Jarlaxle
Well-Known Member
I cannot fathom how that doesn't boil over on the highway! It looks like more than a third of it is completely BLOCKED!
Champion radiator for ~500hp small block??
- Thread starter gzig5
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Jarlaxle
Well-Known Member
You're blocking most of the airflow from the radiator. I cannot fathom how this WON'T overheat.
Big Dad
Well-Known Member
google radiator shroud .. look at the pictures
Jarlaxle
Well-Known Member
That's not a radiator shroud. That's BLOCKING the airflow, not directing it.
Just Send It
There goes the neighborhood!
What?!
The shroud is on the backside of the radiator. It's not blocking any incoming air at speed. The puller fan draws the cool air through the shroud at low speeds. This is a proven system that literally every radiator manufacturer uses.
If you're speaking to the fact that I didn't incorporate louvers into the shroud - louvers only help when the fans utilize < 60% of the shroud's surface area. Hence, why I purchased the largest fan I could find. My fan takes up 75%, thus not necessitating louvers for proper heat exchange.
I live at 4300ft in the high desert where Temps stay above 100°. My engine is 12:1 421 stroker and the coolant has never been above 185° at the track.
The setup works well. Plain and simple.
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Jarlaxle
Well-Known Member
Your radiator is oversized enough that you can get away with it. If this system were "proven," the OEMs would use it. They do not and never have, because it quite obviously is blocking airflow. There is a substantial part of your radiator that has zero airflow at any speeds, because the back of it is blocked. It would probably run cooler if you removed the block.
Just Send It
There goes the neighborhood!
Okay...I'll play
So how would removing the shroud help when stuck in traffic, or at a stop light, or in the staging lanes during the Summer? When the only air that passes over the core, is what the fan is drawing through its surface area. I don't pull out of my house and immediately onto a highway. I have miles to drive to get there.
Are you willing to trade a marginal temperature decrease at highway speeds for a significant temp increase at idle? I don't see the net benefit of that.
Jarlaxle
Well-Known Member
Put down that goal post. I never said that.
What I ACTUALLY said was...
Nonsense. There will be little to no difference at idle as long as the fan is working properly. There is a reason that exactly ZERO original manufacturers block off part of the radiator.
Exactly. Those cookie tray “shrouds” are straight junk.
But the companies sell them so they must work. Not!
Just Send It
There goes the neighborhood!
I know you know your ****...I respect you
I ran this car with the exact same radiator, fan, engine, sensors, fluids, altitudes, and ambient air temps. No other variables were changed.
I added a shroud and the coolant temps dropped by -15° at idle and -5° at speed.
Please explain how that happened.
It speeds the air through the radiator. But at road speed it’s a giant backwards parachute.
You need more fan area and get rid of the cookie sheet.
Good grief. Let's address some of these claims being made.
So, this is an OEM 1995-2000 Ford Contour fan assembly. This is the same one I've had on my Duster for like 11 years now. The plastic shroud is not perfectly flat, and that does make a difference, but, it's pretty flat. These are the dimensions of the fan shroud assembly.
And let's do some math. Total shroud area is 384 square inches. The green shaded section is 1/2 of the open area of the shroud, the really wide fan motors absolutely interrupt air flow. Total fan motor surface area is 47.5 square inches (both motors). Total fan area is 207.74 square inches (both).
So just fan area is 207.74/384 = 54.1% , that's already substantially less than @Just Send It 's shroud. But really, we should take out that fan motor area too because they are absolutely obstructing flow to some level
160.24/384 = 41.7% .
Now I suppose you could argue the core is actually bigger than 24x16", and it is, it's 17.5" x 26.25" according to the manufacturer. So that's 459.38 square inches. If you knock out the 384 for the whole shroud, that's another 75.38 square inches. Assuming that's totally open air flow is a little bold but even then adding that into the total open area is only 235.62 square inches
235.62/459.38 = 51.3% of the total core area that's open/not covered by the shroud.
So do the OEM's block off the radiator core area with fan shrouds? Absolutely. Look at any of the modern electric fan assembly's and shrouds. New Challenger, new Mustang, etc, etc. They all have fan shrouds that look very similar to the Contour one above. Obviously the percentage of fan opening to shroud is going to vary by make/model, as will how flat the shroud is, but saying no OEM does anything like what Just Send It did isn't accurate at all.
The other thing is that the whole "air stacking" argument for the flat shroud is really complicated. Is it possible to interfere with the flow THROUGH the radiator with a flat shroud behind it? Yes, it is. But it's not easy, and the distance between the shroud and the back of the core makes a BIG difference. As does the open area in the shroud. As does the speed, air density, all kinds of variables that no one here is going to test. And yeah, the difference between a perfectly flat shroud and one that has even a minor angle on it would also be important, but ALL of those variables are important. And the OEM's are testing stuff like that, and they're still making shrouds like the Contour ones above.
The fact that @Just Send It had a significant temperature drop at idle speeds isn't surprising, his shroud lets him pull air across the entire core instead of just the section the fan is in front of. But the fact that he saw a small drop in temperature at speed would definitely imply that he's not getting some big air stacking effect. Maybe 5° is within his error margin for measurement, I sure don't know. But it's not worse, so, his shroud is probably close to neutral effect at speed. Or at least the speeds he's usually doing.
I certainly don't see jumping all over him because he built a fan shroud set up that WORKS. Maybe it's not ideal, but it works for him and there are certainly flat fan shrouds like that on the market that don't work. And flat shroud set ups with louvres, or rubber flaps, both of which indicate that there's a design issue with the shroud. I'm certainly not saying that all the "cookie sheet" shrouds out there work or have been tested. But his shroud blocks LESS area than the Ford Contour OEM set up I use, so at that point you're now arguing about the aerodynamic efficiency of those two fan shrouds, which nobody is going to be able to test and compare unless you've got a wind tunnel in your pocket.
So, this is an OEM 1995-2000 Ford Contour fan assembly. This is the same one I've had on my Duster for like 11 years now. The plastic shroud is not perfectly flat, and that does make a difference, but, it's pretty flat. These are the dimensions of the fan shroud assembly.
And let's do some math. Total shroud area is 384 square inches. The green shaded section is 1/2 of the open area of the shroud, the really wide fan motors absolutely interrupt air flow. Total fan motor surface area is 47.5 square inches (both motors). Total fan area is 207.74 square inches (both).
So just fan area is 207.74/384 = 54.1% , that's already substantially less than @Just Send It 's shroud. But really, we should take out that fan motor area too because they are absolutely obstructing flow to some level
160.24/384 = 41.7% .
Now I suppose you could argue the core is actually bigger than 24x16", and it is, it's 17.5" x 26.25" according to the manufacturer. So that's 459.38 square inches. If you knock out the 384 for the whole shroud, that's another 75.38 square inches. Assuming that's totally open air flow is a little bold but even then adding that into the total open area is only 235.62 square inches
235.62/459.38 = 51.3% of the total core area that's open/not covered by the shroud.
So do the OEM's block off the radiator core area with fan shrouds? Absolutely. Look at any of the modern electric fan assembly's and shrouds. New Challenger, new Mustang, etc, etc. They all have fan shrouds that look very similar to the Contour one above. Obviously the percentage of fan opening to shroud is going to vary by make/model, as will how flat the shroud is, but saying no OEM does anything like what Just Send It did isn't accurate at all.
The other thing is that the whole "air stacking" argument for the flat shroud is really complicated. Is it possible to interfere with the flow THROUGH the radiator with a flat shroud behind it? Yes, it is. But it's not easy, and the distance between the shroud and the back of the core makes a BIG difference. As does the open area in the shroud. As does the speed, air density, all kinds of variables that no one here is going to test. And yeah, the difference between a perfectly flat shroud and one that has even a minor angle on it would also be important, but ALL of those variables are important. And the OEM's are testing stuff like that, and they're still making shrouds like the Contour ones above.
The fact that @Just Send It had a significant temperature drop at idle speeds isn't surprising, his shroud lets him pull air across the entire core instead of just the section the fan is in front of. But the fact that he saw a small drop in temperature at speed would definitely imply that he's not getting some big air stacking effect. Maybe 5° is within his error margin for measurement, I sure don't know. But it's not worse, so, his shroud is probably close to neutral effect at speed. Or at least the speeds he's usually doing.
I certainly don't see jumping all over him because he built a fan shroud set up that WORKS. Maybe it's not ideal, but it works for him and there are certainly flat fan shrouds like that on the market that don't work. And flat shroud set ups with louvres, or rubber flaps, both of which indicate that there's a design issue with the shroud. I'm certainly not saying that all the "cookie sheet" shrouds out there work or have been tested. But his shroud blocks LESS area than the Ford Contour OEM set up I use, so at that point you're now arguing about the aerodynamic efficiency of those two fan shrouds, which nobody is going to be able to test and compare unless you've got a wind tunnel in your pocket.
What you have is far different than the aftermarket cookie sheet “shroud”.
It really isn't. And look, my point is not that the fine details don't make a difference, because they absolutely do when it comes to aerodynamics. The slight curvature that you can see here on the inside of the Contour shroud assembly is important, that little detail of directing air into the fans will absolutely improve efficiency.
But again, this is not the only OEM fan shroud out there and some are absolutely more flat than this one is. Heck you could probably manage this level of curvature by putting the other shroud on a frame around the edge and stepping on it in the middle.
And even without that, what are we comparing? Efficiency percentages. Is the curvature on the Contour set up worth blocking ~20% more of the radiator core area compared to @Just Send It 's set up? That's a BIG number, and surface area is a HUGE factor in both thermodynamics and aerodynamics. So now we're comparing the efficiency lost by the flat panel to the curved panel vs a 20% -ish difference in covered area. And unless you've got a wind tunnel, you can't say which one is better.
The fact is that he built a shroud and it WORKS. His car runs cooler at idle and low speeds, and it might even run cooler at speed. Like it or not, that means his shroud works. The whole point of the shroud is to improve fan efficiency at idle and low speeds. And sometimes that means losing some free air flow efficiency at higher speeds when the volume of free air flow is typically more than enough to handle the cooling needs. But it doesn't even seem like that's an issue for him, so, his shroud works. Not all flat panel fan shrouds do, and I'm sure the large open area of his shroud is an important part of that.
And I'm not arguing that people should just buy whatever cookie sheet fan shroud and underpowered electric fan that comes with their eBay aluminum radiator, because a lot of those set ups do not work for various different reasons. But @Just Send It doesn't have a cooling issue, so, he doesn't need to do anything to change his set up.
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