Cooling results without Thermostat vs. with

[earlbrown]

It could be cavitation that's going on without the head pressure of the themostat.
I had situation with my pool pump. I had a pump for my pool cleaner that pumped water to the cleaner to make it move and clean the pool. I went with an electrical cleaner so I decided to use the pump to just recirculate water in the pool. Without any head pressure the pump cavitated, made a strange noise, and the flow was low. I had to add a valve to the exit port to restrict it and provide some backpresure. The result was higher flow than when it was cavitating.
Maybe this is what's going on,

That was my original guess, back on page one, as well. I believe Turbo Nasty has a huge radiator that flows more than a normal stocker so the thermostat keeps the lower radiator hose from going berzerk.

 

[garyk1970]

I guess we can all agree that its better for a thermostat. At least. Ive had several car that would overheat without a stat (some had a gutted stat) where a simple stat install make them run in the proper temp range.....im gonna move mine up to a 180°, its too cool.. On a 95° day , its running 159° cruisng, 167 in town.....i would like better fuel economy...

 

[750H.P.V6]

So what can we glean from this conversation? Aside from Earl's lengthy post on engineering and thermodynamics which was well intentioned but probably served to confuse a lot of people. I think it's fair to say that if you don't run a thermostat or a restrictor in it's place then you risk cavitation in the water pump due to lack of head pressure resulting in uneven cooling in the engine. With this said it's not too far off the mark to say that keeping the restriction of the thermostat in the cooling system slows the flow of coolant thru the block and radiator and keeps the system working in a harmonious fashion.

Neal

 

[turbo nasty]

THIS^

 

[mgmshar]

Not sure if you were referring to Earl's post or mine, but for those who don't want to understand the science...

1. It is not inherently obvious whether removing your thermostat will result in a lower or higher coolant temperature. "It depends."

2. The engine cooling system was designed to have the restriction of the thermostat in place, so I recommend keeping it.

Mike

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[T- Type Tim]

As nick stated and as an Arizona guy , I went with nicks recommendation and haven't ran a thermostat for a few years


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[longball]

"So what can we glean from this conversation? "

Well, it seems the more I am 'learning' about this, the more confused I am?

 

[Buick Mark]

I dont run a radiator

 

[bryesh]

Not sure if you were referring to Earl's post or mine, but for those who don't want to understand the science...
1. The value for "h" inside the engine will increase.
2. The value for "h" inside the radiator will also increase.


1. It is not inherently obvious whether removing your thermostat will result in a lower or higher coolant temperature. "It depends."

2. The engine cooling system was designed to have the restriction of the thermostat in place, so I recommend keeping it.

Q = h * A * deltaT
"Q" is the amount of heat transfer
"h" is the "heat transfer coefficient" (more later)
"A" is the surface area of the piece of metal
"deltaT" is the temperature difference between the piece of metal and the coolant

Mike


Posted from the TurboBuick.Com mobile app

mgmshar,
Thank you for your informative posts and your efforts to enlighten us further on this subject.
I've had some thoughts that seem contradictory to your assertion that this matter would require further testing and was wondering if you would feel free to weigh in on your thoughts of what I write below. I think that to consider the effect of removing the thermostat, one needs to use your equations buy first looking at an idealized steady state condition of a TB traveling down the highway at constant speed with thermostat installed.

By the definition of steady state, coolant temps and engine speed will be constant and the heat transfer rate "Q" will be the same between the engine and coolant as it is between the coolant and radiator (After the car is warmed and coolant temps are constant).
For our purpose we must expand on your definitions to include:
T_amb - "Outside ambient temperatures"
T_eng1 = "Average temps of metal in the engine"
T_coolant1= "Coolant temps as read by gauge, scanmaster or whatever"

Note that a "1" in a variable indicates the state of the thermostat being in place where a 2 indicates removed thermostat.
So,
Q_ eng1 = Q_rad1,
By defining the average engine temperature as T_eng1, Re-writing the above yields,

h_eng1 * A_eng * (T_eng1 - T_coolant1) = h_rad1 * A_rad * (T_coolant1 - T_Amb) (Steady state, cruising down the road with thermostat). (1)

Now for arguments sake, assume the thermostat is instantaneously removed... You only have to look at the radiator side of the equation to see what happens:
h_rad2 * A_rad * (T_coolant1 - T_Amb) = Q_rad2, notice that Q_rad2 > Q_rad1 because h_rad2 > h_rad1.
In other words, and as Earl was saying, the heat transfer through the radiator has increased. I think it can be shown that this change can only do one thing... lower the coolant temperature unless something crazy is going on.

The new steady state is determinant by assuming constant heat transfer into the system (Q_eng1 = Q_eng2) (2). This is true if the engine efficiency is independent from the operating temperature, so probably only valid for small temperature changes, but still valid to show if coolant temps decrease.

The new steady state is written as:​

​

h_eng2 * A_eng * (T_eng2 - T_coolant2) = h_rad2 * A_rad * (T_coolant2 - T_Amb) (3)​

by solving (1), (2) and (3) simultaneously we can solve for all unknowns: T_eng1, T_eng2 and T_coolant2.

Doing so yields:

T_coolant2 = T_coolant1 * h_rad1 / h_rad2 - T_amb (hrad1/hrad2 - 1),​

so conclusively, T_coolant2 < T_coolant1 when, h_rad1 < h_rad2 and T_amb < T_coolant1 (which are normal conditions driving down the road).​

This proves that, under normal conditions engine coolant temperature will decrease when heat transfer coefficients increase, and is what earl has been saying from the start. Because, heat transfer coefficients increase when flow increases, removing a thermostat should make temps go down. This is why prof. earl took offense to issue with the opposite notion in the first place. To my knowledge he did not dismiss people who said that it happened to them, but he instead pointed us to other things that might be happening, like heater hoses collapsing and such which would actually decrease heat transfer coefficients.

Please if you wouldn't mind taking some time to clarify the math, we'd be much obliged to learn more on this topic.

Bryes

 

[earlbrown]

I didn't take offense from being told otherwise.

but based on my personal experience when something 'obvious' doesn't jive with science, I start looking for the factor I missed. (because Murphys law will bring that factor up with I'm 200 miles from home!)

Like I've said earlier, I'm not anti-thermostat, I run one. On my car if I omit it, the engine never warms up.


Back when I still had the clogged up original radiator I ran without one to overcome a flow problem. It ran hot on the interstate.

 

[bryesh]

I shouldn't have made it sound like you were offended like I did so I edited the error.

 

[mgmshar]

@bryesh (using one of those snazzy "@" things...)

I like your approach of considering the car going down the road at steady-state. However, as is often the case, it's the ASSUMPTIONS made that sometimes cause analysis problems. Here is the assumption you made that I do not necessarily agree with...

The new steady state is determinant by assuming constant heat transfer into the system (Q_eng1 = Q_eng2) (2). This is true if the engine efficiency is independent from the operating temperature, so probably only valid for small temperature changes, but still valid to show if coolant temps decrease.


This is where you and I might disagree. You said yourself that when you instantaneously remove the thermostat, h_rad will increase. To use your terminology, h_rad2 > h_rad1. This is true. However, coolant is also flowing more rapidly through the engine, is it not? Therefore, shouldn't h_eng2 > h_eng1? In other words, the coolant will do a better job removing heat from the engine. (To say this, I am assuming, there's that word again, that nucleate boiling or other oddities are not skewing the results). This also means that the temperature of the cylinder walls, combustion chambers, etc. will be cooler. This will also mean that the combustion gases will transmit more heat to the walls/combustion chambers/etc. So, Q_eng2 > Q_eng1.

The proof of this is simply - why do engines use thermostats? They use thermostats to warm up the coolant so that the engine metal runs hotter, less heat is transferred to the engine metal, and more energy gets transferred to the piston. If Q-eng didn't change regardless of coolant temperature (T_coolant), then the engine designers wouln't even bother using a thermostat, right?

If you therefore disallow the assumption that Q_eng1 = Q_eng2, then all of the following math in your post is inaccurate, and you can't "conclusively" say that coolant temperature will be lower when you remove the thermostat.

I stand by my earlier assertion - by removing the thermostat and increasing the coolant flow rate, both h_rad and h_eng increase. Therefore, both Q_eng and Q_rad will increase. If Q_eng increases more than Q_rad, then the steady-state coolant temperature (T_coolant) will be higher. If Q_rad increases more than Q_eng, then the steady-state coolant temperature (T_coolant) will be lower. It is not inherently obvious which of these two outcomes will occur on a given engine/radiator combination.

Hopefully this makes sense.

It's Friday, been an exhausting week. But now it's beer-thirty...

Mike

 

[turbojoe1]

Im confused.............

 

[626gn]

Im confused.............

Just so you don't feel lonely...I was confused after eb's 2nd post. After mgmshar and bryesh joined the discussion I now have a full blown brain cramp. Beer thirty sounds good right about now

 

[robzombie]

By the definition of steady state, coolant temps and engine speed will be constant and the heat transfer rate "Q" will be the same between the engine and coolant as it is between the coolant and radiator (After the car is warmed and coolant temps are constant).
For our purpose we must expand on your definitions to include:
T_amb - "Outside ambient temperatures"
T_eng1 = "Average temps of metal in the engine"
T_coolant1= "Coolant temps as read by gauge, scanmaster or whatever"

Note that a "1" in a variable indicates the state of the thermostat being in place where a 2 indicates removed thermostat.
So,
Q_ eng1 = Q_rad1,
By defining the average engine temperature as T_eng1, Re-writing the above yields,

h_eng1 * A_eng * (T_eng1 - T_coolant1) = h_rad1 * A_rad * (T_coolant1 - T_Amb) (Steady state, cruising down the road with thermostat). (1)

Now for arguments sake, assume the thermostat is instantaneously removed... You only have to look at the radiator side of the equation to see what happens:
h_rad2 * A_rad * (T_coolant1 - T_Amb) = Q_rad2, notice that Q_rad2 > Q_rad1 because h_rad2 > h_rad1.
In other words, and as Earl was saying, the heat transfer through the radiator has increased. I think it can be shown that this change can only do one thing... lower the coolant temperature unless something crazy is going on.

The new steady state is determinant by assuming constant heat transfer into the system (Q_eng1 = Q_eng2) (2). This is true if the engine efficiency is independent from the operating temperature, so probably only valid for small temperature changes, but still valid to show if coolant temps decrease.
The new steady state is written as:
h_eng2 * A_eng * (T_eng2 - T_coolant2) = h_rad2 * A_rad * (T_coolant2 - T_Amb) (3)

by solving (1), (2) and (3) simultaneously we can solve for all unknowns: T_eng1, T_eng2 and T_coolant2.

Doing so yields:
T_coolant2 = T_coolant1 * h_rad1 / h_rad2 - T_amb (hrad1/hrad2 - 1),

so conclusively, T_coolant2 < T_coolant1 when, h_rad1 < h_rad2 and T_amb < T_coolant1 (which are normal conditions driving down the road).

Please pass me the BONG!!! After reading that I realized I'm not high enough to understand WTF I just read.

When in doubt buy a bigger rad and fan with more cfm and screw the long winded physics/algebra lessons.

That's what works for me anyways.

 

[robzombie]

Im confused.............

As you should be after reading this thread.

 

[garyk1970]

Ha!

 

[mgmshar]

Here's a two sentence summary of my posts...

If you take your thermostat out, your coolant temperature may go up, or it may go down. It just depends.

All of the other stuff I posted is the engineering rationale behind the above two sentences. I understand that it's really confusing to those who don't do engineering stuff for a living.

Next time you meet an engineer, buy him/her a beer. We have to think about and understand that kind of crap for a living so that your car doesn't explode as soon as you leave your driveway.

Enjoy the bong.

Mike

 

[turbo nasty]

I'll take another toke....cough cough cough...

All this math bizness is proving flow imo is showing radiator performance and not heat absorption.
Now that everyone is confused or not on the flow of water in a radiator and all the science of it...very simple.....two tanks, flues/core and two outlets.
What is left........ how very high flow of water through the water jackets/heads affects the engine....instead of focusing on only on half of the cooling system let's see the other part.
What are we trying to do...cool the water? Or use water to absorb heat in the block and then cool it via the radiator.
Blast water through the engine without a tstat or restrictor and your water maybe cooler but is your engine getting cooled evenly in all its nooks and crannies ???
Flow is going to go the easiest route if you look at the size of the passages in the block to head to intake its easy to see when blasting through where the water will or will not go for the easiest path and areas are going to be cheated.
Since the water jacket network is far from a balanced flow system I still stand by the use of a restrictor for better cooling.....not radiator operation...ENGINE cooling.
Slowing flow down in the system will greatly help with getting a better balance on heat absorption in the water jacket system as a whole.
We are not running water through the system to cool it we are heating and cooling it. The restrictor allows the cooling media to do both otherwise your getting cooler coolant.

 

[turbo nasty]

Ok next hit from the bong...lol