average GPM concerns

g4sbrg wrote:
is it more the weight or the exposure, I am pushing about 32 feet, some old literature on the truck stated not to exceed 60 feet above what the truck exposes, and do any drafting device show potential. V shape wedge on the top of the cab ??

From what I've seen most people don't think those wings and such do any good unless they are custom designed to fit the truck and trailer. Semi's use wings like which are custom fitted to the tracter and trailer that but the out of the box ones you buy aren't custom fitted. And even when they work they gpm improvement is small. Semi's drive hundreds of thousands miles per year and a small mileage improvement pays for itself. But you aren't pulling that fiver that far.

I'm a little surprised that you managed 9-10 gpm. You must of had a tail wind. 250/350 gassers are doing good to get that high a mileage pulling heavier 5vers.

I'm in with a big block (8.1L 496) ... and 4.1 rear end.
I put a mid-ship replacement tank on to help with the
distance between refills. Out in the south west it is better
to start looking at the 1/2 tank left point.

Keep TV tuned, run both truck and rig as light as possible (re-visit
often), keep tires at proper inflation levels. Build a buffer in to
your gas budget for trips. I set cruise control at comfort RPM for
the Vortec/Allison combo. Work on smooth starts and stops (i.e.
plan ahead and stay involved). Keep an eye on the gauges. Learn
not to rush.

Know that many of us are in the same situation... I prefer sticking
to the flatlands unless I have a long enough time off to get to the
ocean.

Your MPG sounds good to me.

Charles

OK OK yall having fun with the typo!!!!! anyways it appears I have no major issues and have a few items that may help. SLOW DOWN, GO DOWN HILL. anyways that one comment put thing into idiot terms I understood HA. thanks guys, tune up. intake and exhaust may get a little but not much!!

Thanks

g4sbrg wrote:
OK OK yall having fun with the typo!!!!! anyways it appears I have no major issues and have a few items that may help. SLOW DOWN, GO DOWN HILL. anyways that one comment put thing into idiot terms I understood HA. thanks guys, tune up. intake and exhaust may get a little but not much!!

Thanks

Honestly, I didnt gain any increased mpg with the intake & cat back, but the truck performs entirely different & doesn't seem to labor as much pulling the load.

Good luck !

You were expecting with a 2000 5.4 pulling near max load. I would expect for you to get what you are getting.

PUCampin wrote:
Power to overcome aerodynamic drag increases as a CUBIC function of velocity. Going twice as fast takes 8 times as much power!

It's cubed? I always thought drag increased with the square of the speed, but I'm no physicist.

I find this very interesting. I am towing the trailer in my sig. It is around 7800 -8500 lbs. I tow with a 2007 F150HD, 5.4. 373 gear. I tow with OD off at around 65 mph and almost never use cruise. In approx 6000 miles towing, over the last two years, I am averaging right at 10 mpg. I did switch all lubes to synthetic, but wouldn't think it would make that much difference. Is it possible that keeping the 5.4 closer to it's power band makes a difference. Usually runs around 2500 rpm.

rjstractor wrote:

PUCampin wrote:
Power to overcome aerodynamic drag increases as a CUBIC function of velocity. Going twice as fast takes 8 times as much power!

It's cubed? I always thought drag increased with the square of the speed, but I'm no physicist.

That's something I've been wrong about, it is cubed. Force required increases by the square but power increases by the cube:

BK

rjstractor wrote:

PUCampin wrote:
Power to overcome aerodynamic drag increases as a CUBIC function of velocity. Going twice as fast takes 8 times as much power!

It's cubed? I always thought drag increased with the square of the speed, but I'm no physicist.

Food for thought: atdynamics - AERODYNAMICS 101, TRACTOR-TRAILER AERODYNAMICS

I seemed to recall that a good portion of resistance was actually from under the vehicle/trailer and from the rear as air will hold, not releasing increasing the drag. The above link goes into that detail a bit but equates drag at about 25% in different areas.

Another area that shocks me is those who go and lift their truck but also want better MPGs. :h

patnchris wrote:
I find this very interesting. I am towing the trailer in my sig. It is around 7800 -8500 lbs. I tow with a 2007 F150HD, 5.4. 373 gear. I tow with OD off at around 65 mph and almost never use cruise. In approx 6000 miles towing, over the last two years, I am averaging right at 10 mpg. I did switch all lubes to synthetic, but wouldn't think it would make that much difference. Is it possible that keeping the 5.4 closer to it's power band makes a difference. Usually runs around 2500 rpm.

Have you checked to make sure your odometer is accurate? I check my odometer using the mile markers on the interstate. I once had a new Chevy that had an odometer that logged more miles than I had actually traveled. I thought I was getting great gas miles until I figured out the odometer was not correct. It appeared to be setup for a truck with 17" tires and my truck came with 16" tires.