Cooling myths.

[Clone TIE Pilot]

There are a lot of myths about cooling systems. The cooling system's job is to quickly warm the engine up to operating temperature and keep it there. It's not to keep the engine as cold as possible. The big grand daddy myth states that coolant needs time to absorb heat from the block or to transfer it through the radiator into the air which is incorrect. The equation for heat transfer proves that this myth is indeed false.

Heat transfer rate (Q) = mass flow rate (M) × specific heat capacity (C) × outlet temp -inlet temp (Delta T). Q=M×C×Delta T.

Here is a helpful link for more cooling basics.

BillaVista.com-Cooling Bible Tech Article by BillaVista

 

[bracketchev1221]

It’s not true. I left the water in my engine overnight not moving and it cooled down. It just needed more time!!!

 

[69hurstolds]

This is why increasing mass flow rate helps immensely when things start heating up. It's mathematically proven as Clone TIE Pilot pointed out. It's a closed system so if you you're a believer that slowing down the coolant in the radiator gives it more time to give up its heat, you also must slow down the coolant in the engine at the same rate so it picks up more heat. Meaning that you're losing the war against overheating.

The components also need to be sized appropriately to ensure that the heat rejection by the radiator is at least capable of keeping up with the heat picked up by the coolant from the engine. Also, materials and configuration make a difference. This is why a 3-row aluminum radiator can be just as efficient or even better than an old-school 4 row brass one. Or a better flow water pump impeller is optimal to a cheese-ball water pump impeller.

Thermostats only make the engine heat up to operating range faster. Once opened, the engine is going to rely on the coolant flowing to the radiator and back to regulate temperature along with a fan clutch or temperature operated electric fans, if so equipped. 180 is considered to be a good T-stat opening setpoint for old-school non-CCC engines. OEM's liked 195 because it ensured your engine is totally warmed up and clearances are spec'd right, etc., etc., and good for emissions. Keep in mind some of the sensors may come into play at certain water temps and IIRC, things like the ECM need to know what you're engine coolant temps are before they even start working correctly. So if you have your CCC system still on the car and working, it's advisable to retain the 195 thermostat.

All that said, 160 thermostats are a waste of time on a street engine.

 

[Rt Jam]

The cooling systems j8b is too quickly warm the engine up to operatingvtemperature and keep it there. Not to keep the engine as cold as possible.

This part is true.

All you need is to observe how a normal factory car behaves. My work Caravan, daily Silverado and every other stock vehicle gets to normal temperature in 4 or 10 minutes in any weather.
I had a 95 Ram 1500 with a 5.2L 5 speed. I put way to much trailer behind it 20 years ago. I had it to the floor for 4 hours, the temp gauge was in the middle, as usual. This is what I strive for now. Any conditions, normal temp. Who cares about the formula. If your car gets hot in traffic or on a hot day. You need more cooling system.

 

[Built6spdMCSS]

There are a lot of myths about cooling systems. The cooling systems j8b is too quickly warm the engine up to operatingvtemperature and keep it there. Not to keep the engine as cold as possible. The big grand daddy myth isvthat coolant needs time to absorb heat from the block or to transfer it in the radiator which is false. The equation for heat transfer proves this to be false.

Heat transfer rate (Q) = mass flow rate (M) × specific heat capacity (C) × outlet temp -inlet temp (Delta T). Q=M×C×Delta T.

Here is a helpful link for more cooling basics.

BillaVista.com-Cooling Bible Tech Article by BillaVista

I see you took the thermodynamics class and missed the English grammar class. 🤣

I've heard if you drill holes in your radiator so air gets through it faster that helps too. 🙂

 

[g0thiac]

Science like this: *solely exists for a reason*

Backyard mechanics: *removes thermostat entirely*

 

[Clone TIE Pilot]

I see you took the thermodynamics class and missed the English grammar class. 🤣

I've heard if you drill holes in your radiator so air gets through it faster that helps too. 🙂

Typing on a tablet doesn't help either, the damn touch screen is always jumbing around. Half the time when I press the spacer bar I getvinstead.

 

[Built6spdMCSS]

Science like this: *solely exists for a reason*

Backyard mechanics: *removes thermostat entirely*

One of them uncle daddy told my pappy under a shady tree tricks.

 

[doood]

The cooling system's job is to quickly warm the engine up to operating temperature and keep it there.

So botched, yet arguably true. LOL.

FIFY: Cooling system's job is to establish and maintain desired operating temperature.

About the only thing you can measure well in this scenario is the dT, so the math doesn't really lead anywhere.

 

[81cutlass]

AHHHH, yes. AND time to split hairs.

I feel like some clarity is needed to add because adding flow isn't always the solution to improve cooling.

I never was overly fond of thermo but I didn't have to retake it so I guess I'm not inherently bad at it-
The equation is correct and the point that more flow = more cooling is generally true. I won't say it IS and ALWAYS is true I because I deeply distrust absolutes, but I don't disagree. Short of the heat transfer rate between the cast iron/aluminum (heat source) and the cooling media (water/heat rejecting destination) per square area changing between something like laminar and turbulent flow, or putting SO MUCH heat into the water to pump it that you are mechanically heating the water up with the pump, increasing flow will cool better.

A gallon of water at 100F can absorb X energy when it's heated to 150F. It can absorb 2X energy when heated from 100F to 200F. It can absorb the same X energy when heated from 50F to 100F. As long as the water is in liquid state (32F to 212F) the water will absorb the same energy. The latent heat of fusion or vaporization will take a LOT of energy but you don't run steam cooling or ice cooling so no point there.

A good indication of too little flow would be the water outlet temp being very near the tstat temp. Say the block is at 210F and the water going in is 100F, and the water going into the rad is 208F, the water has become fully 'saturated' in heat capacity.

However if the water is going in at 100F and the water going out is 120F and the engine is still overheating, there might be a flow disruption or 'short circuit' because the water is not absorbing the heat. Increasing the flow isn't likely to help.

DItto, the math is right, but only a small piece of the overall pie.