Towing MPG lower than anticipated

[jmpidgeo]

Hi all, i have a 1995 chevy k2500 4x4 6.5TD, HD package (L65 code IIRC) with 3.73 gears and 267/75/R16 tires and all stock stuff (no upgraded exhaust, etc). I recently towed my Jeep up to school. here is a pic of the towing setup:

http://img.photobucket.com/albums/v723/xj_man_646/truckandtrailer.jpg

The trailer weighs in at 3000 lbs empty, plus the Jeep. I am guessing a 7,000 lb load.

Now, i have heard great things about these trucks for towing...commonly not hearing of MPG's less than 13-14 while towing, but over 350 miles, at about 60 mph average i got 11.5 MPG, which sort of dissapointed me since I will more than likely be using this truck to make the 3200 mile round trip to moab this summer, because I think the old man is selling the 2003 dodge 3500 dually CTD that he has.

any way you know that i can increase my mileage? any help would be great. Thanks in advance, guys.

[Robyn]

Thats a lot of drag and depending on the road surface, hills ect you are most likely not going to do a lot better. The total gross wt is about 14K I would guess. It takes fuel to move stuff. The jeep sitting back where it does really messes with the air flow and is not helping the issue.
I dont see any real help for the problem, at least not one that is very cost effective.
Two years ago I went to LA to get a Bronco II and I hauled it back to Oregon on a car hauler behind a 95 Burb with a 454 in it. No problem towing up over the grape vine and the Siera's but it only got about 10 MPG It had 4.10 gears in it.
We were running about 70 on the flats and when the old girl would hack it 55-60 in the mts.
The vine worked it really hard, I was down to 50 at the slowest but had the pedal on the floor for much of the steapest part.

Sorry I cant be more positive. :0)
Robyn

[jmpidgeo]

darn...not exactly the answer i was lookin for, but oh well.

anyone else have any input?

[rjwest]

DRAG is a killer

Keep TCC locked , keep it below 60 , and stay off
the Cruise control ( easy on the throttle on hills, let the MPH
fall off a little on the small hills ( overpasses ).

May squeeze another MPG.

But: your still doin better than a gasser..!!!

Or buy a cummins

[jmpidgeo]

DRAG is a killer

Keep TCC locked , keep it below 60 , and stay off
the Cruise control ( easy on the throttle on hills, let the MPH
fall off a little on the small hills ( overpasses ).

May squeeze another MPG.

But: your still doin better than a gasser..!!!

Or buy a cummins

I wanna buy the old man's cummins, but being I am a college kid, the price of this diesel was a bit better :D

[Mark Rinker]

From an optimal load carrying point of view, the Jeep appears too far forward on your trailer in the picture. Try backing it up 12" or so to get the trailer to carry more of the weight, less on the trailer tongue. Keep going back until you get negative tongue weight, then go ahead 6". (Be careful - don't set it too far back on my advise, and discover it on a downhill grade when the trailer starts to whip...!)

From an aerodynamic point of view, it would appear that your Jeep should be loaded facing forwards, like it is in the picture. However, without a wind tunnel, who knows for sure. I'd try it next time loaded backwards, with your wheels in roughly the same locations as in the picture. (This should also transfer some load from the truck rear wheels to the trailer, spread out over 4 tires instead of 2 drive tires, since your Jeep is probably nose-heavy, tail light.)

What size of rubber on the trailer? Run them at MAX rated inflation, investigate taller, skinnier trailer tires to lessen rolling resistance. Same goes for truck tires - MAX inflation when running heavy. Check trailer brakes, trucks rear drums, they are notorius for hanging up slightly and wasting fuel.

Your mileage isn't that bad, from my 6.5 experiences. Be glad you don't have 4.10s like alot of us. Open up the intake and exhaust (at least 3.5" mandrel bent pipe), lose the cat, slow down you could find 12's or maybe 13s.

[moondoggie]

Good Day!

All of Mark's advice, as usual, is excellent, with one exception: "From an optimal load carrying point of view, the Jeep appears too far forward on your trailer in the picture. Try backing it up 12" or so to get the trailer to carry more of the weight, less on the trailer tongue. Keep going back until you get negative tongue weight, then go ahead 6". (Be careful - don't set it too far back on my advise, and discover it on a downhill grade when the trailer starts to whip...!)" You should have 10-12% of your trailer's weight on the tongue; the Jeep (or whatever) needs to move to wherever it takes to accomplish this.

BTW, 11.5 mpg on one tank only means you got 11.5 mpg on that tank under those conditions. That may be the best or worst or middle of what your towing mpg winds up being, there's no way to know until you've actually done it. My pickup's best mpg was on a couple trips to MI; my worst was on a couple trips to NC. I had lots of headwinds & cross-headwinds on the NC trips, so my trip averages were barely 20 mpg; apparantly conditions were perfect on my MI trips, as both trips averaged ~ 22.8 mpg. That's a 15% difference due to the conditions at the time - the truck was empty for all trips.

When I towed our US Cargo SM625TA2 trailer (looks like the US Cargo SM727TA2 (http://www.uscargo.com/uscargo/products/enclosed/snowmate.asp) [Click in colored text] except it's 25' long instead of 27') when my daughter raced her junior dragster, I got 12 - 16 mpg, which is a pretty wide range.

Good Luck & Blessings!

Blessings!

[Mark Rinker]

Yeah....what Moondoggie said.

After writing that, I realized it wasn't very accurate advice. After loading so many wheeled vehicles on dual axle trailers, I simply 'feel' the sweetspot, but watch the towing vehicle carefully as I move the weight forward and aft.

10-15% is correct, my only question is how you can accurately measure that, without a trip to the CAT scale nearest you. (And even then, most won't work with you to take multiple weights while you move things around, they are simply too busy behind the fuel desk to care...)

[jmpidgeo]

I will try it backwards, but I just moved the Jeep forward on the trailer until the rear end squatted 2-3 inches, which put the gap from the tire to fender the same for the front and rear. It towed absolutely beautifully, I just wish I could have gotten better MPG

[jmpidgeo]

Mark, how do you like the Heath Max e Tork chip? I am thinkin about getting it for mine.

[TAG]

Are you sure about the weight of the trailer? That thing doesnt look anywhere near 3000 empty. 11.5 seems low from personal experience. You need to post empty numbers for comparison, maybe not getting full boost or restricted exhaust.

[sturgeon-phish]

Adjusting driving habits is the quickest and cheapest modification to improve mileage, especially with a trailer. Easy acceleration anticipating stops and coasting, slow to speed limit all adds greatly to fuel savings. Opening the exhaust and intake will give you big gains. Synthetic fluids helps also.
Jim

[jmpidgeo]

I looked up the specs on the trailer online. Its a utility trailer for Fabco, used for hauling skidders and small excavators...weighs between 2900 and 3100 depending on the configuration

Driving habits:
below speed limit (65) in interstate (averaged about 62 i'd say)
58-60 on 55 zones

I'd say i got somewhere between 12-13.5 with the trailer empty. it was definitely noticeable back there even when empty. i did the 350 mile trip wtih the jeep and went home without it, just the trailer.

[Mark Rinker]

I like the Heath chip. It won't save you fuel, but you will enjoy towing more with the extra power. Should do exhaust at least before adding more fuel, you'll want the ability to dial up some extra boost, too. http://www.thedieselpageforums.com/tdpforum/showthread.php?t=25351

FPG (Fun Per Gallon) also must be factored in... :)

[DennisG01]

Have you re-configured your VSSB after your tire change (245's are stock size)? If not, your mileage on your odometer is reading a little low. Not a lot, but does make a little difference.

[JohnC]

Food for thought - what mileage would the Jeep get at the same speed by itself?

(My point is that with those high profile tires and that dirty undercarriage, it's a drag queen! ;) )

[jmpidgeo]

Food for thought - what mileage would the Jeep get at the same speed by itself?

(My point is that with those high profile tires and that dirty undercarriage, it's a drag queen! ;) )

actually, at 60 it got 18 MPG.

[jmpidgeo]

Have you re-configured your VSSB after your tire change (245's are stock size)? If not, your mileage on your odometer is reading a little low. Not a lot, but does make a little difference.

I have not, but I think the previous owner(s) did because it seems to be near exact

[DennisG01]

Going from 245's to 265's isn't that big of a jump so the difference isn't going to night and day. The difference might only be .5 to 1 mpg. Not that big of a deal, but it's still something! You could check your speed with a GPS or use a measured mile on the highway to be sure. Also, as stated above, do some more trips before you get too concerned. There's too many variables in only one trip.

[jmpidgeo]

Alright guys, thanks for the info.

[Scooby]

Heath's computer is great, but you really need to upgrade your exhaust, and get the Turbomaster control at the same time. You should also have boost and EGT gauges to keep from meltdown. Check out the DRAG in my picture. I havent towed far enough to give you mileage, and I am in Florida, so hills arent an issue.