• Want to add an app icon for this forum to your mobile device's home screen? Check out this thread to see how.
  • Have an event you want to share? Check out the new forum event calendar and how-to use it in this thread here.
  • To both new members and existing members, please read this thread about posting your topics in the correct sub-forum. It makes my job (and my life) a lot easier!

Do grille inserts affect airflow through the condenser and radiator?

L J

TJ Enthusiast
Joined
Nov 26, 2017
Messages
795
Location
SoCal
TJ's look near perfect from the factory, body wise. I've never wanted to alter the body in anyway. Sure, mine is lifted, but stock hood, stock grill, stock fenders, stock lights, no added chrome, no added blackness.
:unsure:

What does this have to do with the OP's question?

Kinda like option 1
those aren't going to do anything noticeable to the airflow
 

Goatman

TJ Addict
Supporting Member
Joined
Apr 23, 2019
Messages
1,862
Location
Upstate NY
Where did those TJ bug screens come from? 🤩I couldnt find any so resorted to the hardware cloth.🤮 And, did Mr Bill's just agree with me?🤯 But seriously, where can I find those TJ bug grills?🤔
 

Tim Redman

TJ Enthusiast
Joined
May 25, 2018
Messages
103
Location
Tampa Bay, FL
I've been running with these for the past four or five months, in Florida weather, with no noticeable difference in function or performance of the vehicle, even with the off-road lights and winch in front. And I spend less time digging leaves and twigs out from the space in front of my radiator. As an aside, it really doesn't do much for insects, only for objects as large or larger than, say, a dime. I joke about the mosquitos here, but the little blood suckers and love bugs would easily pass through.

I believe the primary issue with the angry eye grills (other than the fact that, well, they're angry eye grilles) is that they typically have vertical slots that don't line up with the seven slots in the stock grill. For TJ's, that causes overheating because those atrocities are overlaid on top of the existing grill. For JKs, they replace the grill entirely, so I wouldn't think it would be as much of an issue, beyond the obvious.

bad-wolf-grill-inserts.jpg
 

Sundowner

Compliment Dispenser
Supporting Member
Joined
Feb 6, 2019
Messages
1,146
Location
Republic of Dave
Nope, math is the same.
I didn't say that it wasn't; I said that the math was undermined.

To explain: your calculations - correct as they may be - were based on a theoretical reduction in the amount of open area of each grille slot; no specific definition of "grille insert" was defined until much later in the thread. Without defining exactly how much blockage or lack of blockage a specific product may or may not create, no amount of calculation can attempt more than answering the most basic form of the OP's first question: "Do grill inserts affect airflow through the condenser and radiator?" I think that if anything, your calculation proves that grille inserts do, in fact, affect airflow...but without knowing exactly what product the OP had in mind, the second part of the question - "Would it cause the AC to not work as well, or the engine to overheat?" - cannot be accurately answered. Any given grille insert could offer either more, less, or the same amount of reduction in airflow that your calculations assumed... so even though the numbers you posted strongly suggest that most inserts will have no meaningful impact, they cannot be extrapolated to prove the impact or non-impact of an as-of-yet unnamed and unmeasured product. In that light - and to address your last comment - the math may or may not be the same; it all depends on exactly what kind of reduction any given product offers.

Edit: I do have a question for you, though: where'd you find the stock fan CFM number? I've looked for it in the past and I've never found any sort of source that I thought to be reputable; most people are just posting numbers with no citations at all.
 
Last edited:

pagrey

TJ Addict
Joined
Apr 10, 2018
Messages
1,676
Location
Los Angeles, CA, USA
I didn't say that it wasn't; I said that the math was undermined.

To explain: your calculations - correct as they may be - were based on a theoretical reduction in the amount of open area of each grille slot; no specific definition of "grille insert" was defined until much later in the thread. Without defining exactly how much blockage or lack of blockage a specific product may or may not create, no amount of calculation can attempt more than answering the most basic form of the OP's first question: "Do grill inserts affect airflow through the condenser and radiator?" I think that if anything, your calculation proves that grille inserts do, in fact, affect airflow...but without knowing exactly what product the OP had in mind, the second part of the question - "Would it cause the AC to not work as well, or the engine to overheat?" - cannot be accurately answered. Any given grille insert could offer either more, less, or the same amount of reduction in airflow that your calculations assumed... so even though the numbers you posted strongly suggest that most inserts will have no meaningful impact, they cannot be extrapolated to prove the impact or non-impact of an as-of-yet unnamed and unmeasured product. In that light - and to address your last comment - the math may or may not be the same; it all depends on exactly what kind of reduction any given product offers.
I assumed 25% reduction in are just to make the math easy. 25% is a large number. Even with that drastic of a change the total extra power required to draw the same air was very small. That's the point. Large changes to the grill openings have very little total effect with our cooling setup.

The math shows why these inserts don't have an effect. Not knowing the type of insert doesn't undermine anything, in fact the math shows exactly why it doesn't matter what the exact reduction is.
 

pagrey

TJ Addict
Joined
Apr 10, 2018
Messages
1,676
Location
Los Angeles, CA, USA
You could do another calculation at say 30% or 40% blockage but the result at 25% is so absurdly low there is no point. It is just not a real issue, fun to discuss, but not an issue.
 

Sundowner

Compliment Dispenser
Supporting Member
Joined
Feb 6, 2019
Messages
1,146
Location
Republic of Dave
I assumed 25% reduction in are just to make the math easy. 25% is a large number. Even with that drastic of a change the total extra power required to draw the same air was very small. That's the point. Large changes to the grill openings have very little total effect with our cooling setup.

The math shows why these inserts don't have an effect. Not knowing the type of insert doesn't undermine anything, in fact the math shows exactly why it doesn't matter what the exact reduction is.
I understand that the numbers you used are based on assumption, which is fine to show general principle...but even though you're saying that the inserts don't have an effect, the numbers say that they do. No, it's not much of an effect, but it is present...and whether or not that impact would grow, lessen, or remain the same when specific data is fed into the equation is still a matter of conjecture.

Have you put any thought into how the overall disruption of airflow - i.e. the reduction of laminar flow and the changes in air pressure - would impact cooling capacity?

Also, I really would like to know how much air the stock fan is capable of moving, so if anyone has those numbers I'd be most appreciative.
 

pagrey

TJ Addict
Joined
Apr 10, 2018
Messages
1,676
Location
Los Angeles, CA, USA
I understand that the numbers you used are based on assumption, which is fine to show general principle...but even though you're saying that the inserts don't have an effect, the numbers say that they do. No, it's not much of an effect, but it is present...and whether or not that impact would grow, lessen, or remain the same when specific data is fed into the equation is still a matter of conjecture.

Have you put any thought into how the overall disruption of airflow - i.e. the reduction of laminar flow and the changes in air pressure - would impact cooling capacity?

Also, I really would like to know how much air the stock fan is capable of moving, so if anyone has those numbers I'd be most appreciative.
The calculations I used do factor in disruption of airflow both from the reduction in area and turbulence caused by this reduction. Obviously it changes depending on the shape and type of the restriction but that seems to still leave you with small changes in the final answer.

The air is being pulled through the radiator and not pushed, non-laminar flow before the radiator might increase the pressure on the high side by a small amount. Since adding a winch or lights doesn't seem to have an effect I'd say it doesn't matter much.

From what I could find the stock fan is capable of at least 4000 cfm or more but most electric fan manufacturers say an engine our size can deal with only 2000 cfm. Don't know the real number but I picked 2200 based on the recommendations of those electric fan manufacturers just so I was in the right ballpark.
 

Sundowner

Compliment Dispenser
Supporting Member
Joined
Feb 6, 2019
Messages
1,146
Location
Republic of Dave
The calculations I used do factor in disruption of airflow both from the reduction in area and turbulence caused by this reduction. Obviously it changes depending on the shape and type of the restriction but that seems to still leave you with small changes in the final answer.
So, you're good at math...what does the reduction look like with the aforementioned 40% reduction? How about 80%

The air is being pulled through the radiator and not pushed, non-laminar flow before the radiator might increase the pressure on the high side by a small amount. Since adding a winch or lights doesn't seem to have an effect I'd say it doesn't matter much.
Kind of makes me wonder why they had such a hard time cooling the Gladiator, and how they eventually solved the problem with cooling by increasing the width of the grille openings by 10%.

From what I could find the stock fan is capable of at least 4000 cfm or more but most electric fan manufacturers say an engine our size can deal with only 2000 cfm. Don't know the real number but I picked 2200 based on the recommendations of those electric fan manufacturers just so I was in the right ballpark.
Interesting. How does the reduction in opening change things if the necessary airflow is increased to 4000 CFM?