My RV a true mileage efficiency challenge
 

Greetings, I’m in my mid-60’s and a life-long shade-tree mechanic doing 95% of my own car, RV, boat, motorcycle, and appliance repair. I attempt to help the environment by not needlessly replacing things when they fail.

I recently purchased a 33’ 1994 460 Ford V8 powered Holiday Rambler motorhome to both live in full time and use as a home-base while I travel this beautiful country towing my 2005 4cyl Dodge Caravan to use as an exploration/overnite camping vehicle. I’ll be driving the MH mainly on the interstates stopping for weeks and even months at a time in various national and state parks. My travels will initially be throughout the west. I expect the first “loop” will take me from San Marcos TX west to Tucson AZ and then LA followed by north Yosemite and on to Port Angeles WA and finally east through WA, ID, MT and SD. After a 2 month stopover in SD I’ll be heading south to TX, NM or AZ for the winter. Overall about 5,000 miles.

The specific information I’m looking for is how to squeeze more mpg out of my MH. I haven’t had a chance to drive it much but from researching the RV websites I figure to get about 7mpg on the interstate while towing my Caravan.

As far as background regarding the MH, it has a FI 460 Ford V8, running through a Ford E4OD 4-speed automatic transmission and a 5.13 rear axle. The unloaded vehicle weight is 13,898lbs with a total maximum gross vehicle weight of 17,000lbs. The 2005 Dodge Caravan I’ll be towing, with a tow dolly, weighs about 5,000lbs including the dolly. The MH has 58,000 miles but supposedly the engine and trans were replaced 20,000 miles ago (apparently, the previous owner was not into maintenance of any kind).

Sorry, the board won't let me post a photo, I only wanted to post so that people could see the aerodynamics of my MH, oh well...


Any suggestions for cruising speeds. I realize that lower speeds will increase mileage but at the same time I don’t want to have to drive so slow as to antagonize other drivers (angry people do stupid unfortunate things). I know that higher tire pressures can help but there again, with the weight I’ll be carrying I don’t want to compromise safety for an extra mpg. I read through some old threads on this board where someone put plastic sheeting under their MH to decrease wind resistance, a great idea for the future, but I’m a little lite on $$$ at this time. In addition, the MH has a huge grill which I’d rather not sheet over since over-heating can be a problem on these large gasoline powered RV’s.

I’m pretty happy with my Caravan. With no AC running, it gets around 25-27mpg highway, but only about 20mpg city. I usually keep it between 65 and 70 highway, however I probably do drive a little too aggressively around town for optimum mileage. As soon as I can free up some cash I’ll be picking up a used Kawasaki KLR 250 so that I can explore with a vehicle that gets even better mileage, plus motorcycles are fun.

Steve

Hi, and welcome. I reckon a moderator will be along to welcome you much more officially soon enough.

You have an uphill climb with your Rambler but it isn't a lost cause by any means.

I know you state very clearly you're happy with the Caravan, and I was happy with mine too until it puked up its own brain (long story), but it's kind of heavy. Would you be willing to switch to a smaller/lighter dinghy, perhaps something with a manual transmission? That could eliminate the need for a tow dolly.

I thought about recommending a largish scooter or a motorcycle as your exclusive dinghy, but if it rains that just stinks. Bikes are no fun in the rain. They just aren't.

Check this out: http://ecomodder.com/forum/showthrea...d-e-18151.html Forum member Orbywan has a Class C RV, a bit smaller than yours and with a turbodiesel, but he's made some serious aero mods to it and just looking quickly, I see a ~15% improvement. You could extend your aero tail, if you're inclined to make one, to shroud the nose of your dinghy and the dinghy's presence could have the effect of extending your tail even further. Some testing would be required to confirm that.

That'd be pretty cool though, if with the addition of a few aero features you could effectively negate the load of the dinghy, maybe even make further steps toward the positive. An RV that gets better mileage towing than bobtail, funny. Like I said, testing required.

I didn't even know there were 4-pot Caravans back there for that model-year, the only ones I knew were turbodiesel available only in export markets.

Regarding the motorhome, a Diesel swap would sound as a good improvement mileage-wise, also increasing the ability to run on alternative fuels which might eventually be a great benefit on longer trips. Another issue is that they don't have too much room for improvements, altough there is always some way to get a considerable weight reduction in case of interior refurbishments.

To anyone recommending diesel power, I’d love to have diesel power, for many reasons besides increased fuel mileage. However, reality rears its ugly head in the form of $$$$ or lack of $$$$. If I were to go to diesel power it would be far simpler just to buy a used diesel powered RV. Probably won’t happen anytime soon.

The 4 cylinder Caravan is okay, however what I'm really concerned about is the 7mpg RV. As far as the Caravan's concerned, though it’s rated at 150hp it doesn’t have the torque of a V6 with equivalent hp. I had a 1998 Caravan with a 150 hp V6 and it actually got slightly better gas mileage than this 4 cylinder does. I really liked that V6 Caravan, but with 286K on the odometer, a bad AT and a leaking condenser on the AC it was time to sell it. It still ran great, if it were just the AT I probably would’ve fixed it, but with the bad AC and living in Houston at the time, it was time to say byebye.

I’ve thought of selling the Caravan but it’s so nice to live in while exploring the countryside, I hate to give that up. I wish it had a standard transmission, but I doubt if they were even made for the car.

Steve

It might not be so hard to find a suitable transmission from Mitsubishi or Hyundai.

I had a '91 Caravan with almost no bells or whistles. My wife and I immediately added seat covers (homebrew from southwestern style throw blankets) and completely covered the interior carpets with seamless denim from front to back. When it came time to sell the car, we removed these interior treatments and the van looked like it had never been ridden in.

The exterior, however, was graced - temporarily - with factory Dodge paint that didn't adhere to anything but the wind with any kind of tenacity. Giant, hand-sized flakes would peel off. We painted the vehicle with strange designs. My niece painted a huge bare-breasted mermaid on the roof. We asked her if the mermaid wouldn't distract the truckers too much.

"They're grownups," she said. "They can handle it."

Turned out the kids in the school buses were a bit more impressionable. Oops!

Anyway. Yeah, for exploring the Caravan is tough to beat. With a custom tent to go over the liftgate, you can use it as a bare-bones RV in its own right. We covered a lot of miles in ours.

I have a 32 foot RV with a V10 Ford engine in it and get a similar mileage 8 or so. You can use many of the hypermiling techniques with the RV to help. Put it in neutral on slight downgrades where you won't gain too much speed. Pulse and Glide will help you too. On big downgrades you will still need to put it in gear to keep the speed down. Keep your speed down. 55 is plenty. I am in California and am limited to that while towing. I don't see any mileage change whether I am towing a vehicle or not. However, bringing the tow vehicle along saves gas a lot since you drive the RV only between campsites and you drive the more efficient tow vehicle to see the sights.

Also, get a mileage computer, ScanGauge or Ultragauge. That will help you with your technique.


Have fun!

I too had a 1991 Caravan, mine too lost its paint. I bought it used and owned it from 1993 until 2000 and by the time I sold it the van had 251K on it. It was not nearly as good as the 1998 and 2005 Caravans I’ve owned, I was constantly having to do mechanical repairs to it, but I also took my two kids on a lot of outdoor adventures in the thing. My late wife’s idea of camping was staying at a Super 8. However, my adventures with the kids gave her much needed time to herself. I took out the rear seats and put in a 1’ high by 4’X6’ floored area in the back (I’m doing the same with my current Caravan). We’d stow our gear underneath and the kids would play in the back while we traveled (no seat belts back there, but somehow we survived). At night we’d usually sleep in a tent, but if the weather was real bad we’d crowd into the Caravan and sleep in it. As crappy as it was, that 1991 Caravan made great memories my adult kids still talk about. Like all my Caravans it got around 26mpg highway.
Steve

^^
Yup, that's what we did too, or nearly. We built a platform to rest on the folded-down wayback, and that doubled as a bed (with an anti-tumble guardrail) for our kids, about 2 and 4 years old at the time.

The wife and I slept in sleeping bags on the ground under the tent, the floor of which wasn't attached on our first trip. Raccoons came under the edges, and then when we got home we attached the floor to the walls.

Ah, good times.

The impression I am getting is that you want mods that will pay for themselves pretty quickly- so either super cheap mods, or super effective.

Some things that are dirt cheap, easy, and should make a difference...
-Deleting things that aren't needed
--take off a mirror if you don't need it, antennas, roof racks
-Smooth wheel covers (election signs)
-Rear arch covers (election signs)
-Dropping unneeded weight (Do you have things you don't need?)
--For example, if you had a granite countertop, is it worth the extra weight verse a basic plastic?
-Grille block (or partial- either way, easy to remove)
-Partial underbody
-streamline your vehicle into the trailer/caravan (would be more costly)
-Test pulling the caravan flat vs on the trailer. Better or worse?
-Warm Air Intake
-DEFINITELY an air dam
-start switching fluids to synthetic

One fantasy I have is an MP5 (or MPV) in a standard, setup to road trip in. You'd have a standard, could pull flat, and they are pretty cheap relative to other vans in its class. Another alternative is a estate. On past road trips, three of us have slept in a coupe (2002 Monte Carlo) over several nights. If you want more comfort, an estate would work great. Not hard to find a standard, better aero, would meet the needs you have shown so far. What comes to mind is the Subaru Outback/Legacy estate- which can be found pretty cheap (as low as 1,600 USD).

Just some ideas.

This will help a lot however, being that it's a 94, it won't be obdii, so ultra and scan gauge are ruled out (Both require OBD2 and that was mandated in 96 for passenger vehicles) Your only option (and it is a good one) is an MPGuino if you have multi point Fuel injection.

Thanks for the ideas, I'll be looking into implementing many of them.
Steve

I saw the MPGuino, fortunately my son's a computer tech, actually a network engineer. When I see him over Thanksgiving I'll talk to him about helping me to install an MPGuino system. Heck, I taught him how to do brake jobs, clutch jobs, and swap engines, I figure he can help me with this.
Steve
BTW are you a rock climber? I tried it about 15 years ago as part of my middle-age crazy period. After two years of climbing I decided that even if I was 30 years younger I'd still be lousy at it.

You could always disable an axle- and what would be bad about the AWD? I think even with it, you'll see better fuel economy- and have the opportunity for EOC. I'm sure you know your needs, FF is better for you than AWD, I was thinking your time spent traveling for short(er) trips could go to more aggressive places w/ AWD, or at least, not be as limited as with the Caravan.

Trust me, in an RV YOU NEED YOUR MIRRORS.

Engine swaps :rolleyes: The guy wants to see the country, not a chassis from underneath.

No the handle comes from flying, each wing has specific airspeeds that results in the best rate or angle of climb.

The Guino is pretty easy to install, 4 wires. one to an always hot 12v source, one to ground, one to the fuel injector signal wire, and one to the vehicle speed sensor wire. If you search the forum you may find someone who has installed on on a similar era ford truck or van and that may put you in the right direction.

Geo,

I saw your question re: a partial belly pan. I think any amount of belly pan is going to help. There's so much acreage under those things and it's generally just greeblies and bits out in the wind. You can cover up most of it, I think, with impunity. Be careful around the driveshaft and exhaust lines, obviously.

I haven't done any pan work on my truck, but when I do I intend to start at the rear and work my way forward. A natural stopping place will be directly abaft the rear axle, then pick things up again ahead of it, etc. If I can do any kind of fairing work to smooth the airflow around the axle, I'll do that. But I bet if you take a peek at your underside, it probably looks approximately as smooth as the Grand Canyon.

+1 to what Frank said about mirrors - I drive an Isuzu NPR at work sometimes and that thing is only half the length of your rig. If I didn't have mirrors on it, I just wouldn't drive it. But there are lots of kits out there for adding backup mirrors to just about anything, can you bolster your existing mirrors with a few of those? Maybe you could improve the rearward view to minimize your mirror area and still have a good picture around you.

Photos attached
 

http://i.imgur.com/XUflpEP.jpg
Here is a picture of my RV, as can be seen it actually does have some streamlining, at least compared to today’s RV’s. In the future I’ll probably be removing the roll-down awning.
http://i.imgur.com/wLs8CI0.jpg
Here is the grill I mentioned earlier. Because these large RV’s have such a problem with excessive engine compartment heat I’m reluctant to cover the grill at all, though I may try in the cooler months.
Steve

You could make an adjustable grille block.

This may sound crazy, but what if you attached a grille shield to that metal bar, and it blocked air from going into the grille, but did not seal it?

I don't know if that would allow air to still circulate while reducing air going in- not as hot, and not as much drag. I don't imagine it would create more frontal area or increase drag- but I'm sure a more educated individual can chime in on that idea.

If you are comfortable with heavy fabrication, an aero trailer for your dingy would yield a big gain. Paying another to do it would wipe out any potential savings.
It gets the dingy clear off the ground and takes all the guesswork about flat towing and lubrication of transmissions, transfer cases. It also provides storage for other things.
I have some ideas for the fairing that goes between the trailer and RV, to minimize the gap and resulting turbulent flow in crosswinds.
One downside is finding a place to stow it when you get where you are going. Some places have trailer storage, others not.