If you want to do something effective, take it off. If you don't want the cops to know it WAS you they were chasing like a bat out of hell.
CA

 

Run with it halfway up...it's a huge wing!!!

 

In the 1970s aircraft production went into a slump, and Lockheed started looking.for other customers for its wind-tunnel services.

Prime candidates were automakers, and Lockheed was successful in convincing Ford, among others, that the wind tunnel wouId help them reduce drag and wind noise on their vehicles.

Needless to say, in the past 15 to 20 years, Lockheed has learned a lot about car and truck aerodynamics.

Anyway, they actually performed drag tests on pickups with the tailgate both up and down, and found that drag was actually LOWER with the tailgate CLOSED!

This ran counter to their intuition (and yours). The reason is that a closed tailgate sets up a large "bubble" of stagnant air that slowly circulates around the bed of the truck (we aero types call this a ("separated bubble"). When air approaches the truck, it "sees" the bubble as part of the truck. So to the air, the truck looks like it has a nice, flat covering over the bed, and the air doesn't "slam" into the vertical tailgate.

If the tailgate is open, or replaced by one of those "air gate" nets, however, that nice, separate bubble in the truck bed does not form (it "bursts").

Then the air approaching the truck "sees" a truck with a flat bed on the back of a tall cab. This is a very nonaerodynamc shape with a very LARGE drag.

So, believe it or not, it's best for gas mileage to keep the tailgate CLOSED.

It would also seem to me that if the truck makers had a way of improving gas mileage they would do it by making the tailgate ventible or test with it down.

 

Yeah what they said......

 

Maybe some of you can answer this one??
I have a Hard tonneau cover,weighs about 75 lbs.Tailgate weighs about 50lbs.
I have always removed both of them before running at the track.I've had pretty good results doing this,but it's a real pain in the a**!
Does the benefit of less drag outweigh the added weight?I run consistant 1.79-1.85 60' times without any noticeable wheelspin.
i'm not sure any added weight over the bed would improve this.
I have removed hitch and spare tire as well.
I read a post a while ago stating 100lbs = ? tenths in a 1/4 mi run.Anyone seen this?
Thanks for any help!

 

Not sure if I read it on the board here but I do remember reading that 100 lbs = 1/10th of a second savings.

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Have a great day eh ! ......... Dave

 

Yeah 100lbs = 1/10th sounds about right.
I'm really curious about the Aero-effect I might gain by leaving the Hard cover and tailgate on outweighing the added weight.
Anybody with a hard cover tried a before and after comparison?

 

I did it on a road course - not a drag strip. Removing the tailgate, lid and spare tire helped braking. With the added weight, fade was a HUGE problem. Without the added weight, brake fade was managable but still a problem. On the other hand, it'll force you to learn the line and drive corners faster 'cause if you don't, you're off course.

 

LMAO @ CA

Once I blew a Rail Road Crossing with a Kawasaki Prototype Z-1.
It had wheelie bars, a bottle of NOS bolted to the back, and a multi color custom paint job.
The next day I'm driving NICE AND SLOW and get pulled over, the cop walks over and say's, HOW MANY PEOPLE DO YOU THINK HAVE A BIKE THAT LOOKS LIKE THIS, I answered, hubada hubada hubada hubada hubada hubada hubada hubada

 

Last year at the NMRA event in Reynolds, Ga, I saw JL remove his hard cover and t/g before he ran..............

Dan

 

100lbs = a tenth and 1mph

10 HP = a tenth and 1mph etc.etc.

Those numbers have been around for a long long time and probably work well for our trucks. But as the vehicle gets faster those numbers will change a bit, I think.

For intance if you have a 6000hp top fuel dragtser....I don't thing 10 hp or 100 lbs = a tenth and a mph.
Dale

 

i have also heard that running with the tailgate down will weaken the bed, the tailgate is very important to the structure of the bed and without it holding the sides of the bed together the sides can weaken. this will not hapen when driving around town but if you do a road trip, say 1000+ miles with the tailgate down it is not a good thing.

 

There may be some truth about most of the air sliding over the bed, but I dare you to put 30 or so emptys (soda, ofcoarse) in the bed and take a rip down your favorite freeway! You will find cans banging off your back window, hovering at bed rail level, and evenutally, on the guys car behind you! (this was performed scientifically, like that Twister movie with little scientific *****, certainly not beer cans as suggested!

 

I'll try this experiment, 'not using beer cans' (wink-wink) but, I got a question.

How do I get the cans into the bed if I don't have a slider?

 

Raoul
You can get'em in there from the driver window, you have to adjust for truck speed and it takes a little kentucky windage and a lot a practice.
Dale