taller tires...

 

You most liclely running out of RPM... What rear gear and what size rear tire are you running.

 

1st Gear in Getrag has a Transmission ratio of 5.53, in 4500 it is 5.61, 2nd gear is 3.02 versus 3.04, 3rd gear is 1.60 versus 1.67, 4th is 1.00 and 1.00 and 5th is 0.77 versus0.74. That means a little better fuel mileage with the NV4500.

Not enough to justify the cost. I would look at other things... And teh guys that tell you they regularly get 30+ Mpg a full of it.

Bump your timing...

 

I use 1st from a dead stop, just to get it moving. It feels like 34" tires 2nd is a bit rough on the clutch, even with 4.10 gears.

 

What is your rear axle ratio, what is your rpm @ 60mph, what size tires are you running?
Find these things out first, there maybe a cheap solution in here...
Plus the other cheap engine mods

 

yeah 1st is there for a reason...

 

all the mods i have are in my sig. and i have 3.54 gear ratio and my tires are hancook dynamic radial z-36's, they are 235-85-16's. i love this truck but i have been told i should see 20+mpg. and as far as rpm's at 60mph, idk havent got a tach for the ol girl yet.

 

for shure thats the gearing?
**** man my dodge with the 3.54 gears would haul ***
with the 4.10s i am luckly to see 95mph and thats turnin 4000

 

a getrag in 5th gear with 3.54 rear and 235/85 tire will go way over 80 at 2700 rpm. thats what mine does with 4.10 gear. with 3.54 you should be less than 2400rpm at 80. maby u have 4.10 gears. but at anyrate you should still be gettin 20mpg+. are u sure your odometer is accurate?

 

yea guys i counted the gears the other day. but could a person special order a low gear tranny from the dealer when you bought it?