What's with the plastic lip under the front bumper

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On a lot of vehicles, especially SUVs and now trucks though, I see a plastic lip under the front bumper that hangs down 3-4" and seems to serve no purpose other than reducing the clearance of the front end... What are these for and why shouldn't I remove it from my truck when I get one?

I'm not talking about underspoilers or other appearance things, these are usually unpainted and recessed under the bumper a few inches, by the way.

http://www.osseoauto.com/blog/wp-content/uploads/2013/07/2011-Chevrolet-Silverado-25004.jpg it's the lower part of the unpainted plastic there... It's absolutely huge on some SUVs
 
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"I'm not talking about underspoilers or other appearance things, these are usually unpainted and recessed under the bumper a few inches, by the way."

http://www.osseoauto.com/blog/wp-content/uploads/2013/07/2011-Chevrolet-Silverado-25004.jpg it's the lower part of the unpainted plastic there... It's absolutely huge on some SUVs
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This is throwing me off a bit^^^

Are you talking about the piece below the tow hooks?

Yes, it's for aerodynamics, to control lift, MPG and style! IDK about the radiator thing!

I'm sure it can be removed if you need that little extra clearance!
 
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By all means, take it off. Manufacturers love putting things on cars that aren't needed. There are plenty of other useless items on you car that you should also re-engineer.
 
I'm sure it's purpose is to hide what is behind it... for a cleaner look without adding more weight to the metal bumper. I wish they would paint it though.
 
So what I'm getting is... Remove it. Good. It looks stupid and falls apart if you drive through snow anyway.
 
THe bumpy underside of a vehicle contributes to drag. Giving the airflow a little shove down and away from that bumpy area helps lower drag. What drag the lip spoiler contributes is more than iffset by the reducton it makes. You can seen those devices on race cars and ther're not there for looks.
 
I didnt realize it was for aerodynamics.. I just assumed it was for "style" and snow collection.

My dads old 2011 z71 Tahoe didnt have it.. Its the "off road" version so I imagine that had something to do with it. The fuel economy still sucked and it never over heated. Lol.

The normal Tahoes have that plastic thing there and dad always said if he owned one, that would be the first thing to go.
 
My brother, when he had his auto repair shop, encountered a peculiar overheating problem that involve an air dam. The car would overheat under a particular set of circumstances. After a long highway run up the turnpike to the next exit, when the car slowed for stop-and-go traffic, it would overheat. The customer had it to other repair shops, they replaced the usual culprits, thermostat, engine flush, checked the fan, it may have even gotten a new radiator.

In the end, he noticed the air dam was missing. Replacing the air dam fixed the overheating problem.

My wife's car has an air dam that has big floppy parts in front of the wheels. One of them must have gotten caught on the wheel and it ripped out the fender liner. I did trim the floppy parts in front of the wheels off.
 
AN air dam can also serve as an "you're about to rip your oil pan off on this parking lot cement railroad tie" warning.
 
It's there to create a low pressure area under the engine area, to allow more air to easily enter the radiator. Like when you have a rear window open in a 4 door car and you also have a front door window open. The air seems to just flow through a lot faster. Now, if you closed that rear window,the air would have a little harder time to flow in car.Front of rad.,high pressure. engine area, low pressure. Have you also noticed the the plastic tabs in front of the front tires on a lot of cars and suvs? They're there to SAVE you gas! Lexus Mercedes,etc have them. They wouldn't put 'em if they didn't serve a purpose.
 
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I'll add that when I bought my firebird, 2.8 V6, driving in 35 degree weather in November, it was boiling hard when I parked it. Missing the air dam doohickey.
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The electric fan was running too. Not overheating, but up around 220, above thermostat temp.

That car didn't have much of a grille and counted on vacuuming up air from near the pavement level.

I bent up a scoop out of scrap aluminum flashing, replaced the rad cap for grins, and it behaved itself from then on out.

Saturn s-series, on the other hand, are supposed to have them but very rarely do. When I see one in a car in a picture (dealer lot or whatever) I imagine it living an easy life or being meticulously maintained, something that doesn't happen around here.
 
Originally Posted By: HerrStig
AN air dam can also serve as an "you're about to rip your oil pan off on this parking lot cement railroad tie" warning.


psh that's what suspension lifts and 285/70/17s are for!
 
That plastic lip is known as an air dam. It's meant to push air to the aerodynamically cleaner sides of the vehicle instead of the aerodynamically dirty underside. They are quite effective for what they do, and are cheaper/easier to produce and install than cladding the underside in panels.

Some individual vehicles see a noticeable difference from the air dam, while others have them because spread across the vehicle fleet there is an efficiency gain. 0.05 mpg multiplied by 1,000,000 vehicles is a lot of fuel saved!

Those little things in front of the tires are called spats. Believe it or not, those tire lugs create a measurable amount of drag. By reducing the amount of air hitting the tire, it's less drag. Again, it's a play to increase efficiency across the fleet.

Those tenths of a MPG add up across the 300+ million vehicles in the US, and a lot of fuel saved across the country.
 
Originally Posted By: eljefino
Saturn s-series, on the other hand, are supposed to have them but very rarely do. When I see one in a car in a picture (dealer lot or whatever) I imagine it living an easy life or being meticulously maintained, something that doesn't happen around here.

Awwh, but Saturn S-series deserve to be loved!
Saturn.jpg
 
On trucks it drives me up the wall, when I had my rental Ram I scrapped it on curbs all the time. I'd pull it off if it was my truck.
 
I pulled the lower valence off my Explorer on a trail. Well, the trail pulled it off, and I just threw it in the back. That valence was a lot higher off the ground than the ones on new trucks.

What's with the plastic lip under the front bumper is 0.05 MPG on an EPA test.
 
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