Gas Saver?

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Sep 6, 2005 | 11:04 AM

#16

2000silverbullet

Lead Driver

Joined: Aug 2004

Posts: 5,326

Likes: 18

From: Gilbert

I'd kill for that kind of mileage Art! I get around 8 these days, which is why the truck's parked in the driveway for now, costs too much to drive (LAME!)...

Sep 19, 2005 | 02:17 AM

#17

twags6

Cargo Master

Joined: Jan 2001

Posts: 2,726

Likes: 5

From: Slatington, PA

Quote:

Originally Posted by Lnd Svyr

Yes. From what I have heard, the truck bed already has filled with air and the passing air flows right over that (that's the scientific/technical explanation if you couldn't tell).

If the passing air flows over the air in the bed, why do things in the bed such as soda cans or plastic/glass bottles fly in through the back window and hit me, my buddies, or the windshield?

Take a look at nascar trucks, they have their beds covered (not that they have real beds anyway, but its still solid on top).

Sep 19, 2005 | 05:11 AM

#18

2000silverbullet

Lead Driver

Joined: Aug 2004

Posts: 5,326

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From: Gilbert

Opening the rear window changes the dynamics of the air in the bed and the wind moving over the bed. Keep an eye on that stuff when the windows are closed, the most it'll move is to the forward of the bed when you first start driving (unless you jump on the gas, then it'll go to the rear first, then forward again when the wind picks up).

As far as the nascar trucks are concerned, I'm normally not driving 180mph in a 2 mile circle nor would I have a rear window open at that speed either.

Sep 19, 2005 | 09:03 AM

#19

krewat

FTE Leadership Emeritus

Joined: Jul 2002

Posts: 42,561

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From: Long Island USA

Quote:

Originally Posted by twags6

If the passing air flows over the air in the bed, why do things in the bed such as soda cans or plastic/glass bottles fly in through the back window and hit me, my buddies, or the windshield?

That's the point, high pressure in the bed - if you open the rear window in the cab, that high pressure wants to go somewhere with a lower-pressure - into the cab.

Still, I get 1MPG or so better with a cab-height cap/topper.

Mar 2, 2006 | 07:24 PM

#20

jessejames88

Junior User

Joined: Dec 2005

Posts: 65

Likes: 0

my experiance f-350 ext cab short bed gate off 1-1.5 better mileage but my old k2500 ext cab 8' bed covered or uncovered no difference so depends on the truck i guess

Mar 2, 2006 | 10:38 PM

#21

Deluxe05

Posting Guru

Joined: Jul 2005

Posts: 1,617

Likes: 4

From: Denver, Co

Quote:

Originally Posted by twags6

If the passing air flows over the air in the bed, why do things in the bed such as soda cans or plastic/glass bottles fly in through the back window and hit me, my buddies, or the windshield?

It's called a negative pressure vortex. The air rides over the cab of the truck and the "stagnant" air that sits in the box of the truck. As this happens, some of the energy from the air stream is imparted to the pocket of air in the back of your truck--this is what starts the rolling/spinning within the back of your truck. At the same time, there is a certain amount of air that is pulled out of the pocket of air, thus giving it negative air pressure, as compared to the surrounding air.

Quote:

Originally Posted by twags6

Take a look at nascar trucks, they have their beds covered (not that they have real beds anyway, but its still solid on top).

Two words: down force.

Mar 3, 2006 | 12:34 PM

#22

devildog_0431

Senior User

Joined: Feb 2006

Posts: 245

Likes: 0

From: Carterville, IL

When I bought my 99 250SD V10 it read 10.4 mpg. I have a Flowmaster super 50 exhaust, Tornado Gas Saver, and Fram Air Hog Performance Filter. I noticed when I first had these upgrades put on that I didn't fill it up as much but I have a very heavy foot lately and I'm sad to say my mileage is down to 9.8 mpg, haha, I just love the power and sound, gas price isn't an issue although its at $2.80 here in Hawaii for Regular, ouch. I remember when it used to be at $3.70....that was bad. A good muffler will save you some gas, let u run cooler, give more power/torque.

Mar 3, 2006 | 03:27 PM

#23

mdpopo59

Senior User

Joined: Nov 2005

Posts: 213

Likes: 0

From: Maryland

An answer to the tailgate question.

Has anyone seen the TV show "MYTHBUSTERS". The did an experiment about the tailgate up/down question. With two identical trucks, to everyone's suprise, the truck with the tailgate UP won! Why? Well, according to Adam and Jamie (the Mythbusters) with the tailgate up the wind enters the bed and creates a spinning vortex (thanks Delux05 and function12) which helps the air travel up and over the tailgate with no drag from the back of the cab. With the tailgate down, there is drag created from both the back of the cab and the back of the truck.

Deluxe05 is also right about the NASCAR bedcover, increased down force, which also creates drag. But you can use something from NASCAR to help you gas mileage, drafting. A big semi traveling about 65 mph can help your mileage by about 2. Just don't do like function12 said and get busted for tailgating.