Magnum cooling

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Evan Dutch

Evan Dutch

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Hey guys,

Want to run this by you and see if I should be concerned.

I’ve got a 360 magnum in my 1971 Plymouth scamp. 3 row larger champion radiator, dual electric fans. Fans are set to come on at 200 and they turn off at 185. Car has a 160 degree thermostat.

The car acts like it prefers to operate around 200 degrees. Doesn’t seem to drop lower than that even when cruising down the road on a 70 degree day.

Car has water/water wetter additive in it currently, water is clean. Flushed the cooling system already, new water pump too. Coolant system properly bled as well.

I figured it would run cooler than 200 with all things considered.

Is 200 degrees concerningly high for this setup? I’m not sure. What do you think?

IMG_0144.jpeg
 
Try turning the fans on much earlier say at 170*. What is the amp draw on the fans you are using? How many CFM are they rated at? Do the fans both start at once or are they staggered start?
 
jbc426 said:
Try turning the fans on much earlier say at 170*. What is the amp draw on the fans you are using? How many CFM are they rated at? Do the fans both start at once or are they staggered start?
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I can’t recall the amp draw. I’m running two 12in fans. Each one can pull up to 1550cfm. They’re controlled by the same set point. Both on and off at the same time
 
Evan Dutch said:
I can’t recall the amp draw. I’m running two 12in fans. Each one can pull up to 1550cfm. They’re controlled by the same set point. Both on and off at the same time
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That should be enough CFM to feel them pulling air a few feet in front of the radiator, no? Try lowering the temperature they start at. There are several companies that make staggered and soft-start harnesses to reduce the amperage draw on start up.
 
jbc426 said:
That should be enough CFM to feel them pulling air a few feet in front of the radiator, no? Try lowering the temperature they start at. There are several companies that make staggered and soft-start harnesses to reduce the amperage draw on start up.
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They seem like they move quite a bit of air. I’m concerned that lowering their start temp would have them running nearly all the time.

I think they’re only supposed to be operating intermittently
 
They should be fine running more, and that could resolve the temperature issue you mentioned. They are most likely brushless.

Also, I looked for a picture of your shroud in the Torquestorm thread, but didn't see one. How much space is there between the closed parts of the shroud and the radiator fins? Is there any gaps that allow air leaks from the sides instead of pulling most of the air through the radiator?
 
jbc426 said:
They should be fine running more, and that could resolve the temperature issue you mentioned. They are most likely brushless.

Also, I looked for a picture of your shroud in the Torquestorm thread, but didn't see one. How much space is there between the closed parts of the shroud and the radiator fins? Is there any gaps that allow air leaks from the sides instead of pulling most of the air through the radiator?
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There isn’t much of a gap.

IMG_0402.jpeg
 
I suspect you are having an airflow issue. Looking at the shroud for those electric fans, I think you are losing efficiency because it is not pulling much air from a large portion of the radiator in the corners, since the shroud is very thin.

Is the shroud sealed to the radiator with foam or rubber? Maybe it is leaking around the edges, losing efficiency?

I am hoping to try a clutch fan if I ever get my junk together. The full size truck fan clutch takes up a lot of space, but there are Dakota and Durango fan clutches that appear to be thinner when I see them in junk yards. Hoping to go that route on mine and then run a shroud that is more conventional and doesn't restrict the corner sections of the radiator as much.
 
That extra third row in front could also be impeding some air flow. It's been proven many times over that two wide tubes in a radiator are more efficient. Also I agree with having the fans on longer......or even more fan capacity. Generally speaking, you need 4000 CFM as a minimum. You ain't there.
 
Evan Dutch said:
Hey guys,

Want to run this by you and see if I should be concerned.

I’ve got a 360 magnum in my 1971 Plymouth scamp. 3 row larger champion radiator, dual electric fans. Fans are set to come on at 200 and they turn off at 185. Car has a 160 degree thermostat.

The car acts like it prefers to operate around 200 degrees. Doesn’t seem to drop lower than that even when cruising down the road on a 70 degree day.

Car has water/water wetter additive in it currently, water is clean. Flushed the cooling system already, new water pump too. Coolant system properly bled as well.

I figured it would run cooler than 200 with all things considered.

Is 200 degrees concerningly high for this setup? I’m not sure. What do you think?

View attachment 1716378320
Click to expand...

My 5.9 in my ‘79 Magnum just has bolt on parts
(4bbl carb and intake, headers, chrome box ignition and a MP distributor.)
With a fan that’s not deep enough in the shroud.

195* stat, runs at 210* at max all day long. Nominal 200*’s.
Stock radiator. 2 row, but wide.
 
The test for your cooling system is going to be......what does it do a hot day if you get caught in traffic.
 
Bobzilla said:
I suspect you are having an airflow issue. Looking at the shroud for those electric fans, I think you are losing efficiency because it is not pulling much air from a large portion of the radiator in the corners, since the shroud is very thin.

Is the shroud sealed to the radiator with foam or rubber? Maybe it is leaking around the edges, losing efficiency?

I am hoping to try a clutch fan if I ever get my junk together. The full size truck fan clutch takes up a lot of space, but there are Dakota and Durango fan clutches that appear to be thinner when I see them in junk yards. Hoping to go that route on mine and then run a shroud that is more conventional and doesn't restrict the corner sections of the radiator as much.
Click to expand...
The shroud is not sealed around the edges where it meets the radiator
 
RustyRatRod said:
That extra third row in front could also be impeding some air flow. It's been proven many times over that two wide tubes in a radiator are more efficient. Also I agree with having the fans on longer......or even more fan capacity. Generally speaking, you need 4000 CFM as a minimum. You ain't there.
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Sound like I need better fans
 
Nothing wrong with 200*. Most fwd cars with electric fans were designed to have fan come on around 220*, off at 195.
I just put a thermostat in a Chevy Cruze last weekend for a buddy's kid, and couldn't believe it but all listings I saw said that stat doesn't open til 221*.
My 12, 1/2 ton with 4.7 has a 195* stat and it runs between 200 and 203* on a warm day.
There is such a thing as being too cool as well.
I wouldn't worry about a 200* running temp although you said you have a 160 stat? That's the only surprising part is that you're that much above t stat rating.
I'd run at least a 180 in there if bet that engine runs at the same temp it does now.
 
volaredon said:
Nothing wrong with 200*. Most fwd cars with electric fans were designed to have fan come on around 220*, off at 195.
I just put a thermostat in a Chevy Cruze last weekend for a buddy's kid, and couldn't believe it but all listings I saw said that stat doesn't open til 221*.
My 12, 1/2 ton with 4.7 has a 195* stat and it runs between 200 and 203* on a warm day.
There is such a thing as being too cool as well.
I wouldn't worry about a 200* running temp although you said you have a 160 stat? That's the only surprising part is that you're that much above t stat rating.
I'd run at least a 180 in there if bet that engine runs at the same temp it does now.
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Most of those have computers and emissions equipment that require the higher temps, too. This is an apples and oranges comparison.
 
The sooner the electric fans go away the sooner the cooling problems will go away.
Been there done that.

People can argue that all day long, but it’s still fact.
I had automatic electric on my 5.9 and it ran 200-210 with a 190 stat consistently.
Dumped that setup for a clutch fan belt driven setup and it never goes over 195, even in the summer stop and go traffic here in AZ.

And RRR is right about that 3rd row in the radiator.
Sometimes it’s a disadvantage.
 
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RustyRatRod said:
Most of those have computers and emissions equipment that require the higher temps, too. This is an apples and oranges comparison.
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The fact that you can get the engine running "too cool" still works. Even if not for "emissions" reasons there are reasons to run the engine a little warmer... 180-200 running temp is NOT overheating. With too low temps you're not burning off condensation in the crankcase, and fuel wise fuel puddling isn't good even if not an "emissions tuned"ride.
 
volaredon said:
The fact that you can get the engine running "too cool" still works. Even if not for "emissions" reasons there are reasons to run the engine a little warmer... 180-200 running temp is NOT overheating. With too low temps you're not burning off condensation in the crankcase, and fuel wise fuel puddling isn't good even if not an "emissions tuned"ride.
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I agree with that. There's also the time involved. An engine that runs 180 for short trips for example, is worse off than an engine that runs 165-170 on longer trips. That's why I constantly say "it's all in the tune", because that's true. Were we live, it's about 25 minutes to the closest town we drive to, Gray. That's about the shortest trip we take. Otherwise, it's about 30 miles to Macon and the same to Milledgeville.
 
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That motor was factory designed to run at 195 stock. Only other thing would be to plot/record air inlet temp vs ambient. If the blower puts a little extra heat in, then it will surely get to the coolant.
 
Demonic said:
That motor was factory designed to run at 195 stock. Only other thing would be to plot/record air inlet temp vs ambient. If the blower puts a little extra heat in, then it will surely get to the coolant.
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Correct, but that was with fuel injection and emission controls.
 
TrailBeast said:
The sooner the electric fans go away the sooner the cooling problems will go away.
Been there done that.

People can argue that all day long, but it’s still fact.
I had automatic electric on my 5.9 and it ran 200-210 with a 190 stat consistently.
Dumped that setup for a clutch fan belt driven setup and it never goes over 195, even in the summer stop and go traffic here in AZ.

And RRR is right about that 3rd row in the radiator.
Sometimes it’s a disadvantage.
Click to expand...
I luck up once in a while. Even a broke clock is right twice a day.
 
@Evan Dutch I wouldn’t run any engine with boost on pump gas above 170 degrees. You’ll fight detonation like crazy. 160 would be even better. If you have a 160 stat and it’s running at 200 on a 70 degree day then what you’re seeing is the top of the efficiency range of your cooling system. You need more cooling system. More air, more water, or both. Testing will help decide which is lacking.
 
volaredon said:
Nothing wrong with 200*. Most fwd cars with electric fans were designed to have fan come on around 220*, off at 195.
I just put a thermostat in a Chevy Cruze last weekend for a buddy's kid, and couldn't believe it but all listings I saw said that stat doesn't open til 221*.
My 12, 1/2 ton with 4.7 has a 195* stat and it runs between 200 and 203* on a warm day.
There is such a thing as being too cool as well.
I wouldn't worry about a 200* running temp although you said you have a 160 stat? That's the only surprising part is that you're that much above t stat rating.
I'd run at least a 180 in there if bet that engine runs at the same temp it does now.
Click to expand...
It had a 195 thermostat or whatever the factory magnum rating was
 
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