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Another "how hot is too hot" thread
https://slantsix.org/forum/viewtopic.php?t=68081		 Page 1 of 2
Author:  MadScientistMatt [ Sat Feb 08, 2025 3:32 pm ]
Post subject:  Another "how hot is too hot" thread
I'm having trouble fitting enough electric fans in my '66 Dart for my liking. The radiator is a circle track aluminum piece put in before direct fit aluminum radiators were reasonably priced, and has less clearance than stock. Today it appears the crank pulley contacted the lower fan and knocked it off the radiator. :shock:

I decided to do a temperature run to see how well it cooled on just one fan. I ran this test by hot starting the car and letting the car idle without moving, in 80 degree weather. Temperatures are live data through the EFI system. I believe it's a 180 degree thermostat.

After starting, the temperature dipped to 177 degrees. It then climbed over 4 1/2 minutes to 217 degrees. As the temperature was still rising, I decided to stop the test and shut it down.

This test may be something of a worst case - temperatures here do get hotter, but the car was just not moving for nearly five minutes. It is likely the temperature would have climbed higher. Is this something that you would be concerned about if it was your build?

Also, any thoughts on really compact fans or other airflow solutions?
Author:  volaredon [ Sat Feb 08, 2025 3:44 pm ]
Post subject:  Re: Another "how hot is too hot" thread
On my Durango there's a belt driven mechanical fan, and an auxiliary electric fan that comes on with the ac compressor. In your car i don't know if there's room in the engine side for both but maybe you could do a mechanica driven by the engine, l and then a pusher fan on the bumper side?
Author:  MadScientistMatt [ Sat Feb 08, 2025 4:35 pm ]
Post subject:  Re: Another "how hot is too hot" thread
This might be tricky as I have a transmission cooler and intercooler in front of the radiator. I may have some spots alongside the transmission cooler that could fit a pusher fan...
Author:  Dart270 [ Sun Feb 09, 2025 4:52 am ]
Post subject:  Re: Another "how hot is too hot" thread
Hi Matt,

How big and what CFM are the fan(s) you used? Also, please share the dimensions (all 3) of the radiator core.

Lou
Author:  lgu32 [ Sun Feb 09, 2025 5:31 am ]
Post subject:  Re: Another "how hot is too hot" thread
I have just one fan front of Griffin aluminum radiator and it is fine for all conditions. But I dont have intercooler there and that is the difference. My tranny oil cooler is at the side too, not front of engine radiator.

My fan does most of the time at 10-20% pwm and the coolant temperature is constant. My efi has the temp sensor at the heater hose.
Author:  Dart270 [ Sun Feb 09, 2025 7:15 am ]
Post subject:  Re: Another "how hot is too hot" thread
Oh yeah, Matt, where is your temp sensor? At/near the factory location in the head near the tstat?

Lou
Author:  MadScientistMatt [ Sun Feb 09, 2025 12:14 pm ]
Post subject:  Re: Another "how hot is too hot" thread
Yes, the EFI temperature sensor is just an inch or so away from the gauge temperature sensor.

Here are the key dimensions. The transmission and intercooler ones are not as precise since I did not take things apart to measure them.

Radiator: 22" overall width, 17" core width, 19" height, 2 1/4" core thickness
Transmission cooler: 17" core width not including side loops, 7" core height, 1" core thickness
Intercooler: 21" core width not including end tanks, 7" core height, 3" core thickness

Fans: 10.5" (still in place) and 9" (temporarily removed)

Water pump clearance: 1.5" from water pump to radiator, pulley center offset 7" from driver side of radiator, 9.5" from top
Author:  Reed [ Sun Feb 09, 2025 1:37 pm ]
Post subject:  Re: Another "how hot is too hot" thread
Quote:
Yes, the EFI temperature sensor is just an inch or so away from the gauge temperature sensor.

Here are the key dimensions. The transmission and intercooler ones are not as precise since I did not take things apart to measure them.

Radiator: 22" overall width, 17" core width, 19" height, 2 1/4" core thickness
Transmission cooler: 17" core width not including side loops, 7" core height, 1" core thickness
Intercooler: 21" core width not including end tanks, 7" core height, 3" core thickness

Fans: 10.5" (still in place) and 9" (temporarily removed)

Water pump clearance: 1.5" from water pump to radiator, pulley center offset 7" from driver side of radiator, 9.5" from top

A 10 in diameter fan will not move enough air through a 17 inch wide radiator. At idle you will be passing air through less than half of the overall radiator cooling surface. 10 inch diameter means little to no airflow outside of the edges of the fan unless you are running a shroud

I recommend converting to a single larger fan on the bumper side of the radiator pushing air instead of pulling it. Definitely run a shroud if possible.

Derale has nice products and a dowloadable catalog to research what will fit in your application.

https://derale.com/images/pdfs/Derale-Catalog-2023.pdf

Part no. 18916 looks like it might work for you, but it doesn't come with a shroud.
Author:  SlantSixDan [ Sun Feb 09, 2025 1:43 pm ]
Post subject:  Re: Another "how hot is too hot" thread
Quote:
I'm having trouble fitting enough electric fans in my '66 Dart for my liking
What is driving your liking? What is it you want to see, in terms of engine temperature behaviour?

Keep in mind the thermostat does not set the maximum operating temp, but the minimum operating temp of the engine. "Oh, no! It's up to 217 degrees even though I have a 180° thermostat!" is not a valid worry, unless it just keeps going higher and higher or there are other signs of actual, real overheating. Read this.
Author:  MadScientistMatt [ Sun Feb 09, 2025 2:05 pm ]
Post subject:  Re: Another "how hot is too hot" thread
My goal is to have a cooling system that will not put the engine at risk of overheating even if driven in stop and go traffic on a 100 degree day - while commuting in Atlanta traffic isn't the car's usual use, it is an intended occasional use. Unfortunately I have a hard time getting a clear number on how high is too much temperature. The temperature was still rising at 217 degrees; I wasn't sure how far past that I wanted to go.

The large pusher fan might be a good idea if I didn't have such a large stack of other coolers in front of my radiator, but the intercooler sits right where the pusher fan motor would go if using a big single fan, and it's not easily relocated. The transmission cooler could be moved up or down pretty easily and could possibly be relocated elsewhere. For example, I could move the transmission cooler to the top of the radiator and then have a pair of pancake pusher fans at the bottom.

I have also thought about using a mechanical fan - trouble is, there's no clearance for a clutch mechanism.
Author:  Rick Covalt [ Sun Feb 09, 2025 2:38 pm ]
Post subject:  Re: Another "how hot is too hot" thread
I run a 3" Griffin universal cross flow radiator in my 65 Valiant. Race motor, 11.5 to one big cam...etc. I run a 180F thermostat and I rarely if ever have to turn on the electric fan if I am moving at all. It runs cool with near 100 degree temps in Wilkesboro and Bristol. If I set still for a while I flip on the fan manually, but only till we start moving. My electric fan is a 14" pusher fan (Which is supposed to be worse)
Author:  SlantSixDan [ Sun Feb 09, 2025 2:41 pm ]
Post subject:  Re: Another "how hot is too hot" thread
There might be room for a clutch other than the kind you might have in mind; read the fans chapter in that 5-part series I linked to.

By all means, make sure your thermostat is a good-quality one, working properly, and not jammed or blocked as installed. If you want a high-flow thermostat for a Slant-6, and you don't like the Stant Super-Stat (maybe they're no good any more? Donno, haven't needed one in years), Tridon make really nice ones in Australia—the TT2000 series, available in 160°, 170°, 180°, 190°, and 192°F ratings. Thiz 2025 and we have the internet, so they can be bought from afar.

Beyond that, though…I still don't hear any alarming evidence that you actually have an overheating problem. There is no reason, need, or benefit to spending money and effort to try to keep the engine from exceeding the thermostat temperature rating; that's now how this stuff is supposed to work.
Author:  Reed [ Sun Feb 09, 2025 10:16 pm ]
Post subject:  Re: Another "how hot is too hot" thread
My brother has been on a 1+ year journey putting a turbo on the 03 PT Cruiser that has been in our family since about 2005.

He had a terrible time getting the engine to run at a safe temperature after he added an intercooler and auxilliary oil and trans coolers. He ended up going with remote mounted fluid coolers mounted in the wheel well that have little auxiliary push fans mounted on the coolers. Just an idea if you want to try putting the intercooler and trans cooler somewhere else.

He has a youtube channel documenting his journey. It is called "PTBubbles."

I would get worried if the engine got above 220 and kept going up and didn't steady out. Most engines that I check the idle coolant temp on run about 190-205 Fahrenheit if the cooling system is working well.
Author:  SlantSixDan [ Sun Feb 09, 2025 11:09 pm ]
Post subject:  Re: Another "how hot is too hot" thread
Quote:
My brother has been on a 1+ year journey putting a turbo on the 03 PT Cruiser that has been in our family since about 2005.
Holy flaming snotballs. Is your brother trying to beat out tough other candidates in the Masochist of the Year competition‽
Author:  MadScientistMatt [ Mon Feb 10, 2025 2:59 am ]
Post subject:  Re: Another "how hot is too hot" thread
Thanks - the site had been slow to load and I missed page five. The thin clutch fan is a very handy find and thank you for posting the thickness. In my case, it's still too thick.

To back up a little, in this case I am concerned about potential overheating issues due to what conventional wisdom would suggest (small fan, turbo, hot climate, would like to go drag racing once this is sorted) and would like to find a way to test to see if these are present without risking damage to the engine or having the issues crop up in the middle of a commute and having to pull over and take a bunch of time to cool the engine down before I can make it home. So I'm trying to come up with some sort of stress test and criteria for how to establish if the potential for an overheating issue is there and head it off before it causes any problems.
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