7 years ago when I joined this forum BEFORE I actually bought my LATE '99 F350 CC 7.3 Dually I learned that the 7.3s most fuel efficient RPM was 2k at highway speeds.

I have experimented with my truck at that RPM and find the info true.

In MY truck with stock size tires, and 4.10.1 gears @2k RPM is right at 60mph.

How is this RPM found for each engine?

I also have an '03 Ranger with the 3.0 V6 and feel that with ITS 4.10.1 gears is spinning WAY to high at highway speeds and wasting fuel--it turns nearly 3k at 70mph.

 

That does seem high. 5-spd?

Just install one of these at the unbelievable low price of $3K

https://www.gearvendors.com/ag3s.html

I have a buddy that has the Gear Vender on his 95' 7.3L F350 DRW.

He's claiming:

12.5/ 13 city/Hgwy without the GV
15.7-16 city/Hgwy with the GV

 

60-62 mph @ 2000rpms is correct with the, I will assume, 4r100 in front of a 4.10. Unfortunately the only way to change this is to swap both front and rear differentials if you have a 4x4 and intend to have full use of it at all times. 3.73's will net you about 1 mpg and at most 2.5 mpg's with all else remaining the same. You can install a Gear Vendor but will be limited to 2wd while it is active as it creates different drive ratios between the front differential and the rear differential. IE: a 4.10 DR on the rear is reduced to 3.20 DR when the OD is engaged while the front remains at 4.10. This is due to the GV being placed between the transfer case and the rear drive shaft. You will have to shorten the rear drive shaft(s) to install it.

If you have a 2wD you do not have to take the 4x4 portion of the above into consideration. All else applies.

Fuel economy with the GV improves as much as 2-3 mpg. To achieve that, all else has to remain the same. IE: you would still have to drive the same speed on the same type of terrain and resist the temptation to go faster which you WILL be able to do. With a 3.20 DR, 2000 rpm's suddenly becomes 83 mph instead of 60-62.

Finally, the F350 to Ranger comparison is not apples to apples. One is diesel and has a lot more torque and hp in a lower rpm range while the other is a gasser with the opposite.

 

Also, you can occasionally find a used GV on CL or eBay for a much better price than new.
Be advised that there are some limitations to the GV that you need to know up front.

 

Ranger is 5speed AUTOMATIC and spins at 2800RPM at 70mph......

MY 7.3 truck HAS gotten 17mpg at 60mph (2krpm) with just its 4speed AUTOMATIC....

 

That would be about right depending on speed. GV does not help mpg much in the city.
It also gives you a few extra gear ratios while pulling which is nice.

 

64mph @ 1800rpm

Auto, 3.73 gears and 285/75-16 tires on 16x8" rims

 

What kind of mpg's are you getting with the 3.73?

 

123 let us know how you like that gear vendors. I've heard mixed reviews but always wanted one. I've also heard they bang really bad going in and out, so splitting the gears is a loud project. Please I'm not trying to say anything bad just like the real skinny.

 

I think we all misunderstood the question that the OP was asking....
https://www.ford-trucks.com/forums/1...eedometer.html

 

14.5mpg overall (mixed highway/city)

The BFG Mud-Terrain KM2 tires do not help...but there are great in the dirt! I should add that there are a few leaks under the hood (I can see the dusting) but I'm still pulling almost 22psi with the stock turbo.

When I had all-terrain tires I was getting 15.5mpg.

 

I think, for the most part, amongst others, like size of the fish he caught, how much one makes ($$), the length of ones appendage, the next thing in line is the MPG one gets.

I've heard the stories. Install this Tuner, I get 20 MPG now. Or, change your intake and get 20 HP.

These are not a prius'. and if you're using any other method than a hand calculation, it can't be trusted.

Of what I've personally owned:

The 2WD, 3.73, with a 6 Speed Manual Transmission gets the best overall mileage. The average being 17-20 Highway. About 13 around town.

The 2WD, 3.73, with a Automatic is next, best overall mileage. The average being 15-18 Highway. About 12 around town

The last being the DRW 4.10 4WD Auto, best overall mileage being 12-15 Highway. About 11 around town.

My current 4WD, 3.73 Auto gets about 14-16 Hwy and about 12-13 City. I "try" to keep it around 2,000 RPM's but that's almost impossible because most speed limits here are 70 and 75 MPH and I'm at about 2,600.

I don't even try to calculate it or maintain the "2,000 RPM Rule" unless I traveling hundreds of miles towing. That way I can get in the R/H lane and pretty much just take my time. And, even at that I'm just getting around 13 or 15 depending on weather I have the 5,000 or 10,000 lb. trailers loaded.

Two things we can't really change is the Automatic Transmission and the Engines rotational value. Which leaves us with just a few considerations one being 4x4 or not.

The ideal way to improve mileage is by adding additional gears to the Automatic transmission. As much as I would like to see, and would buy, no one makes one that I'm aware of.

It is what it is.

 

My dad has a 6 speed auto on his Duramax and I drool over what my truck would be like with 50% more gears in the slushbox! Even a 5R110 would be more than what my 7.3 would know what to do with.


I agree with whitetmv. I didn't buy my truck to sip fuel nor do I expect it to. Do I drive conservatively, sure. Do I anticipate the lights, sure. I am not young (I'm in my mid-40s) and I'm not worried about cracking 10 seconds in the quarter mile and needing a roll bar (these are the jokes people).


I do, however, hand calculate my fuel economy every fill-up. I'm happy with anything over 14mpg for regular driving but too much of a shift from my menial 14-ish means there's a problem I need to start chasing. With over 265K on the clock I never know where the next challenge (or puddle) is going to come from!

 

Thanks a lot guys!! Got my answer!! Thanks Mark!!