Sounds like the 'sweet spot' for the 6.5 is around 2100rpm. That's sure better/quieter than the 2700 I see now at 70mph! I had never considered anything lower than 3.73, because of the weight of my truck. Which gear ratio are you using in your dually? How has it affected mpg and acceleration? I'd like to get as close to 18mpg as possible, but "I don't want to create a slug that can't get out of its own way.
I think the sweet spot is closer to 1700-1800rpm.
Well, my 93 is far from stock, so its hard to say, but I dont regret the switch. It still accelerates pretty good, even though I'm wasting some power through the two speed(thinking about taking it off, never needed it), plus the added rotational weight of the 22's(atleast 350lbs)(same height as a your 235/85's) and my truck prolly weighs atleast 750lbs more than yours.
It hurt accelleration to about 10mph, after that I dont notice it, its by far my quickest 6.5 truck, though my other two are closer to stock, my D-max is not much quicker.
The 93 gets around 15mpg driving locally 30 miles to work(usually running late), but I dont baby it at all, usually run 75-80(when traffic permits) and hit 85-90 on a daily basis(passing ect.) and jackrabbit starts. I dont have an accurate highway mpg yet under decent driving conditions.
I plan on taking it on a road trip this Thanksgiving, so I may have you some mpg's figures next week.
I need to get my IP timed, its just set line to line right now(DB2), I think its retarded or the advance is not working right, as the EGT's get hot quicker and builds boost alot easier than the old pump. Any one know what the timing specs are for a 92-93 db2, @idle and say 3krpm to check advance, I bought a timing light but havent played with it yet.
For your truck, I recomend 3.42's and stock size tires for best mpg's for the way you drive, next I would suggest 3.73's and 235/85's(like you have).
My 92 has 3.42's, but its a 5sp, it gets 18-20mpg's running around here local and 22 highway, I have put over 700 miles on a tank several times highway driving.
