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Typical fuel efficiency for towing a Travel Trailer


sushidog
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What mileage I can expect towing a 10,000 lb. (loaded) TT with a 6.4l F-250 at slower speeds?

 

There is a similar thread in the 5er section. The consensus was that one could expect around 10 mpg pulling a 16,000 lb. 5er with a 6.7l F-350 dually.

 

Though I haven't yet purchased my TT, on a couple trips (mostly flat lands and rolling hills, but some mountains) towing a 1,700 lb. Aliner low-profile camper with 2 motorbikes, large loading ramp, generator, etc. (about 600lbs in the bed) it averaged 17-18 mpg (about 1mpg less than an empty, unfettered truck.) I plan on keeping my speed as low as practical (50-55 mph), traveling during low traffic times, minimizing starts and stops, slowing on the up-hills (without tying up traffic and getting stupid about it) and letting it accelerate naturally on down-hills when practical (to conserve momentum). I also plan on building an aerodynamic bed topper to divert the wind over the top and sides of the TT and adding a lightweight tail cone (like seen on some 18 wheelers these days) to also help reduce it's aerodynamic drag (reduce sway and improve stability overall). I know 6.4s have a reputation for poor fuel economy, but mine doesn't do so bad on the highway, though around town it does suck (14-15 mpg).

 

Here's a pic of my current set-up:

344pjc5.jpg

 

Is a 12 mpg avg. realistic towing a 10k TT, considering I'm anticipating a conservative driving style? Is anyone doing materially better than this with a similar rig? If so, what's your secret?

 

Thanks,

 

Chip

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The first few months we were on the road full time, we had a 27 foot conventional trailer that weighed about 8,000 pounds loaded. With our F-250 7.3 liter diesel we averaged about 12 mpg towing at 60-65. The same truck pulling our 14,000 pound 5th wheel gets about 2 mpg less towing at 55-60. I believe that the major reason is that the 5th wheel has more frontal area and thus more wind resistance, rather than the higher weight, Of course the additional weight is more of an issue with braking, one reason we have slowed down some.

 

Safe Travels...

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I agree with Roger that the major change will be wind drag from the frontal area of the travel trailer. Based upon my experience towing our tt I think that your anticipated 12 mpg is probably in the right general area. Our V-6 powered SUV got about that over this past summer's travels of roughly 5,000 miles. While we have a smaller tow vehicle we also tow a lighter weight RV. From all that I've read I doubt that your frontal deflector will make a very big difference, but the combination you are planning is one that I've never seen used so hesitate to guess. I see truckers beginning to use them so there must be some improvement. I'll be very interested to hear how this works for you.

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Thanks for the replies, guys!

 

Kirk, I agree that rear drag is more important than front aerodynamics, but while you're at it, why not do both? Like you say, the big trucks do, so there must be some savings to be gained by the combo. The biggest problem to front aerodynamics is the gap between the truck and the trailer. The more you shrink this gap the more effective it will be. My Coroplast wind deflector flaps mounted behind the topper will do just that, as will the addition of Air Tabs mounted on the wind deflectors to help keep the airflow laminar (inducing small stabilizing vortices) to keep the air flowing over and around the trailer rather than swirling into the gap in front of the trailer. Most deflectors I've seen only focus on airflow over the top and not on the sides, limiting their effectiveness. I intend to do both, and may even fill in the bottom of the trailer's A-frame tongue to block air flow from swirling up on the bottom (similar in function to an air-dam on a car). It will be an experiment for sure, but the worse that can happen is that these changes have little to no beneficial effect and I'm out the cost of a few sheets of plastic, some hinges and a little time. On paper it should work. Time will tell if it works in practice.

 

12 mpg it is then (for planning purposes only). If my aerodynamics eek out another 1-2 mpg then all the better, but I'm not counting on it. I think good defensive driving and hypermiling techniques, speed reduction and such will have more effect in fuel saving than aerodynamics ever could, but both combined will yield the best possible results.

 

sushidog, I am curious to know if the ice bear cycles you have in the back of your truck are clones of the Honda trail 70 and how do you like them?

 

I'm very happy with my purchase decision for these 2 little bikes. Here's a pic of the pair after I first got them.

 

28cir6a.jpg

 

I've had them for a little over a year now. Unfortunately I don't get to ride them much, but they have proven very reliable and have exceeded my expectations so far. I replaced the stock 19mm carbs and air cleaner with 22 mm carbs that are used on Honda TRX 125s. The stock, EPA complaint carbs had fixed jetting and were jetted too lean for sea level (where I live.) They start and run much better now and have more torque too.

 

jt0v36.jpg

2w2o9ig.jpg

 

My latest mod was to put a hand operated rear brake cable on them like the vintage Honda CT70s had to make them easier to unload from my truck. I also added a 2t bigger front sprocket to improve their top speed (from around 50 mph to 60 mph) this improved their fuel economy too (in the 95-100 mpg range) by lowering their operational rpm. I had to replace the mirrors too, with bar end mirrors that allow me to see around my fat body as the handlebars are too narrow for the stock mirrors, just like the original CT70's were.

 

1ebf2g.jpg

 

There are many upgrades on these 125cc clones, like a center stand and luggage rack that were missing on the original CT-70 Hondas. I love the 12v, electric start and electronic ignition system that eliminates maintaining mechanical ignition points. I like the hydraulic disk brake up front and the real hydraulic telescopic front suspension - my old CT70's had grabby drum brakes and simple bouncy springs up front. The rear shock springs are stiffer and hold quite a bit more weight too. I guess they are designed for adults (or fat American kids) ;). On the down side, like the old Japanese bikes from the 60's, neutral is very hard to find unless you are rolling. The chrome plating is a little thin too - again like the old 60s and 70s era Japanese motorcycles as the chrome tends to rust more easily than todays Japanese motorcycles, so I must keep the fenders, handlebars and such well waxed.

 

Their overall quality is much better than I expected, especially based upon what I paid them (only about $1,100 each shipped my door). So far nothing has broke or worn out (as I expected it would by now.) I'm impressed. I would definitely buy them again or recommend their purchase. They are lots of fun for the money spent. They are a great value and very economical transportation too - a lot cheaper than firing up the diesel. I bought them for around town use, mundane errands and cheap, fun sightseeing when we go FT. And if my truck breaks down a couple hundred miles from nowhere, I've got a couple spares to go for help, getting us out of an otherwise sticky situation. Think of them like a couple of 100 mpg fair weather toads. Registration was pretty cheap, and insurance costs only $99/year for the pair (through GEICO), so I'm saving there as well.

 

Chip

Edited by sushidog
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sushidog:

 

I pull a 9,000 lb trailer with a 3/4 ton diesel. I get 12 to 13 mpg. However that is in the Midwest and not going through the rocky mountains.

I have a friend who pulls a 8,000 lb trailer with a gas Suburban 2500. He gets 9 to 10 mpg pulling; again in the Midwest.

 

Hope this helps.

 

Dave

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Thanks Tumbleweed! All indications are I'm in the right ballpark (for planning purposes) then at 12mpg.

 

If a 1 ton dually pulling a 16k lb 5er (with a larger frontal area creating more wind resistance) typically manages around 10 mpg, I think I might actually do a tad better than 12 mpg with a lighter, easier rolling 3/4 ton pulling a 60% lighter, lower drag trailer. Time will tell. Let's say I average 15k miles/yr. over 20 years (assuming I live that long) for 300,000 total miles. If diesel prices average say $5/gallon over this time, that small 2 mpg savings from 10-12 mpg =$25,000 or $1,250/yr. If my driving habits and planned aerodynamics allow me to eek out a single MPG more, then the savings jumps to over $1,700/yr. or about 5% of our annual income - not an insignificant amount on our tight budget. That will buy dinner for two at an upscale sushi restaurant each and every month for life (or 2-3 nice sushi meals/mo. at home) - just to put things in perspective for this sushidog. ;)

 

Chip

Edited by sushidog
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  • 2 months later...

Silverado 1500 Z-71 4x4, 5.6 liter w/towing pkg from factory, pulling 1999 Jayco Qwest 30' avg about 11-12 in the mountains of eastern Tn. I do have a topper on the bed of the truck that provides a little aerodynamics to the package as well as a safe place for 250lbs of dogs, generator and tool box. TT is roughly 7500 lbs loaded. Once we get out of the mountains onto flatter terrain, I expect that fuel rate to go up 1-2 mpg hopefully.

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  • 4 weeks later...

Curb guy, I would expect a little better from a 7.3 which are known for their excellent fuel economy. A lot depends on terrain, but I suspect you might have a mechanical problem with your truck, such as an injector problem to get that low of mileage from a 7.3. What do you get when not towing? Most 7.3 owners that I know brag of getting 19-20 MPG when not towing.

 

Chip

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Is that typical for you, Kirk? Or is it atypical for your rig that you ascribe to an unusual situation, ie. did you fight a strong headwind, tow at high speed, etc.? Could it be that your V-6 SUV is underpowered for your trailer's frontal area? My low profile Aliner doesn't hardly affect my 6.4l diesel's MPG, but really makes my 4 cyl. Chevy Cobalt's mileage take a dump (from 32-34 mpg unfettered to 22-25 MPG towing) - because it is underpowered for the task at hand compared to my overpowered diesel truck. I'll bet if you towed it with one of those new Dodge 1/2 ton diesels your MPG would improve dramatically. I'll bet even towing your lightweight trailer with my truck you would still get around 14-15 MPG (as I currently get 17-18 MPG towing my Aliner).

 

Chip

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When matching a tow vehicle and trailer its important to look at the frontal area of the trailer. The bigger the area, the more effort it takes to pull it down the road.

With the Dodge diesel I had, I could pull a flatbed trailer up to 14-15000lbs with little drop in fuel mileage, 16-18mpg, but a tall load or a 5'th wheel RV weighing the same 14-15k that was have to move alot of air got 10-12mpg.

The tow rating of the vehicle is important to follow, but the vehicle and trailer that allowed that particular tow rating is also very important to consider.

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...What mileage I can expect towing a 10,000 lb. (loaded) TT with a 6.4l F-250 at slower speeds?...I plan on keeping my speed as low as practical (50-55 mph),...Is a 12 mpg avg. realistic towing a 10k TT, considering I'm anticipating a conservative driving style?

I tow a 9,850# travel trailer with a 2008 Chevy 2500 Duramax with the 6 speed Allison transmission. Average on long cross country trips is 11-12MPG. The Allison transmission will go into 6th gear even in tow haul mode. 60-62MPH gives the best fuel economy. At 50-55MPH the transmission is in 5th, engine RPMs are a little higher and fuel mileage is actually a little worse(10MPG) than at the higher speeds.

Edited by trailertraveler
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We pulled our 21' Streamline (think Airstream with two axles) down to SoCal and back with our 1994 Dodge 3/4 Ton Cummins 5-spd manual and got 16mpg. The truck does have a camper shell on it that sticks up just a little above the cab so the result is pretty aerodynamic. Trailer unloaded weight is listed at 3500 lbs.

 

With a 1993 Dodge Cummins 5-spd 1-ton dually we got 14mpg with a cab-over camper.

 

That same 1-ton pulling a 29' Alpenlite 5th wheel at 7500lbs (empty)l got 11 to 12 mpg. I bought a flow-through tailgate for that truck to see if it would help but I could see no difference in mpg.

 

All in the west with mountains everywhere you go.

 

I think that if you pull a travel trailer with a pickup truck you will get better mileage if you install a canopy on the pickup if only because it smooths the airflow and eliminates the eddy behind the cab.

 

WDR

Edited by wa_desert_rat
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Is that typical for you, Kirk? Or is it atypical for your rig that you ascribe to an unusual situation, ie. did you fight a strong headwind, tow at high speed, etc.? Could it be that your V-6 SUV is underpowered for your trailer's frontal area? My low profile Aliner doesn't hardly affect my 6.4l diesel's

As stated, that was for the total trip from Texas to Goshen, IN and then to Hot Springs, SD then to Cheyenne, WY and then back to Texas by way of Kansas, from April 29 through September 28, 2014. There was wind on occasion but nothing notable and clearly not for the entire summer. We did drive up some hills but we also came back down and we were never towing in major mountains. I tow at speeds of 55 to 65 mph depending upon conditions, probably averaging 60 mph over all when out on the highways.

 

There is a huge difference in towing a popup with very little frontal area and most of that below the tow vehicle's roof line and towing a travel trailer of full size, even if there is no difference in weight. We have some friends who tow a travel trailer that weighs about 1400# more than ours with the same vehicle except that theirs has a V-8 and they actually get about 4 mpg less than we do when not towing and they get about 2 mpg more than we do when towing. A larger engine is less effected by the added weight & wind drag than a smaller one, but you must buy the fuel to feed it even when you don't need the extra power.

 

Our tow vehicle is rated to tow up to 5000# and our trailer has a GVWR of 3600#. I have considered trading for a stronger tow vehicle and at some point we likely will do so, but you must remember that most tow vehicles spend no more then 20% of their time actually towing something and many are far less than that. Last year we drove our tow vehicle a total of 18,000 miles and of that somewhat less than 4000 miles was towing. It might be a good decision to get a stouter tow vehicle if it was used only to tow, but since we own only one vehicle it must be balanced between performance when towing and performance when not. I find our current tow vehicle to be a pretty reasonable choice for our use.

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Kirk -

 

I hope you are keeping your eye on your transmission fluid. This is the weakest area for failure after a long haul. Personally, I think that your choice of vehicles is questionable and I would strongly suggest that you entertain the idea of a pick-up truck.

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Hello folks,

 

Interesting topic for sure.

 

We have a 1997 Freightliner Century with a M11 Cummins set at 370HP / 1350 lb toq and we tow a 10,000 lb // 30 ft rec. hitch toyhauler.

 

We only have a few trips so far on the above combo but we have avg of 13.52 mpg so far.

 

Here is the rub...... according to Cummins almost NO driver can come even close to the fuel efficiency that is obtained when operating the truck under cruise control ( Cummins indicates that up to 30% loss of fuel efficiency occurs when the driver controls the engine).

 

Below is the Cummins link that is very good reading.

 

 

http://cumminsengines.com/uploads/docs/cummins_secrets_of_better_fuel_economy.pdf

 

Fuel Efficiency Rock-Solid Rules (Cummins Engine Co.)

 

Every 2% reduction in aerodynamic drag results in approximately 1% improvement in fuel economy.

 

Above 55 mph, each 1 mph increase in vehicle speed decreases fuel economy by 0.1 mpg

 

Worn tires provide better fuel economy than new tires, up to 7% better fuel economy.

 

Used lug drive tires can get up to 0.4 mpg better than new lug tires.

 

Ribbed tires on the drive axles provide 2–4% better fuel economy than lugged tires.

 

Every 10 psi that a truck’s tires are underinflated reduces fuel economy by 1%.

 

The break-in period for tires is between 35,000 and 50,000 miles.

 

Tires make biggest difference in mpg below around 50 mph; aerodynamics is the most important factor over around 50 mph.

 

The most efficient drivers get about 30% better fuel economy than the least efficient drivers.

 

Idle time is costly. Every hour of idle time in a long-haul operation can decrease fuel efficiency by 1%

 

Happy travels,

Mike, Carol & Dolly the Paint-Horse

 

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I hope you are keeping your eye on your transmission fluid. This is the weakest area for failure after a long haul. Personally, I think that your choice of vehicles is questionable and I would strongly suggest that you entertain the idea of a pick-up truck.

You are certainly entitled to your opinion. I learned many years ago to monitor all fluids in vehicles on a frequent basis and so continue to do this. I have also used an oil analysis service for both engine and transmission for most of my RVing experience. If it will make you feel better, the transmission was just serviced 3 days ago & early by service mileage charts, as a prep to our coming month of travel. Fluid was at normal level and only slightly discolored, as reported by the servicing dealer and Blackstone Labs just give the sample a positive analysis report. :)

 

Edit: I should have mentioned that the manual calls for transmission service every 36,000 miles. It has been serviced at 30K since I purchased it.

Edited by Kirk
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You are certainly entitled to your opinion. I learned many years ago to monitor all fluids in vehicles on a frequent basis and so continue to do this. I have also used an oil analysis service for both engine and transmission for most of my RVing experience. If it will make you feel better, the transmission was just serviced 3 days ago & early by service mileage charts, as a prep to our coming month of travel. Fluid was at normal level and only slightly discolored, as reported by the servicing dealer and Blackstone Labs just give the sample a positive analysis report. :)

Thank you for confirming my suspicion on my opinion.

 

My point being that just monitoring your fluids is not going to avoid a transmission break down. You have to be aware of what degree of heat that your transmission is producing. You won't know until your parked in a rest area and you notice fluid puddling under your vehicle.

 

To avoid this, now don't get excited, I recommend that you look into purchasing a transmission cooler and temperature guage. You can install both yourself for about $150.00. You'd be surprised on how much the temperture variation is when towing. It could save your transmission.

 

Pick-up trucks are meant to haul heavier loads and even then, getting back to my opinion, they should have this arrangement installed. They also have a larger capacity of fluid but they are not fail safe. I always carry a couple of extra quarts of fluid with me when towing. So, now, I'm feeling better. ;)

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I highly recommend a transmission cooler too, for anyone towing with an automatic. I have towed my 1,700lb Aliner with a 1,000lb tow rated 2.4l Chevy Cobalt (with an aftermarket tranny cooler) for over 40,000 miles with no problems. I have now retired it from towing since I purchased my truck, as my Cobalt now has 308,000 miles on the original engine and transmission. Of course by now my automatic transmission is about shot, but how many 4 cyl cars have over 300,000 miles on their transmission without even towing anything, much less 40,000 miles up and down mountains at 170% of the vehicle's tow rating? (Disclaimer: please don't try this at home kids.) I always change the fluids and filters ahead of schedule, using Mobile-1 in my engine (which still doesn't burn a drop of oil between changes.) I also had my ECM and TCM (engine and transmission computers) tow tuned for less slippage, lower heat, longer life, more power and better fuel economy. No it wasn't cheap, but worth every penny. I also had it dyno tuned for a cold air intake, header and full Corsa exhaust which helps keep the engine heat down and adds a little more in the power and mileage dept. too.

 

Chip

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Actually all vehicles have a transmission cooler installed from the factory but they are inefficient to safely disipate the heat from towing. Your main concern is to pay attention to the temperture of the transmission oil by installing a guage. The larger cooler is secondary but it gives you a better chance of not overheating when you see your temperature escallate. I might add that watching your water temperature is not going to be an indicator of what's going on with your transmission.

 

Avoid the puddle under your vehicle. Get a guage and if need be, a larger cooler. Why do you think they sell them?

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Unless you get a huge cooler you still need the temp gauge since the transmission can pump out a huge amount of heat. There are several options on where to put the sensor and you need to decide which is best for your needs.

 

I picked putting the sensor on the transmission output line that is sent to the cooler as that gave me a nearly instant notification of any rise in the heat output of the transmission. The downside is that you see the fluid temp bump up when you do hard shifts and such so at first you tend to worry about it. The good side is that if you see the temp start rising and you haven't done anything that you think should have caused the rise you have more advanced notice and more time to deal with the issue before the transmission has heat problems.

 

If you add the sensor to the transmission pan you'll be seeing the temp of the oil after it returns from the cooler. That gives you a nice low temp that is comforting to see but it masks any heat creating issue until the cooler is unable to deal with it giving you very little time to deal with the situation.

 

Sensors in both spots would be the ideal situation.

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