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Old 06-29-2014, 01:56 PM   #1 (permalink)
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Aero a tank

Hi, I'm new here and want to begin helping my 2500 Ram, its a 2012 with the CTD.

Until I get the nerve to do rip it all off, the factory mapping and equipment will need to stay on the truck, cause its under warranty, but 'regen' is driving me nuts; it drops instant MPG by over 30%, no tow, or about 20% towing. The tank MPG effect depends on driving conditions; city vs. highway, etc. I have no way to calculate tank-by-tank or mile after mile effect. But, am quite sure the way I drive, this government silliness is costing me somewhere near 8%; maybe more. The truck is set up to meet 2024 EPA numbers, so I am told. I am not educated on it, but why is burning off the little bit sot; changing it to 'white' smoke, while pumping an unnecessarily rich mixture of diesel fuel helping the environment? Could it be that the impact of the chemicals pumped into the air, are not being considered; or not being tested for? I'm off my soapbox now.

So, even with the nonsensical 'regen', I want to work on the aero and save dollars. I understand that the lack of a bed cover; essentially the air-ugly shape in the back-end is the first priority; that and a front air dam.

One of the members had built a nice metal air dam, but I was thinking more of a cut to size conveyor belt or equivalent mounted to allow hitting something not prove to be fatal to the dam. My truck is not lifted.

I see many of your ideas and want to try making one myself. I would need it to have a hatch for loading and access, but don't think windows are worth the pane.... oops, pain. I would use a good rear camera and a 7" of better display. I am fairly handy with wood and consider building the bed cover from cedar used for ribs and cover with door skins or foam and coated with fiberglass and then painted. The foam seems like the best material since it can be shaped and will keep the insides cooler.

The large towing mirrors is something that I fiddled with a few times. Kind of like your A-B-A thing. Since the truck went into regen, the numbers are a guess-tamation, but I think the mirrors folded in resulted in about .005 to .01 % improvement. Even folded in they still hang out quite a bit. I need these for towing, so I was thinking that maybe a convex could be fitted to the mirror that would still allow folding.

Just for fun, compared open windows (all 4) to closed. The result was about .2 of a MPG.

I have mud flaps, which I know are hurting, but until I make some kind of aero flap, they have to stay. I often travel muddy roads.

I read that blocking the grill might not be a good idea. I do wonder if blocking the top half, all the way across might work. It might help warm up times and could help the MPG. This beast has to be hot to get its highest MPG. I can see both water and trans temps and would be able to monitor the result. If the block was easily removable, it will try it.

I am including a photo with the template overlay and any of you old timer ecomodders could comment, I will appreciate it very much.
Wolf

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Old 06-30-2014, 02:20 PM   #2 (permalink)
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RAM 3/4-ton

I don't have any 2500 info near me.And I don't know when the model change occurred.
The 2008 1500 2wd was rated at Cd 0.44 and 34.49 sq-ft frontal area.
The same year Quad Cab was rated at Cd 0.52.
---------------------------------------------------------------------------
The 2013 RAM 1500 has a model with Cd 0.363.It's the lowest drag full-size half-ton.
It has:
*Active suspension which lowers truck for highway
*Active grille-shutters
*Factory tonneau cover
This would be a good pickup to find and inspect.You could investigate the grille area and consider between it and your truck.
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*Feysel Ahmed (SP?) did a masters thesis on a RAM pickup using Computational Fluid Dynamics and a cap as you've illustrated returned a 19% drag reduction.
*I used an old Chrysler racing hull to create a cap which is paying for itself

With some boat-tailing,you can see from the tufts that it is allowing the streamlines to come back together without separation

Your proposed tail is even more 'aggressive',so you ought to do a little better,and I'm pushing 40 mpg at a constant 60 mph on a good day without any tail.
-------------------------------------------------------------------------
I would recommend you not take the air dam any lower than your lowest under-chassis components.Ahmed tested this and it raised drag.Some members report similar results.
Check out that new RAM.
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Old 06-30-2014, 02:24 PM   #3 (permalink)
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Quote:
I am fairly handy with wood and consider building the bed cover from cedar used for ribs and cover with door skins or foam and coated with fiberglass and then painted.
Others will have more opinion on diesel issues. Characterize 'fairly handy'; have you built a boat?

Consider plywood for the ribs and cedar for the skin. A friend of my built a egg-shaped house on a Ford flatbed truck back in the 70s. He made plywood ribs, ran light wood stringers and shingled the whole thing. When it was done he had it sprayed out inside with polyurethane foam. What was a wobbly structure turned into a solid block of foam with the shingles embedded in the outer surface.

Where he shingled it vertically like a stationary house, you could turn the shingles 90 so they lay like fish scales.
___________

Then there's the whole subject of that boat tail. Drop the tailgate and bungee a plank twice as long as the bed to the tailgate. (red flag, of course.) Drive around and decide if you can live with the extra length. The last 10-20% of that length will make about as much difference as folding in your mirrors. Even an 18" truncation will make some difference, and you could split it in the middle and have it open like cupboard doors.
___________

What's the use case? contractor truck, recreational, single-passenger commuter?
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Old 07-01-2014, 02:13 PM   #4 (permalink)
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Looks like a nice design. I think your back bottom “new lower line” may be too steep, Aerohead has a graph on this site of changes in drag based on the slope of that line. I would suggest a less aggressive lower line, and truncating the tail a bit shorter, no need for it to come to a point. I like the topper and then the separate tail on a hitch, so the tail would be removable to haul a trailer.

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