Cooling issue on highway

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I get it, most people here are into drag racing. Pro-stockers try to run 100-120° at the start of a run. Well, NASCAR runs at 300° (not kidding). Both are detrimental for the life of the engine and highly specialized to that type of racing and class rules, and those engines all get torn down after the race.

Running a normal engine cold just damages parts.

If you've got a 16 psi cap on your radiator your boiling temperature is closer to 250°F.
Meh, I like mine in the 170-180 range.
 
I get it, most people here are into drag racing. Pro-stockers try to run 100-120° at the start of a run. Well, NASCAR runs at 300° (not kidding). Both are detrimental for the life of the engine and highly specialized to that type of racing and class rules, and those engines all get torn down after the race.

Running a normal engine cold just damages parts.

If you've got a 16 psi cap on your radiator your boiling temperature is closer to 250°F.
Yeah but lord hammercy. 16psi sure doesn't do the cooling system any good. I have a 13 on mine. I try to run as low a psi cap as will work. Nice and easy on everything.
 
Meh, I like mine in the 170-180 range.

Hey as long as you like it who cares what your engine wants?

Yeah but lord hammercy. 16psi sure doesn't do the cooling system any good. I have a 13 on mine. I try to run as low a psi cap as will work. Nice and easy on everything.

The 6.4L GenIII this thread is about probably had an 18 psi cap at the low end, might have been 21 psi. Even a 12 psi cap still puts the boiling temp of plain water at 242°F. And if you're running a 50/50 with antifreeze its more like 259° (16psi 50/50 would be 267°).

Regardless, nothing it going to be hurt running that engine at 200°F, absolutely nothing. It will probably run BETTER.
 
Hey as long as you like it who cares what your engine wants?



The 6.4L GenIII this thread is about probably had an 18 psi cap at the low end, might have been 21 psi. Even a 12 psi cap still puts the boiling temp of plain water at 242°F. And if you're running a 50/50 with antifreeze its more like 259° (16psi 50/50 would be 267°).

Regardless, nothing it going to be hurt running that engine at 200°F, absolutely nothing. It will probably run BETTER.
That's where it runs best so that's what it wants. Much hotter and it has light spark knock, so that's where it has to run.
 
Also on the Holley you can set parameters for on/off conditions and keep the fan on/off temps where they are. You might have to use a generic input/output but you should be able to configure it however you like.

for instance….
Wiring an Electric Cooling Fan - Holley EFI
 
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Thoughts you say?

Select the desired temperature thermostat that you want your engine to run at.

Lose the shroud and electric fan. Install this 18" silent run fan without a shroud, and let the air flow through the radiator at highway speeds.

20220627_134158(0).jpg


This setup is working on a 440 that had electric fan and shroud, and was overheating.

Running at operating temp now, now that the restricting shroud is gone.

1st test was with a 15" silent run fan we had on hand, overheating issue went away.

Screenshot_20220621-205007_Gallery.jpg


Ordered In and installed the above 18" Silent Run fan for even more cooling.

All is good now. Took it out on the highway for a workout. Yes all is good, working like it should. Stays running cool at lower rpm also.
 
Causes of high freeway temps [ other than already mentioned ]:
- insufficient ign timing. With that CR, you want about 45*
- lean mixture
- t'stats take 20-25* to fully open for max flow. So a 195 might get to 220* before flow is at a maximum.
 
So there isn't "zero" airflow through the fans on the freeway. That's completely untrue.

But the fan may be limiting the airflow more than it's improving it, the turbulence of the spinning blades can reduce airflow. And if the air speed coming into the fan is too high it can lower the fans efficiency too.

If the engine wants to run at 195° on the freeway, that's absolutely fine. Like I said, the stock 6.4 doesn't even open the thermostat until 203° which means it's ALWAYS running hotter than that once it's past warm up, and on those engines that means anything past a few minutes of run time. Turn the fans on at 205° and off at 200°, I bet it still runs 195° on the freeway.



Why? Lots of really smart people designed that engine to run at 203° or above. Maybe if you wanted absolute max power for a short time (ie, a drag race) you'd want it cooler than that. But if you're just driving around town, on the freeway etc, it's going to be better for the engine to run it at the temperature it was designed to.
Maybe not zero air flow but I took the fan off to cut all the pass throughs and at some point on the freeway the fan distorted enough to scuff and melt the plastic on the fan.. it’s not letting air through it’s flexing the fan itself to let air through.
 
Ignition is 20 at idle 35 cruise and 22 wide open. Haven’t really tuned the car yet just driving it around normally.
Cool. As part of your tuning, start adding timing at cruise 2-3 degrees at a time in that very narrow area of the map. Then smooth it. You should be able to get up near 42-45 degrees maybe more on e85. It will run cooler and get better mileage. The smoothing is a big deal. On your 3d map you don’t want any huge spikes.
 
Maybe not zero air flow but I took the fan off to cut all the pass throughs and at some point on the freeway the fan distorted enough to scuff and melt the plastic on the fan.. it’s not letting air through it’s flexing the fan itself to let air through
That is odd. The air speed if greater then the fan can provide should just cause the fan to spin faster.

I am in the mechanical fan crowd. Tried and true.

I also think you are trying to control the coolant temp too closely.

A 20 deg difference depending on conditions is nothing.

Set the fan to a temp just over the normal highway temp, if the temp goes that high the fan will turn on and bring it right down.
 
That's where it runs best so that's what it wants. Much hotter and it has light spark knock, so that's where it has to run.

I feel you. I started the 340 in my Duster out with a 180° thermostat and a dumb flex fan, never had a problem keeping it below 190°. Except that the engine runs better at 200° than it does at 180°, so I ditched the flex fan for the electrics with a programmable controller and ran a bunch of different fan on/off temps. Just runs better at 200°F. Obviously that's tuning, and if I wanted to do nothing but drag race I would retune my A/F richer and all that and run it colder for more power at WOT. But on the street I rarely see WOT, so, I'd rather it be happy where I actually drive it.

Thoughts you say?

Select the desired temperature thermostat that you want your engine to run at.

Lose the shroud and electric fan. Install this 18" silent run fan without a shroud, and let the air flow through the radiator at highway speeds.

View attachment 1715952481

This setup is working on a 440 that had electric fan and shroud, and was overheating.

Running at operating temp now, now that the restricting shroud is gone.

1st test was with a 15" silent run fan we had on hand, overheating issue went away.

View attachment 1715952490

Ordered In and installed the above 18" Silent Run fan for even more cooling.

All is good now. Took it out on the highway for a workout. Yes all is good, working like it should. Stays running cool at lower rpm also.

Funny, I got rid of a POS flex fan like that on my 340. Bottom line is, if the electric fans weren't working for you they were the wrong fans. Plenty of fancy electric fans out there that don't move enough air, and there are plenty of dumb ways to trigger fans. Build a bad system, get bad results.

Maybe not zero air flow but I took the fan off to cut all the pass throughs and at some point on the freeway the fan distorted enough to scuff and melt the plastic on the fan.. it’s not letting air through it’s flexing the fan itself to let air through.

Something is wrong with your fan or your shroud. That kind of interference shouldn't be happening. That's why I'm not a fan of aftermarket fans on aftermarket shrouds, nobody designed all that to work together they just put a couple of aftermarked fans and bolted them to a baking sheet. That's not a proper shroud.
 
I hate flex fans. I have a solid five blade non symmetrical fan on now. Sounds like a single prop Cessna goin down the road but it is really moving some air. Way more than the old four blade. I'd run a clutch fan, but I don't have the room.
 
I hate flex fans. I have a solid five blade non symmetrical fan on now. Sounds like a single prop Cessna goin down the road but it is really moving some air. Way more than the old four blade. I'd run a clutch fan, but I don't have the room.

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.
 
Elec fans might have less parasitic drag, but they are useless if they do not keep the engine cool...
 
Plastic electric fans overheat and melt, along with the restrictive full aluminum shrouds not a great setup.

Trapping engine heat in the radiator leading to an overheating situation.
 
Elec fans might have less parasitic drag, but they are useless if they do not keep the engine cool...

Which is why you have to size them correctly, run a proper controller and not just a toggle switch, and why they should be an assembly that was designed with their shroud.

My 340 is .060" over, runs 9.8:1 compression with iron heads, has pretty decent sized cam and makes somewhere north of 400 hp with the stock stroke. I've never even come close to overheating with my Ford Contour fan set up, and I have sat in traffic when it was 110°F out.

If your electric fans aren't cooling your engine, you have not picked the right electric fans for your set up.

Plastic electric fans overheat and melt, along with the restrictive full aluminum shrouds not a great setup.

Trapping engine heat in the radiator leading to an overheating situation.

I agree about the cookie sheet aluminum shrouds, those are terrible.

But if your electric fans are melting, you picked lousy electric fans.
 
Which is why you have to size them correctly, run a proper controller and not just a toggle switch, and why they should be an assembly that was designed with their shroud.

My 340 is .060" over, runs 9.8:1 compression with iron heads, has pretty decent sized cam and makes somewhere north of 400 hp with the stock stroke. I've never even come close to overheating with my Ford Contour fan set up, and I have sat in traffic when it was 110°F out.

If your electric fans aren't cooling your engine, you have not picked the right electric fans for your set up.



I agree about the cookie sheet aluminum shrouds, those are terrible.

But if your electric fans are melting, you picked lousy electric fans.

Had to go in and straighten out someone else's electric fan overheating build. That's why they came to me. Had to install the low profile, silent running non-flex manual 18" fan.

Low parasite loss, moves lots of air as it cuts the air not flexing the blades. Runs Quiet, keeping the engine cool without worry even on the hot days.

Simple Fix . . . without all the added electronics and headaches and worries if all the sudden it's going to overheat.
 
You are trying to manually control the timing, fuel ratios, O2 sensors, knock sensors etc.. running temps that normally are controlled by a sophisticated computer making 1000's of adjustments all the time. This is not a carbureted 318. A 6.4 with 11.5:1 CR ? who knows what else done to the engine and an aftermarket EFI/computer. Who knows what "normal" is on that setup. This engines cooling system is 2000's technology.
Did you know that The stealth bomber can't fly without a computer ? Modern engines are designed to run at much higher temps then the "old days" Going through the desert with no coolant only water. No recovery system only water loss every time it got hot. A canvas bag full of water hanging in front of the radiator to cool/humidify the air before it passed through an overloaded radiator.
And all because " I don't like it when it is "hot" ?. Hot is relative. Hot on a non pressurized cooling system with water is a lot lower than a 16+ pressurized system with the proper mix of modern coolant. A computer controlling everything and a coolant recovery system so you never need to top off the radiator. That is today. Modern engine/computer technology with a 1960's cooling system, just doesn't get it. Modern engines/cooling systems are designed to operate well over 212 °
What Pressure Radiator Cap Rating Should I Use?
The Functions of a Radiator Fan
 
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Elec fans. Sigh. An elec fan that can pull as much air as my 7 blade, 19" mech fan, would need an enormous motor to drive it. Substantial parasitic loss. I do not see anything clever in moving from a reliable, stand alone, mech fan to a complicated elec fan that needs a controller or relay to run it along with heavy wiring.
 
Every modern car including the 6.4 Mopars have run nothing but electric fans for more than 30 years. Millions on the road with no problems.
Problems always start when homegrown engineers think they know more than the companies that have invested millions of dollars in engineering and testing the systems. They have to warranty the drivelines for up o 100,000 miles so they have a vested intertest in there being minimal problems.
Factory stuff works, why always trying to reinvent the wheel...
 
First thing I'd be trying is taking off the fan and shroud completely then quickly jumping on the freeway and seeing if the problem still exists. If it runs cooler, bam there's your issue.

If it turns out to be the fan/shroud... I'd dump that shroud entirely and just mount the fan basically up against the radiator core. Or get a fan and shroud out of a Charger/300 that came with the 6.4L.

Does seem like your cruising ignition advance is pretty low though. I know those engines don't need much timing from the efficient chambers and dual spark plugs but below 40* at cruise is nothing. Probably getting extra heat rejection into the engine from the late burn.

Food for thought, my Duster runs about 185* around town but on the freeway it gets up closer to 195*. Has a high-flow 195* t-stat, high-flow Milodon water pump, ECP aluminum radiator and 7-blade mechanical fan with viscous clutch drive and factory shroud. But it's also a carbed 360 with 9:1 compression, quite different than a EFI 6.4L Hemi with 11.5:1 compression so not a great comparison tbh.
 
Every modern car including the 6.4 Mopars have run nothing but electric fans for more than 30 years. Millions on the road with no problems.
Problems always start when homegrown engineers think they know more than the companies that have invested millions of dollars in engineering and testing the systems. They have to warranty the drivelines for up o 100,000 miles so they have a vested intertest in there being minimal problems.
Factory stuff works, why always trying to reinvent the wheel...

Exactly, G3 Hemis weren't designed to run with mechanical fans except in trucks and those fans are gigantic. Just like our old carbed engines weren't designed to run with electric fans. It takes some work and know-how to get that stuff right, thermal management is no joke.
 
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