Lower front valance removal

[kennythewelder]

GMT 400s were the first truck to be desinged in a wind tunnel. That being said, I would think the valance was added because they were trying to prevent drag from the undercarriage, but that is just a guess.

 

[Thatfordguy]

These trucks are fairly close to the aerodynamics of a brick. I'm not too worried about it

 

[kennythewelder]

These trucks are fairly close to the aerodynamics of a brick. I'm not too worried about it

True enough, but they do well at speeds over 100 MPH. They don't float at high speed at all. I turned off my speed limiter (or set it to max,,228 MPH when I tuned my truck) , and have had mine well over 100 MPH more than once. Like I said, the valance has been off of mine for years, well before I reset the speed limiter. I was very surprised how well the truck handles at high speeds. After doing some research, I found out that these trucks were the first to be built in a wind tunnel.

 

[df2x4]

As far as I understand it, the front valence was originally put there to help with aerodynamics. AKA fuel economy. How much it actually helped is probably so negligible you couldn't even measure it. Wind tunnel designed or not, they're still giant cinder blocks on wheels. Though I do agree, they're surprisingly stable at high speeds.

Never heard of the front valence having any effect on cooling on the 6.5s either. I can't imagine it would, for any reason.

 

[shovelbill]

the valance does indeed reduce the drag coefficient. at least on the stock height trucks....thereby helping with fuel economy. GM first introduced them on the 2nd generation face-lifted trucks in 1981(the "squares"). same "air deflector" was used through 1991......my 1986 had it and that promptly went in the dumpster.

i check my fuel economy every tank, yea i'm stupid like that....been like that forever.......anyway, when i got my new(to me) '98 it came to me with the lower valance.....after i removed it i found out i had kept loosing 1-1 1/2 highway mpg's thereafter........

i do know that if you put a roof roof rack with 4 Hella 220's on a Jeep Cherokee you'll loose the same 1-2 mpg on the highway.

on lifted trucks with larger tires, etc there's no difference.........gearing DOES play a roll, but all things equal, it's for fuel economy. tell your friend to stop spreading misinformation...........or you could slap him as others suggested.

nothing helps in city bumper to bumper traffic, but my long distance driving IS important to me so i'll be putting another air deflector back on, probable on with good fog lights in it......may as well make it useful too.

 

[TylerZ281500]

theres more to it in terms of fluid dymanics and creating a negative pcoket of air around that area but not worth goign into deteail about. 6.5s have their bumper to help cool, thats about it

 

[BluC10]

The valance has nothing to do with cooling the radiator. You are correct about the air moving across it, and what air the fan pull across the radiator at low speeds and when stopped. My valance has been off of my truck for years, and it never over heats, even in the hot south Louisiana summers.

Cool, thank you. I will have to tell him that to prove him it is mainly for looks and/or MPG. But driving a gmt400 I'm already not to worried about my mpg lmfaoo.

 

[BluC10]

the valance does indeed reduce the drag coefficient. at least on the stock height trucks....thereby helping with fuel economy. GM first introduced them on the 2nd generation face-lifted trucks in 1981(the "squares"). same "air deflector" was used through 1991......my 1986 had it and that promptly went in the dumpster.

i check my fuel economy every tank, yea i'm stupid like that....been like that forever.......anyway, when i got my new(to me) '98 it came to me with the lower valance.....after i removed it i found out i had kept loosing 1-1 1/2 highway mpg's thereafter........

i do know that if you put a roof roof rack with 4 Hella 220's on a Jeep Cherokee you'll loose the same 1-2 mpg on the highway.

on lifted trucks with larger tires, etc there's no difference.........gearing DOES play a roll, but all things equal, it's for fuel economy. tell your friend to stop spreading misinformation...........or you could slap him as others suggested.

nothing helps in city bumper to bumper traffic, but my long distance driving IS important to me so i'll be putting another air deflector back on, probable on with good fog lights in it......may as well make it useful too.

Haha don't worry about it man I keep mpg every single tank too. I'll see if I can tell a difference after it is now off. But before it was took off I was averaging 12.2 MPG over about 2,000 miles since I got the truck.

I do a lot of highway driving to go up north and back in summer to haul my dirt bikes. Might have to put one back on for the highway driving now. ThanK you

 

[Thatfordguy]

I had zero change with it on or off as a stock height 4x4. However I added a bed cover and that added 1.5. That's with mainly hwy miles running at 72-75mph and I'm getting 14.5

 

[mattillac]

Bought my gmt400 new back in late 1999, it didn't come with a valance.

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Could there be an RPO code for the air deflector(option), C43 maybe ?

C43 : DEFLECTOR, AIR

http://www.early3rdgen.com/forum/viewtopic.php?t=24