Sometimes I lay awake at night trying to figure out how you can average 10MPG towing your 35" TT while I get 10.4 MPG in my daily driving. I know it all done with Smoke & Mirrors (gearing). SO as I was making a run into town yesterday I had a thought !!! A dangerous prospect in and of it's self. I noticed most of my run was in 1500 to 1900 RPM range while using OD. Kicking it out of OD put me at 1900 to 2500 RPM. On the drive back I worked at staying over 2000 RPMs & it looked like I had a gain of .7 MPG (much to short of a test to tell anything BUT things were in the right direction !)


SO THESE ARE MY QUESTIONS :


Do you think I could gain MPGs by NOT USING O/D whenever it puts me under 2000RPM ??


At what RPMs do I want to run for max MPG ??


For conversation sake lets say that 2100 RPM is my target #. At 60MPH I'm at 1800RPM in O/D & 2400RPM W/O. Which RPM would be the best for MPGs ??


If higher RPM's would be better (2400) at what RPMs would I be headed for - gains (2700) ??


If lower RPMs would be better (1800) at what RPMs would I be headed for - gains (1500) ??


THANKS in advance for your thoughts.

 

When I had my v10 I did 4.30 gears, the banks headers, a less restrictive cat back and kept her always maintained.

The ONLY fuel savings I noticed was in city driving (because of the gears).

 

I got a mouse whisker under 15mpg in my truck on back to back runs from NYC to Myrtle Beach SC. Cruise set to 70mph the whole time, equaling roughly 1925~2000RPM in OD.

My truck has 3.73 gears.

NYC bumper to bumper city driving I get under 10mpg, maybe 10mpg even if I am very lucky and hypermile with a tailwind.

 

Well, to be precise I actually get between 8 and 9.25 MPG pulling the 41' 11k lbs TT. Typically most of those miles are on the Interstates or other highways with only slower speed roads at the beginning and end of the trips. At 68 to 70 MPH on the Interstate using cruise control I recently got 13 MPG running unloaded (rare event) going from Philly to Savannah, saw the same mileage coming back home pulling a 1650lb car on a U-Haul tow dolly.
There is more to it than running at a given RPM, the load on the engine at that RPM is a major factor. I used to be able to get 15.5 MPG running solo with the stock 3.73s and 265 tires and the lower RPMs that they provided. But those same lower RPMs really hurt the mileage when towing heavy, the engine just wasn't making enough power to pull the combined load efficiently and it would drop out of OD if it ran over a shadow with double downshifts on any larger Interstate grades. Now with the better effective ratio of 4.39 (35" tires and 4.88 gears) it has dropped some solo mileage but the increase in engine output at the higher RPMs (along with the Banks headers and 5Star Tunes) has made a big improvement in towing performance AND economy. In stock trim we used to see 6 to 7.5 MPG on trips up and down I-95 to/from Philly to the Carolinas pulling the old 31' 9500lb toyhauler. Now we regularly see 8 to 9.25 MPG over the same routes pulling the 10' longer 11,000lb TT. This past March we made the run home from Charlotte NC (560-ish miles) at a moving average speed of 61 MPH, that's a damned good average speed considering getting out of Charlotte, gas/food stops, a side trip in VA to visit Apoc and Baltimore's Beltway traffic. I was pedaling a little faster than usual due to some time constraints and fitting in our Apoc visit. Traveling North up I-81 through the Blue Ridge Mountains I was able to hold OD up all of the grades if I hit the base of the hill at 72/73 MPH. If I held the throttle opening at 65% it would bleed off speed slowly but hold OD and we were typically at 60/65 MPH at the top of the hill. Staying in OD = better MPGs and the custom tunes really help to make that happen. With the 87 Octane Performance tune loaded I can hold to about 55% throttle opening at 65-ish MPH under high loads climbing grades without downshifting. The 89 Octane tune allows for up to about 66% throttle opening and holding onto OD, both big gains over stock. Coupled with that I always have one eye on the instant MPG readout on my Ultra-Gauge and am adjusting throttle and speed to improve my average MPG if possible, yeah, I hypermile a V-10 powered 19,000lb combo. And I NEVER use cruise control while towing, NEVER!

With your 37" tires do you do the calculations to correct your speedo/odometer when figuring your MPGs?

 

"With your 37" tires do you do the calculations to correct your speedo/odometer when figuring your MPGs?"






Different X, This is my daily driver I'm working on. 265/75/16 Tires,3:73s. It saw 13MPG twice on the drive from OH last year when I picked it up. I'd say around 11.5 MPG was the total average for that trip.

 

When I first got mine, it was a task keeping it above 10 MPG.

Now, I'm anywhere between 11.5 and 12.5.

I plan to get the super-nifty-mega-gauge-endorsed-by-Tom one of these days to monitor my mpgs a little more closely.

 

Well Hel Stan, What have you done to gain 2.5 MPG ??? See In the sig you got the banks up & running, these & the 5 star account for it ??

 

Who cares with gas being cheap and likely getting cheaper (some saying now Oil could hit 20 dollars)

 

I don't think Stan can type, he's a Ford Excursion....

 

This was a two tank average going from durango colorado to grand junction colorado over red mountain 3 times. Got back at 13.3 as i drove the last 80 miles in a blizzard in 4 wheel drive on red mountain after it was closed.

 

This is what is known as an "outlier".

 

Trying to get back to my thought ( they take off if I lettem)


What RPM do you think is the most fuel efficient ??


Do you think I would improve MPG keeping it there as much as possible whether in or out of OD ??


At what RPMs should I EXpect diminishing returns High/Low.


What got me thinking about all this is 2 fold :
1st, It pisses me off I'm ALWAYS 5MPG less than others reported MPG

2nd, The V-10 sucks fuel at idle like there is no tomorrow, so as I was headed into town using OD, I noticed my RPMs might have been less than optimal. So I'm wondering if running in the power band ( wherever that is, I forgot ) of the 6.8 would improve my MPG ?? Improved MPG while not using OD is not a conventional thought, I get it. But it is a thought.

 

Save the Dinosaurs !!

 

Welcome aboard Mikpsdad!
Do you have any actual MPG calculations to compare to the overhead display? Is your V-10 EX totally stock, stock sized tires and all? What gear ratio are you turning?

 

Part way thru that trip my daughter asked what was wrong with the excursion and why are we going so slow. I told her I was setting an excursion record. I tried very hard to not get above 18 or 19 hundred rpm.