city/highway. Figuring I had about a gallon left in the tank, thats only 19.1 mpg. Kinda low.

My 90 SC w/ tight head gaskets, has a 195 t-stat and a relay on the fan w/ a switch. I only run the fan in the city when I am sitting in traffic. It gets 21 mpg city and 24-26 on the highway. I am very happy with that. I had a 160 in it and this past winter it wouldn't put out much heat so I put a hotter stat in it.

Oh and if I go w/ a 180 will the computer lean out my mixture so I can get better gas mileage and more power? Or will I need to get a chip? I am holding off on a chip till I get a better blower or bigger injectors. Right now I've just opened up the intake and exhaust, changed the gears, and spin the blower faster.
 
When I worked at Auto Zone I realized the small block chevy t-stats fit in the SC. They don't have the littly bypass hole, but I haven't ran into any problems running them in the SC.

Part numbers are:

400-160 = 160 Degree
400-180 = 180 Degree
400-195 = 195 Degree

Auto Zone doesn't have a listing for a t-stat gasket for our SC's (at least not the Auto Zones up here) so I have a bunch traced onto gasket paper and I cut them out with an exacto knife when I need one. I use a little bit of super high tack to hold the gasket to the housing, and a little dot of red loctite on the top and bottom lip of the t-stat to hold it into the housing. That way when you go to install it, it won't slip down causing the gasket to leak. And its easily removable when you want to replace the t-stat.
 
Delta current control

I am gagaah over my Delta current control, I works great! :)
http://www.dccontrol.com
I can jumper set whatever temp I want to run the engine at by
varing fan speed.

With my MP FMIC i did NOT like the (1) one speed fan.

The Delta variable speed fan control keeps the engine at
a CONSTANT temperature by regulating fan speed.
In other words, if the engine temp increases so does the fan speed,
and as the engine cools the fan speed decreases.

I had installed a Hayden temperature sensor and relay
to turn on the fan sooner because FORD sensor/computer does not turn
fan on until what 210+ or NOTHING.
So we are looking at a temp change of at least 180 to 210 = 30 degrees?

The one speed fan would go full blast when engaged
by the Hayden thermal sensor OR nothing, and very noisy.
I did not like the noise from the fan at full blast.

I did not like the engine temperature CHANGING between
medium and low temperature on the FORD gage, due to the way
FORD's or Hayden's temp sensor is set up.
Running the fan full on has got to reduce the fans lifespan.
Engine temperature fluctuation can NOT be good for the HG.

I just put a Delta Current Control in and it WORKS as claimed.
and is surprisingly quiet, and fan turns slow.

Just set the radiator temp per http://www.dccontrol.com/fk35.htm

Now when I turned off the engine the fan is still turning but very quiet.
(vs full blast). I like the post radiator cooling.

However, I wedged the temp probe sensor between the fins and the housing,
as I could not get the probe between the fins.

I think I may put a Delta current control on my tranny cooler fan.

With the stock fan, I guess I would disconnect either the high speed fan
or low speed fan, and use one or the other with the Delta Current Control.
 
Caution about 180 or lower degree thermostats

For those that live in northern climes and run their cars in the winter I would caution against running a 180 degree or lower thermostat. At the least switch back to a OEM rated for the winter. The EEC doesn't get out of Cold Start Strategy until like 185 degrees coolant temps. In cold weather you will never get there with a 180 degree thermostat. The effect is essentially running around with the electronic "choke" ON all the time. MPG goes down dramatically as well as fuel dilution of the oil due to all the "extra" and uneeded fuel dumped in the cylinders. BTDT
 
Ok, tomorrow afternoon I'll be replacing my t-stat with a hotter one and hope to gain back some gas mileage. I'll also change the oil and filter to be on the safe side.
 
Scott,

You misinterperted what I wrote. My caution only applies to situations where due to low outside temperatures the engine can't maintain a temp. above 185 degrees due to the lower rated thermostat being installed. In the summer it is doubtful that the condition noted would occur even with a 180 degree thermostat installed.
 
Well I have a 160 in there right now and the car runs pig rich and gets 19 mpg on the highway. So I am going to put in a 180 tomorrow. That should let the fuel burn more efficiently and get the computer into normal mode so that I am not running it in "choke" mode.
 
1) the higher the coolant temp, the more efficient the radiator is
I agree with this, but that is only because a heat exchanger efficiency goes up with a temperature difference.
and the more effective the coolant is at removing heat.
All this means is that it is removing more heat, because there is more heat there.

XR7 Dave said:
3) If you do run a cooler thermostat, you may find that the radiator is less effective at maintaining a set temperature. It was marginal in size in the first place, and with a cooler desired operating temperature, it may have difficulty keeping up, particularly if you have numerically higher rear end gears or live in an overly hot climate.
Yeah, but so what. It will run cooler longer. Worst case senaro it will maintain at the temperature the radiator was designed for. You aren't lossing any cooling capacity. You are just trying to delay the designed operating temp, which in most cases kicking the fan on earlier w/ the the lower thermostat temp will do.

Now, I agree with everything David posted here, it just seems like it could easily be taken out of context.

It, however, makes absolutly no logical sence why only putting in a lower t-stat will cause your car to run hotter. There might be a little more overshoot and/or settling time, but once it hits the 195+ or whatever they are going to function the same. And if you are operating at that temp, then the 195 t-stat will simply put more osciliation into the temperature of the system.
 
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