JustCruzzin

Diesel Pusher Mileage When Towing

56 posts in this topic

My wife and I just purchased our first DP (2009 Winnebago 37G) 12500mi, even though the towing

assembly was part of the purchase we really have not thought much about towing as we did not

tow with our 1998 Southwind V10. I was trying to estimate a good average speed to try to maximize

mileage when on the Freeways. I've driven tractor trailer up and down the East Coast hauling

heaving equipment but that just gives me experience with power. Any good guessimates would help.

Thanks Roy & Kathy

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Roy,

Please tell us what chassis/engine you have so we can better answer your question.

Also, at what speed do you go into 6th gear (assume Allison 6 speed)?

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Roy,

Please tell us what chassis/engine you have so we can better answer your question.

Also, at what speed do you go into 6th gear (assume Allison 6 speed)?

340-horsepower Cummins® ISB 6.7L turbo-charged diesel engine (brochure), but when
I looked up the engine at the Cummin's site it says its 350HP, confused?
We are having extra's done so not in possession right now, I can't remember
when test driven ... sorry

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Roy,

Generally most economic speed is just after shifting into 6th gear with transmission in economy mode. On most coaches that translates to 58-62 MPH. The exception is some coaches that are geared for speed where they don't shift into 6th gear until going "higher than any reasonable economic speed".

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I drive with the Allison in Economy Mode, red light on on the shift pad, unless I'm mountain driving.

Find the speed/RPM sweet spot. With my Cummins 325HP ISB, 1800-1900 rpm's equates to 62-64mph and thats where I drive.

I recently returned from a 4000 mile trip from the Houston area to Las Vegas towing a 4000# Jeep Wrangler. I had many miles of 20-35mph head winds and or crosswinds. One day I had a 15mph tailwind.

Mileage for the trip was 9.1mpg. I have gotten as high as 9.8 and I don't want to talk about the lowest...eek!

I don't notice much difference in mileage towing or not plus I wouldn't be without a toad at my stops.

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I set my cruise on 62 or thereabouts to get the best mileage on my coach.

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Towing (actually the weight of the toad) has little affect on MPG on flat ground where aerodynamic drag accounts for the majority of the HP demand.

However, weight (of coach and toad) becomes quite important on grades. So, if you live in FL, the affect on MPG will be quite different than if you live in CO.

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Look up the spec of your engine and drive just above max torque in high gear as that is usually where the sweet spot is.

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I have the odd unit it will not shift into 6th until it hits 65. I am then running about 1650 rpm. I am at the same rpm in 5th at about 56-57 mph.

Elkhartjim and Medico are you sure you are in 6th? When I first got this coach I always had the feeling the speedometer was a little slow. I installed a Banks IQ with a good GPS unit and calculated I was actually going 5.8% faster than the speedometer was showing. Also before I didn't know what gear I was in except by guessing. It now shows what gear I am in. I have checked the GPS with mile markers and it is right on the money. I haven't figured the milage I got on the trip last month (Perry) but last summer on 18 fill ups I averaged 9.966. I was towing my Civic on a tow dolly all the time.

Brett I wonder what kind of milage that gentleman got on his coach, the one who complained in the Suspension seminar about having a vibration problem when he was cruising 85+.

Bill

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I believe I am in 6th. I will check again in a couple of weeks when we head out. My GPS speed agrees exactly with my Silverleaf speed and my odometer speed. The mileage I get is taken directly from the Silverleaf computer. My large, heavy coach gets around 6.5 mg towing our Jeep Liberty on fairly level roads. It generally does not vary much with wind, but does vary with speed.

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I shift into 6th according to the shiftpad around 58mph. According to Mike Cody, the Camp Freightliner guru, thats the correct speed for my engine/transmission.

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Jim my older shift pad only shows the gear selected not what gear it is in. That is why I had to do an upgrade.

Bill

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The Old way to calculate ones speed, is to use the mile markers along the road. When the road has them.

Watch the second hand of your watch, as you pass one note the second hand location at the next marker read the time is seconds.

Then use time in seconds divided into 3600

55 seconds / into 3600= 65.4545 MPH----- 60 seconds / into 3600=60.0 MPH

Do the Speedometer and the Odometer match the mile post points and the speed calculated.

Handy should one loose that part of the instrument panel and the tachometer is still running.

I do use a GPS now days, but nice to have a backup.

Rich.

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I believe I am in 6th. I will check again in a couple of weeks when we head out. My GPS speed agrees exactly with my Silverleaf speed and my odometer speed. The mileage I get is taken directly from the Silverleaf computer. My large, heavy coach gets around 6.5 mg towing our Jeep Liberty on fairly level roads. It generally does not vary much with wind, but does vary with speed.

Medico you just made me happy I have a ISC 330 and went a little smaller. My mileage is up to 9 towing my Jeep Liberty but I'm sure you can beat me up those mountain grades. I won't feel so bad now when I get passed. :D

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Ray,

With no wind on straight level roads I can get up to 7.5 + depending on conditions, but my overall average mileage is 6.5, and that included driving Rte. 77 over the Blue Ridge mountains from Asheville, NC on the way south to Florida. I did not consider that too bad with this bad a _ _ engine. Yes it does pull the hills quite nicely.

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My coach has a 500HP Cummins and a 4000 Allison, the gross coach weight is 40,000lbs, just weighed. I tow a Jeep Commander, 5400 lbs. Just finished a 7200 mile trip, from Boston to Nashvile to Quartzite, Lake Havasu City, San Antonio, New Orleans, Destin FL, Perry GA, Myrtle Beach, and back up the east coast. Our average mpg was 6.5. I generally travel at 1500rpm's about 62 mph. I hope this helps.

Poppo

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Just an added info... if your Allison won't shift into 6th until a little bit higher speed than you want to travel, you can (once you are in 6th) gradually reduce your speed back down a few miles per hour and the Allison will stay in 6th.

Works for me.

Ron

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Ron, Yes I can do that but only down to 62-63. At the first slight overpass or grade it will down shift but won't up shift till I get the speed back up.

Bill

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I installed a 1998 ISB 275 with an Allison 3060 in my 93 32 ft. I tow a 1500 Silverado and coast to coast I average between 10 and 11 mpg. I drive at 58-62 mph, mine shifts into 6th gear at 54 mph.

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My current toad is a Jeep Wrangler, prior to January it was a Chevy Colorado with camper top...have a 425 Cummins, Allison 3000, 45' 2010 AMC Tradition and average 6.4 mpg at 65mph....I let the Allison alone, start in 6 economy and only downshift on grades to maintain RPM. Perhaps that's wrong, done it on 3 DP's and am happy!

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Cummins DP 400, Allison 6 speed, 2012 Winnebago Journey 42E. About 7 mph is all we hope for. We're towing a 2012 Cadillac SRX. We didn't buy this beast for fuel economy! We didn't do any better when we had a 1999 Dodge RAM 2500 pulling a 28' Cardinal. We don't whine about fuel economy. I like to say, "If you can't afford the fuel, you should've have spent that kind of money on the vehicle!".

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