I agree with ya, i've tried it both ways on several trips to Dallas (with
and without the tailgate) and NO difference in MPG.
Now what happens to that aerodynamics theory when some of us either install
Headache racks, Tools Boxes, or Tonneu Covers??
<spark...spark...spark....>
- Bernd
----- Original Message -----
From: "Barret, Matt" <MATT_BARRET@earthtech.com>
Subject: DML: RE: attn.Steven. tailgate up or down
> No, .25 to .50 seconds in the quarter mile is alot of time. Would normally
> take 20 to 50 HP for those gains, or 200 to 500 lbs of weight reduction. I
> really don't believe in the theory of drag from a tailgate at highway
speeds
> 90 mph or less. The design engineers take that into consideration when
> designing the aerodynamics of the truck. They engineer the roof lines to
> deflect most air up over the tailgate. I won't say there is no air drag
> from a tailgate, but I believe the significance of it is a non factor
under
> normal speeds.
> Now, in older trucks, like anything older than say 1990, they probably
> didn't do any aero work on the design, so the tailgate down theory may
apply
> to these designs. But by todays standards they are tweaking fuel economy
as
> much as possible.
> I have raced with the tailgate on and off, and observed no difference in
> ET's.
>
> The subject of the tailgate up or down and its effects on fuel mileage and
> drag has always been a hot topic . Most people are either in one side of
the
> fence or the other. I have had 3 trucks, 84 Ram, 85 F-150, and now the
Dak.
> I have experimented with the tailgate down/up and have never seen any
> increased MPG with it down.
>
> Lockhead Aircraft did wind tunnel testing on trucks in the 90's with
> tailgate up and down and actually found that leaving the gate up created
> less drag than putting the gate down!! A "separated air bubble" forms in
> the bed of the truck at highway speed which lets the air flow freely over
> the tailgate.
>
> I'm sure this will spark some interesting comments :)
>
>
> matt
>
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