Advice on aero mods for truck (2001 Dodge Ram 2500) - Fuel Economy, Hypermiling, EcoModding News and Forum

wjbell · 03-09-2011, 07:56 PM

I have a 2001 Dodge Ram 2500 with the cummins diesel and I'm trying to get better mileage. Right now it gets about 18mpg at 70mph and 16 in town. This is with the winter diesel fuel that I think have additives that make it get less mpg. In the summer I get 19 hwy 16 city. If I slow down to 60-65 I can probably get 20. It has a 4" exhaust, open air filter and a programmer.

So I've heard that 60% of your engines power at higher speeds is being used just to fight wind drag. So I'm trying to find ways to reduce that.

My truck has a rack and side boxes. It's my work truck and I have to keep them otherwise I'd pull those off for starters. But I'm thinking maybe the boxes help a little. The create more of a flat side down the whole length of the truck. So instead of a large drag area behind the cab, maybe it keeps a majority of the air flowing down the side of the truck.. I don't know.

Another thing is the tailgate up or down debate. From what I've heard, with the tailgate closed wind pressure creates a bubble in the bed and new air coming over the top of the cab hits this bubble and it almost acts like a bed cover. I don't know about that either.

So then the wind exits at the back of the vehicle. And with my boxes it creates a huge square abrupt end to the truck that I'm sure makes a huge amount of drag. So I was wondering about a tailgate that was in a 45 degree position, like a wing.This might allow wind to have a continuous flow over the cab, down into the bed and out. This would also change the big blocky back and maybe the air coming through the bed would meet with the air coming around the outside of the truck and help push each other straight back instead of making a big drag point.

I don't know, I'm new to this and want to get some opinions of what I suggested, and also some suggestion of what I could do to help this truck aerodynamically.

Here are a couple pictures of my truck and the tailgate idea.

Thanks for any help on this.

I can't post images or links yet but if you copy these two links you can see the pics

belletc.net/truck/truck1.jpg

belletc.net/truck/truck2.jpg

BamZipPow · 03-09-2011, 08:14 PM

BamZipPow · 03-09-2011, 08:59 PM

How often do you use the rack?

I'm not sure the angle that Droptail uses fer their setup...but I don't think it was 45°.

Have you considered gitting an Ultra-Gauge to monitor yer MPG progress?

nj trucker · 03-09-2011, 09:50 PM

Hi wjbell. What type of work do you do? The only problem I can think of with the tailgate at a 45 would be it completely coming off going over a big bump or pot hole at speed.

You could make an aero bed cover that fits between you boxes to help air flow over the bed. It could be a soft cover that starts at the top of your tool boxes up front and slopes down to the tail gate with snaps on the tail gate or simple strap set up.

Or it can be a hard cover also made to fit between your boxes. Starting just below your third brake light and going to the tailgate like the soft cover with 2 locking latches on the back of your tool boxes to keep it in place. When you need to use your bed for bulky items it could pivot up out of the way and store in the upright position with a 2 hooks on your ladder rack.

wjbell · 03-09-2011, 10:08 PM

Quote:

Originally Posted by BamZipPow

How often do you use the rack?

I'm not sure the angle that uses fer their setup...but I don't think it was 45°.

I don't use the rack that often, but sometimes I need it for a big ladder. And as soon as I took it off, then I'd need it.

But I could get rid of it and get a headache rack for the times I do need to carry a 20+ ft ladder.

The droptail is where I got the idea. I don't know what my angle is exactly. Do you know if the droptail actually improves aerodynamics? I can make mine at whatever angle I need to if it works.

I have a scangauge2 now. Is the ultra gauge better?

Reply to nj trucker: I'm a painting contractor and at the most carry a 28 ft extention ladder (14 ft long) but that's rare, more likely a 24 ft.

Yeah, I didn't think of the gate coming off because of the easy removal design. Good point!

I thought of the idea of a sloped cover, but I didn't like the idea of not being able to see out the rear view mirror. Maybe if I made it from the top of the boxes it would give me enough sight out the back. Also, if I made it right it could be a quick hookup before hwy trips and could remove it quickly it town. Now with that there will be a gap between the cab and the start of the cover, do you think that would catch air? If I made it out of canvas would it act like a parachute and balloon up?

Joenavy85 · 03-09-2011, 10:19 PM

the scangauge compared to the ultragauge is all a matter of preference. i have owned both and personally prefer the ultragauge. i think it's easier to use and i like the display options better

nj trucker · 03-09-2011, 10:36 PM

Do you have blind spot mirrors on your truck? I have the stick on 2 inch blind spot mirrors on my truck and I have a rear view camera on the back of my truck, and it works great. It was on the more expensive side but it is commercial grade and it is wired up to stay on all the time, not just while in reverse. Backing into a parking spot with my truck at night with tinted windows is a real hassle (especially when the car behind me is an 80k luxury car or suv).

If you make the cover drape over and attach to the front of the box to completely closing in the box it shouldn't. I didn't think of that at first. Could have snaps on the front of the bed box, an angle iron cross bar bolted to the boxes up front (silicone around the mounting holes so it doesn’t leak), and snaps on the tail gate. I think that would help keep air from getting underneath and causing it to balloon up.

nj trucker · 03-10-2011, 02:42 AM

I just thought of this now. You could get a piece of sheet metal or plastic that is long enough to start at the front of your cab to the back cross bar on ladder rack. Rivet to the back cross bar, front cross bar and let it droop down to you cab in front. Having that end held down by an end cap that is stuck to cab with 3M double sided tape. Don't think you would want to mess up your roof with rivets.

wjbell · 03-10-2011, 02:53 AM

Quote:

Originally Posted by nj trucker

I just thought of this now. You could get a piece of sheet metal or plastic that is long enough to start at the front of your cab to the back cross bar on ladder rack. Rivet to the back cross bar, front cross bar and let it droop down to you cab in front. Having that end held down by an end cap that is stuck to cab with 3M double sided tape. Don't think you would want to mess up your roof with rivets.

Wow, that's a pretty good idea. Keeps the flow of air out of the bed all together. I'm going to look at that idea tomorrow and brainstorm a little...