180 T-Stat

[wykabryan]

Hey there guys.

I just came back from the dealer where I found out my t-stat is bad. They wanted to replace it with the normal 210 T-stat. I declined because I want to put a 180-195 in its place. This pissed the service guy off. He then went into a rant about how I was not going to get anything and the car would never work again. He did mention something that did strike me.. Do I have to do anything about the computer chip that regulates the t-stat? I have a 04 prix gtp. I was under the impression that once the new stat was in place the computer would self-adjust. Any input would be great.. otherwise I may have to go back for factory.

[TDCRacing]

You can put a 180 or a 160 in and have no problems what so ever as far as the computer or car goes. The PCM commands closed loop at about 78*F. You may hear stories about it washing down the cylinders because of excess fuel because the pcm is commanding too rich of a fuel mixture but all of wich is untrue.


You probably wont see any differences in town on your temp gauge because of the temp that the fans are set to come on at but on the highway you will notice a pretty good drop. My opion is to go with a 160. Even with a 160 you will see temps around 175 on the highway...and if the fans were set to come on lower you would also see around 175-180 in the city.


There is really no power increase in doing this.(lower temp t-stat) but things that get hot do last much longer when they run cooler. Like computers or electronics for example.


bottom line is it wont hurt anything to put a 160 or 180 t-stat in and will run you about 10-12 bucks.

[JoshMcMadMac]

210° is not stock. Stock is 190-195°. Your fans are set to come on above the 195° thermostat, so going to a 180° one your fans will not correlate. Just leave it stock; there is barely anything to be gained from anything else for you at this point.

[Freebeer187]

160 T-stat will make the car take forever for the cabin to heat up.

[TDCRacing]

I don't have any problems. Although I hardly see under 30*F here

[Zef_66]

While I agree that you can safely and without issue run a cooler t-stat, even a 160°, I don't agree that you should go ahead and do it.

I know I have said this all before, and some people may agree with me, but there is nothing to be gained by running a cooler t-stat on a car that is properly modded, and it will in fact, lessen your performance and increase your fuel use. So not only will you be spending more money on fuel, but you will not see any increase in performance, and often will see a decrease in performance.

As stated, stock should be a 195°F thermostat. If you are going to run a cooler thermostat, like I do at the track in the summer, to get the most benefit, you will need to change your fan turn on points. Otherwise, you fans won't turn on until the stock points which is somewhere around 210°.

Again, you can do what you want, but many people don't understand what happens when they run a cooler t-stat, and 98% of the time, it is not needed (if modded correctly), especially on a stock car.

[Freebeer187]

I don't have any problems. Although I hardly see under 30*F here

Lucky!!!!!!!!!!!!!!!!!!!!!!!!

[Freebeer187]

While I agree that you can safely and without issue run a cooler t-stat, even a 160°, I don't agree that you should go ahead and do it.

I know I have said this all before, and some people may agree with me, but there is nothing to be gained by running a cooler t-stat on a car that is properly modded, and it will in fact, lessen your performance and increase your fuel use. So not only will you be spending more money on fuel, but you will not see any increase in performance, and often will see a decrease in performance.

As stated, stock should be a 195°F thermostat. If you are going to run a cooler thermostat, like I do at the track in the summer, to get the most benefit, you will need to change your fan turn on points. Otherwise, you fans won't turn on until the stock points which is somewhere around 210°.

Again, you can do what you want, but many people don't understand what happens when they run a cooler t-stat, and 98% of the time, it is not needed (if modded correctly), especially on a stock car.

Ive noticed on zzp and places like that, the say you need to have a 180 T-Stat in to run a 3.4 pulley... And from the looks of it it doesnt not do very much for you. I understand its role in the car (keep your parts more cooled than normal). Do you think you could just skip it?

Chicago winters are cold enough, my car wont have any problem keeping cool

[TDCRacing]

Ive noticed on zzp and places like that, the say you need to have a 180 T-Stat in to run a 3.4 pulley... And from the looks of it it doesnt not do very much for you. I understand its role in the car (keep your parts more cooled than normal). Do you think you could just skip it?

Chicago winters are cold enough, my car wont have any problem keeping cool

Yes

[TDCRacing]

While I agree that you can safely and without issue run a cooler t-stat, even a 160°, I don't agree that you should go ahead and do it.

but there is nothing to be gained by running a cooler t-stat on a car that is properly modded, and it will in fact, lessen your performance and increase your fuel use. but you will not see any increase in performance, and often will see a decrease in performance.

If you are going to run a cooler thermostat, like I do at the track in the summer

I agree except on one thing. How will it make you're car preform worse? I am not trying to bash or anything like that. but you say you use a colder one at the track,where performance is essential. Just explain to me what you mean is all im asking. Maybe i'll learn something.

[Zef_66]

I agree except on one thing. How will it make you're car preform worse? I am not trying to bash or anything like that. but you say you use a colder one at the track,where performance is essential. Just explain to me what you mean is all im asking. Maybe i'll learn something.

It is the basics of how an engine works. A hot engine, with cooler air will perform the best. As the engine cool or the incoming air/fuel gets warm, the performance suffers. Power is made by burning fuel and using the heat that is produced to force the piston down. The more heat that is made, the more force the piston is pushed with, the more HP the engine has. If you are running coolant and thus cylinder walls at 195°F (I know the cylinder walls will not be this temp, but it is all relative, so work with me here), a certain amount of heat is lost to the cylinder walls and into the coolant during combustion. If you lower the coolant temp, the cylinder walls will be cooler, and more heat will be lost during combustion. The more heat that is lost during combustion, the less heat there is to move the piston, thus the less HP.

The reason that many people started using a cooler t-stat is to cure problems with knock retard. This knock retard was caused by excessive heat due to the forced induction on our cars. If modded properly, a car will not have any KR on a stock t-stat, and thus a cooler t-stat is not needed. Only when a car is not modded correctly will KR occur. In these cases, it may seem that the cooler t-stat, which is preventing KR, improves performance. While really, it only corrects a problem that was limiting performance. Again, if modded correctly, KR isn't a concern and a stock t-stat can be used.

Now when drag racing at a track, heat is an issue due to the nature of the racing. Many times racers need to sit in the staging lanes idling and heat soak becomes an issue. Also, multiple back to back WOT runs to get a car dialed are sometimes necessary. In these extreme cases, a cooler t-stat can keep things from excessive heating up. But the cooler t-stat obviously needs to be tuned in, in order to be effective. But again, this is an extreme case that many people don't experience on a daily basis.

So this is a general line of thinking that affects most people that drive their cars on a daily basis. As I said, racing at the track I consider an extreme environment where conditions are different than daily driving and occasional street racing. But for the majority of people on this board, a stock t-stat will work better, both performance and economy, in most applications.

[wykabryan]

Thank you all for your input. I would have to agree with Zef_66 that I do not see it as being essential if you properly mod it. My car only has CAI on it for now. I do plan on doing additionally stuff but does it make since to have a cooler stat with the onset of winter in chicago. The car does need some warmth to keep things moving correctly. Logically there is no point to do it until additional mods are made and level are monitored in both city and highway driving.

[TDCRacing]

Thanks for explaining you're self. And again the only reason i have a thermostat is to keep the engine as cool as possible. Not for performance.Not for any gains in mpg or horsepower but to simply not let the engine heat up as much to try to preserve it as long as i can lol.Is it really helping in doing that? ehh...probably not... but sometimes as you said it's the little things that count.

Take it easy man.

[Sabrewings]

My main complaint with the stock tstat setup is this. It heat soaks and absolutely saturates the heads until it opens up. With the tstat closed, there is precious little coolant flow through the block and heads (only the heater core is getting flow, really). Your coolant sensor is right beside the tstat on the LIM.

While the tstat and ECT sensor are seeing about 190* (just before opening of the stock tstat), the coolant that is just sitting still in the heads and block around the cylinders could be reaching 250+. It's just stopped soaking up heat and letting the heads get super hot. If you're viewing the temp on a digital gauge (since the dash gauge is sluggish to react), you can see at the point of the tstat opening the coolant temp spikes as all this super hot coolant comes out towards the radiator. Now, what's worse is in winter after all that super hot coolant is gone it's replaced with super cold coolant from the radiator. This alone can crack parts.

The bottom line of all this... get a drilled tstat, even if it is only stock temp. This will keep coolant from just sitting still. Yes, the car will take longer to heat up (about 50% longer, as I am realizing after installing a drilled Saturday) to full temp. But, to me it's worth it to keep sudden shocks to the system minimal. Can you imagine what it must be like for your engine to have some parts with coolant sitting at over 250*F then suddenly get jammed with -15*F coolant?

[Zef_66]

Thanks for explaining you're self. And again the only reason i have a thermostat is to keep the engine as cool as possible. Not for performance.Not for any gains in mpg or horsepower but to simply not let the engine heat up as much to try to preserve it as long as i can lol.Is it really helping in doing that? ehh...probably not... but sometimes as you said it's the little things that count.

Take it easy man.

I don't understand this? I don't see any gains in keeping your engine cool. No performance. No economy. I just don't see the point in keeping the engine cool. You need a hot engine to make more power and better economy. Just take a look at Nascar engines. They typically run 230°-250°F. They don't try to keep their engine down to 160°F because they know there is no point in it.

My main complaint with the stock tstat setup is this. It heat soaks and absolutely saturates the heads until it opens up. With the tstat closed, there is precious little coolant flow through the block and heads (only the heater core is getting flow, really). Your coolant sensor is right beside the tstat on the LIM.

While the tstat and ECT sensor are seeing about 190* (just before opening of the stock tstat), the coolant that is just sitting still in the heads and block around the cylinders could be reaching 250+. It's just stopped soaking up heat and letting the heads get super hot. If you're viewing the temp on a digital gauge (since the dash gauge is sluggish to react), you can see at the point of the tstat opening the coolant temp spikes as all this super hot coolant comes out towards the radiator. Now, what's worse is in winter after all that super hot coolant is gone it's replaced with super cold coolant from the radiator. This alone can crack parts.

The bottom line of all this... get a drilled tstat, even if it is only stock temp. This will keep coolant from just sitting still. Yes, the car will take longer to heat up (about 50% longer, as I am realizing after installing a drilled Saturday) to full temp. But, to me it's worth it to keep sudden shocks to the system minimal. Can you imagine what it must be like for your engine to have some parts with coolant sitting at over 250*F then suddenly get jammed with -15*F coolant?

I agree that heat soak can be an issue when drag racing. For that reason, I run a cooler t-stat when racing. But not any other time because heat soak isn't really an issue. What do I care if my incoming air is a little hotter while sitting in bumper to bumper traffic. I don't WOT immediately afterwards. So performance isn't really an issue in that case.

As for the coolant just sitting in the heads, sorry, but it doesn't. Typically the open and close of the t-stat during normal operation is a constant in and out. Usually soon after it closes, it will open right back up. It doesn't stay closed for long. And the water pump is a constant moving part that is pushing the coolant all the time. So it has that pushing the coolant around as well. And not to mention that warm water will rise, and cold will fall, so as the coolant is heated, it will immediately rise to the top of the coolant system, which is where the t-stat and temp sensor is.

Also, you mention the -15°F coolant hitting 250° coolant. Again, this simply does not happen. As mentioned, the water pump is churning all the time. While it is taking in cooler coolant, it is constantly mixing that with the hot. So by no means will -15°F coolant ever meet 250°F metal. Unless of course you are silly and run without a t-stat or something like that. But even on the coolest of days, down below 0°F, after my drive to work, my radiator is warm, almost hot to the touch. So I would imagine that on the coldest of days, the coolant in the radiator still gets to a warm 140°F.

And I think you are thinking that the t-stat opening will let in this rush of freezing cold coolant. It just doesn't happen that way. Your t-stat functions very quick at the operating temp. Put it in a pot of boiling water and watch it move. Then drop it in a pot of cold water. It closes immediately. So as soon as the coolant temp hits 195°F, the t-stat will start to open, and as soon as it drops to around 190°F, which doesn't take too long, it will close shut.

So in no way does the coolant ever, ever sit still. Simply not an issue because it never does this. It has the water pump pushing all the time, the t-stat constantly opening and closing, and the fact that as the coolant gets warm, it rises automatically to the top, where it will contact the t-stat and make it open. It never sits still.

[Sabrewings]

Yes... it sits still any time it is closed (which is during the entire warm up cycle, which is what my post was referring to). This is with the exception of the small amount routed to the heater core. Once you've hit your warm up temp, the tstat can settle at a partially open position to keep the temperature constant for the load. Going down the highway it isn't constantly opening and closing.

And, the coolant in the radiator doesn't move until you first hit operating temp. Don't believe me? Hold the upper radiator hose. It will stay ice cold on a winter morning until the tstat hits operating temp then you will feel a rush of extremely hot coolant. Every vehicle I've owned or worked on has done this (dead give away on when it's good to bleed). There are tons of reports in northern Canada where they're recommended to run a small hole in their tstat to gently warm the radiator coolant prior to the opening of the tsat. Yes, engine damages have been reported from this happening.

Ever looked at specifically how coolant is routed through the engine? The heater core is somewhat "parallel" to the radiator. It has one hose on the higher pressure side of the pump and one on the lower pressure side. It can pick up enough heat during the warm up cycle to give you heat. But overall most of the coolant in the engine is at a stand still. Yes the pump is pumping but due to its design (centrifugal veins) it can pump against a near solid wall of water without caring.

The entire time you're driving before you hit your operating temp your radiator coolant is just sitting, the same as most of the coolant in the block. Once that tstat finally opens (yes, it does seal 100%) then it starts to displace the hot coolant in the block. This is where you get cracked blocks from sudden temperature changes. If the car was flowing coolant through the radiator the entire time, then drilling it should have little to no effect and I can tell you it has a major effect on warmup time. Simply due to having to heat a lot more coolant during the warm up cycle, and having to keep it warm if you're driving.

And running without a tstat would never have the "-15*F coolant meeting 250+*F parts" effect because all the coolant would heat evenly because none would be isolated (either in the radiator or in the block).

I think you're under the impression when the tstat is closed there is still some flow to the radiator with the stock tstat. This is simply not the case, and is why we have drilled tstats in the first place (to prevent heat soak on parts like the heads which can lead to knock). I've already seen a drop in knock with a stock temp tstat but drilled due to the heads remaining at the intended coolant temp and not getting too hot during the warm up cycle.

Here's more info for you, from Wizbang:

To help resolve these theories and conjectures, I obtained a test vehicle (Pontiac Grand Prix GT, L36 engine) with a complete factory powertrain system. No performance modifications were done to the vehicle other than swapping out the thermostat for this test. The testing would involve replacing the factory 195ºF thermostat with a modified 180ºF thermostat obtained from ZZPerformance. The 180ºF thermostat was modified by drilling four small hoses around the thermostat body to permit a small amount of coolant flow through the cooling system even when the thermostat is closed. This modification results in reducing the thermostat's opening reaction time when the engine is relatively cool to begin with and is then challenged with prolonged wide open throttle runs. Without a drilled thermostat, the temperature of the cylinder heads can become quite elevated before the thermostat has a chance to open and establish coolant flow through the heads to cool them down.

[TDCRacing]

I don't understand this? I don't see any gains in keeping your engine cool. No performance. No economy. I just don't see the point in keeping the engine cool.


I agree that heat soak can be an issue when drag racing. For that reason, I run a cooler t-stat when racing..

Sorry but im going to have to dissagree with you now. You just said you dont see any point in keeping you're engine cool? Shoot just run the damn thing without water then. You say you don't see the point but you use one at the track? Why? I know why because you told me. But that cintridicts what your trying to get across to us.


You're comparing apples to oranges here with the nascar thing....Do you rebuild you're engine every time you come back from driving you're car?? Nascar does....why dont you?


Guess you don't belive in cold air intakes either huh? Just a big gimmick??


Go ahead and unplug that fan on the computer that you're typing on right now....see how long it lasts....Why do you think the computer rooms that the test equipment run in on military bases are ice cold? Come on man...Heat is a killer of almost everything....even people...

Ever heard of heat stroke?



AGAIN...i'll agree that you probably won't see an increase in fuel economy...and that adding a thermostat wont give you any kind of performance increase. I personally belive that it won't even combat KR...


You say the coolant doesent sit in the heads? You're wrong. Coolant sit's in the entire engine untill the thermostat opens...What you think it just by passes the thermostat somehow? Thats what it is there for. To stop coolant flow untill a certain tempeture is met.


If you want to prove you're self wrong next time you're out before you start you're car up for the first time take the upper radiator hose off...No coolant comes out while the engine is running until the thermostat is open. Therefor what is the coolant doing??


SITTING!!

[Zef_66]

Yes... it sits still any time it is closed (which is during the entire warm up cycle, which is what my post was referring to). This is with the exception of the small amount routed to the heater core. Once you've hit your warm up temp, the tstat can settle at a partially open position to keep the temperature constant for the load. Going down the highway it isn't constantly opening and closing.

And, the coolant in the radiator doesn't move until you first hit operating temp. Don't believe me? Hold the upper radiator hose. It will stay ice cold on a winter morning until the tstat hits operating temp then you will feel a rush of extremely hot coolant. Every vehicle I've owned or worked on has done this (dead give away on when it's good to bleed). There are tons of reports in northern Canada where they're recommended to run a small hole in their tstat to gently warm the radiator coolant prior to the opening of the tsat. Yes, engine damages have been reported from this happening.

Ever looked at specifically how coolant is routed through the engine? The heater core is somewhat "parallel" to the radiator. It has one hose on the higher pressure side of the pump and one on the lower pressure side. It can pick up enough heat during the warm up cycle to give you heat. But overall most of the coolant in the engine is at a stand still. Yes the pump is pumping but due to its design (centrifugal veins) it can pump against a near solid wall of water without caring.

The entire time you're driving before you hit your operating temp your radiator coolant is just sitting, the same as most of the coolant in the block. Once that tstat finally opens (yes, it does seal 100%) then it starts to displace the hot coolant in the block. This is where you get cracked blocks from sudden temperature changes. If the car was flowing coolant through the radiator the entire time, then drilling it should have little to no effect and I can tell you it has a major effect on warmup time. Simply due to having to heat a lot more coolant during the warm up cycle, and having to keep it warm if you're driving.

And running without a tstat would never have the "-15*F coolant meeting 250+*F parts" effect because all the coolant would heat evenly because none would be isolated (either in the radiator or in the block).

I think you're under the impression when the tstat is closed there is still some flow to the radiator with the stock tstat. This is simply not the case, and is why we have drilled tstats in the first place (to prevent heat soak on parts like the heads which can lead to knock). I've already seen a drop in knock with a stock temp tstat but drilled due to the heads remaining at the intended coolant temp and not getting too hot during the warm up cycle.

Here's more info for you, from Wizbang:

I guess maybe I am not explaining myself well enough. I in no way think that coolant will cycle through the engine or radiator with the t-stat closed. I realize that it won't go through a closed t-stat. But, the coolant in the engine, during warm up, does not just sit there. It moves in the engine. Take a glass of warm water, put in ice. The water looks like it is sitting still. But the molecules are moving inside the glass. As the ice adsorbs heat and the water cools off, it will sink to the bottom. And the warmer water will raise to the top. Same thing happens in your engine. The water is not "sitting" in your engine. There is no "wall" of water at your water pump. Even with the t-stat closed, the water inside your engine is moving. Yes, not moving to the radiator. But by no means is it sitting there.

I am not disagreeing that a drilled t-stat may not be beneficial. I am sure it is. I personally don't have an opinion on that. But this entire thread is about the need to 180° stat, which I don't see one.

As for running without a t-stat, it has been proven that running without a t-stat will increase the surface temperature of your heads. The coolant is flowing too fast to transfer sufficient amount of heat from the heat, causing a substantial increase in cylinder head temperature. Your cooling system needs to be regulated to slow down the flow of coolant to increase the time the coolant is in contact with the cylinder head. This allows enough time for the heat to be transferred from the head to the coolant. Otherwise, the coolant is moving too fast for heat transfer to take place.

Again, I know there is no flow to the radiator when the t-stat is closed. But like I explained above, the coolant by no means sits in the engine. There is movement of the coolant due to the heating. And substantial movement inside the engine. But no, it doesn't flow to the radiator.

Sorry but im going to have to dissagree with you now. You just said you dont see any point in keeping you're engine cool? Shoot just run the damn thing without water then. You say you don't see the point but you use one at the track? Why? I know why because you told me. But that cintridicts what your trying to get across to us.

You're comparing apples to oranges here with the nascar thing....Do you rebuild you're engine every time you come back from driving you're car?? Nascar does....why dont you?

Guess you don't belive in cold air intakes either huh? Just a big gimmick??

Go ahead and unplug that fan on the computer that you're typing on right now....see how long it lasts....Why do you think the computer rooms that the test equipment run in on military bases are ice cold? Come on man...Heat is a killer of almost everything....even people...

Ever heard of heat stroke?

AGAIN...i'll agree that you probably won't see an increase in fuel economy...and that adding a thermostat wont give you any kind of performance increase. I personally belive that it won't even combat KR...

You say the coolant doesent sit in the heads? You're wrong. Coolant sit's in the entire engine untill the thermostat opens...What you think it just by passes the thermostat somehow? Thats what it is there for. To stop coolant flow untill a certain tempeture is met.

If you want to prove you're self wrong next time you're out before you start you're car up for the first time take the upper radiator hose off...No coolant comes out while the engine is running until the thermostat is open. Therefor what is the coolant doing??

SITTING!!

Again, I must not have conveyed my thoughts correctly. Your engine needs to be kept cool, yes. Hence the cooling system. I understand that you can't run without coolant in a normal car. But there is no reason to make your engine run cooler that stock temp, in a daily driver, on the street. I thought I tried to explain that. But I will try again.

Like I said, yes, you need to keep your engine cool to keep it from overheating. But putting in a cooler t-stat than stock is making the engine run too cool. You will lose performance and lose economy. So what is the reason that you want a cool t-stat on a street driven vehicle?

Again, I tried to explain why you would want one on a track vehicle. Heat soak is a major problem on track cars. But not really an issue on street cars. Unless you are drag racing on the street for money or something, I don't see this as an issue. But for a daily driver, cruiser, weekend warrior car, heat soak when you are sitting in traffic isn't really a problem because you don't need to got WOT immediately afterwards. And if you do, the couple tenths that you lose due to the heat soak won't make much of a difference.

As for the NASCAR thing. Yes, I understand they build a different engine everytime. But I have seen engines after they have been in a 500 miles race. the bearings don't look any worse than my truck with 150k miles on it. They still need to run their engine in a way that it will last. They can't take a chance and build engines and race them that they will only last 1000 miles, because they are only going to run 500 and rebuild it. They are using the same technologies that are in our engines. And they run at elevated temperatures to get more power. And their engines hold up just fine. Not saying that I want to run my engine at 230°+, but my point is that there is no point to putting in a cooler t-stat, it goes completely against logic.

As for your statement about CAIs, as I mentioned before, that is totally different than keeping your engine cool. A most efficient engine is one with the cool fuel, and hot exhaust. Again, heat loss to the cylinder walls takes away from the work the heated gas is doing on this piston. The greater the heat loss, the less work, therefore less power, and less efficiency. Read up on the Otto Cycle, thermodynamics, and its efficiency and you will see this correlation. But cooler intake air is totally separate from the cooling system, and t-stat temperature. You want cool air/fuel mixture, and hot combustion and exhaust.

As for the last couple statements, like I said above, I know there is no coolant flow through the t-stat to the radiator when the t-stat is cold. But I also know that the coolant by no means sits still inside the engine. This is basic fluid dynamics.

[JoshMcMadMac]

Tossing my 2¢ off to the side, here...

Why do folks think that it takes longer to get warm with a lower rated thermostat? A lower thermostat will open sooner then a higher thermostat, thus circulating the coolant through the heater core sooner and allowing you to get heat quicker.

[Zef_66]

Tossing my 2¢ off to the side, here...

Why do folks think that it takes longer to get warm with a lower rated thermostat? A lower thermostat will open sooner then a higher thermostat, thus circulating the coolant through the heater core sooner and allowing you to get heat quicker.

The t-stat has no effect on coolant cycling through the heater core. It will cycle coolant through the heater core with the t-stat closed.