cooler thermostat opinions

[beihl304]

first i want to say i understand completely what a thermostat is and how it works. i aslo understand what happens when a car is being ran colder than it was originally designed to.

however my question is what is a good thermostat temp for 2g's? yes i know stock is but i get knock with little timing and was thinking about going to a 170 degree thermostat.

i have searched here and ecmlink forums but have not came across anything set in stone. so what does everyone think about a 170 degree stat on a 2g?

thanks

also i know a colder thermostat isnt going to be magical and erase knock. i just want to try and see if it helps any

 

[dsmtun3r98gst]

Well first you need find out exactly what is causing this knock instead of changing something that isn't the problem. If your not having overheating issues there shouldn't be a reason for you to change your thermostat.

Unless you believe that its your thermostat, but even you said it that it ain't so I don't see how your talking about 2 different things.

 

[96 420a-t]

Decreasing the engine temp will decrease temps in the combustion chamber. Thusly reducing the chance of knock. No its not the best way but it works. I personally will be doing this as well in the near future just to make sure. Not the best idea but not a bad idea.

 

[beihl304]

Ya my bad wasn't very clear. I have seen people saying they put in colder thermostats to help reduce knock. I was going to try this to see if it helped me any and like I said I kno it isn't really going to help an incredible amount. I wanted to see what other people were running and how it helped/didn't help.

 

[UofACATS]

first i want to say i understand completely what a thermostat is and how it works. i aslo understand what happens when a car is being ran colder than it was originally designed to.

however my question is what is a good thermostat temp for 2g's? yes i know stock is but i get knock with little timing and was thinking about going to a 170 degree thermostat.

Well if you understand the drawbacks I don't understand why you would ever want to run colder than 180º.

-Worse mileage
-Possibly worse power
-Your car will never enter ECU Learn Mode

also i know a colder thermostat isnt going to be magical and erase knock. i just want to try and see if it helps any

Well if you just want to try it, you don't have to buy and install another thermostat... just do a pull when your coolant temps are 170º

 

[LiquidX]

Well if you understand the drawbacks I don't understand why you would ever want to run colder than 180º.

-Worse mileage wrong
-Possibly worse power wrong
-Your car will never enter ECU Learn Mode wrong




Well if you just want to try it, you don't have to buy and install another thermostat... just do a pull when your coolant temps are 170º

I run a 170* tstat and don't have any problems at all. The only draw back is it takes a little longer to get up to 180* during the winter. Other than that it works fine. I use a Stant 14077 thermostat which I picked up from Autozone for under $15.

It's not exactly going to help with knock as your cylinder temps are much greater than the block temps. On average the car runs around 210*. There is another issue associated with the reason why you are knocking, whether it's too lean, too rich, wrong plugs, bad sensor, too much timing, etc.

 

[BigBeans]

-Worse mileage
-Possibly worse power
-Your car will never enter ECU Learn Mode

A few clicks on the coolant offset feature and you won't run into any of this.

 

[gofer]

In ECMLink you don't have to worry about the t-stat temp you decide to run, if you'd like you could even run the Mishimoto 143* t-stat. Whatever t-stat temp you choose just go to your Dash tab and raise the coolant offset temperature. This will make the ECU think coolant temps are warmer than they actually so it will kick your fans on sooner and enter closedloop even if its below 180*.

---EDIT---

A few clicks on the coolant offset feature and you won't run into any of this.

UGH. He beat me to it.

 

[UofACATS]

I run a 170* tstat and don't have any problems at all. The only draw back is it takes a little longer to get up to 180* during the winter. Other than that it works fine. I use a Stant 14077 thermostat which I picked up from Autozone for under $15.

Why would you run a t-stat colder than stock if I may ask?

In this case the user has a way to circumvent the issue with coolant offset (I should have checked his mods, that's my bad) but I otherwise stand by what I said. An engine running suboptimal operating temperatures will get worse mileage. If I'm wrong, can you substantiate that please? In stock trim, the ECU enters learn mode at 180º, if he runs a t-stat that opens 10º earlier then it's possible the car will heat normally, but it's also possible that it won't.

This is the first article I came across when searching "engine suboptimal operating temperature." http://findarticles.com/p/articles/mi_qa3828/is_200308/ai_n9294683/

Just because you don't have an issue doesn't mean the OP will experience the same. When my t-stat was faulty, I drove around for a while at ~150º coolant temperatures. Sure the fans never kicked on, but it didn't matter, it was cold enough that my car never reached proper operating temperature. In this scenario, if I'd had a properly operating 170º t-stat, that's where my car would have run. So, if he (or another user reading this thread) has no way to offset temps, then it's possible running a colder t-stat than specified as oem would have the negative consequences I listed ealier.

A few clicks on the coolant offset feature and you won't run into any of this.

You're right, I didn't check to see if he was running ECMlink first

 

[BigBeans]

Why would you run a t-stat colder than stock if I may ask?

I also have a 170*

My reasons were to slightly increase knock threshold, lower the chances of heatsoak on long pulls/hot lapping, and to decrease the stress a bi-metal engine puts on the headgasket.

 

[UofACATS]

I also have a 170*

My reasons were to slightly increase knock threshold, lower the chances of heatsoak on long pulls/hot lapping, and to decrease the stress a bi-metal engine puts on the headgasket.

Certainly beneficial reasons. Did you do any testing on these? Thanks! I'm very interested in the findings.

 

[gofer]

A 170* t-stat isn't going to effect coolant temperatures enough to have any negative effects on engine operation, even without a way to offset it with something like ECMLink. Just because the t-stat opens at 180* what DSM actually keeps 180* operating temps? Personally I can say I've never seen a 2g hold below 200* without an aftermarket t-stat, and even then its high 190*. Running a 170* t-stat vise the 180* OEM one will drop coolant temps maybe, and I stress maybe, 5* or possibly the full 10* difference which will still hold engine temps at 200* or so.

I've never heard of too low of coolant temperatures hurting a motor, gas mileage might suffer but how much? I'd rather the motor be idling stuck in traffic too cold then watching my temps climb passed 215* and possibly blow the HG.

 

[96 420a-t]

My engine sits at 206* while running. I would like it lower since I'm running higher compression and boost. But I still want driveability. I want to go with a 180 t-stat.

 

[LiquidX]

I choose a colder t stat to help lower my coolant temps. I would be around on average 210-220 even during the winter with the stock t stat during the winter. Switching to the 170 dropped me to the 190s in the winter.

The only downside with the coolant offset is depending on how much you alter it you will loose timing due to it. IIRC once you pass 210* the ECU starts to pull timing and by chaining the offset say 10* you ECU will always think it's 10* hotter than what it actually is.

180* is the OEM t stat temperature by the way. However being a 420a it's 190*.

 

[beihl304]

I honestly dont think a 10* colder thermostat is going to hurt gas mileage enough to where it is clearly noticeable. Besides, im not that worried about gas mileage.

I didnt mention it but i was also liking to go colder not only to try and help with knock somewhat but to also just in general have my car run a little bit lower temps. Like gofer said its not going to lower enough to potentially have any real draw backs.

 

[UofACATS]

A 170* t-stat isn't going to effect coolant temperatures enough to have any negative effects on engine operation

What if it's cold? Like in my example, the t-stat was "open" all the time. I was running 150º coolant temps. It happens that I was tuning the car at the moment, but was having a very difficult time since an ECMlink feature like the MAFcomp requires the car to be at proper operating temperatures to function correctly. In this case, it was having a negative affect. I'm not saying "everyone" will suffer from running a 170º t-stat, I'm saying "it's possible" someone will suffer, and if that's true, then personally I'd like to see sufficient reasoning to alter that temperature before doing so.

Just because the t-stat opens at 180* what DSM actually keeps 180* operating temps?

Well, this applies to 1% of DSMers, but it takes a car running no FMIC. And, of course the right freezing cold conditions. My car actually keeps much lower temps than that when the coolant is being circulated without restriction. Maybe it's just my car?

I've never heard of too low of coolant temperatures hurting a motor, gas mileage might suffer but how much? I'd rather the motor be idling stuck in traffic too cold then watching my temps climb passed 215* and possibly blow the HG.

I'm not sure how much, I don't even have a guess. But If I know anything it's that engines are designed to operate at a certain temperature. As the engine warms, mileage increases. Personally I'll take as many MPG's as possible, and will accept less than optimal performance as a trade-off for not running a FMIC, (aka not overheating).

I choose a colder t stat to help lower my coolant temps. I would be around on average 210-220 even during the winter with the stock t stat during the winter. Switching to the 170 dropped me to the 190s in the winter.

The only downside with the coolant offset is depending on how much you alter it you will loose timing due to it. IIRC once you pass 210* the ECU starts to pull timing and by chaining the offset say 10* you ECU will always think it's 10* hotter than what it actually is.

180* is the OEM t stat temperature by the way. However being a 420a it's 190*.

Right, 206º, but of course we can just add that degree right back in.

Running a FMIC like most of us are, I think the t-stat temp matters little. I had a faulty t-stat for a while and didn't even know it because I was blocking all the airflow to my radiator anyway. I ran hot for the most part so the t-stat would've been open anyway. (In this case, 170 vs 180 would have shown no difference.) The only negative was increased warn-up times, which I consider inconsequential.

 

[LiquidX]

What if it's cold? Like in my example, the t-stat was "open" all the time. I was running 150º coolant temps. It happens that I was tuning the car at the moment, but was having a very difficult time since an ECMlink feature like the MAFcomp requires the car to be at proper operating temperatures to function correctly. In this case, it was having a negative affect. I'm not saying "everyone" will suffer from running a 170º t-stat, I'm saying "it's possible" someone will suffer, and if that's true, then personally I'd like to see sufficient reasoning to alter that temperature before doing so.

Even for me being in NE PA in single digit weather I've still gotten above 180* coolant temps. Also if it is that much of an issue, then as Korey said, you change the coolant offset. If you are constantly running 160* temps than bump the offset 20* to make it 180*. Just change it when it gets warm out.

Well, this applies to 1% of DSMers, but it takes a car running no FMIC. And, of course the right freezing cold conditions. My car actually keeps much lower temps than that when the coolant is being circulated without restriction. Maybe it's just my car?

If what you mean is you are not running a t stat then you are going to pose a greater issue to the efficiency of how the motor operates. As it will take even longer to be taken out of the warm up state if all the coolant is constantly being cooled when it in fact needs to be heated up.

I'm not sure how much, I don't even have a guess. But If I know anything it's that engines are designed to operate at a certain temperature. As the engine warms, mileage increases. Personally I'll take as many MPG's as possible, and will accept less than optimal performance as a trade-off for not running a FMIC, (aka not overheating).

The motor doesn't need to be at a certain temperature, it's the ECU that wants it there so it will stop dumping "warm up fuel". Coolant offset will change the temperature the ECU sees and I'm pretty positive that the AEM EMS will alter the ECU temperature reading as well so you can have a colder motor.

The only draw back is it takes longer to receive hot air from the vents.

Right, 206º, but of course we can just add that degree right back in.

Running a FMIC like most of us are, I think the t-stat temp matters little. I had a faulty t-stat for a while and didn't even know it because I was blocking all the airflow to my radiator anyway. I ran hot for the most part so the t-stat would've been open anyway. (In this case, 170 vs 180 would have shown no difference.) The only negative was increased warn-up times, which I consider inconsequential.

Actually it helps out greatly if you are at a low enough t stat. The 180* stock pieces is fully open in the high 200* range, well above where I want my temps. The 170* is fully open around 190* range cooling off more coolant before it gets too hot.

And you are right, for most people with a FMIC it will be useless as they aren't efficiently directing airflow to the radiator so it won't matter as the radiator isn't getting cooled off as it should. For those of us that do, it does help out as I've even had it help me out.

I personally would even run 160* if one was available for a 2g and not just the 1g. This of course would be ran in the summer and I would still hit 180* coolant temps. If I was off by a little then just use the coolant offset and everything will be where it should.

There isn't a real reason why you shouldn't run a colder t stat as long as you can monitor the temps and be sure of where they are at so you can compensate for it IF needed.

 

[96 420a-t]

my car really does run at exactly 206* with a fmic and only one fanon an otherwise stock cooling system.

 

[UofACATS]

I see what you're saying about the colder t-stat benefits. I just might end up tossing in a 170º this summer.

The motor doesn't need to be at a certain temperature, it's the ECU that wants it there

Discussing this further, perhaps my non-specific, general thought process that tells me an engine gets the best MPGs when it's at proper operating temperature is based on ECU behavior. Still, I think there's a relationship between heat and efficiency. I mean why does the ECU add fuel when cold?

In theory, if you were running too cold and the ECU was adding fuel, with ECMlink, adjusting the coolant based temperature fuel compensation (CoolantTempFuelAdj) to a lower temperature would circumvent the problem. If you zeroed-out the values at 176º and above, then a coolant offset wouldn't be necessary to stop the additional (unnecessary?) fuel. Coolant offset however is probably the easier and better solution.

 

[gofer]

The ECU adds fuel when its cold to heat the motor up to operating temperature faster, getting it to the 180* operating temperature so it can go into "learn mode".

 

[96 420a-t]

The ECU adds fuel when its cold to heat the motor up to operating temperature faster, getting it to the 180* operating temperature so it can go into "learn mode".

The computer adds fuel because cold fuel doesn't burn as well and condences in the cylinder.
Since fuel can't burn properly unless atomized the ecu adds more. But same idea ya. It will affect milage but for those of us that don't have a means to control timing its ok.

 

[gofer]

Optimum combustion chamber temperature has to be upwards of 315* to completely atomize ALL the fuel, which is obviously WAY too hot for any of our motors to handle. Dropping coolant temps to 150-170* might effect atomization but by how much? I say not enough to know any better, especially on a DSM with ECMLink that can control AFR's to keep fuel trims in check.

The ECU adds fuel when its cold to bring the car up to operating temperature for the ECU to go into "learn mode" at 180*. With the coolant temp offset in ECMLink you can tell the ECU the coolant temperatures are at 180*...

I'd also like to note that if you run a colder t-stat and still have coolant lines running through your OFH you might want to by-pass it and run an external oil cooler. You want oil temperatures to be about 190-200*, if you run a colder t-stat and circulate coolant through the OFH it might drop them too low and it won't have the same protective properties.

I want to put a 143* t-stat in just because now.

 

[UofACATS]

I'd also like to note that if you run a colder t-stat and still have coolant lines running through your OFH you might want to by-pass it and run an external oil cooler. You want oil temperatures to be about 190-200*, if you run a colder t-stat and circulate coolant through the OFH it might drop them too low and it won't have the same protective properties.

Good point.

 

[beihl304]

I'd also like to note that if you run a colder t-stat and still have coolant lines running through your OFH you might want to by-pass it and run an external oil cooler. You want oil temperatures to be about 190-200*, if you run a colder t-stat and circulate coolant through the OFH it might drop them too low and it won't have the same protective properties.

That has never even crossed my mind until you said that. I also didnt see that in any other post I viewed. But that is a very good point that should be known.

 

[MIdsm]

Just a side note, not necessarily pertinient here, but I have previously read that the F3 cars, as well as the new NGTC turbo touring cars run about 75C (just below 170F). The ECUs start retarding timing as water temps increase past 170F. Of course, these vehicles are true race cars that live at the ragged edge.