Road trip question

[BillR]

With 4:11s and 31s, I'm running about 2500 RPMs at 75mph. Is this too high for a 14 hour drive? I can take a different route w/slower speeds, but it's a little longer.
When should I be concerned about freeway RPMs?
TIA!

[Kejtar]

you're worried about 2500? AFAIK XJ's can take a LOT higher RPM's....
In any case, I don't think I ever drove that long straight with it being regeared, but I did got as much as 7 hours or so doing close to 3000. Only thing is the normal stuff: what your temp and oil pressure :D

Kejtar

[Eagle]

Remember that the basic engine from which the 4.0L was derived is a mid-60s design. AMC didn't start using overdrive trannies until the early 80s. In "the old days," these engines were all geared to run 2500 RPM at 60 MPH (24 MPH/1000 RPM). We raced them, and we cruised them all day at 70 to 75 MPH (a bit over 3000 RPM). They still lasted 200k to 300k miles. 2500 RPM is just a high idle. Go for it.

[BillR]

Cool!
The other option was taking my wife's ZJ on the trip, but I like driving mine, and she HATES getting in and out of the XJ after the lift.:D

[Beezil]

no problem......

I've himmed along out to Moab and back between 2900-3000 rpm.......

[Bronco]

Heck mine’s not even happy on the big road till I gets to 2200

[evldave]

I just got done driving Chicago-Portland (OR). Most of it was in 4th gear (31" tires, stock gears = no power in 5th). Except for the 12 hrs stopped for the replaced water pump in des moines, I drove almost 40 hours straight. RPMs were anywhere from 2500-3000 the whole way. I was totally loaded with gear (moving back cross country). Still no loss of power, still runs smooth, 180k+ miles...

The motor made it, but now I'm due for a xfer case rebuild, new rear leafs, new clutch, new ??. But dangit-the motor still runs strong!

[techno1154]

BillR Your results make me happy. My XJ does 50K+ per year on the highway. With 235-75-15 tires, the AW4 hunts between 3rd, 4th and OD going up some hills which I do not like. I also want to switch to 4.10 gears and 30 or 31 tires. Knowing that the 4.0 has more torque above 2500 rpm which is where mine spend most of it's time while on the highway. I always wanted to run 2800 - 3000 RPM with the cruise on without havng to look for blue flashing lights in my rear view mirror. I would take your setup any day over what I have now.