Aerodynamic fun

VGs increase turbulence. A turbulent boundary layer has more momentum than a laminar one, so it can stay attached longer over a curved surface (like the back of the cab/topper in the OP). A laminar boundary layer produces less shear (drag), so you want the flow to be laminar everywhere possible, then trip it to turbulent right before it would normally separate.

The OP is putting them in the correct places; locating them anywhere forward on the vehicle would just increase drag.

For your rack bars, you might try Turbulator tape:
http://wingsandwheels.com/tapes-seals/turbulator-tape.html

It will break up the low-frequency shed vorticity from the bars, shedding many smaller turbulent structures instead. Will increase the frequency of the noise, which may be more or less annoying.

 

Wow, old post and never saw it.

OP, since you're in the north, try closing off some of the shutters (maybe just the upper half) on the grille opening. That always helps helps with aero count in our wind tunnel testing. Every little bit counts. You shouldn't have any real overheating/ cooling issues if the weather is cool where you are.

One way to check where detachment actually starts is by adding some kind of watercolor dots or visible fluid, that won't stain the paint in specific questionable areas you want the air to stay attached. Then drive it fast! You will probably figure out a newer optimal position to place your little VG gadgets at these points and angle the side ones differently to see if helps optimize flow and your KPL tests even more.

That's how we run tests in a tunnel, with ink blots on the surfaces of our models. Would love to see ink streaks on a full size vehicle. LOL. Fun project you've got going on!

Since I can't post pics of the secret stuff in the tunnels, here was an example we used before to observe flow on a race car speed form. Hope this gives you an understanding of what I was talking about with the water color and identifiable marks. (Please be careful with what you end up using as I don't want to be held responsible for you paint staining should you decide to try this).

 

This is true. Also lower quarter panels.
But they are way less obtrusive than these stick on fins.
Props to you for improving functionality, but it looks like a drunk weekend at autozone.

 

Nah man you put too many on and then you start to fly and have to use Av-gas, then your MPG turns in to lbs/hr and shit gets real expensive.

 

I betcha all those things make washing and waxing a breeze too, eh?

 

I'll gladly take a 1mpg hit then...

 

This is great, but would we need to get an STC for these and then go through MEL approval so that they can be deferred should one come off? (All you non aviation people have absolutely no clue what I'm talking about)

 

If this could be done uniformly like a golf ball, I'd be up for it.

 

I'm no aero guy but I think the biggest robber of MPG is how high our truck sits of the ground.

Would, putting under armor to flat bottom out the underneath of the truck help more?

 

that's hot.

 

I just stumbled upon this and while I think the look needs a little to get used to. I don't think it is that bad. Especially since it is body colored. Covering the underside of the truck with aluminium or compound plates should give you 10% increase in mpg

 

I had a truck like that once, if your theory is correct without all those dents I would have gotten like 2 mpg. It was a 67 GMC with a 305 cid V6 and a 4 spd. Thing could pull a house but was a bummer to get parts for.

 

This is cool. I'm not going to do it, but it's still cool.

 

It turns out to be closer to 5% after testing on the same 150+ mile round trip that I make once a week using the same gas and highway speeds. The only variable out of my control was the wind speed and direction. Averaging out the results over many months showed a 1.25 MPG increase with the belly pan. The following pictures show my revised V.2 version while the following link gives a more detailed write up and a link to my V.1. I will be selling my V.1 for 75$ but will not be able to ship it. It will be for a Florida or Georgia pick up only.

https://www.tacomaworld.com/threads...-3rd-gen-today.399305/page-5882#post-20070643

 

7 years of payments and 7 mins to make it look ugly as fuck

 

Thanks for sharing! Quite interesting how little effort increases the mpg that much. Keep us updated. I bet it is not even visible when walking around the truck.

 

Honestly, I would do this if I was taking a long road trip 1000+ miles, but not for daily driving.

 

Is this contagious? Can my truck accidently catch this?