A Practical Guide to Pickup Truck Aeromods

[crashnzuk]

To get back on pick-ups, I have a new 15 Ram crew cab, short bed, 4x4, Cummins, 6 spd manual, 3.42 gears with 275/70r18 firestone trans force HT tires (whew ). I have a little over 4k miles on it now and have been knocking down about 17.4 mpg in my mixed driving to/from work. My calc'd mileage is amazingly within a tenth or so of the lie-o-meter. Last week I put cab length steps on my truck similar to the "good" picture posted previously (post #17 by Vman455) and filled my tank the next day. 17.3 I think it was, great! Now, this tank is reading 16.2-ish give or take. I'm thinking my new steps have stolen about 1 mpg. I haven't made any other changes and hadn't thought it could be the steps. I guess I'll have to see if this tank is just off, or if my mpg stays in the 16's. Just thought I'd post up some real time insights.

Also, FWIW, I think the Ram 29 mpg claim is for a 2wd EcoDiesel.
Travis..

[skyking]

nice truck! I hope it was just a bad tank. My 2007 3500 4x4 SRW QCSB G56 6 speed, 3.73 gears with the 285/75R17 Nitto grapplers (whew back at ya ) gets no more than 19 on the highway now, and 17 in mixed driving. It needs some help.

[crashnzuk]

I'm pretty happy with the mpg's so far. We did a trip of about 2500 miles in 8 days and got high 16s to mid 18s. This included lots of interstate travel in Nevada and Idaho where the speeds are 75-80 mph. This truck is getting as good or better mpg's than my 91 Dodge Cummins. That is saying something since the old truck could never cruise comfortably at those kinds of speeds. I wouldn't be opposed to some improvement though.
Travis..

[skyking]

my 2nd gen averaged 22 over several thousand miles. This "new" truck is a little hard to take in that regard. Of course the 2nd gen was 2wd and made enough noise to wake the dead.
I am sure these mud tires are not helping.

[Big Dave]

Re: Post #40

My air dam is 3/8 inch rip-stop belting. You can only get it from industrial rubber supply houses. I'd think in a port area like Sea-Tac somebody is selling this stuff.

My air dam sits 10 inches above grade inboard of the wheels and tapers to 7" above grade in front of the wheels. That's about as low as i could go without dragging hitting parking curbs. This setup works. In A-B-A tests it was good for a 1.0 MPG improvement over no air dam.

The conveyor belt is nearly indestructible. I hit road kill, debris, tire strips, and even wooden boxes - not even a hint of a problem. It bulldozes snow just fine.

Rip-stop does have its downsides. It isn't easy to find even when you know where to source it. It is EXPENSIVE. Figure $75 for enough for a full-sized pickup air dam. It is maddeningly difficult to fabricate if you don't have the tools. If I were doing it again, I'd make a paper pattern and pay the $50/hr shop rate to have it professionally fabricated. Rubber-supply houses have the 15 ton punch and shear presses needed to fab the stuff.

The stuff is fairly heavy and you'll have to modify your bumper to hold it.

I tried making the air dam to one and a half inches above grade. that only yielded another 0.25 MPG. Going lower increases net frontal area. It dragged every time I hit the brakes. The dragging didn't hurt the air dam but drove me crazy.

I also tried a pair of belting skirts between the wheels but a rail crossing tore one off. I didn't notice anty difference in the short time I had the side skirts.

[skyking]

The new truck is a 4x4 and sits pretty tall. I think I can make a little on side skirts.


No real room up front to lower with the pan and differential clearance. I can take out a 1.2" block on the rear springs.
going to stock tires would get me another 1.5" but that is a double edged sword. It ups the cruise RPMs too.

[greengeeker]

Thanks for amassing all the information together into an article - very helpful to have this all in one place.

I've put together a TDI Ranger and have been driving it for the last two years with the intentions of improving on the rock steady 39mpg (stock aero) with some aero mods. What I haven't seen (not necessarily directed at your article) is a list of priorities as far as aero is concerned. Which heavy hitters do you need to tackle first to make aero gains so that subsequent aero mods are actually beneficial. On a truck, which has the highest impact on aerodynamic drag? Is the airflow over the bed? Airflow under the truck? Yes, the answer is likely to be different for each truck but the order is going to be different for a truck than it is for a car.

Anyway, on my truck I've tried two things to improve the FE: 1) removed the 3.73 rearend and installed a 3.08 dropping cruising 5th gear rpm by 450rpm. 2) installed a hard tonneau cover on the bed

Neither of these showed any impact on my long term mileage.

I'm considering moving forward with some underbody mods (dam, belly pans) to see if this has a more significant impact.

(I don't have enough posts to include links or pictures so if you want to see info on my truck just google "tdi ranger build tdiclub")

[88m53453]

Nice thread , thanks. I've been driving a 2015 2wd 5.3L Silverado for about 7k now ( in about 10 weeks) Currently has 23000 miles. I drive a commute into Columbus Ga every day of about 70 miles and generally put about 40-50 miles additional every day. I have averaged by actual calculations over 22 mpg over the 7k ( indicated 22.7), Being very careful and no AC have gotten right at indicated 30 between LaGrange and Columbus. No mods and have added a step bar front to back 4dr crew cab. My lie-o-meter is usually off under 1 mpg. I am planning on lowering the rear a bit and possibly adding the rear soft cover and see what happens

[gumby79]

1 more
My redneck wind tunnel. 35-40Mph sandstorm.
Hears my buld
http:// http://ecomodder.com/forum/s...cap-31981.html


If you check my garage. You'll find my fule log mpgs. Have improved vastly.as shown in#17 27%gain (some is driver improvement but almost 5mpg sone aba testing will clear up how much )

In short add your round roof spoiler to the rear of the taunto aswell. And above all. Rember12°angle to keep the air attached

91 Dodge D250 cummins 518A od trans 3:54diff 5520lbs. Airocap
Odomiter is off 2%short (1000mi on Odomiter =1020mi.per gps)

More pic hear. http:// http://ecomodder.com/forum/m...250pickup.html

[skyking]

Originally Posted by greengeeker

Thanks for amassing all the information together into an article - very helpful to have this all in one place.

I've put together a TDI Ranger and have been driving it for the last two years with the intentions of improving on the rock steady 39mpg (stock aero) with some aero mods. What I haven't seen (not necessarily directed at your article) is a list of priorities as far as aero is concerned. Which heavy hitters do you need to tackle first to make aero gains so that subsequent aero mods are actually beneficial. On a truck, which has the highest impact on aerodynamic drag? Is the airflow over the bed? Airflow under the truck? Yes, the answer is likely to be different for each truck but the order is going to be different for a truck than it is for a car.

Anyway, on my truck I've tried two things to improve the FE: 1) removed the 3.73 rearend and installed a 3.08 dropping cruising 5th gear rpm by 450rpm. 2) installed a hard tonneau cover on the bed

Neither of these showed any impact on my long term mileage.

I'm considering moving forward with some underbody mods (dam, belly pans) to see if this has a more significant impact.

(I don't have enough posts to include links or pictures so if you want to see info on my truck just google "tdi ranger build tdiclub")

Another TDI fan here, I have a couple of beetles.
Your ranger is a good candidate for an aeroshell. how you build it depends on your skills and time.
One method that I'd do for the fun of it is wood strips, like a cedar strip canoe.
Instead of removing the plywood formers, plan on cutting most of them away and leave a 2" bulkhead there. This does a couple of things. Now you can glue and fasten the strips to that for easier construction, use less formers, and it will be stronger. It also give you attachment points.
If you want a lift lid, cut it out and build a gutter down each side of the fixed part for the lid to rest on and to carry rain to the back.
4 oz fiberglass is invisible and will show the wood perfectly. 6 oz is not too bad either.
coupled with a few other mods it should net 10% MPG improvement. That is where my beetle is at, around 45 or so.