Another tidbit: Every extra lb on the read cap,the cooling system can handle= roughly works to three degrees lower on the temp gauge. There's a reason why cars run difference in rad cap ratings.
180 or 190 thermostat?
- Thread starter fnaramore
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Lonewolf3165
Living the Dream!
If the cooling system is properly bled free of trapped air then the pressure is constant throughout the whole system The cooling system doesn't have much pressure in it at all until the engine reaches & exceeds operating temperature. Additionally, if the water flows through the engine too quickly it may cause cavitation inside the water jacket & that reduces coolant.
The point is that the flow needs to be reduced, whether by t-stat or some sort of restrictor, venturi, disks or otherwise, in order to cool efficiently.
The point that I keep trying to make is that the pressure is NOT constant thru out the whole system. Put your thumb mostly over the end of a garden hose with the valve wide open and tell me that the hose didn't get slightly larger under your hand. An increase in local pressure due to the restriction of your thumb did that. Same thing happens between the pump and the t-stat. The t-stat is effectively your thumb partly blocking the exit and raising the pressure of the coolant behind it.
The lowest pressure in the system is between the t-stat and the pump inlet, and that is the cap's pressure. Between the pump's discharge and the t-stat it is at a higher pressure due to the restriction intentionally provided by the t-stat. The goal is to increase the pressure in the block so that cavitation and localized boiling are less likely to happen. Even if it is only a couple psi above that of the cap it has bought the system a 6°F higher boiling point. Look at what it does for you if it is 10 psi above the cap.
This all about heat transfer (rejection) rate. Slow the coolant down and you will reduce the transfer rate. The rate of heat transfer is directly proportional to mass flow rate. <- I stole that from here: http://www.overclockers.com/water-cooling-flow-rate-and-heat-transfer/ Found that looking for some simple math to prove it. That formula is:
Q = M x C x Delta T
Where:
Q = heat transfer rate
M = mass flow rate
C = Constant, specific heat of the coolant
Delta T = the change in temperature of the coolantUgh, Now that I see it, I recall that formula from Thermodynamics.
Notice that none of the factors are fractions or divisors. That means that any change in them has a direct rather than inverse effect on the thermal transfer rate. Increase any of them and the heat transfer rate goes up. Decrease any of them and the heat transfer rate goes down.
The factory knew about how much flow they needed to have to keep the engine cool and designed the pump and the drive ratio to work together to provide enough flow. Why do those who go to underdrive pulleys sometimes have over-heating troubles when going slow? They don't have enough coolant flow. That is the only thing that they changed.
The lowest pressure in the system is between the t-stat and the pump inlet, and that is the cap's pressure. Between the pump's discharge and the t-stat it is at a higher pressure due to the restriction intentionally provided by the t-stat. The goal is to increase the pressure in the block so that cavitation and localized boiling are less likely to happen. Even if it is only a couple psi above that of the cap it has bought the system a 6°F higher boiling point. Look at what it does for you if it is 10 psi above the cap.
This all about heat transfer (rejection) rate. Slow the coolant down and you will reduce the transfer rate. The rate of heat transfer is directly proportional to mass flow rate. <- I stole that from here: http://www.overclockers.com/water-cooling-flow-rate-and-heat-transfer/ Found that looking for some simple math to prove it. That formula is:
Q = M x C x Delta T
Where:
Q = heat transfer rate
M = mass flow rate
C = Constant, specific heat of the coolant
Delta T = the change in temperature of the coolantUgh, Now that I see it, I recall that formula from Thermodynamics.
Notice that none of the factors are fractions or divisors. That means that any change in them has a direct rather than inverse effect on the thermal transfer rate. Increase any of them and the heat transfer rate goes up. Decrease any of them and the heat transfer rate goes down.
The factory knew about how much flow they needed to have to keep the engine cool and designed the pump and the drive ratio to work together to provide enough flow. Why do those who go to underdrive pulleys sometimes have over-heating troubles when going slow? They don't have enough coolant flow. That is the only thing that they changed.
fnaramore
POWEEERRRRRR
Okay, I'm gonna be honest, this is really started to annoy me. Lets get this straight. First off, if you are going to start spouting physics equations at me, at least get them correct. If you actually knew anything about physics, you would know that heat transfer is a incorrect statement. Heat=transfer of energy. You are basically saying transfer energy transfer. Second, C is not a constant by any means, it is material specific. Third of all, that equation is wrong, that process only accounts for one material, where you would need two specific heat variables. Also, to use delta T, you need two comparison points. Obviously you are missing two parts of the equation. The equation are using can only tell you what the coolant is capable of, not the system. What you want is the Carnot Heat Engine efficiency equation, which you could use to derive and find the variable Q's. Fourth, your localized pressure would only be present, wait for it, at the t-stat. Six degrees of higher boiling point at the t-stat is completely immaterial. If i have a gauge with a sensor right next to the t-stat that says 190* F and plain water (NOT EVEN WITH ETHYLENE GLYCOL IN IT) boils at 212*, why does six degrees matter And do you wanna know why I can say all this? Because I have taken a thermodynamics course, I have taken a mechanics physics course, I have taken a modern physics course and many more... its the perk of having a major in physics.
Inertia
Well-Known Member
lol .. Rick.. ! !
Fine, you're the chemist/physicist, I'm just the dumb Engineer with nearly 40 years of messing with engines who took the watered down thermo class more than a decade ago because I didn't need the full blown class.
C is a constant for any particular material or combination of materials. I didn't feel the need to muddy the waters with mentioning that. Most eyes glaze over as soon as the math goes past simple Algebra. You're taking this way too literal and in-depth.
The t-stat can't produce the pressure, it is a resistor. Something else produced the localized increase in pressure. Wait for it, the only thing that it could be is the pump!
So if there is a localized increase in pressure then it MUST be in the conductor between the pump and the restriction. That pressure will be uniform in that whole section of the conduit. Which just happens to be the coolant passages in the block. (Note: I'm intentionally leaving out other stuff that is there, but conceptually doesn't matter and only serves to muddy the waters more.)
I really don't care if you're too immersed in your own ideas to even consider that I might have a point. Mislead folks with your blindness to the fact that in spite of your education you may not actually fully understand the whole system. It is clear to me from some of your statements that you don't. I won't claim that I do, that's why I've been calling it a theory, not a Law.
I'm done here.
C is a constant for any particular material or combination of materials. I didn't feel the need to muddy the waters with mentioning that. Most eyes glaze over as soon as the math goes past simple Algebra. You're taking this way too literal and in-depth.
The t-stat can't produce the pressure, it is a resistor. Something else produced the localized increase in pressure. Wait for it, the only thing that it could be is the pump!
So if there is a localized increase in pressure then it MUST be in the conductor between the pump and the restriction. That pressure will be uniform in that whole section of the conduit. Which just happens to be the coolant passages in the block. (Note: I'm intentionally leaving out other stuff that is there, but conceptually doesn't matter and only serves to muddy the waters more.)
I really don't care if you're too immersed in your own ideas to even consider that I might have a point. Mislead folks with your blindness to the fact that in spite of your education you may not actually fully understand the whole system. It is clear to me from some of your statements that you don't. I won't claim that I do, that's why I've been calling it a theory, not a Law.
I'm done here.
fnaramore
POWEEERRRRRR
I am sorry, but that is simply not how pressure systems work. You said it yourself, LOCALIZED PRESSURE. The pressure is NOT uniform. Look, 1 atmosphere of pressure is 16 psi about. At 1 atm, water boils at 212* F. We know that altitude can change waters boiling point. Why do you think most radiator cap pressures are about 16 psi? So water boils at 212* at every altitude the car is at. And one more time, PLAIN WATER boils at 212*. Ethylene glycol boosts it's boiling point to about 230-250 depending on the mols. I respect your experience, but you are simply wrong my friend. A 6 psi change is pressure by the t-stat/ water pump combo is immaterial
fnaramore
POWEEERRRRRR
And if you had actually read my earlier posts, you would have seen that I did give your point some validity and say I somewhat agree
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