Yes, it's primary purpose is to create a low pressure area and aid in cooling. It appears to also effect the hood lift and also play a role in aerodynamics (mpg). IMO, it also keeps water out of the engine bay as well. I agree it would have been nice to have it made of steel and be more functional.

 

Don't think it does much to keep water out, my muted horn can attest to that. With the hole in the air dam, you hit enough water with any kind of speed and it's instant geyser right into the engine bay.

All the Jeep literature also calls it a "Removable Airdam", so yeah, they know people are going to remove them, it's not built into the bumper for example, thank $DEITY for that.

 

According to MOPAR it is a splash guard and has no effect on mileage/hood lift. I ripped mine off the first day I got my JK.

 

Mine popped a whole lot more.

 

To quote the Jeep literature:

"Wrangler's new AIR DAM is removeable for better off-road clearance and provides a low-pressure area to aid cooling and streamline airflow around, rather than under, the vehicle"

 

I haven't tested it without to really compare, but I have accidentally nailed a couple good amounts of standing water on the highway and was impressed that nothing came close to my air intake, I would be more concerned doing the same without the air dam in place. Just an observation, not empiricle though.

 

I purchased a new front bumper from MOPAR and according to the instructions from the factory the dam is only a splash guard and nothing more. The instructions mentioned it can be removed with no effects. It had to be removed anyway to install the bumper.

 

Sorry, I meant 1-2' of water, the kind of stuff that's made me lose 2 front license plates in as many weeks

With the air dam in place, it's going to push the water, and a fair amount will be forced up through the hole in the dam. Without the dam, your still going to push water, but it doesn't look like there's anything that's going to shoot it up to your hood.

 

Kinda scary that Jeep and MOPAR are not on the same page with stuff like this. Though in this case, it is insignificant.

 

I have had mine off for awhile and no after effects. As far as cooling I have never had a problem. The hood lift problem I just took the spring out.