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but you would think that you would go faster because the wind can escape
I think the studies show that the air gets trapped in there and makes it's own barrier that allows the stream to come over the bed and slip behind the gate. When the tailgate is down it doesn't allow this to happen and it causes more drag on the vehicle.
 

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Tailgate Up

I think the studies show that the air gets trapped in there and makes it's own barrier that allows the stream to come over the bed and slip behind the gate. When the tailgate is down it doesn't allow this to happen and it causes more drag on the vehicle.
This is correct. I watched a wind tunnel test on this. The initial air creates a mini vortex just behind the cab. The wind just flows over the vertex as if there were body panels there and continues on. The gate down causes the wind to curl up back onto itself as it tries to create a big vortex. The wind coming up hits the wind trying to pass over the truck and actually causes resistance. It was pretty cool to see how it works.
Of course, this only matters if you are going fast enough. If you're drag racing, the run is so short that it may not make that much of a difference.

Cheers
 

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the new wheels may be a little heavier but they are also bigger than the stockers giving you a different final drive axle ratio giving you a little better acceleration but limiting you more in the long run... its the same concept of why people put a lower gear in there car to go faster off the line, but it limits them top end.. I dont know if anyone has said this I didnt read all the posts but its my .02
 

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Discussion Starter · #27 ·
You lost because of your 22''s. how much did you lose by? im looking into getting 20''s but getting low profile tire to keep the final ratio the same.
i lost by two truck lengths but this was like a month ago i raced him again like 4 days ago and he beet me again but i was right next to him at the end im thinking about buying the 07 tahoe stock rims
 

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yeah, mythbusters already confirmed this myth..
Plus trucks without tailgates look trashy to me..and nets are meant for beat up 89 tacomas.
it probably is your wheels.. throw an intake and put some of that racing octane in before the drag.:great:
 

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Despite the aerodynamic testing of Mythbusters, it hasn't kept a company from developing a useless product that turns your tailgate into a spoiler:
[media]http://www.youtube.com/watch?v=ncHDICujq88[/media]
The motto: Just because it's on a Porsche, don't mean it should be on yer truck!:lol:
 

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i lost by two truck lengths but this was like a month ago i raced him again like 4 days ago and he beet me again but i was right next to him at the end im thinking about buying the 07 tahoe stock rims
Hey! I'm looking to replace my 08 Tahoe stock rims with aftermarket. Let me know. Maybe we can do some wheeling and dealing. :money:
 

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let it down. there's less wind resistance with it down so i would assume it wouldn't hold the truck back as much. but that just rounds off a small part of the brick :)
 

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myth busters did a test both ways . tail gate up won. creating a vortec thing was right.
They re-tested it because of veiwer complaints and it turned out that tailgate down was more efficient.
 

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They re-tested it because of veiwer complaints and it turned out that tailgate down was more efficient.
I must've missed that episode. When did you see that? I found that they revisited the tailgate down theory (http://kwc.org/mythbusters/2006/12/episode_64_more_myths_revisite.html) but only because the viewers suggested they test one with a hard bed cover, a mesh tailgate and one with the tailgate removed altogether. The tailgate up was proven again more efficient then tailgate down. Either way, you can't dispute wind tunnel testing (see http://www.nrc-cnrc.gc.ca/highlights/2007/0705uplands_e.html) and the test proved there was more drag with the tailgate down.
 

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when u have the tailgate down, the air that comes over the cab pushes down the bed of the truck causing you to lose MPG...but with the tailgate up like said before it causes some vortex or wind tunnel in the bed of your truck and actually pushes your truck.
 

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I don't know if lowering the tailgate will help, but removing any excess weight will help. Do you know if the other truck is completley stock?
 

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Has anyone actually tried it both ways with the tailgate up and the tailgate down. DRiving my normal style and got just a hair less on MPG with my 07 Z71. I normally get about 13.5 with the tailgate up and I got about 13.2 with the tailgate down.

Regardless, If you're losing by two truck lengths you're going to need to do something more significant than lowering you're tailgate or taking the tailgate off.

Besides, are you sure his truck is stock or "stock"? Has he had different gears or maybe even a hypertech programmer without you knowing? There's too many variables to pinpoint why you're getting beat...and no its not the tailgate.
 
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