After driving 3100 miles within the last 10 days, 2400 miles of it while pulling approx 8000 lbs, I'am absolutely discusted at the gas mileage I'm getting while pulling a load. The last 700 was a box trailer that I used to separate my stuff from the soon to be x wife's stuff at out house in North Carolina. This trailer couldnt weigh more than 3500 lbs at the most. I was getting 250 miles to the tank, and that was stretching it. I was discusted. Does areodynamics have that much affect on gas mileage? I do run Hypertech on level 3 and never mess with it. Driving down to NC, I made it from Syracuse to Richmond on 1 tank of fuel. It was 494 miles from fill up before I left. Then I made it to Fayetteville with just under half a tank remaining. I was surprized. Someone please tell me that They're not all like this. Is it Hypertech? I'm up to 31000 miles with no problems so far.

Does areodynamics have that much affect on gas mileage?

Yes it does, I've noticed towing the FEMA trailers that the flat fronted ones reduce my MPG's by at least 2mpg.

I've also had good/bad batches of fuel that increase/decrease mpg with all else equal. But also a flat front trailer like that is like pulling a parachute down the freeway. My cow trailer is like a big windsock and on far trips just forget about gas mileage pulling something like that.
my .02

I figured weight would have more effect on MPG.

You left your to be X wife here in NC and you moved to NYU and you got better gas milege on the way up there or on the way back down?? Does the weather play a rol or is it just the weight and what mods you have??? Don't worry I got GROSS-:tgas mileage too when i pulled my trailor and jeep up to the mountains. It was better as I lightned the load and went downhill. Take care and good luck.

BIGNASTY

I left my wife in NC....Well, she's leaving me...So I'm getting on with my life. I got great gad mileage driving down, empty, and horrible coming back up, loaded.

How fast were you running on average? Speed makes quite a difference when you are punching a big hole through the air.

If the speed limit was 65, I'd set the cruise at 72. If it was 70, I'd set it at 78.

Fan running a lot?

I tow a 12' tall 9.5K# 5er and see between 10-12mpg at 65mph. Anything over 2K rpm/65mph seems to dramatically drop mileage. Stop/go also takes a bit away.

I have never heard the fan kick on, ever, not once in 31,000 miles and 27000 in south west Louisiana.

Towing my gooseneck horse trailer at 75mph I get 13.5 to 13.7 mpg. With my enclosed racecar trailer (big box) at the same speed I get 3 mpg less. Slowing down to 70 mph really seems to help and with diesel prices now I might go even slower.

I just pulled a 22' wedge from SC to CA and back had the same issues. The best thing is to slow your speed down. I got better milage going 65 then going 75. And I'm stock.:(

I have never heard the fan kick on, ever, not once in 31,000 miles and 27000 in south west Louisiana.

Do you know what it would sound like? Maybe it has never shut off.

If your fan didn't engage towing 8K, I'd say something is abnormal.

BTW, a real CAI is good for 2 mpg towing, 3 mpg towing real heavy in heat and mtns.

No, I dont think so, the motor isnt loud at all. I would know if the fan kicked on.

I don't know anyone who can tow 8K at 78 mph in warm weather, and never hear the fan. You should hear it pulling away from every stop.

Broke?

Speed is a killer when towing. If I pull between 65-68 my mileage is about 13-15mpg pulling my 30ft gooseneck or my 28ft 5ver. If I go up to 70 or above it drops horribly. 78 pulling a large enclosed trailer seems a little fast for my tastes.

Pulling 38' 5ver which is around 15K when loaded with 3 sportsman 500 HO quads and topped off on fluids. In Arizona the fan comes on and off at all times of the year. More so during the summer. Gas mileage with Juice on Level 2 and tow haul is around 10-12 on most terrains. Pulling up hills drops down to 8-9 MPG. I just grin and bear it as it is cheaper than taking two vehicles one to pull the quads and another for a smaller TT...my $.02..Jim

Jabs, you should look into the KOOL "improvements".

Thanks KB, I will read your link..

I have a 24' enclosed car trailer @ 8000# and towing around 70 MPH I see about 11.5 MPG at best. with the prices the way they are on fuel my next trip I will set the cruise on 65 and see what she does.

"I don't know anyone who can tow 8K at 78 mph in warm weather, and never hear the fan. You should hear it pulling away from every stop."

I hear the fan on occasion when I start it up and make it a couple blocks down the road then it disengages. I have never heard it kick on while pulling or even cruising down the road. Most of my driving, before I moved, was in 95-105 degree humid weather. My truck barely even runs at 200 degrees. Now, up here in the north east, cool weather and lots of rain, it usually runs at 185. I guess I'm not plagued by the "overheating issues" that a lot of LLY owners have. I guess I should feel lucky or content for having a normal truck.

The "sweet spot" for towing with the Dmax is about 62mph. Or, less than 2100 RPM's. More than that and the mileage drops off pretty quickly.

It's pretty true whether you are towing or not, come to think of it.

Mine loves 1800 rpm. Good mileage and plenty of torque.

That's what I was thinking the sweet spot was for mpg EMPTY.

Of course 285's vs stock lowers RPM at a given speed. But FWIW, with 315's , I get much worse mpg at 2100 (75 mph) vs 1800 (60 mph)

High load, the sweet spot is going to be ...

unit453:

aerodynamics is a MAJOR variable. i had an enclosed cargo trailer that i ran. couple times i had it in that weight range and 250 miles was my range. it was tall and flat front bumper pull (=parachute). combine that with your speeds = the perfect storm. a gasser would dry heave at those speeds.

edited to include: weight didn't seem to be a big variable comparable to speed & aero.

heyman... don't feel too disgusted... the trip is behind you, you are movin' on, and you've got your truck.

It's all a matter of perspective. Pull that same load with a gasser and you would $hit a red worm. My 6.0L got aroud 6.5mpg. My diesel gets 10-12, this isn't great mileage but compare it to a gasser and you gotta be thankful. As far as the shape of the trailer, I've pulled V-noses and flat-noses (which I currently own) and the V's are never an aggessive enough angle to make any difference. Maybe at best 1MPG. Your biggest difference is going to be in your speed, I've got 265's and 63 mph is the "sweet spot" for mileage. anything over that drops the mileage significantly.

Yeah, keep it at 62 may sound good but, I'm not driving under the damn speed limit. I pulled a 7x20 tandem axle, steel, car hauler from Louisiana up to here. I had the Crown Vic loaded on it. The trailer weighs in at 2900 lbs empty and the car at 4200. It was actually a very areodynamic load. I had a mattress in the bed with a tarp on it and the air flow actually went down into the bed and right over the grill and windshield of the car. I got better mileage pulling that than a friggen 6x10 box trailer that maybe weighed 2500-3000 lbs. I do feel kinda discusted and 3200 miles travelled since the 29th of September, I have spend my share on fuel. I have spend around 800 and some change on fuel since I started my move. Its kinda funny how we need to account for fuel costs in moving expenses.

I generally get 9-10 mpg when towing my 13K lb. horse trailer. A gooseneck or 5th wheel is so stable that you might not notice a head wind, but 10-15 mph against you will make a huge difference in gas mileage, much greater than the additional parasitic drag (bearing load and additional tire flexing) cause by a heavier trailer. A 15 mph head wind at 65 mph will increase drag by 50%!

i get anywhere from 6-7 headwind to 12-13 no headwind, towing between 10k-12k, of course these numbers are on the flats. i have 305/70/16's almost all towing on trips is running around 60-70mph. I think my overall for most trips is around 10. my old gasser would be around 6-8.

I guess I should feel thankful that I can maintain 75 plus mph while going up an down all the mountain ranges all along the east coast. I have passed so many people that are pulling weight that have no earthly business pulling anything with some of their rides.

You do not say what the mileage was. ??? 7,8,9,10,11,12???????????

I made a cross country trip, 9500 miles, and averaged 10 mpg.

I can't complain. I was driving at 72 mph everywhere but in Calif.

My .02

Never bothered to calculate it. Put it this way: Stopped to get a cup of coffee. Topped off since I was stopped. Got back on the interstate, set the cruise at 72. Buy the time I had finished my cup, no long, I had burned a quarter tank. I was completely discusted. I couldnt believe I had burned that much fuel.....

towing 8,000 pound toybox trailer to glamis last weekend I got just over 10 m.p.g. Crewcab 4x4 duramax with edge.