Gear ratio for oil field work pulling tanker?

The 6nz really doesnt like living at 1200, eats more oil, more mpg, more total vibration, and the bigger the hp, the worse that is.

yes the torque peak is at 1200, but its pretty flat till 1500, with hp peaks tending to be between 1500 and 1700

While 1200 isnt lugging, its as low as you want to run it period. I have had much better pulling power AND mpgs in the 1350-1450 range. (+200 rpm and drop 1 gear for same speed and mpg with more oomf)

But thats with 80k, hes looking at mountains and 120k, he needs to spec for 1500-1600 rpm at his target road speed in top gear.

 

As long as start ability is good I wouldn’t change it till it’s broken .. with 3.25 you can run in 17th and be sitting around the rpm as 3.90 ratio would .. The main issue is does it pull itself out of the mud currently. If running those weights down around 1200 watch pyrometer it will climb most likely .

 

Let it ride until you have to swap them out for a mechanical failure.

 

You got decent drive tires on it ?

 

That's really the only issue you have right now. Starting that weight in soft ground or on a steep incline will tax the components including the clutch a lot more. And I second keeping a 6nz above 1500 when pulling hard.

 

A friend of mine had 3.90's on a Freightliner he once had. Truck was super ugly, but he ran the road with it for 5 years or so. It had a 500 Detroit and got decent fuel mileage.