Diesel fuel mileage

[Browning42]

Hi, I'm looking at upgrading to a Ram 3500 SRW with the 6.7 and aisin 6speed auto. Right now I'm pulling a 28' Jayco TT, what kind of fuel economy can I expect?

 

[Jere and Laur]

After the break in period you should get 11-15mpg towing 10,000lbs, could be more or less depending on your driving.  I get 10mpg towing 17k.

 

[brujomar]

I get 10.2 without fail whenever I pull. .....I can baby it, kick in the turbo when needed etc...up hill, down hill, flat land.......at the end of the day it will invariably end up at 10.2......That's pulling a 16k fiver. 2011 Dodge 3500 , srw, megacab
14-16 city/highway when not pulling.

 

[Browning42]

Thanks for the info, I know a 3500 is slight overkill for a 7000lb trailer, I'm buying it for a future upgrade to a 11,000-12,000lb 5er.

 

[Browning42]

On a side note, what size(gallons) is the tank on a Ram 3500?

 

[vinceherman]

I know a 3500 is slight overkill

Too much power is almost enough! 

 

[Frizlefrak]

My 2014 Ram 2500 crew cab Cummins got 14.2 average pulling my 7800 lbs travel trailer last summer on a 900 mile round trip.  And yes, too much truck is just right.

 

[Jimmy & Joan]

My 2011 3500 has a 36 gallon tank.

 

[Browning42]

Thanks everyone for the info

 

[John From Detroit]

Thanks for the info, I know a 3500 is slight overkill for a 7000lb trailer, I'm buying it for a future upgrade to a 11,000-12,000lb 5er.

There are basically three choices when it comes to Tow Vehicles:

OVERKILL:  Nothing wrong with overkill, does a great job of towing,

Just the right size: Nearly impossible to obtain, the other two options are way easier to find.

Too Small: Many tow this way, and they scare me.. Cause that little pickup can NOT properly control that big trailer.

So you did it right.

 

[Frizlefrak]

There are basically three choices when it comes to Tow Vehicles:

OVERKILL:  Nothing wrong with overkill, does a great job of towing,

Just the right size: Nearly impossible to obtain, the other two options are way easier to find.

Too Small: Many tow this way, and they scare me.. Cause that little pickup can NOT properly control that big trailer.

So you did it right.

Sure it can....most of the time.  It's the times that it can't that scare the bejeepers out of me.  I err on the side of overkill.  My truck literally manhandles my trailer.

 

[drewtk]

Towing at 65 mph, I would estimate around 10-11 mpg.  I'd be *very* surprised if you got 15 mpg as suggested above.

 

[Frizlefrak]

Towing at 65 mph, I would estimate around 10-11 mpg.  I'd be *very* surprised if you got 15 mpg as suggested above.

There would be the problem.  Drop to 55 and you'll gain 2 mpg.  Wind resistance is what kills mpg towing, much more so than weight.  My last big trip was 14.2, and most of that was towing the mountains of NM.

BTW....if you have ST tires on your trailer, they're rated for 65 MPH MAXIMUM. 

 

[drewtk]

There would be the problem.  Drop to 55 and you'll gain 2 mpg.  Wind resistance is what kills mpg towing, much more so than weight.  My last big trip was 14.2, and most of that was towing the mountains of NM.

BTW....if you have ST tires on your trailer, they're rated for 65 MPH MAXIMUM.

Yup, that's why I noted my towing speed up front.  But to get 15 mpg you'd have to go unreasonably slow on the freeway, if it's even possible at any speed for the OP's size TT. 

I'm aware of the ST speed issue, which is why I switched to LT's

 

[Frizlefrak]

Yup, that's why I noted my towing speed up front.  But to get 15 mpg you'd have to go unreasonably slow on the freeway, if it's even possible at any speed for the OP's size TT. 

I'm aware of the ST speed issue, which is why I switched to LT's

My TT is 3' longer than the OP's.  I don't get 15, but I get north of 14 on average.  No problems on the freeway...just stay in the right lane.  The Cummins is just loping along and barely knows the trailer is there.  BTW....unloaded the truck got 21.2 on a 200 mile round trip last weekend.  I am more than pleased with it.

Good move on the LT tires....I'm considering that when it's time to change these, though still have no desire to tow any faster.  If something bad happens, the less time to get the rig stopped, the better.

 

[Idahocountryboy]

I pulled the rig set up in my signature with a 2000 2500 Cummins 6 speed manual which does make a slight difference. I got 10 -12 MPG, 400-390 Miles to the 40 gal tank (safe fill up, did not stretch it to the bare empty, avg. gallons per fill up was 35 gals) Empty I get about 560 miles to the 35 gal fill up (city & Hwy driving). The trip took me from San Angelo Tx, to the Grand Canyon, through Utah, Montana to N. Idaho. The way back I went to Yellowstone, through Wyoming, South Dakota, Nebraska, Kansas, Oklahoma, back to Texas. I kept very close records of fuel and other things for another forum.

Trip map: https://www.google.com/maps/dir/San+Angelo,+TX/Grand+Canyon+National+Park,+Arizona/Sandpoint,+ID/Yellowstone+National+Park,+WY/Gillette,+WY/San+Angelo,+TX/@35.0303251,-112.4002943,5z/data=!4m48!4m47!1m5!1m1!1s0x8657e583a53b7191:0x827e3d0b3754c742!2m2!1d-100.4370375!2d31.4637723!1m5!1m1!1s0x873312ae759b4d15:0x1f38a9bec9912029!2m2!1d-112.112997!2d36.106965!1m5!1m1!1s0x5363d1332dff4541:0xab5434ebcfe9717b!2m2!1d-116.553465!2d48.276577!1m5!1m1!1s0x5351e55555555555:0xaca8f930348fe1bb!2m2!1d-110.588455!2d44.427963!1m15!1m1!1s0x533494232dacbc1f:0xc7202c31f4c9984b!2m2!1d-105.5022205!2d44.2910915!3m4!1m2!1d-103.5587894!2d43.6157286!3s0x8762d53b3801d4b9:0x64bb72e20ed52727!3m4!1m2!1d-100.8646875!2d36.6059551!3s0x8707ef14e10ffe97:0x2f18709b9e622209!1m5!1m1!1s0x8657e583a53b7191:0x827e3d0b3754c742!2m2!1d-100.4370375!2d31.4637723!3e0

Some Specs that will matter: My specs
Gross weight (truck & 5'er) = 26,200 lbs
Gears: 3.55
Edge Comp box +120 HP
avg speed = 60-65 mph @ 2,000 RPMS (this is the biggy more than speed) (It didn't matter if I went 55 mph/tank or 65-70 mph/tank... I still got 10 mpg!  ???)
My 5'er was a lot taller than my tuck and being an '03, it was flat at the nose and it was like pulling a parachute!!! This will make a big difference i believe.

If you go over the 2K RPM mark, that is when a Cummins falls off the face of the earth in MPG. It's happy zone for pulling is 1,800 - 2,200 RPM... how fast that is depends on the gears (lower gears {4.10's} that RPM zone is about 55 mph, 3.55's its about 60-62 mph, and every truck is slight different. Fords and Chevy's have V8 motors and are higher reving, so it may be 2,400 RPM mark that your MPG drop... you have to find that for your truck, this is more strictly Cummins Trucks.) Gears are everything. Low gears such as 4.10's are great for hauling heavy, but your not going to go fast 65+ mph if you want more than 10 mpg. 3.55 are higher, a slightly harder time getting going with a heavy load, but do-able (better have a HD clutch). But you can go 65 mph and get 10+mpg. 3.73's are the "Happy Zone" in my book, 'best' of both  mpg and mph.

This trip as you can tell is long, about a 4,200 mile trip. Crossed the Continental divide 7x, and hit some big plains. So that gives you a little bit of an idea of the terrain. Hope this helps.

 

[Frizlefrak]

All of the new 2500's (2014 and up) with the Cummins and auto are 3.42 gears.  At 55 mph it's turning over at about 1600 rpm in tow/haul, which locks out 6th gear.

 

[Idahocountryboy]

Unfortunately so.. 

Thus, we refer back to the to the post about there IS NO SUCH THING AS OVER KILL!!! Get a 3500, get options and be done with it.  ;D

 

[Old Blevins]

At 55 mph we average about 11 mpg.  We can do a little better if we're towing through very level terrain, but where we go it's usually all up and down.  And most of that seems to be up.  :

 

[Frizlefrak]

Unfortunately so.. 

Not really....the ratio is optimized for what it does.  It's turning over 1450 RPM @65 MPH.  Power isn't an issue with a new Cummins....drop the hammer, it downshifts and pulls like fighter jet.  800 ft lbs of torque is a beautiful thing.  It doesn't need a lower final drive ratio.