Question: RPM's at Different Speeds - 4 Speed V8

[BMWSTOY]

My 2000 UZJ 100 is being delivered - but...

The person driving is asking me what should the RPM's be at the different speeds. I would think these would be in the manual in the glove box, but perphaps someone can help.

What should the RPM's be for cruising speeds:
60:
65:
70:
75:

I know it only has 4 speeds, but it is a V8. Most likely overconcerned and will be filling up at gas stations more often - but I would be at more ease if someone could post them up. Stock 275X75RX16's.

Thanks

 

[uzj100]

The rpms are pretty high for a v8 at these speeds. I will check tonight in my 99 with 285s and let you know.

 

[Jim_Chow]

With the 5speed, stock tires, flat ground:
60mph: 2K rpm
70mph: 2.3-2.4K rpm

4speed in OD should be almost the same (estimate: 0.71*4.3=3.053, 0.75*4.1=3.075, 4spd OD is ~0.7% lower than 5th gear, so 2400*1.007~2417 rpm...so about 20 rpm higher for 4spd than 5spd).

 

[BMWSTOY]

Just received an update and Jim_Chow is right on. At 70mph it is turning about 2300. Thanks Jim. Although I would have thought the 5-Speed would be much different.
This seems really high for a very large V8. The V6 Honda pilot that is ridding along side is turning about 1700-1800 with better gas mileage of course too.

Guess it proves, its not the size of the engine, but how its tuned. They should have made this a 6 speed or more like the new LS.

 

[Jim_Chow]

It all depends on the engine design, torque band, gearing, etc. The extra gear on the 5 speed tranny gives you a much lower first gear and smaller jumps in between.

 

[spressomon]

It all depends on the engine design, torque band, gearing, etc. The extra gear on the 5 speed tranny gives you a much lower first gear and smaller jumps in between.

But 4.10 r&p...although it has been posted here somewhere I don't recall the tranny ratio differences and final drive ratio comparison between the 4 & 5-speed.


FYI: With 4.88 and 315/75R16 MT/R's I am at 2,000 rpm @ 60mph and 2,300-2,350 rpm @ 70mph in OD...flat and calm.

That is why my UZJ100 gets fairly good mpg (relatively) at 60mph...it loves 2,000 rpm or below!

 

[ShottsUZJ100]

The V6 Honda pilot that is ridding along side is turning about 1700-1800 with better gas mileage of course too.

And there's a HUGE weight difference.

43-4500 lbs vs 5400

 

[BMWSTOY]

Thanks everyone.
I would have bet money it would have been 2000 or less below or too 70mph. Easy to understand why the poor mileage, or good mileage per weight depending on how you look at it.

Thanks for all the knowledge. As always, I know I can trust the mud folk for good response