Cooling issue on highway

-
Another vote for manual fan. Went over to the neighbors tonight for a get together.

A guy came in with his '70 Maverick 302 from 30 miles away, came in running cool.

20220713_190005.jpg


Everyone enjoying looking at his setup.

20220713_190027.jpg

Another Success

20220713_190058.jpg


20220713_190431.jpg

Simple, with the tranny cooler in front of the radiator too.

☆☆☆☆☆
 
My four blade fan gave no overheating issues at all. In fact, I could throw it in the ditch and it still wouldn't run hot, I'm sure. But this five blade fixed fan is LOUD. It's comin back off in favor of the little four blade. lol
 
I love how this thread went from a guy with a 6.4 Hemi that needed to reprogram his fan controller to a bunch of guys with bone stock low horsepower ‘70’s engines not even running shrouds saying mechanical fans keep their cars cool.

Yeah man, if you don’t make much horsepower, you don’t need much cooling either.
 
72bluNblu said:
I love how this thread went from a guy with a 6.4 Hemi that needed to reprogram his fan controller to a bunch of guys with bone stock low horsepower ‘70’s engines not even running shrouds saying mechanical fans keep their cars cool.

Yeah man, if you don’t make much horsepower, you don’t need much cooling either.
Click to expand...
Oh you just be quiet. lol
 
72bluNblu said:
I love how this thread went from a guy with a 6.4 Hemi that needed to reprogram his fan controller to a bunch of guys with bone stock low horsepower ‘70’s engines not even running shrouds saying mechanical fans keep their cars cool.

Yeah man, if you don’t make much horsepower, you don’t need much cooling either.
Click to expand...
And for the record, my slant 6 has over 175PSI cranking pressure so it generates some heat for a six.
 
RustyRatRod said:
And for the record, my slant 6 has over 175PSI cranking pressure so it generates some heat for a six.
Click to expand...

If you are going back to the 4 blade fan, move it in closer to your radiator like 3/4" off the radiator, that will help to pull more air through the radiator without a shroud.

You can do the 9 x 11 paper test (or use a paper towel). Put the paper towel on the front of the radiator with the engine running, it should suck it up tight against the radiator.

This will show you if you have enough air being pulled through the radiator to keep it cool.

Was a good test when we went from the solid mount 15" silent run fan test fan, to the 18" solid mount silent run fan.

There was a huge difference of how much air was being pulled through the radiator between the 2 fans.

The 18" fan sucked the paper towel up tight to the radiator, to the point you could hardly peel it off of there.

Same tests work for the electric fan/box shroud setups to see if there is enough air being pulled through them.
 
RustyRatRod said:
And for the record, my slant 6 has over 175PSI cranking pressure so it generates some heat for a six.
Click to expand...

My 340 is about the same, 175-180 cranking PSI.

And for the record I never said a mechanical fan can’t work. I just said it’s less efficient.

Like I said before, I’ve got no problem with mechanical fans. I just hate all the guys that say electric fans can’t work because they set up a lousy system because they have no idea what they’re doing. They work great if you use the right fans and set up the system properly.

George Jets said:
If you are going back to the 4 blade fan, move it in closer to your radiator like 3/4" off the radiator, that will help to pull more air through the radiator without a shroud.

You can do the 9 x 11 paper test (or use a paper towel). Put the paper towel on the front of the radiator with the engine running, it should suck it up tight against the radiator.

This will show you if you have enough air being pulled through the radiator to keep it cool.

Was a good test when we went from the solid mount 15" silent run fan test fan, to the 18" solid mount silent run fan.

There was a huge difference of how much air was being pulled through the radiator between the 2 fans.

The 18" fan sucked the paper towel up tight to the radiator, to the point you could hardly peel it off of there.

Same tests work for the electric fan/box shroud setups to see if there is enough air being pulled through them.
Click to expand...

Yeah that test won’t tell you if you’re moving enough air to keep your engine cool. It takes VERY little airflow to stick a piece of paper to your radiator.

Now if your fan can’t even do that it definitely won’t cool your engine. But just because it can hold a piece of paper on the radiator doesn’t mean it will keep your engine cool by any stretch of the imagination.

What would tell you is the CFM rating for the fan, which is readily available for most electric fans and should be available in a cfm vs rpm graph for any mechanical fan worth the effort.
 
72bluNblu said:
What would tell you is the CFM rating for the fan, which is readily available for most electric fans and should be available in a cfm vs rpm graph for any mechanical fan worth the effort.
Click to expand...

I've always wondered - are electric fans all rated the same way (like a static air flow at a specific voltage measured at a specific distance from the fan)? Or do the manufacturers decide the parameters that they rate their fans under? I've always felt like you kind of have to take advertised cfm numbers with a grain of salt. Unless there's some universal test method or something? Who knows.
 
72bluNblu said:
My 340 is about the same, 175-180 cranking PSI.

And for the record I never said a mechanical fan can’t work. I just said it’s less efficient.

Like I said before, I’ve got no problem with mechanical fans. I just hate all the guys that say electric fans can’t work because they set up a lousy system because they have no idea what they’re doing. They work great if you use the right fans and set up the system properly.



Yeah that test won’t tell you if you’re moving enough air to keep your engine cool. It takes VERY little airflow to stick a piece of paper to your radiator.

Now if your fan can’t even do that it definitely won’t cool your engine. But just because it can hold a piece of paper on the radiator doesn’t mean it will keep your engine cool by any stretch of the imagination.

What would tell you is the CFM rating for the fan, which is readily available for most electric fans and should be available in a cfm vs rpm graph for any mechanical fan worth the effort.
Click to expand...
And also for the record, I agree with you! You wanna know the only reason I don't go to an electric fan? It's not money, I can save up. It's the fact that it's not old school. It won't match the rest of the car. Stupid I know but that's it. Were I having over heating problems, it might be different, but I'm not.
 
Last edited:
How not to install a fan:

Screenshot_20220714-120745_Gallery.jpg

Will not pull any heat out of the corners of the radiator. Although the rest of the car is done up nice.

This radiator will not pass the paper test in the corners, no air flow in the corners reguardless of the CFM they had in mind.

Electricity is not free power, it takes horsepower to turn the extra load on the alternator to spin the fan.

Just as the electric car crowd think electricity is free to charge their cars. Electricity has to come from somewhere, they burn coal to make electricity in the first place. Not to mention the resources it takes to mine the coal and transport it to market.
 
72bluNblu said:
See, that's why I like electrics. When I don't need my fans, they're not running. Way more efficient without all that parasitic drag. My fans pretty much never run unless I'm stopped, going light to light in traffic, or it's 110°F. And even when it's 110° they shut off if I can sustain 35mph or so for more than a few minutes at a time.
Click to expand...

and I would guess that’s what the OP’s problem is. At freeway speeds, the airflow is not the problem, it should be getting plenty of air. I would suspect that he doesn’t have a radiator or hood seal, or the lower cowl seal in place, letting air pass by the radiator opening. He also needs a conical shaped shroud, and a clutch fan to draw air through the radiator like a funnel. It create a vacuum on the outside of the fan to draw the air through the radiator.
 
George Jets said:
How not to install a fan:

View attachment 1715955764
Will not pull any heat out of the corners of the radiator. Although the rest of the car is done up nice.

This radiator will not pass the paper test in the corners, no air flow in the corners reguardless of the CFM they had in mind.

Electricity is not free power, it takes horsepower to turn the extra load on the alternator to spin the fan.

Just as the electric car crowd think electricity is free to charge their cars. Electricity has to come from somewhere, they burn coal to make electricity in the first place. Not to mention the resources it takes to mine the coal and transport it to market.
Click to expand...

That's better than having the corners sealed with a flat shroud though. As long as the fan can move enough air through that 75% or so of fin surface area it'll work fine and driving down the road at speed the air will be able to freely flow through the entire rad, not that I'd recommend it. Having the typical flat shroud that only sticks back 1/2" off the radiator will perform the worst of anything.

Also yes the electrical power has to come from somewhere but it still uses less power overall because it's not running constantly, only turns on when needed.

BTW coal power is gradually going away and doesn't account for a whole lot of the U.S.'s electricity generation compared to natural gas, and adding up the small but growing amount of wind, solar and nuclear power.

Aaanyway so about those 6.4L Hemi cooling issues......
 
George Jets said:
How not to install a fan:

View attachment 1715955764
Will not pull any heat out of the corners of the radiator. Although the rest of the car is done up nice.

This radiator will not pass the paper test in the corners, no air flow in the corners reguardless of the CFM they had in mind.

Electricity is not free power, it takes horsepower to turn the extra load on the alternator to spin the fan.

Just as the electric car crowd think electricity is free to charge their cars. Electricity has to come from somewhere, they burn coal to make electricity in the first place. Not to mention the resources it takes to mine the coal and transport it to market.
Click to expand...

Honestly...that will probably cool fine.
 
72bluNblu said:
I love how this thread went from a guy with a 6.4 Hemi that needed to reprogram his fan controller to a bunch of guys with bone stock low horsepower ‘70’s engines not even running shrouds saying mechanical fans keep their cars cool.

Yeah man, if you don’t make much horsepower, you don’t need much cooling either.
Click to expand...
No **** lol all I really wanted to know if the air flow was blocked on the freeway with the electric fan on.. update. I did add an air damn that helped level out the temp at 193 in the city.. didn’t try it on the freeway yet…

Side note.. all the guys saying to run a mechanical fan.. I can’t no provision for a mechanical fan on a gen three hemi..

Second I know your rock stock 2020 hemi challenger runs at 220. They do this for emissions. Everything gets hot and thin and spins faster. ( almost to thin) for emissions. No other reason for it! This engine is NOT stock and in a totally different car. 190-195 is my happy spot. Air flow is the current issue. The 318 in here did the same thing.. along with the slant 6. I believe air flow is not evacuating down under the car. It’s getting trapped, the whole engine bay is cylinder head and there’s not really a way for air to come through and escape is my theory. Going to get a core support to hood seal( don’t have one)
 
I think what most of us are saying is to try to keep it at 190 all the time under all conditions is a tall order.

The fact that you had the same issue with a slant 6 shows maybe it's not an issue

If you look at any stock temp gauge there is a range for normal. The low end would be thermostat temp and the high end would be the upper limits of the engineers design for tolerances etc. With a safety factor tossed in.

To test your air flow out therory, take the hood off.
 
SlantedDart said:
No **** lol all I really wanted to know if the air flow was blocked on the freeway with the electric fan on.. update. I did add an air damn that helped level out the temp at 193 in the city.. didn’t try it on the freeway yet…

Side note.. all the guys saying to run a mechanical fan.. I can’t no provision for a mechanical fan on a gen three hemi..

Second I know your rock stock 2020 hemi challenger runs at 220. They do this for emissions. Everything gets hot and thin and spins faster. ( almost to thin) for emissions. No other reason for it! This engine is NOT stock and in a totally different car. 190-195 is my happy spot. Air flow is the current issue. The 318 in here did the same thing.. along with the slant 6. I believe air flow is not evacuating down under the car. It’s getting trapped, the whole engine bay is cylinder head and there’s not really a way for air to come through and escape is my theory. Going to get a core support to hood seal( don’t have one)
Click to expand...

Some YT video I watched recently about Gen 3 Hemis mentioned that even stock they put out a lot of heat and thermal management can be tricky. So I'd reckon it's not abnormal for yours to be running on the hot side and having a tough time keeping it cool.

The only way I can see an air dam helping in city driving is if the fan was recirculating hot air from the engine bay around the bottom instead of cool air through the grill? Strange that it helped but if it works...

Core support to hood seal is a good idea too. Reminds me I need to put one back on my car, old one was in bad shape and I just pulled it off and threw it out.

I thought trucks still used mechanical fans but just did a quick search for 'Ram 1500 radiator fan' and the results were electric fans. So yeah definitely no point in even thinking about trying to use a mech fan setup.

EDIT: Another obvious option if you aren't set on having a pristine flat hood would be to add louvers or a scoop to vent the engine bay.
 
Last edited:
I watched a Richard Holdener video earlier today on 4.8/5.3 LS engines. One had a large plastic clutch fan with 9-10 blades. I would pick that one....
 
"Generally" speaking, over heating at road speed is a coolant flow issue and over heating at idle or slow speeds is an air flow issue. I don't understand why that would change simply based on what engine you have. Just food for thought.
 
I've seen high-speed overheating from insufficient air flow-albeit usually on trucks and 4x4s with stuff obstructing the grille.
 
oldkimmer said:
How do u think they got the name. Hot water six. Kim
Click to expand...
I've never heard that one......but mine runs below 180 even on the hottest days here. I had to fight with it for a minute to get it there. lol
 
I know most ppl don’t believe this but: if u run a 195 T stat most if not all your over heating issues will disappear. I’m talking about a good T stat like the Stewart Componets ones not a cheap *** one. Kim
 
oldkimmer said:
I know most ppl don’t believe this but: if u run a 195 T stat most if not all your over heating issues will disappear. Kim
Click to expand...
That proves true for a lot of things, but there are some exceptions. To me the biggest is to thing is to use a high flow thermostat. That helps a lot.
 
Little update.. so I contacted a couple companies about this issue and both said the shroud is the issue.. so I popped a bunch of holes into it and raised the ON fan temp to 205 and OFF at 193.. on the street it doesn’t get passed 194/5 same on the freeway. Went for a half hour ride around town then on the freeway and the fan didn’t turn on until on got off the freeway sitting at a light with the heat soak. Came right back down like I should.. not much of a shroud left but it seems to work just fine.
7C9A023A-01A9-4542-B64C-1D8CBFAB9DE6.jpeg
 
You must log in or register to reply here.
-

Back
Top