Aluminum radiators? How do you feel about them?

When I worked for Mopar in 74/75 the factory rep said : the water pump for a motor WITH air conditioning moved the coolant slower than a non A/C. He said it was to keep the water in the rad longer to cool more.

 

When I increased my copper/br*** 2 row radiator to a 3 row, it kept the engine cooler on hot desert freeways trips during mountain climbs.

Was that because I changed flow or had more radiator surface or both (or something else) ?
I only changed the radiator core, nothing else.

 

ah Thermodynamics.

Using the formula quoted above.
Qdot=mdot*c(Th-Tc)

Condition: When the thermostat is open at a constant engine/waterpump RPM,

mdot is a constant (and 'c' is a constant).

'Th' (temperature of the coolant entering the radiator) can be ***umed to be the thermostat temp (say....185F?) if the system is balanced.

So then what you don't know is what is coming out of the bottom of the radiator: 'Tc'.

To increase our heat transfer we want Tc to be as low as possible right?

So how do we do that?

 

So far as I am concerned, that is proof of how misunderstood this subject is.

 

Surface area. Thermostat controls flow rate (usually).

 

He wasn't much of a factory rep. In all OEM systems, the thermostat regulates the FLOW RATE of the coolant m***. In those system, except in extreme conditions, the thermostat is never fully open. When the thermostat IS fully open, the coolant m*** is moving the FASTEST and the cooling system is operating af MAXIMUM COOLING CAPACITY. Actually, aside from mis/mix/matched componets, hot rods work that way too.

 

Good point, and I think it's important to note that the correct maximum flow rate is engineered for a particular engine/car combination. Not to be confused with simply saying that "faster is better"...

Another important function of the thermostat is to build block pressure. That's why they are always found on the outflow side of the engine. The more block pressure in the system, the more conductive heat transfer into the coolant from the metal. Remember, it's not the water temperature we're really concerned with, it's the temperature of the metal parts of the engine. Sometimes the relationship between the two can get complicated...

 

I just ordered a new 3 row, br*** '32 rad from Br*** Works in Paso, Ca...got a fantastic price to boot!

Pete-

 

question:


If the thermostat alone, controls the flow "rate", then why are there non-A/C versus A/C water pumps for those Mopars? (been too many years but one had less blades on the impeller?)

 

Yes, even Pontiac spec'd different water pumps for the AC cars.

You need to learn how **** works. A T-stat DOES NOT regulate flow rate! It is open or closed. Here is some remidial reading w/ footnote links
http://auto.howstuffworks.com/question248.htm

 

Ummm...yes it does, regardless of whether it opens partially or just fully.

 

Yes thermostats are an on/off deal but they will only allow so much m*** flow for a given pressure no?

mdot=rho*v*a

In other words
M*** flow = density * Velocity * Area

Density and area are constants....velocity may change for a given water pump rpm. (more pressure may force higher water speed)

From Incompressible Flow Eq.
P1 + rho(V1^2/2) = P2 + rho(V2^2/2)

V2= SQRT ((2*(P1-P2)/rho) + V1^2)

So from that you can see that as P1 grows so does exit velocity (V2).

So the thermostat area can control the m*** flow. You can get different thermostats with varying area's right? or no?

 

No, it will "restrict" flow somewhat , compared to no t-stat at all, because it partially blocks the coolent path when fully open. REGULATE would mean it is infinately variable from fully closed to fully open which they do not do.

 

Ok. You are correct about that. My point was that thermostat size along with pump RPM and efficiency act to provide correct coolant flow for optimum engine cooling.

I was trying to keep it simple for those who don't completely grasp all of this...

 

And it seems there are quite a few needing it simple!

 

Tman; I'm amazed that you would depend on what a tech writer for "how it works" that possibly never put a thermostat in a pot of water, but explains what will happen if you do. YOU need to learn how **** works. If I tell you how it works, you can bank on it. If I don't know how it works, I'll tell you that too.
Put a thermostat in water on the stove. Heat it up. It will start opening at a certain point. From that initial temp, unless you elevate the water temperature it will not open all the way. Then elevate the temp until it is open all the way. Watch trhe thermostat. As the water cools, gradually, the thermostat will start to close, gradually. That type of hermostat regulates the m*** flow of coolant through the system, That's how they work.


I'm open to the possibility that there may be some designs that pop open and closed at a very narrow change in temp, but none of the ones I have ever worked with do that.

 

Ha! Good call! But look at the ****storm you started! Geez! Who knew?

 

Of course "the thermostat alone" does not regulate flow. System resistance and pump speed are additional factors, but remember that the pump is turning even though the thermostat is closed, with no coolant flow, and cavitation is at maximum. The thermostat is the gate that regulates the coolant flow.

 

they work great ,,,worth every penny

 

I just put my 3rd aluminum radiator in my coupe due to failed corners. It always ran at 195 with a 195 T-stat. PRC told me I was cracking the corners due to a thermal rush on cold days (0 F) when the t-stat opens. So, using the exact same T-stat, I did as recommended and drilled two 3/16 inch holes in it to 'bleed' coolant through to avoid thermal shock. Well, even on a hot day now, it now does not get hotter than 160. So, it appears those two small holes p*** enough for the T-stat not to even open. T-stats are ****og, not digital. They control the temp with partial openings with a fairly long time constant. When your car is running hot, the t-stat is all the way open.

 

running too cold isnt good either

 

So, let's summarize...
Either type of radiator should cool the vehicle adequately, IF
1) It is sized correctly for the engine and application
2) The water pump and thermostat are providing adequate coolant flow and block pressure
3) There is (like everything else) a lot of conflicting information on the subject...

 

So with all you genious' answering the questions about water and thermostats and flow rates and all of those good things. No one is talking about the general construction of br*** versus the Aluminum. 1st off if you are a traditionalist in the pure sense then Br*** is the way to go. Get a 4 or even 5 row radiator. The more rows gives more area so that the air can cool the water. Water or antifreeze does nothing but transfers heat from the engine to the cooling fins that are in contact with the tubes the air flows across the fins and in turn cools the water that goes back into the engine therby cooling it.

The difference between the aluminum and br*** technologies is the fact that Aluminum can utilize larger tubes than Br***, however br*** has better cooling properties than aluminum. The larger tubes in aluminum allows for more surface area for the air to move across. The Br*** utilizes more rows and tubes but they have to be smaller. The air cools the water. The radiator is just a vehicle that carries the water.

The auto manufacturer uses the cheapest method possable at the time. Aluminum is much cheaper to manufacture now than Br***, They study these things in the 100ths of cents per part.

Cooling is about airflow that's my dumb*** opinion

 

I bought one for my '37 Chevy. I'm running a ZZ4 Chevy, 355hp, no mechanical fan (I have an electric set at 200 degrees). The fan rarely ever runs even on hot days, 100+, and idling in a cruise. It has been in for about a year now with no problems.

 

uuuuummmm


Smells like fish taste like chicken????

 

I don't care what mine is. Car feel the same at 70 either way. I am not building museum pieces but appreciate those that do.

 

have been very happy with Superior Radiator Mount Clemens, Mi. Price is right , VERY good fit, keeps em cool....painted em black. Rods, customs and just finished putting one in XKE Jaguar tonite...perfect fit !!!

 

"Thermal Rush", "Thermal Shock"...Seems like a professionally built, expensive radiator should be able to withstand some extreme temp swings. Guess everything has it's limitations. I sure like that terminology though. I'll be sure to use it in my vocabulary, maybe not always in reference to cooling systems in cars.