milage- tail gate position

[drno]

i know i've seen information that shows that milage decreases when you ride with the tail gate down/off vs up either in a forum or in the tdr mag. , but i can't find it with a search. i would appreciate any help directing me to this information.

 

[NLamke]

I don't remember where I saw it, but remember reading a paper published about the effects of mileage on pickups. Tailgate down was better than up or removed. Best mileage was obtained when a cover was added from the top of the cab, sloping down to the closed tailgate. Don't remember where I read that though, have to see if I can find that again.

 

[2Gen3Gen]

I thought the only thing you got with the tailgate down was rock chips in it.

 

[TRAMPLINEMAN]

I watched a program on the Discovery channel a while ago on this topic. They had several different pick-ups in a wind tunnel testing the mileage effects with tailgate up and down. Having the gate up actually proved to have the best mileage. When the airflow comes over the roof it slopes down to the tailgate. The tailgate reflects the air and pushes against the back of the cab like having a tail wind. This is not my opinion, just something I watched on TDC. Mike

 

[dhill]

I saw a study in a mag. a couple of years ago that said, with the tailgate up was the best milage, down was next and off was bad. The best thing to do is to try it over the same road, same speed.



Dave

 

[BSkinner]

i know i've seen information that shows that milage decreases when you ride with the tail gate down/off vs up either in a forum or in the tdr mag. , but i can't find it with a search. i would appreciate any help directing me to this information.

I used to have ths site bookmarked. I believe it was a university site but the site is no longer active. Here's a couple of sites that talk about drag:



http://www.awtrucks.com/tailgateup.htm

http://truck-bed-covers.com/Tonneau_covers_save_fuel.htm



Bob

 

[JHardwick]

When the airflow comes over the roof it slopes down to the tailgate. The tailgate reflects the air and pushes against the back of the cab like having a tail wind. Mike

Your partially correct here. The air actually forms a bubble behind the cab. This bubble of dead air doesn't produce a tail wind effect against the cab, but the airflow goes over/around this bubble.

Best mileage was obtained when a cover was added from the top of the cab, sloping down to the closed tailgate.

This is exactly what the dead air bubble does, but not as efficiently.



"dead air" "bubble" etc are not scientific terms :-laf guys with pocket protectors have different terms

 

[NLamke]

Found this, good info is at the end of the article.



http://www.findarticles.com/p/articles/mi_qa3828/is_200405/ai_n9439015#continue



The one I was looking for compared toppers, bed covers, spoilers, and all sorts of things among tailgate positions, can't find it now though.

"dead air" "bubble" etc are not scientific terms :-laf guys with pocket protectors have different terms

I think the pocket proctector clad community would call this "bubble" Locked Vortex Flow.