Max RPM

[Medsker]

I am regearing and deciding what to go with, what is the max RPM that you guys would cruise on the freeway at? I was thinking 3000 would be the max but with 4.56, an 3 spd auto and 35 (34"actual) that would put my max cruising speed at 67 mph. I have 4.10's right now with 32.5 actual height and the power seems to be lacking. So what's the max RPM?

 

[pokeyYJ]

Moabrat, has the five speed and 35's with 4.88's, and he cruises at about 70 mph at 3000 rpm.

 

[Shawn]

Try this.
http://www.la4x4.com/gearcalc.html

 

[Cruiser]

my cruiser will cruz like 75 at 3400...4.88's....37's
dont know if that will help due t the toy vrs jeep factor

 

[Medsker]

I guess I forgot to add that I have a 2001 tj with the 6 cylinder and am looking for how high I dare keep it reved for extended periods of time. (i.e. on freeway)

 

[jp008]

I've been cruisin at 5000rpm at 70mph for 3 years now. But that's "my" sami engine.

 

[1968jeepthing]

i have a chevy 250 engine and i dont usualy go over 3000 to 3500 rpm unless i am passing or such. i did it for 48 hours almost straight going 2,500 miles and it didnt seem to effect it any.

 

[BBowski82]

Randys Ring and Pinion website has a real nice calculator and a chart that tells what cylinder engines should run RPM wise at what speed...check it out.

 

[tweakeyjeep]

I have the stock gearing in my 95 wrangler with the I6. I believe my 4.0 Liter is rated at about 230 HP (after my mods). Stock that engine is at about 190 HP. I think it is 3.53's or 3.73's not sure, but running 33's I can go tops about 90... Never tried higher. That was in 4th gear at 3500 RPM. I can go about 70 - 75 if there aren't any hills at about 2500 RPM in 5th gear. I don't know if that helps. If I hit hills, I usually have to downshift to keep speed up, or I can keep it in 5th and slow down, but still make the hill. I usually drop down to 60 MPH on a hill in 5th gear. Hope this helps.

 

[trpl xj]

My XJ with 4.56's 33's and a stock fourspeed auto. It will turn about 3000 rpm's at 70 or so. I personaly wont go higher than that for an extended amount of time. I will run it up to 3500 if I'm going up a hill in a canyon or something like that. I think more than 3000 on a inline 6 for an extended amount of time is not very good.

 

[pokeyYJ]

I have heard that the stock 4.0 can take running at around 3000 rpm for extended periods of time. The only drawbacks are going to be noise and gas mileage, also there will be a slight decrease in engine life, but nothing that any motor would get if you ran it at 3000 rpm also.

 

[tweakeyjeep]

Originally posted by trpl xj
My XJ with 4.56's 33's and a stock fourspeed auto. It will turn about 3000 rpm's at 70 or so. I personaly wont go higher than that for an extended amount of time. I will run it up to 3500 if I'm going up a hill in a canyon or something like that. I think more than 3000 on a inline 6 for an extended amount of time is not very good.

Don't quote me on this one, cuz I'm just a stupid teenager. But why would the redline be at 5k on a 4.0. I think it is okay to drive in any range below 5k rpm... Right? Correct me if I'm wrong. (I don't mean cruising down state in 2nd gear at 4,500 rpms... I mean like to hurry and pass someone rev it up to 4500 so you can get going before you have to shift.)

 

[trpl xj]

Originally posted by tweakeyjeep


Don't quote me on this one, cuz I'm just a stupid teenager. But why would the redline be at 5k on a 4.0. I think it is okay to drive in any range below 5k rpm... Right? Correct me if I'm wrong. (I don't mean cruising down state in 2nd gear at 4,500 rpms... I mean like to hurry and pass someone rev it up to 4500 so you can get going before you have to shift.)

I think you answered your own question. Sure you can run it at any rpm below redline. Just because redline is at 5000 doesn't mean you can run it at 4500 for miles on end and expect it last. 4500 or even redline for short bursts isn't going to hurt it that much (just a little more wear and tear). I do it all the time in mine, to pass or merge into traffic.

I was just saying that I try and not run mine over 3 grand while I'm cruising down the freeway. In fact I watch my tack on the freeway more than I do my speedo.

 

[tweakeyjeep]

Originally posted by trpl xj


I think you answered your own question. Sure you can run it at any rpm below redline. Just because redline is at 5000 doesn't mean you can run it at 4500 for miles on end and expect it last. 4500 or even redline for short bursts isn't going to hurt it that much (just a little more wear and tear). I do it all the time in mine, to pass or merge into traffic.

I was just saying that I try and not run mine over 3 grand while I'm cruising down the freeway. In fact I watch my tack on the freeway more than I do my speedo.

Okay, makes more sense now... I believe the highest I've run mine was 3500 in 4th gear going 90 to try and catch up to my friend. He ditched me on a huge hill and we were out of range on the CB's and he was going to exit soon, and I didn't know which exit!

 

[sloppyjoe4by]

I am running 4.88's and 35" MTR's. 4.0L 95 Wrangler. On the freeway doing 70 I am at about 2600RPM's and at 3000RPM's I am doing 77MPH.

HTH
Adam

 

[cyberduke]

Yea, for that reason I'm considering going back to my 4.10's (from 4.56's) and putting a 4:1 kit in my D300. While driving on the freeway and keeping up w/ traffic I'm turning 3500 rpm. I calculated it out once and figured out my Seedo is actually pretty close. 80MPH at 3500 rpm.

So Low Low right now is 77:1. However, If I drop to 4.10's in my pumkins and go w/ a 4:1 set in my tcase, freeway would be a bit over 3100 and LL would be 103:1. I think I could live w/ that. Being that it's not a daily driver and all.

Earl

 

[1968jeepthing]

heh heh, you want low gears? try 5.86s on the highway without overdrive. i get about 55mph at 3000 rpm. gas mileage at this elevations at about 5 mpg. it sucks, but its great for towing or crawling.