average GPM concerns

[g4sbrg]

OK so I took my first trip that was more than 40 miles down the road. My 2000 F150HD 5.4L gas and the drive train in the truck are rated for 8700 towing, my 5ver was at approx. 7600, I was hoping for 10 GPM but didn't come close, did reach almost 9 gpm in a family easy stretch between Texarkana and Dallas (60 to 65 MPH) most of the rest of the trip 8 gpm (a bit faster, windy, more uphill return) is this what I should expect ??? asked a guy at the dump station with a new tundra pulling a TT @7500 and he stated that didn't sound too bad to him. I am not using cruise or overdrive, pretty much made the whole 1000 mile trip running between 2700 to 3300 rpm Comments Please

[g4sbrg]

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.

someone had gave me advice on a thread and it was to look at rpm more than speed, find the "sweet spot" that will "getter done" I wonder if I can track down a curve on that old truck ? may try, 2500 rpm is slightly slow in my truck, 2800 is pretty smooth going, 3000 to 3300 up small grades.

[2oldman]

GPM=gallons per minute.

[patnchris]

You are correct..the 2007 is a three valve and the 2000 is an old two valve. However I am also hauling more weight. I guess it may be apples and oranges.

[PUCampin]

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.

You are correct in that the FORCE required to overcome drag is a square function, and since POWER is Force x velocity, the Power to overcome drag is a cubic function of velocity 🙂

[g4sbrg]

not sure but I think by 2007 the 5.4L ford had a few extra valves that increased HP and performance ?? I think this 2000 5.4 only has one of each per cylinder ??

[buddyIam]

Patnchris


Hi
Your the first I noticed from back in 2002.
Glad to see your still kicking around.

[patnchris]

On a recent trip my gps said it was 212 mile to destination. Filled as I was leaving and filled again on arrival. Drove home and filled again. Total of 43 gallons for 424 miles driven.

[patnchris]

Not sure about the odometer, but the speedo reads exactly the same as my gps.

[Ridgerunner29]

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.

[RedRocket204]

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

[agesilaus]

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

[patnchris]

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]

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.

[rhagfo]

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

[Dakota98]

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 !