Boosted Owners: Who changed the thermostat?

[Vanishing Point]

So please excuse my ignorance but I’m not getting it. If you set the thermostat to open and cycle at 160, and the engine temp is always above 160, does it ever close and stop cycling?

If not, how does the coolant ever get a chance to cool back down if it’s just running a constant race around the whole circuit, never stopping long enough in the radiator to be effected by diffusion or rushing air be it naturally or by fan?

And if the engine is always above 180 and the fluid is just constantly cycling, then how would a 160 tstat have any different effect from a tstat that’s 170 or even 180?

I know if my ac can’t keep up and it won’t cool below 75, it doesnt matter whether I set my house thermostat at 70 or 60 or 50. It’s still going to be 75 in the house and due to that the ac ain’t stopping.

I’m sure there’s a logical answer I’m just not understanding. Thanks.

[Vanishing Point]

I’m going to venture to answer my own question. Is it because the engine temperature reading is not telling you the temperature of the coolant but rather the temperature of the engine block in a location away from the coolant, and the thermostat is measuring the coolant itself?

So maybe the coolant is 140 out in the radiator, cycles to the engine that is 200, then the engine cools down to 195), then the coolant rises to 160 and the engine back to 200 and the cycle happens and it repeats. Still the vane of coolant isn’t high diameter. It can’t take that long for a 200 degree engine to heat the coolant from 140 to 160. And from 160 to 170 must be an even shorter difference of time. Could be mere seconds to raise the coolant ten degrees. But I guess it could make a difference.

But I could also imagine it possible to heat that coolant so fast that by the time it enters the engine to the time it runs its circuit to the other side of the engine and against the thermostat its already heated enough to keep it open, thus constant cycling. The hotter the engine gets, the faster the coolant hits 160, the shorter the cycle, so the radiator coolant only gets to 150, causing it to hit 160 faster when it hits the engine, causing the coolant in the radiator to only get down to 155, then eventually it getting to a constant cycle. I think I just described a nuclear meltdown.

I guess I see both possibilities. The lower (160) cycle temp keeping it cooler at lower stress but doing nothing at higher temps when you need it most.

But again, I am fairly ignorant to a lot of this stuff so if I’m missing something in this picture, please illuminate that for me.

[dreksnot]

The 160*F is supposed to help because it starts to open sooner (at the lower temperature). I can't remember if the 160* is where the stat is fully open, or if that's the temperature it starts to open. Our motors are only about 25% efficient, and the remainder 75% is lost via heat. Gotta manage that heat, get rid of it, and a 160*F stat helps do that.

[Vanishing Point]

[QUOTE
Don and Nighthawk make a valid point that you don't increase the cooling systems abilities, but you do introduce a bigger buffer with a low stat even without any fan tuning.[/QUOTE] - acammer

Sorry, couldn’t figure out how to do a partial quote properly.

It keeps coming clearer for me. Yes a lower tstat only keeps it cooler under low stress, and yes, nuclear meltdown can and will happen under high stress to where the lower stat makes no difference at that point, but the key word in all of this was when acammer used the word “buffer”. If you keep it lower when you can, then when you start the higher stress meltdown cycle, you’ll at least start it from a lower point, and it will take longer to get it to total (constant cycle) meltdown. It won’t prevent meltdown, just dampen its beginnings, which should keep the end (peak) of the high stress meltdown lower as well, say 180 degree constantly cycling coolant instead of 190 degree constantly cycling coolant. I Got it.

Back to the ac scenario it would be like knowing your ac wont keep it 70 today because its forecast to be 110, so if you cool it down to 65 overnight, then when the ac can’t keep up, it will only lose ground to say 75 degrees instead of 80 (if you would have only cooled it to 70 on the overnight). Beautiful - crystal clear. Sorry, I just can’t take a word on trust. Do this cause we know better. Need to understand it for myself. Thanks for that.

Kinda worked myself through that understanding but only because it was all there from earlier posts, and I just had to organize it in my head more cohesively. Thanks guys.

I can see now why OP said there was quite a debate. There are both sides of the meltdown to consider. There is a time (light stress) when the lower stat keeps it cooler than the higher stat. And, there is a time (what I coined as meltdown) when the lower tstat no longer has any more effect than the higher temp tstat. So you can see how people could fall on one side or the other, but that’s because the buffer effect isn't often being explained well (or at all). That’s what connects the two sides of meltdown into one correct answer. Use the lower tstat. It’s residual buffer effect will result not only in lower pre meltdown temps, but also lower post meltdown temps. Good on ya acammer!

[acammer]

Originally Posted by Vanishing Point

So please excuse my ignorance but I’m not getting it. If you set the thermostat to open and cycle at 160, and the engine temp is always above 160, does it ever close and stop cycling?

If not, how does the coolant ever get a chance to cool back down if it’s just running a constant race around the whole circuit, never stopping long enough in the radiator to be effected by diffusion or rushing air be it naturally or by fan?

And if the engine is always above 180 and the fluid is just constantly cycling, then how would a 160 tstat have any different effect from a tstat that’s 170 or even 180?

I know if my ac can’t keep up and it won’t cool below 75, it doesnt matter whether I set my house thermostat at 70 or 60 or 50. It’s still going to be 75 in the house and due to that the ac ain’t stopping.

I’m sure there’s a logical answer I’m just not understanding. Thanks.

So, I think you answered some of your own questions below - but I wanted to jump on a common myth I saw you elude to - coolant needs to slow down to have enough time in the radiator. You'll hear people say "don't take your thermostat out, it'll run hot". That's not accurate - heat transfer is exponentially more effective the bigger the differential between the source giving and the source receiving the heat. You want to move coolant faster, not slower, to improve cooling. Doesn't matter what type of system were talking about, your car, home heating, or an arc furnace at a steel plant.

There is a point where if you introduce turbulence in the system, you're actually hurting things and can cause overheating and problems. This is where this rumor gets started, some body will remove a thermostat and observe an engine running hot, and will (wrongly) attribute that too too much coolant flow. They'll put a restriction in the system, and suddenly the problem is gone, so it affirms their theory. The problem is, they've misunderstood, the excessive turbulence introduce into the system will very negatively impact the engine's ability to cool - but the increased flow in an of itself would be a help, not a hindrance in the absence of that turbulence.

[Vanishing Point]

Originally Posted by acammer

So, I think you answered some of your own questions below - but I wanted to jump on a common myth I saw you elude to - coolant needs to slow down to have enough time in the radiator. You'll hear people say "don't take your thermostat out, it'll run hot". That's not accurate - heat transfer is exponentially more effective the bigger the differential between the source giving and the source receiving the heat. You want to move coolant faster, not slower, to improve cooling. Doesn't matter what type of system were talking about, your car, home heating, or an arc furnace at a steel plant.

There is a point where if you introduce turbulence in the system, you're actually hurting things and can cause overheating and problems. This is where this rumor gets started, some body will remove a thermostat and observe an engine running hot, and will (wrongly) attribute that too too much coolant flow. They'll put a restriction in the system, and suddenly the problem is gone, so it affirms their theory. The problem is, they've misunderstood, the excessive turbulence introduce into the system will very negatively impact the engine's ability to cool - but the increased flow in an of itself would be a help, not a hindrance in the absence of that turbulence.

That wasn’t quite what I was alluding to, but good to know anyway. What I was saying was “meltdown” seemed inevitable because eventually all of the coolant would hit 160, 170, 180 or beyond (or always be 160 when it hits the tstat), and once the thermostat was constantly open (for either temp tstat), what good would the lower one be. I thought proving meltdown would prove no benefit to a lower tstat, at least not when you needed the help the most. I still agree that meltdown is inevitable unless you’re always driving in cool weather, not sitting in traffic or running hard. I just now understand that the buffer effect is carried over and still there even during meltdown.

I wasn’t really saying causing a delay in circulation would help during meltdown. I probably would have always agreed with constant circulation during meltdown being better than a high temp delay during meltdown. While the coolant got less and less sitting time in the radiator, and that would contribute to meltdown, its not a good trade to keep excessively hot coolant in the engine just to cool the fluid in the radiator down. Overall more heat is lost by exposing as much as possible to the radiator even if in a constant flow than holding hot fluid in a hot engine. That one I think I would have always agreed with. I understand your explanation on that.

The turbulence thing brings new light to the whole process though. So basically you’re saying the constant flow could introduce air pockets into the system and they would hold heat. Good to allow it to burp via hesitation in the flow? That sounds tricky. How do you burp it without causing the unwanted locking of overheated coolant in the engine? You state the reason some want to create a delay is wrong but that the outcome is beneficial nonetheless. Sounds like you’re supporting a higher tstat with that remark.

Or...does that only happen when there is no tstat at all and always constant flow even when not in meltdown? So is what you’re stating is to use a lower tstat, just don't go all the way to no tstat to avoid turbulence? And then you’re stating that for some poor confused guys they think if a low tstat is better than no tstat, then a higher tstat is better than a low one?

Again, I think I just worked myself to an understanding of your statements. I am an intelligent person, but have a defect that if things aren’t said in just the right way, I miss the meaning. But I’m getting just enough from your words to read into them enough to work my way through it, at least I think so. Is that what you meant?

[acammer]

Originally Posted by Vanishing Point

That wasn’t quite what I was alluding to, but good to know anyway. What I was saying was “meltdown” seemed inevitable because eventually all of the coolant would hit 160, 170, 180 or beyond (or always be 160 when it hits the tstat), and once the thermostat was constantly open (for either temp tstat), what good would the lower one be. I thought proving meltdown would prove no benefit to a lower tstat, at least not when you needed the help the most. I still agree that meltdown is inevitable unless you’re always driving in cool weather, not sitting in traffic or running hard. I just now understand that the buffer effect is carried over and still there even during meltdown.

I wasn’t really saying causing a delay in circulation would help during meltdown. I probably would have always agreed with constant circulation during meltdown being better than a high temp delay during meltdown. While the coolant got less and less sitting time in the radiator, and that would contribute to meltdown, its not a good trade to keep excessively hot coolant in the engine just to cool the fluid in the radiator down. Overall more heat is lost by exposing as much as possible to the radiator even if in a constant flow than holding hot fluid in a hot engine. That one I think I would have always agreed with. I understand your explanation on that.

The turbulence thing brings new light to the whole process though. So basically you’re saying the constant flow could introduce air pockets into the system and they would hold heat. Good to allow it to burp via hesitation in the flow? That sounds tricky. How do you burp it without causing the unwanted locking of overheated coolant in the engine? You state the reason some want to create a delay is wrong but that the outcome is beneficial nonetheless. Sounds like you’re supporting a higher tstat with that remark.

Or...does that only happen when there is no tstat at all and always constant flow even when not in meltdown? So is what you’re stating is to use a lower tstat, just don't go all the way to no tstat to avoid turbulence? And then you’re stating that for some poor confused guys they think if a low tstat is better than no tstat, then a higher tstat is better than a low one?

Again, I think I just worked myself to an understanding of your statements. I am an intelligent person, but have a defect that if things aren’t said in just the right way, I miss the meaning. But I’m getting just enough from your words to read into them enough to work my way through it, at least I think so. Is that what you meant?

I don't know what happens with these cars with no t-stat. There are examples of vehicles that run hot, likely due to turbulence, because of that scenario - I'm not sure that would be the case here. T-stat temperature would not impact overall velocity.

In the absence of turbulence, more velocity is a good thing, the faster you cycle the coolant the hotter the radiator gets, which increases it's efficiency. Slowing the coolant would result in a cooler radiator, but a hotter engine!

[hammdo]

More velocity?

Yep...

https://www.camaro5.com/forums/showp...postcount=2138

I have both the mechanical and electric pumps in mine...

-Don

[StingrayblueSS]

I'm using a 169° thermostat and some pretty aggressive fan tuning and temps stay around 175 to 185.

[Greenhornet2]

I put the 160 in mine. Tune has the fans on quite early so they are just about always running. Added some water wetter, my temps are lower than stock for sure

[UNRIVALED SS]

Originally Posted by acammer

I'm not sure you've got the right audience in this thread - usually if you want better responses you should just go ahead and start a new thread. Or, you could try that magically little search button.

But, as a rule of thumb, the car has a 15psi rad-cap, so that's going to put your max temp before boil over at ~247*F. So, you're going to push the coolant out the cap before you should have to worry about head gaskets. Although, if you're seeing over 225-230*F on a routine basis I would question if there might be a problem in your cooling system somewhere.

Or I could generate some information flow so everyone interested actually knows if they actually have an issue or not. I don’t ask questions in a forum on this site unless I know the answer. Thanks for sharing.

[UNRIVALED SS]

Originally Posted by hammdo

More velocity?

Yep...

https://www.camaro5.com/forums/showp...postcount=2138

I have both the mechanical and electric pumps in mine...

-Don

Great technique. If that mix of water doesn’t work, nothing will keep it cool.

[Greenhornet2]

Originally Posted by UNRIVALED SS

What is the max temp an LS motor can take before risking a head gasket or other problems? I see stock corvettes here running 230-235 in the city. When it’s 102 it’s challenging to cool anything big inch making power. I’m curious what the generally accepted Max is for engine coolant temp.

Any engine could be different depending on mileage wear and tear ect. There isn't going to be an exact number. under 250 will probably be ok for short term but running over 230 constantly I would be worried personally. above 250 I would start to panic. But i'm old school these engines might be able to handle more I don't honestly know and I have not had to find out yet!

[acammer]

Originally Posted by UNRIVALED SS

Or I could generate some information flow so everyone interested actually knows if they actually have an issue or not. I don’t ask questions in a forum on this site unless I know the answer. Thanks for sharing.

Is that a typo and you're saying you don't ask you don't know the answer to? Or, are you saying your method of generating "helpful" information flow is to ask questions you already know the answer to and then post sarcastic follow ups when nobody provides input.