6.9 IDI that gets 16mpg under heavy load?

[mankypro]

I've been hauling masonry block to the dump for about a week. I get between 2200 and 3000 lbs in the bed each trip. The truck behaves amazingly well. I just calculated my MPG - I'm getting 16mpg with these loads. This is AMAZING. I'm just wondering how this is possible. Isn't 16mpg what its supposed to get empty?

 

[FordGuy100]

Not really. 6.9's seem to get better fuel economy than 7.3's. My truck gets around 17mpg. The lowest was 14.6mpg, which I was pulling a boat over to the coast (had to go over some good grades), it was about 4-5K pounds. The best I've seen was 19.7mpg, driving no more than 55mph, this was before the turbo. Now I bet with the added fuel I could get into the 20's, but my right foot just wont allow me to drive like that for more than a couple miles before it goes WOT

 

[Diesel JD]

That's true but you also have to remember that with the GV overdrive you should be getting that kind of mileage. Also 2200-3000lbs is not really heavily loaded for a 6.9 or 7.3 either. The GV lets you stay in the peak torque band approx 1400-2200RPM for much longer than a C6 or even a ZF5. If you stay below 2000 RPM and you don't do much stop & go you get great mileage on these things if you stay below 2600 RPM and stay at a constant speed you avoid the worst of the high RPM mileage penalty.

 

[funnyman06]

i got about 20 in my truck, it has a about a 300 pound camper shell on it. I took some new picks of it with my new wheels and tires.

 

[mankypro]

For the most part I don't push above 2200 and keep 'er above 1600. This is a 3/4 ton truck - a ton and a half would seem to be a pretty heavy load for it if you ask me

 

[Diesel JD]

It is a heavy load, but when these guys talk heavy we mean a big TT, a heavy 25 foot boat, 2 cords of firewood, tree service equipment etc. In the 8,000-10,000lb range, not that its really safe to haul/tow some of those loads but isn't it nice to know you could? Believe me some people do use them like that.

 

[82F100SWB]

2200-3000 lbs really isn't enough to make it work hard. With a 16K GCWR mine ran 15.8 mpg on one decently long road trip last summer, with some pretty good hills, 33's, and a heavy throttle foot(I never grabbed a gear on a hill, just made it pull)
With an 18K GCWR on another long towing trip, on a much less hilly highway, I ran 15.7. This is with another F250 on the trailer behind the truck, 33's on the tow rig, 35's on the one on the trailer, and spare parts/tools/etc for a weekend of racing. The second trip was with a real trailer(tilt deck 14K GVWR ... VERY nice to pull) that weighs a good 2000 lbs more than the car hauler I used for the first one.
This is with 3.55's and a 4 speed, with a 2400 rpm criuse, as that's where the power was on demand with the non gated banks.

 

[lotzagoodstuff]

Nice work putting in the GV overdrive, you are certainly seeing the benefits of the lower rpms. My 7.3 ZF touches 20 if I drive about 62, your 6.9 should get about the same, maybe better. As far as load, 2000-3000 pounds isn't that much.

Welcome to never owning a gasser truck again

 

[Diesel JD]

What are your RPM at 62mph?

 

[mankypro]

~2100-2200

What are your RPM at 62mph?