Cooling system question...

[Steve Blair]

Good morning everyone,
I have some questions related to the cooling system on a stroked 440 (512), my questions are:

1. What temp thermostat should I run? (The current thermostat is a 195 thermostat but with a fan stat that turns the fans on at 210 degrees and off at 180 I'm thinking the engine is getting too warm before the fan stat turns on the fans),

2. The car is running a 26 inch wide down flow aluminum radiator with duel electric fans so where should the fan stat be installed? (The fan stat is currently in the lower radiator tank to the left of the lower radiator hose so the engine coolant has to heat up before the fans turn on).

3. What temp fan stat should I run if I change the thermostat to a 180 degree thermostat? (I'm thinking the fan stat should turn the fans on at 190 degrees and off around 170 to keep the fans from running all the time when the car is sitting still).

Does anyone know what the rule is when it comes to the selection of fan stat temp as it relates to the engine Thermostat?

 

[Ccas]

The thermostat is not as critical as one might think. Your motor has a certain operating temperature that it will run at no matter what thermostat you install. The t-stat simply gets the motor to that temperature a little faster or a little slower. Generally, a well built motor is going to run between 180-210. You can put a 160 t-stat in there to open up sooner but within minutes, it's going to still go to the temp it wants to go to.

When choosing temps for the fan to turn on and off, it's best to first determine what the motor wants to generally run at. Then you avoid situations where the fan it constantly running. ie; In your example, if the motor wants to run at 190, it's going to be hard for those fans to ever get the temp down to 170 and therefore turn the fans off.

Ideally the temps should be taken at the top of the motor at the hottest point. Off the intake if possible or before the fluid enters the radiator.

More important questions to ask yourself if the motor is consistently running in the 210+ range.
1. What is the capacity of radiator
2. what type and size of fans
3. Are the fans on a shroud. What type of shroud

 

[Steve340]

I would keep the 195 thermostat for now.
I think the on/off spread of your fan stat is too wide and the location is probably not right either.
I have a similar radiator/fan combo to you - description wise anyway. I have a switch that is ON at 203F and OFF at 194F mounted in the intake manifold below the thermostat. It is a Tridon TFS111
In my opinion the fan switch needs to be in the engine behind/below the thermostat in case the thermostat fails to open.
This set-up works good.
Fan does not run all the time and the fans kick in and knock the heat down. The fans actually go off and on in traffic.

 

[moparleo]

Yep. The engine needs to operate at a temerature that seems to be much higher than a lot of people think.
Remember that this is a closed system that is under pressure and contains more than water. The cylinder heads ( combustion chamber) needs heat to operate efficiently. That is why aluminum cylinder heads needs different heat requirements to operate at peak efficiency.
If the engine is running strong, and you have no detonation under acceleration you are good to go.
Just another recommendation that is often overlooked. Run a coolant recovery system.
This system uses a special radiator cap that has a 2 way valve. It allows coolant to escape the radiator when it expands under heat and also for the coolant to return to the radiator when the system cools down.
This keeps the cooling system full at all temperatures and doesn't leak the heated coolant out on the street. You don't have to top off this type of system.
All modern cars use a recovery system. Pre 73 Mpoars would like most other car manufacturers just allowed the excess coolant to leak out the overflow hose.
At the very least make sure that you have a good functioning radiator cap.
If it does not hold the marked pressure you will have overheating problems.
The coolants boiling point is raised when under pressure.The cap is a very important part of the system and is rarely tested/checked.

 

[Steve Blair]

Turns out the thermostat is a 180 degree stat, I believe the fan stat that came with the radiator is designed to turn the fans on at 180 degrees and off at 160 degrees. I'm going to verify the temp range of the fan stat and move it back to the upper passenger side of the housing the water pump bolts to.

The people that sold me the radiator, fan relays, wiring, fans, and fan stat said once the engine reaches operating temperature (180 degrees) the fans would run until you shut the engine down. I don't really like the noise the fans make so I was trying to move the fan stat to a location that had enough of a temperature swing that the fans would cycle on and off.

The engine never ran over 180 degrees with the temp stat mounted by the thermostat even with the engine idling so I think I'll move the fan stat back and either put up with the noise the fans make or switch the car back to the fan set up it originally had?

Thanks for the feedback everyone!

 

[Steve340]

I agree that there seems to be little point running an electric fans all the time.