I have 265/75's and 3.54 gears. When in overdrive, I'm turning about 1900 RPM+/- @ 70mph and when I turn O/D off, I'm at about 2800 RPM @ 70mph. Do these numbers sound about right? I only ask because this truck is new to me, it's my first diesel, and it just doesn't "feel" right in 3rd @ 70mph, but then again, I don't really have any other experience to compare it to.

 

1900 @70 sounds right on the mark. Why doesn't that feel right, or is it the difference between OD on and OD off?

 

O/D on feels great.... it's more of the difference between O/D on and off. When O/D is off and I'm at 2800 @ 70mph, it just doesn't feel like it has much power...

 

At 2,800 RPM you are pretty much past the stock usable power band. You are really going to have to lean your foot into the pedal to go.

A Gas motor wil give you a certain % of power as you mash the pedal down, example, 25% of pedal, is 25% power. On a Diesel,, that rule goes out the window. If you hold the pedal down 25%, you get 25% RPM. The Pump Govener takes care of how much power you need. So, at 2,800RPM, it's going to take 75%+ of your pedal travel just to maintain RPM. That would explain why it doesn't feel like it has much more oomph.

Put an EZ box on it and it will really liven it up at lower RPM, increase MPG, and will help your top-end a little.
The top-end could really be taken care of with bigger injectors, or a "bigger" fueling box, but your tranny will make sure you don't do that. (It will need upgraded)

HTH,
Merrick

 

Thanks for the explanation, Merrick.... that puts my mind at ease quite a bit.