Eco-RV thoughts?

[PNW_Steve]

Hey Everyone,

I have been lurking here for some time and enjoyed the community. I finally decided to jump in after completing a 5000 mile road trip in my 2001 Dodge Ram 3500 4x4 Diesel truck hauling a 27' 5th wheel trailer.

I managed a trip average of just over 12.9mpg. My best tank was 13.2mpg.

I managed to do a pretty good job of maintaining my "self imposed" 60mph speed limit. The onboard mpg display is not terribly accurate but it will demonstrate deltas in mpg and shows a significant drop in mpg over 60mph.

My previous RV was a converted Eagle 10 bus with an 8v71NA Detroit Diesel and an Allison 740 transmission. I got a consistent 7.25mpg with that rig. That started when diesel prices were well under $1.00 a gallon. As fuel prices increased and my ability to afford fuel diminished I finally gave in and sold my trusty bus.

Here I am again trying to balance my love of travel with the cost of fuel.

On my recent trip I spent a great deal of time talking to other RVers about fuel mileage, driving habits, rig and accommodation details. I have come to the conclusion that as much as I enjoy a 40' rig that will cruise comfortably at 70mph I don't NEED it.

Our 27' 5th wheel was very comfortable for 5 weeks on the road and certainly much more economical..... What can I say... I want more! (MPG).

I have been searching for a solution that I can afford and see that the new breed of eco minded factory RVs are way beyond my budget. That got me contemplating a build.

I am contemplating a 12V Cummins based platform. Either a Ram 3500 truck or a B350 van. Some sort of "hybrid" Class B/C. Basically take the Dodge cab & chassis and build an aero "box" around 20' long & 8' wide for the "house". Features to include:

12V Cummins Diesel with minor mods aimed at economy.
5 or 6 speed manual transmission.
2 speed rear end or Gear Vendors overdrive.
Tire selection to maximize economy.
Full fairings on the "Box"
Ground effects: Air dam & side skirts as appropriate.
Smooth wheel covers.
Partial wheel skirts.
Airbag suspension that will allow me to lower the rig when needed.
General "smoothing" of the exterior as I am able.

Picture one of the newer "AeroCab" semi's with a smooth box on the back. Some kind of ducktail included.

Has anyone out there tried something of this sort? Results?

I am really hoping to see something that is really livable and can accomplish 20+ mpg highway. Being able to run 65mph and still get 20+mpg would be a bonus.

Any tips on the aerodynamics would be quite helpful.

Thanks

Steve

[Ecky]

Big gains will be in the back. If you can design it with a sloping roof toward the rear, you'll really help your highway mileage. Take a look at some of the boat tails members here have designed.

Frontal area is also a huge factor. Longer + lower + narrower for the same living area will return better highway mileage.

[Frank Lee]

Go in a Metro; stay in hotels. It'll be cheaper.

[PNW_Steve]

Originally Posted by Frank Lee

Go in a Metro; stay in hotels. It'll be cheaper.

Staying home would be even cheaper...

Seriously: My average nightly cost for accommodations was $20. What kind of hotel can you get in beach destinations for that ?

[Frank Lee]

$20? The rig and fuel were free?

[Ecky]

Frank has a point; Buying the rig and driving it around will almost certainly be far more expensive than staying in hotels, but if you're willing to throw money at it, I'm interested to see what you come up with. Not all decisions in life are based on economy and practicality.

If you don't mind my asking, how much are you thinking of spending on this, and what kind of fabrication is within your abilities?

[redneck]

B350 van. Some sort of "hybrid" Class B/C. Basically take the Dodge cab & chassis and build an aero "box" around 20' long & 8' wide for the "house". Features to include:

12V Cummins Diesel with minor mods aimed at economy.
5 or 6 speed manual transmission.
2 speed rear end or Gear Vendors overdrive.
Tire selection to maximize economy.
Full fairings on the "Box"
Ground effects: Air dam & side skirts as appropriate.
Smooth wheel covers.
Partial wheel skirts.
Airbag suspension that will allow me to lower the rig when needed.
General "smoothing" of the exterior as I am able.

Here you go...








>

[Frank Lee]

^ I love that thing!

I only pointed it out because I've done some cost analysis on my own RV vs car + room for trips and that is only for the operating costs (fuel + food and such) not purchase/maint/repair. For shorter length of time trips the car wins by a huge margin but at some point IIRC well over a month long the RV started to save a bit of money.

I was mathing out several RV things at the time; another was what would the payback on a Gear Vendors OD and/or a diesel conversion be? The answer was many, many miles would have to be put on annually for it to pay off.

[Hersbird]

I think just sticking with and improving a 5th wheel is the way to go. First most 5th wheels are to tall, they go for that stand up bedroom over the truck bed. I think if you just put a crawl up bed over the bed of the pickup and kept the rest of the 5th wheel to a overall max height of 8' off the ground sort of like this:

Then get the A/C in the wall and off the roof and then even better taper the top down as it goes back.

[Frank Lee]

This is a successful RV aero project: Google Search Results - EcoModder.com