3000 RPM Sustained on a 4.0L?

Freeride · Jul 27, 2006

Will a stock 4.0L handle 3K RPM sustained for hours on the freeway?

I'm regearing from 4.56 to 5.42s to handle the 40's and with no OD at 65 MPH, I should be at just under 3000 rpm. I could do 5.13s, but I'd like to go as low as possible.

MarcW · Jul 27, 2006

my jeep does it. but why no OD? swapped in trans? my 4.0 liter gets beat on, i run freakin 10-50 synthetic though :flipoff:

Freeride · Jul 27, 2006

Stock transmission is a TF999 3 speed auto with no OD.

zig80toy · Jul 27, 2006

A little under 3K should be fine.

junkyard jim · Jul 27, 2006

Run 15W40 and it'll take it. You may need to clean your air filter when you get there tho! (I did 70+ going to Colorado in '02 in hotter than current temps with 200,000+ miles)

JOOP · Jul 27, 2006

they redline at like 4-4500 RPMs. You should be fine.

MarcW · Jul 27, 2006

JOOP said:
they redline at like 4-4500 RPMs. You should be fine.

i hit the fuel cutoff on my 96 HO all the time.. :flipoff: 5100 or 5200 RPM.

Cascade_Crawler · Jul 27, 2006

MarcW said:
i hit the fuel cutoff on my 96 HO all the time.. :flipoff: 5100 or 5200 RPM.

Thanks cause you drive like a dirtbag :flipoff:

JOOP · Jul 27, 2006

MarcW said:
i hit the fuel cutoff on my 96 HO all the time.. :flipoff: 5100 or 5200 RPM.

whats a fuel cutoff :flipoff: How many miles do you have on it?

MarcW · Jul 28, 2006

JOOP said:
whats a fuel cutoff :flipoff: How many miles do you have on it?

i think its a fuel or spark cutoff. it dont rev no more :redneck: 220,000 miles or so. pretty high milage, still pulls hard.

MarcW · Jul 28, 2006

XJonathan said:
Thanks cause you drive like a dirtbag :flipoff:

thanks

Six-Nine · Jul 28, 2006

Freeride said:
Will a stock 4.0L handle 3K RPM sustained for hours on the freeway?

I'm regearing from 4.56 to 5.42s to handle the 40's and with no OD at 65 MPH, I should be at just under 3000 rpm. I could do 5.13s, but I'd like to go as low as possible.

Do it. I am running 5.13's w/36's and I drive mine in 3rd most of the time unless I am going down hill:flipoff: You will need the extra ompf to push them 40's you might just have to drive in the slow lane...

TreeClimber · Jul 28, 2006

Freeride said:
Will a stock 4.0L handle 3K RPM sustained for hours on the freeway?

I'm regearing from 4.56 to 5.42s to handle the 40's and with no OD at 65 MPH, I should be at just under 3000 rpm. I could do 5.13s, but I'd like to go as low as possible.

Don't do it....

Unless you're already got 60s. Ain't no way you'll recoup the investment of regearing because the axle will be a pretzel the first time it grips something if it's a 44 or something.

edited for clarity

MarcW · Jul 28, 2006

TreeClimber said:
Don't do it....

Unless you're already got 60s under that axle. Ain't no way you'll recoup the investment of regearing because the axle will be a pretzel the first time it grips something if it's a 44 or something.

im confused, why would he stack axles? 60's under that axle? he has been runnin the 40's. but breakin hubs. so it aint no pretzel yet.

Dude · Jul 28, 2006

Freeride said:
Will a stock 4.0L handle 3K RPM sustained for hours on the freeway?

I'm regearing from 4.56 to 5.42s to handle the 40's and with no OD at 65 MPH, I should be at just under 3000 rpm. I could do 5.13s, but I'd like to go as low as possible.

yes, as long as the cooling system can handle it.

but you are over the best RPM range for efficiency.

That would be about 2100 to 2500 rpm depending on the weight of the rig.

Freeride · Jul 28, 2006

Cooling system has been upgraded to a Turbo City Stage 3 cooling kit and never get's over 200, even on the hottest days. Normally runs 175.

I did some freeway runs with it last weekend, and it actually pulled hills at 75 and still had more leftover. But the RPM ranges felt all wrong, and it's sluggish on side streets (stays in first gear forever, and then bogs in 2nd).

And a 60 won't be happening any time soon. I've wheeled it a bit with the 44 and the only problem has been with cheap Schucks import wheel hubs. I have factory Ford wheel hubs now and haven't had a problem since. Haven't broken my stock shafts or 760 joints yet. Balljoints are still tight (thanks to 5" backspacing).

Travis1 · Jul 28, 2006

JOOP said:
they redline at like 4-4500 RPMs. You should be fine.

more like 5,500rpms.

I wouldn't be sweating 3,000rpms. fuel economy just won't be as good.

junkyard jim · Jul 28, 2006

IIRC, at 5,650 RPMS inline 6 cyls get internal vibes. Racers rev past that spot to avoid internal melt down.

KarlVP · Jul 28, 2006

I would ask the Jeep Speed guys. Send them an e-mail and ask. Honestly that would be the best place for this info.

www.jeepspeed.com

bobracing · Jul 28, 2006

I must be missing something, but any modern engine should be able to run that all day. My stock GC runs over 3K in drive (down shifts for most hills) 3.73 and 235 tires.
As stated above, it will be louder and you will loose mileage. I loose about 5mpg when in Drive (3200@70) instead of OD (2100@70).