Pickup tailgate up or down - SAE Studied

[Big Dave]

A squared-off bed top is the worst setup of all. It is worse than running with no bed at all.

[omgwtfbyobbq]

And the best bed cover IMO.


Could be approximated w/ removable wood sides and a taut fabric cover at the same angle, so the truck can still do truck stuff.

[VetteOwner]

hmm what if you made semi permanent sides and have the part that accualy coveres the bed easily removeable? or what if it were elcamino looking? (kinda sloped down sides but flat toneau cover) im trying to think of a way to make it a bit "stylish" ya know? wher eit can look good custom yet secretly be helping FE(like BBQ up there)

[Improbcat]

What would be super cool would be a cap shaped like the one in omgwtfbyobbq's post, but with the center section make like a fiberglass tonneau cover. that way when the bed is empty or near empty it'll have that optimal wedge shape. Then when you need to carry something bigger you can open it enough to make it a regular "square" cap shape. Possibly with canvas/vinyl pieces to fill the gap & rear area (like a jeep soft top). that way to get areo when the truck is empty, and the ability to haul more stuff when needed.

Now I wish I had a pickup (& warmer weather) to experiment with this idea.

[Snax]

Originally Posted by omgwtfbyobbq

And the best bed cover IMO.


Could be approximated w/ removable wood sides and a taut fabric cover at the same angle, so the truck can still do truck stuff.

Who makes that one? We looked all over for something like that.

(Although we have sold our most recent pickup, we will get another to haul our boat.)

[VetteOwner]

Originally Posted by Improbcat

What would be super cool would be a cap shaped like the one in omgwtfbyobbq's post, but with the center section make like a fiberglass tonneau cover. that way when the bed is empty or near empty it'll have that optimal wedge shape. Then when you need to carry something bigger you can open it enough to make it a regular "square" cap shape. Possibly with canvas/vinyl pieces to fill the gap & rear area (like a jeep soft top). that way to get areo when the truck is empty, and the ability to haul more stuff when needed.

Now I wish I had a pickup (& warmer weather) to experiment with this idea.

hmm that would be useful. liek have the rear hatch fold flat to the underside of the roof an dhave it swing down to make a full topper. and have fold in sides(triangular pieces) so it truley will be a hard top cover

[Big Dave]

Nice PhotoShop work omgwtfbyobbq. It shows what my fastback fairing would look like rendered in nice fiberglass.

You are clearly better at PhotoShop than I am. Can you make other changes? I'd like to see what my more radical MPG mod would look like.

[trailrunr]

Dropping the tailgate makes for a large vacumn behind the cab where there was a smaler one before. The air behind the tailgate is much dirtier due to the disturbed air coming from the underbody. dropping the tailgate has very little effect on tailgate air resistance but increases cab resistance. Weight also has little effect on highway mileage but decreases acceleration mileage (city). highway mileage is effected by how much power it takes to maintain a speed more than how much power it takes to get there. GMC found that making a tonneau box fot the front half of the bed increased their top speed in the Sonoma when going for the speed record at bonneville. Making a tonneau box the closes the front half of the bed (level with the top of the bed and squared off down to the bed at the halway point) eliminated part of the bed vacumn without increasing tailgate vacumn. Makes for a handy storage area also. I made one for my '85 S-10 years ago and went from 30 - 32 MPG highway while also helping highway performance, (that 4 cyl 5-speed was quite the dog). It performed more like a '70s vehicle.

[itjstagame]

Originally Posted by RningOnFumes

Mythbusters also tackled this issue. Basically, there is a bubble of air that is trapped in the bed causing the airstream to go over it as if there was something there. So tailgate up is best.

Their method was flawed, even the SAE test posted is flawed. There are more variable changes in the different vehicles they used then simply the tailgate on/off or up/down. Why they didn't just use one vehicle I don't know.

Anyway whether it helps or not the best solution is definately a fastback type tonneau which I had planned to make but didn't have $100 to shell out for a snap fastner riveter (anyone have one I can borrow ? ). I was worried if I'd need an underside frame for it and how taut it needed to be, etc, but BBQs idea is the best and come spring I'll probably try that.

That is: Instead of making a full tonnaeu all sides, etc out of fabric, I can use 2x4s and plywood and make wood sides that slide tightly right into the 3 post holes on each side of my bed and have the tonneae snap onto/over that. It'd probably be less pretty, but certainly more sturdy and pretty easy to make. They'll probably look similar to the Ridgeline but bigger on their own and will probably help on their own to keep turbulence off the sides of the truck from affecting the bed. With the longbed, I plan on going a bit more extreme and openning the tailgate and attaching the tonneau to the open gate (and making the sides to match), should help even more. What I'd really like is something I can slide into the openning between the end of the bed and the tailgate so I can make a half height wall or something so hard acceleration won't have stuff sliding off the bed. Maybe I can make this out of wood too.... hmmm...

[VetteOwner]

i dunno id use the wood sparingly, gets heavy real quick! if ya know how to weld you could weld one up out of small 1"X1" or even 1/2" X1/2" angle iron, strong weatherproof(mostly, i mean the trucks prolly gonan rust and fall apart before the angle iron rusts away)

maybe when its warme rill start designing somehting, i already designed a toneau cover but i dont have the money for the neccessary materials