Years ago, and Big Orn probably remembers it, a handful of people reported that their V10's got better mileage above 65, like running 70-75 was better than 60-65.

Never figured it out - but if you look at the stock 2-valve torque curve in the Ford literature for 2002 (see below) 2000 RPMs is in the beginning of a flat area of the torque curve. I think where that levels off, keeping it as close to that point is the best MPG wise.

But who knows really? Maybe it's aerodynamics of the nose of the truck getting wind off the windshield. Or the tailgate. Or we're all out of our minds?

 

I'm still kinda confused. This trip that I take my truck on is 125 miles. When I set the cruise at 60-65 it downshifts on hills quite a bit. The time I set the cruise at 55-60, it downshifted like 2 or 3 times. I was sure that I was going to have to put less fuel in the tank but I was wrong. In my mind, less RPM=less fuel=better MPG. What gives?

 

Cruise control.

It's not a gas saver, it's a convenience.

If you drive with your right foot, accelerate slowly when needed, and you'd be surprised.

To this day, I am amazed when I hear someone talking about MPGs using cruise control. In my V10, and my '97 cougar, and '96 t-bird, cruise always would nail the gas when needed to get back up to speed like after hitting a hill. I do far less with my right foot, and at least ease into it. And I especially try not to downshift.

 

armynavyguy, My guess is because you have the 3.73's like me and that is how they behave.
I think the 4.30's will get you better MPG in that same situation.
The only time I have seen 3.73 provide better MPG is at 65+ on flat land.
Towing 4.30s better
In town 4.30s better
Just my experience and that of others.

 

I would love to get gears but my wife just let me buy a Suzuki King Quad 700. I wont be getting gears for a while.

 

Cruise control is good for fuel economy on flat highway driving. Bad for fuel economy in hilly terrain, you can do better controling the gas pedal yourself to let it speed up down hill and slow down uphill without down shifting.
In my old F350 with a 460 my gas mileage towing was the same with or without overdrive engaged so I always turned OD of when towing. OD did save gas when empty.
After reading the posts and checking google I have a better understanding of torque and horsepower and I better understand the shift strategy of my torqshift tow/haul mode.

 

FWIW, I took my 2000 v10 CC 4x4 on a 150 mile trip last weekend, a good mix of hills and flat, running 65-70 using the cruise control. Hand Calc mileage was 14.8. I thought that was pretty dang good for the v10 . Was it a fluke? Hard to say, I only topped the tank off 2x, so that's not a very good statistical sample, but I'll take close to 15 mpg with my truck any day .

 

Couldn't agree more! Which is exactly why I can't believe no one has come out with a cruise coupled to a GPS. Think about it....

 

Interesting thought. Not sure if I, personally, need to give up that much control though.

 

ALL you old skool folks are right on as relates to CC and vacuum or mechanical actuators ----BUT if you do not have the 05 and up wire only throttle you don't have a clue about modern cruise control....it is much better then you right foot for fuel efficiency now

HP vs torque and rpm vs out of breath or diminishing returns....

Art had it right earlier and then you all got philosophical on HP math....

all motors have portions of their power band (rpm spread) where they are either increasing or decreasing in the power...BUT!!! we have two series of gear sets to use and MULTIPLY that power... and in the art of moving a LOAD we only care REALLY how much rotational force (TORQUE) we can apply to a lever (TIRE) to move a load at a given speed.......

if we apply 250 (half of our 500 peak) foot pounds of torque directly (1:1 ratio) to a 3.73:1, 4.10:1, or 4.30:1 reduction gear box then we will MULTIPLY that torque by that ratio to arrive at a HIGHER amount of torque

there is no way to really answer the original question because it starts with a false assumption.... the dyno charts given are only RELEVANT to that motor on that machine on that day and condition.... dynos are relative tools.....and as Art tried to point out there are different types as well as different factors....

I have a LOT of dyno time.... with a RPM and speed limited stock V10 I can make better numbers with locking it into 2nd gear then doing a top gear run... on my 4r100 I had a torque converter manual lock up switch that made a hell of a LOT of more Peak HP and torque when I controlled the lock up of the converter.... I could also make bigger numbers by power braking to converter stall before stabbing the WOT to fool the dyno.... (can you tell I LIKE dyno shoot outs with a auto trany yet??)

I also used to put on undersized tires to beat the competition...any one know why?

 

Ooh! Ooh!! Over here!! Is it because smaller tires give you the same benefits as a steeper rear gear? And on a chassis dyno they'll get the drum spinning faster?

 

give bad axxed 4 door a cigar....EXACTLY....

makes me kind of giggle all the time here when guys have a 3.73:1 rear gear and slap on taller tires and wonder why they can not get it up the mountain any more..... on one of my trucks when we planned a trip to the tall Colorado mountain I bolted on a second set of spare tires that had 2 inches smaller diameter then my stock size.... instant gear change.....

I have found over the last 7 years that all my SuperDuty trucks with the V10 and all three typical rear gears (3.73-4.10-4.30) get about the best cruise economy with a full tow haul load if you set the tire and gear combo to give around 2100~2250 Rpm at 70~75mph

All my 2v V10 trucks made the best climbing and acceleration power up tall steep sections around 4600~4800RPM.......on the occasion that speed bled off to below 40 MPH I ended up down in 1 or 2 gear screaming up the hill at 5000~5200rpm @35~30MPH but she did not have enough power to upshift and lower the rpm to gain more speed... that is until I got this 3v v10 with the higher stock power levels, lower rear gear, and more efficient torque converter in the 5r110w trans... I noticed right away that under load this combo will bounce off the rpm limiter before I perceive any significant power drop off

 

O.K., I'm learning a lot but am also having trouble applying it. With my 99 V-10 with the 4.30 limited slip, I'm still wondering what to set as my RPM goal for best power up hill with a big load. I have a gear vendors, so I can split the gears.
Was I correct in an earlier post that 4,000 rpm's is where my max hp is produced and that I'm getting diminishing returns after that?
Sure would like to be able to pull my rig with a new V-10 with 4.30's and see what the difference is. I'm at about 21,500 GCVW.

Thanks, LIKENIT

 

Anything between 2000-3000RPM would be fine... of course, if you're not getting the power you need at those RPMs, in whatever gear you're using, downshift!

With the '99, you might find it losing breath after the downshift, which is what we already talked about.

In some cases, you might have been better off with a 4.10 or a 3.73, keeping you lower in the RPM band at the same speeds, so as not to run out of breath.

 

21,500 is a tad heavy for that vintage rig but that is an entirely different issue and I assume you are a big boy and know how to be very careful towing that load in the steep twisties.... OK that said your probably not going to gain much but grief from the gear vendors unit so don't install it if you have not yet

the 4.30 LS unit is good to go I would shoot for a tire combo for your rims that should get you in the 2000-2150 at 70 mph range as your set point for the drive train set up

Now focus you efforts on keeping you low end grunt but enhancing the top end a bit to broaden the already very broad power band

In your case the 99 2v V10 responds very well to these mods....

1. Zoo Dad.... provide MORE fresh air directly to the snorkel inlet of the air cleaner
2. New MAF
3. New plugs and boots
4. New fuel filter and high QUALITY fuel (find the brand that gives best MPG over three full tanks for mixed driving) in my area it is Chevron others in new Mexico report shell is better...gas is very regional...find the one YOUR motor loves and stick with it...if it is NOT chevron...then use a full shot of "Techron" every other tankful for the rest of your motors life
5. If you live in a gritty sandy dusty abrasive world then stick with new MC paper filters... if you are in clean mountain woodlands and only have occasional dust and it is mostly pollen then get the K&N filter element that fits in your stock snorkle...the FIPK is a BIG waste of money as are ALL other so called cold air KITS
6. your motor is one of the only ones that actually showed impressive HP and TQ numbers from the Gale Banks exhaust products... if you got the bucks get the real deal and enjoy the top end power his stuff gives the 2 V10.... if you are on the cheap then change out the cast headers for e-bay LONG tube headers and have a competent muffler shop fab the two to one "Y" into a fresh large scale converter and piped through a fat flow master or similar to dump BEFORE the passenger tire...keep the plumbing in the 2 to 2.5 inch range... 3 inches and larger will flow more but the velocity is slower and hurts bottom end torque too much...

I have seen several 99 2v V10 on the dyno that good maintenance, modest mods got the owner an extra 25~35HP....still a bit pricey for my taste but a GOOD programmer can add 15 to 20 more to this figure and your vintage motor will surprise the hell out of you what it can do bouncing off the 5200 rpm limiter......