When will replacing a thermostat improve cooling?

[6Stang7]

but people are using flawed logic which to them, doesnt appeard flawed. sometimes making a logic argument like you have doesnt really work out because there are points whihc you are not taking into account. i can use math once again to prove what i am saying, but i really dont see the point.

 

[D.Hearne]

70 Nitrous eater has created a monster here. I think DarkBudda explained it best. "Nuff Said" The replys to this have gotten soo long, as to make it impossible for me to keep up with. Y'all that insist on running without a T-Stat, be my guest. I'll keep mine.

 

[r x F]

but people are using flawed logic which to them, doesnt appeard flawed. sometimes making a logic argument like you have doesnt really work out because there are points whihc you are not taking into account. i can use math once again to prove what i am saying, but i really dont see the point.

Actually, your logic is flawed. In my example, you could apply Newton's Law of Cooling to find the temperature change with distance over the plate, but it doesn't tell you total heat flux. Total heat flux is related to the convection coefficient (flow velocity) and the delta-T.

I see you're a student. If you don't believe my conclusion, go to one of your professors, he'll set you straight (or I can do some more explaining).

Y'all that insist on running without a T-Stat, be my guest. I'll keep mine.

Uh, who has been insisting on running without a T-stat?

 

[10secgoal]

Uh, who has been insisting on running without a T-stat?

This is what started all this more or less.

 

[67coupe351w]

I can't read physics. My brain doesn't work that say. Must have been the bloodletting.

lol, play nice Max. I think I explained why you shouldnt' have taken that badly.

sorry 10secgoal, I miss interpreted your post.

 

[10secgoal]

No worries

 

[2bav8]

Alrightly...
Why don't I drive around in the AZ summer with, and without a T-stat and tell you guys with the mechanical Autometer guage tells me?

 

[10secgoal]

What kind of radiator do you have ?

 

[2bav8]

I have a 3 core radiator by NPD.
Its the hi-efficiency one with the rows very close to each other.

 

[65up2d8]

The link that was posted to that NASCAR site which said un-restricted flow is better is deceiving. Remember, this is under RACE APPLICATIONS! These are motors which are seeing around 8K-9K in RPM, and air running across the radiator at over 170mph. this doesn’t in anyway help understand how a normal car will function.

This is exactly the point I was making. I am not trying to personally attack Boo Boo Foo in my post on the previous page, but I really don't agree that the site he linked is relevant. You, 6stang7, and I have arrived at the same conclusion regarding the relevancy of the site he posted, and his reply is that he is "the only person who's bothered to provide a third party cite regarding this subject - accordingly, whatever."
I have no desire to make this dispute personal, and I'm sorry if I came across in a way that indicated that to Boo Boo Foo. But, I stand by my observation that the site he is relying on compares apples and oranges and is totally irrelevant to this discussion. Maybe my words were a little strong, and for that I apologize if you took offense Boo Boo Foo, but I must also state that the engineering opinions on this thread have also been pretty demeaning towards people who have posted that are not theorizing and are speaking from personal experience.
For those that have posted, including myself, who are not able to express their opinions in engineer speak and equations, that does not mean we are all wrong. It simply means we communicate in a different medium.

 

[Route666]

A high volume water pump performs the same function (in the respect that we are arguing here) as removing the thermostat. Is it sensible to think that this item could cause your engine to overheat?

 

[Hack]

ok, then argue against mathmatics.

At the risk of posting a personal attack, I'm going to respond to your post.

I would never argue against math. However, math by itself will never solve a complicated real-world problem such as heat transfer in an engine/radiator. The assumptions made when applying the math are generally the problem. I won't say anything about your assumptions, except that you already know I disagree with them.

One other thing about heat transfer "math". It's not real math. Many of the equations are approximations set up through empirical observations. As such they contain terms such as Reynolds numbers, Nusselt numbers, etc. which are "fudge factors". There's nothing wrong with approximation used to help solve real world problems. However, the fudge factors mean that no one really knows how heat transfer works - at least not well enough to come up with 1+1 = 2 (real math).

 

[ForceFed70]

Wow.. this has really mushroomed. I think it's impossible that we're going to get everyone to agree here. So I think I'm just going to throw in the towell.

I tried to explain my case, some people may have chosen to listen, others didn't..so is life.

Thanks everyone.. great discussion and mostly polite.

 

[ForceFed70]

Alrightly...
Why don't I drive around in the AZ summer with, and without a T-stat and tell you guys with the mechanical Autometer guage tells me?

Please do! I'd love to see if your guage tells us the same thing that I've seen from experience and believe would happen again:

1) Engine would not overheat (unless it's already prone to overheating)
2) Engine would take a long time to warm up.
3) Engine temp would fluctuate alot with driving conditions and weather.

 

[ForceFed70]

Dbl post.

 

[ForceFed70]

Is it possible (theoretically or in real world application) for coolant to flow through a block so quickly that it is not able to absorb heat from the block? I believe the answer is yes given that heat exchange does not happen instantaneously, but rather it happens over some amount of time.

Actually, heat transfer does indeed begin to happen instantly. Think of this in terms of how the block feals... it's at 1 temperature and the coolant is at another cooler temp. It really doesn't care how fast the coolant is flowing, the amount of heat transfered is the same.

Same think works in reverse for the radiator.

 

[ForceFed70]

let me refer to to a post i made in another thread.


now let me put this is simple terms since some people will not understand this.

the faster the coolant moves through the radiator, the less time it has contact with that cooler surface. look at the equation is red. an increase in time will result in a lower temp. more over, your idea that the coolant would then spend less time in the block, therefore not receive as much heat is flawed to a point. you are right that the coolant wont take on as much heat, but this is to a point. since the coolant wont remove as much heat, or energy, from the block, that means that the temp of the block will get higher because more and more energy is added to it. now, look at the equation is red again and instead of cooling, look at as a heating function (your k should now be positive where as it is negative in a cooling function). the larger difference in temp between the coolant and engine means less time is required to transfer the same amount of energy. now, wait, there will be large temp difference between the coolant and the cooler radiator, so shouldn’t it all work out? no. the radiator has A LOT less surface area then the engine block, which means there is less energy transfer.

Too much math...

Surface area does nothing for this discussion except complicate things needlessly. Our surface area doesn't change with the change/removal of a thermostat and thus doesn't need to be discussed.

Heat will not "build up" in the block. You can't look at total heat 1 minute and then incidental heat another.

Do me a favor. Run your formula 2 times. Through a 2 stage system (heat and cool) pick numbers that are close to those you would see in a vehicle. And pick a flow rate so that coolant temperature doesn't change more than 20* in temp through either stange. Then do the same calculations but double the flow rate.

You'll see than the total energy transfer will be very similar.

 

[pabear89]

We don't need no stinking math!..........

Now think of why and what the stat does.

Yes it holds the coolant till it reaches a preset temp,
But it also opens and closes to maintain that temp.

With the stat in place it will also cause the water to have some resistance from flowing to the rad top side causing a slight backpressure making the pump force the coolant thru the passages and heater hose to the heatercore with even force.

Now........A stat will only hold to it preset temp, when it is reached it will open and allow flow to the rad.
If it is say 180* preset, when a 180 and greater temp is reached it is like it is not really there.
Then the other Factors start to play in the operating temp of the engine, timing a/f mixture parts condition just to name a few.

Just because you have a 180* stat the engines normal operating temp maybe at 187* and it will rise till it gets to that temp.

Thats why an overheating condition has so many variables to check as far as what its cause could be.

Sets off Soapbox for the next person.

PB

 

[65up2d8]

Actually, heat transfer does indeed begin to happen instantly. Think of this in terms of how the block feals... it's at 1 temperature and the coolant is at another cooler temp. It really doesn't care how fast the coolant is flowing, the amount of heat transfered is the same.

Same think works in reverse for the radiator.

I would agree that some heat transfer begins to happen immediately. However, it sounds like you're saying that you could take a piece of steel and heat it with a torch until its glowing red, then grab it with a set of pliers and dunk it in cool water for one second, and voilla, the piece of steel would be at room temperature and the water would be the hottest it could possibly get. I really can't imagine that's what you are saying, but it sure sounds like it. I don't think you meant exactly what you said, but if you did, please don't try my suggested experiment to prove your point because burning flesh is not a good thing.

 

[10secgoal]

Thanks everyone.. great discussion and mostly polite.

:worship: Agreed, by far.
I think you are right if he removes the t-stat. 100%. But I also don't think the thing will ever come up to temp even in that heat, at a cruise. But what about the fellow in the other thread ? He fixed his problem. The t-stat was stuck open.