aerodynamics

[chesspirate]

companies sell plenty of stuff advertised to improve aerodynamics, such as, bug deflectors, front sun visors, taunou covers, etc.

My question is, does any of this stuff actually help in real world driving conditions. For instance, I removed the stock air deflector on my 1991 S-10 and even though it cooled better, I could tell going down the freeway I had to push harder on the pedal, I screwed up the aerodynamics, so I put it back on. Also I had a bug deflector and took that off, never could figure out if that did a darn thing. Although, my MPG's are down, could be from driving style though I'll admit that.

Never had a bed cover, but I'm betting it makes a difference.

Also, if you know of any other tricks to make the truck more sleek that actually are worth a darn let us all know.

[OBI WAN]

Stand up bug deflectors grab the air and slow you down. A curved one that wraps around the nose does keep bugs off the windshield, but still adds a drag. Bed covers DO ABSOLUTELY nothing for anything and at times have been found to slow the vehicle down because it takes off the rear draft coming from under the truck. One things that does help is getting it lower to the ground!

[T Man]

i read an article in some auto mag that leaving the tailgate up actually helped mpg, it was a while ago so i dont remember what the stats were actually, but it did help

[ZR1-S10]

There have been articles for both sides of the agurement. The only real way would be to put your truck in a wintunnel and find out yourself wicth would cost alot. The one thing that seams to be true is lowering the truck inproves areo.

[Supercharged-ZQ8]

Anything that reduces wind drag will help increase gas mileage -- sometimes in a very noticeable way, other times very subtly.

I've seen both arguments about tonneau covers. Personally, I'm of the mind set that a tailgate is a huge parachute hanging on the back of your truck. I've driven both with and without the tailgate, and raced Auto-X both with and without. From my own experience, the tailgate is an impedence to the vehicle's forward momentum. My previous truck ('95 S-10) I drove for a couple years without a tonneau, and then a couple years with a tonneau. According to my recollection, I received better mileage WITH the tonneau than without. Although you ARE trading one thing for another: the reduced wind drag is being traded for increased weight. But, I'm a proponent of tonneaus, myself. A tonneau, due to the extra weight over the rear tires and due to the additional direct downforce of the air coming over the cab, provided better traction -- which, in a way decreases gas mileage marginally. Again, from my own experience, I've noticed improvements both in performance and in mpg by using a tonneau cover (and to specify, NOT the soft tonneaus that are so popular -- that act as sails and increase wind drage -- I mean the hard/smooth tonneau covers that allow the wind an easier exit out the back.

Anything added to the front of the vehicle will immediately cause an excess of wind drag -- no matter how "streamlined" it might seem. Bug deflectors ore nice and all for keeping small rocks and bug off you hood and (sometimes) your windshield -- but in order to do that, they mess with the aerodynamic properites of the frontend. These trucks are NOT the most aerodynamically designed vehicles on the market, and anything the sticks up or out (such as bug shields, windshield visors, front air dams, etc.) are going to not onlyl add extra weight for the poor truck to puch around, but provide a larger surface area on which wind can get caught and inhibit forward momentum. Roof Racks, to a much lesser extent, do the same thing as well.

Fender flares also can decrease economy as well -- four sizeable bumps coming off the sides of the vehicle and presenting themselves to the passing wind current and getting caught in it -- more wind drag. The same with mirrors. Larger (read: stock) mirrors present a rather large area for wind to smack against and decrease the truck's forward motion. Going with smaller (but no less visible) mirrors is a way to also improve mileage. With mirrors, it is mostly inthe design. Large flat mirrors provide a "wind-catching" profile, whereas the smaller, angled mirrors provide a "wind cutting" profile.

Wings. . . Wings DON'T belong on trucks, in my opinion -- or at least in only a few VERY rare cicumstances. Those are spoilers -- they do just that "spoil" the airflow to provide downforce what needed (usually over the rear wheels).

Lastly, a semi rake will also provide a slight increase in mpg and performance. Trucks that site dead even have the fully square portion of their front ends presented to any oncoming wind -- a flat surface that causes drag. Having a slight rake (a "nosedive" if you will) lifts the rear a bit and puts the front end in a more approachable angle to combat winddrag -- instead of a wall, you now have a wedge.

And on lowering: the lower the truck sits to the ground the less air will actually get under there. This is a good thing. The upper portion of the truck is mostly smooth and can even be called sleek when compared to what the road sees. Underneath you have your exhaust, oil pan, suspension, transmission, driveshaft, rear-end, shocks, springs, gas tank, hollow spots, etc. Bascially LOTS of places that wind passing under the truck can get into and cause immense amounts of drag. The lower to the ground you go, the less air can get under there, and the less wind drag you're faced with.

Another one is cowl hoods. The stock hood has no escape for the wind that bottlenecks between the hood and the windshield -- a functional cowl, on the other hand, allows that bottlenecked air to excape into the engine bay and stop becoming a dircet drag on the truck's forward momentum. And there is the side benefit that it's ambient air being drawn in which will help to cool the engine bay a bit (thus yielding a minor performance gain there 1-2 hp if that).

Of course, truck CAPS are a no-no -- they cause more wind drag and add more weight that they're worth -- unless they are specifically for storage/towing purposes.

Anything that streamlines the body will HELP improve mileage. Anything the sticks out away from the body will decrease it. The smoother, sleeker you can get your truck (as hard as that can be at times), the better mileage and performance you'll have.

It all depends on the truck and the modification you're planning.