removing front air deflector thingy

tonycrd · **Posted:** Wed Aug 13, 2008 7:55 am

TJKJ, now you cannot be serious about this on the '02-'04 models, this thing doesn't do anything. I didn't notice any change on engine temp.

tjkoen01 · **Posted:** Wed Aug 13, 2008 8:46 am

under normal conditions, you probably won't notice a difference, however try driving thru the mountains or towing a trailer on the highway when it's 95 degrees out.....i'd bet you'll see a difference then. it will also help with the overall aerodynamics as well (not that there is much to start with).

if your tires are rubbing it, trimming it would probably be the better way to go.

modular · **Posted:** Wed Aug 13, 2008 9:09 am

tonycrd wrote:

TJKJ, now you cannot be serious about this on the '02-'04 models, this thing doesn't do anything. I didn't notice any change on engine temp.

X2

jerbacher · **Posted:** Wed Aug 13, 2008 9:44 am

tjkoen01 wrote:

if your tires are rubbing it, trimming it would probably be the better way to go.

The tires arent rubbing. I just thought it would look better without it. I also wanted to test some different methods to color the grey plastic black and having a piece off of the jeep would be helpful.

tommudd · **Posted:** Wed Aug 13, 2008 9:52 am

jerbacher wrote:

tjkoen01 wrote:

if your tires are rubbing it, trimming it would probably be the better way to go.

The tires arent rubbing. I just thought it would look better without it. I also wanted to test some different methods to color the grey plastic black and having a piece off of the jeep would be helpful.

Go for it Jon, even if it makes a difference you could always bolt it back on, easy to do
Plus I want to see what you come up with to color the bumpers/fenders :lol:

I have my stock bumper if you want to try everything on yours then if it doesn't work you have a spare here :wink:

tonycrd · **Posted:** Wed Aug 13, 2008 10:01 am

tjkoen01 wrote:

under normal conditions, you probably won't notice a difference, however try driving thru the mountains or towing a trailer on the highway when it's 95 degrees out.....i'd bet you'll see a difference then. it will also help with the overall aerodynamics as well (not that there is much to start with).

if your tires are rubbing it, trimming it would probably be the better way to go.

Here's some pics. Now what does this thing have to do with cooling? Or aerodynamics. (it's fitted flat, not at an angle )

The '05-'07 may have a function, although there is nothing but the radiator support beam behind that gap....

IMO It's fitted there to prevent you seeing the sub chassis / suspension parts.

pokefan · **Posted:** Wed Aug 13, 2008 10:30 am

So are you saying all of us that have trimmed our bumper are screwed? :lol:

tjkoen01 · **Posted:** Wed Aug 13, 2008 10:36 am

in terms of aerodynamics, the air dam is nothing new. the idea is to divert air around the vehicle and keep it out from underneath it. look at a NASCAR, the air dam is basically skimming the ground, pushing the air to the sides of the car where the surface is smooth.....not very practical for a jeep. we've all see the bottom of our liberties, not smooth at all, large caverns for air to get trapped in. that is why a lift by itself will decrease gas mileage...more air gets under the jeep, creates turbulence and drag.

in terms of cooling, the air dam increases the air pressure directly in front of the jeep and also will decrease the air pressure below the jeep as well as the engine compartment. fluids flow from areas of high pressure to low pressure (yes air is a fluid) and thus more air pressure in front and less pressure behind the radiator will create more flow thru the radiator. this is the primary source of getting air across the radiator at highway speeds, not the fan. the fan's purpose is to keep from overheating at idle and low speeds.

tjkoen01 · **Posted:** Wed Aug 13, 2008 10:38 am

pokefan wrote:

So are you saying all of us that have trimmed our bumper are screwed? :lol:

not at all. you just need to be aware when you are putting larger than normal loads on the engine....you are more likely to start overheat without the air dam.

tonycrd · **Posted:** Wed Aug 13, 2008 11:01 am

That sounds pretty good and I am sure it works on a Formula 1 or a Nascar. Or a Lexus. But not on a lifted 4x4.

All the poor old XJ's would have had steaming hot engines straight from the factory...they do not have this air dam.

I do not mean to argue with anyone but someone stating that his engine temp went up after removing this piece of plastic sounds a bit weird to me.

You probably all have the 3.7, now how can that get hot? Mine has the intercooler in front of the engine rad and it doesn't.

Not even when I do this with 110 degrees. And it doesn't have an electric fan.

tjkoen01 · **Posted:** Wed Aug 13, 2008 12:54 pm

tonycrd wrote:

That sounds pretty good and I am sure it works on a Formula 1 or a Nascar. Or a Lexus. But not on a lifted 4x4.

All the poor old XJ's would have had steaming hot engines straight from the factory...they do not have this air dam.

I do not mean to argue with anyone but someone stating that his engine temp went up after removing this piece of plastic sounds a bit weird to me.

You probably all have the 3.7, now how can that get hot? Mine has the intercooler in front of the engine rad and it doesn't.

Not even when I do this with 110 degrees. And it doesn't have an electric fan.

i'm not trying to pick a fight or argue here either

i'm just trying to explain.

as you stated, for people who are going fast, it will make more of a difference with aerodynamics, but while you are 4 wheeling, the air dam will not make any difference. on a lifted 4x4, since the aerodynamics are already pretty bad, the only noticeable effect would be a reduction in cooling at high speeds.

i have taken fluid dynamics, granted it has been awhile, but i believe everything i stated to be based in fact. if i have mis-spoke, someone please correct me :oops:

so basically, having all that been said, if you remove the air dam, there is a greater chance of overheating on the highway.

Guest · **Posted:** Wed Aug 13, 2008 1:05 pm

the way I understand it, the theory seems sound.

The air dam blocks air from entering underneath, keeping the high pressure in front of the radiator, forcing air through it.

so, again, in theory, it sounds good...as far as practical application...mine is still on, and I've no desire or gumption to remove it under my own power. I'll just let rocks and trees and stuff remove it for me.

And Tony, two things:

First...cool pic!

second...the XJ is a bad example. a lot of 'em have cooling issues;)

*EDIT*

Oops...didn't realize it was already explained on the last page. Sorry...

LIV42DY · **Posted:** Wed Aug 13, 2008 7:53 pm

A few final words on the air dam issue, aerodynamics and if it did not have a function they would not have designed that way. If you offroad with your KJ 100% of the time then you would not see or feel any changes. Some models may differ from others, bottom line it has a function and it does aid in the cooling of the engine. taking it off its your choice. good luck

JJsTJ · **Posted:** Wed Aug 13, 2008 9:00 pm

Strange. I have two KJ's, one IFS and one SFA, Both w/ steel ALL J bumpers, No air dams, driven all over the Desert in all kinds of conditions, too and from Moab on multiple trips, To Arizona, etc. for years now and Never had an overheating problem or higher temps reading on the guage.
Think I'll call the mythbusters..... :lol:

However, If anyone has a removed air dam for sale, cheap, LMK.

LIV42DY · **Posted:** Wed Aug 13, 2008 9:05 pm

you are correct "After Market" bumpers are fine some have been tested and compensated for the air flow. the issue is the Stock Facia and the design to work with the air dam.

JJsTJ · **Posted:** Wed Aug 13, 2008 9:07 pm

BTW, Not saying it doesn't have a purpose or Work for that purpose just saying it must not make that big of a difference if it isn't noticeably affecting my two KJ's driven in some pretty high temps.

JJsTJ · **Posted:** Wed Aug 13, 2008 9:08 pm

LIV42DY wrote:

you are correct "After Market" bumpers are fine some have been tested and compensated for the air flow. the issue is the Stock Facia and the design to work with the air dam.

I know for a fact that the ALL J bumper was never tested or designed to Care much about the air dam or affecting air flow. :wink:

Blue KJ in PA · **Posted:** Wed Aug 13, 2008 10:21 pm

Good thing for me I can't afford the gas to drive fast on highways...I stick to the curvy side roads and keep me tire inflated to save the oil...save the earth... :roll:

...extreme sarcasam alert

rescu2000 · **Posted:** Wed Aug 13, 2008 11:11 pm

I'm betting the air dam on our KJ's is more for looks than function. It covers the suspension and undercarriage from view, which is the whole reason I took mine off. I'm no expert, so I could be wrong, but I'm pretty sure the thermostat will still keep the temp in range. The absence of the airdam would have to overwhelm the cooling system to cause your temp to spike.

tonycrd · **Posted:** Thu Aug 14, 2008 6:42 am

Blue KJ in PA wrote:

Good thing for me I can't afford the gas to drive fast on highways...I stick to the curvy side roads and keep me tire inflated to save the oil...save the earth... :roll:

eeeh...you're kinda in the wrong car for that....get a Prius? lol

ThunderbirdJunkie wrote:

And Tony, two things:

First...cool pic!

second...the XJ is a bad example. a lot of 'em have cooling issues;)

First: Thanks!

Second: you are right :oops:

removing front air deflector thingy

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