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post #1 of 8 Old 11-14-2008, 05:34 PM Thread Starter
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Max RPM

So I'm getting tired of my overdrive kicking on and off constantly. I was saving up for a supercharger but we spent the money on Lasik for my wife instead

So my question is: If I just switch the overdrive off and cruise, what is the max RPM I can safely cruise at for extended periods of time? I was thinking anything under 3500 but can I go higher? Is that to high?

What everyone's opinions?

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post #2 of 8 Old 11-14-2008, 06:40 PM
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You are asking what rpm you can safely drive at?

Anything up to the redline.



Um, you'll be going really fast even with a 1:1 ratio w/o over drive...you know that. right?



If you want gas mileage to be good, keep it under 2K - 2.5K

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post #3 of 8 Old 11-14-2008, 06:45 PM Thread Starter
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At 2500 RPM with 37's and 5.13's I'm only at 53.7 MPH which is a little slow for cruising on the freeway. I don't really care about mileage. I'm just wondering what would be safe to cruise at. At 75 MPH I'm at about 3500 RPM...so is it safe to cruise all day at 3500 RPM?
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post #4 of 8 Old 11-14-2008, 06:56 PM
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I have a similar setup, 37's w/5.13's but manual tranny. At 75 mph in 6th I am at 3000 rpm. To keep up with traffic on the long trips to CA I am commonly at 3300 rpm's for extended periods of about 2 hrs at a time. By then one of the kids or the Mrs. has to have a restroom break.

The Jeep seems to travel pretty nicely at 80 mph with the long arms now in place. It's just the mileage that seems to get exponentially worse the faster I travel.


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post #5 of 8 Old 11-14-2008, 07:36 PM
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Quote:
Originally Posted by medsker View Post
At 2500 RPM with 37's and 5.13's I'm only at 53.7 MPH which is a little slow for cruising on the freeway. I don't really care about mileage. I'm just wondering what would be safe to cruise at. At 75 MPH I'm at about 3500 RPM...so is it safe to cruise all day at 3500 RPM?
YES, As I said, anything under the redline is good...that's what its for...to tell you how high is too high.

That's why I mentioned the MPG...in case you cared, which you don't.



Obviously, the more rpm, the more wear and tear on the engine...but, in the mid-rpm range, you should be witin reason anyway.

Are you using a GPS to get the speed, or did you already recalibrate the speedometer?

- TEEJ

2008 JK 4 Dr X. 5 Speed, LSD, JKS QD, 3.73 Diffs. Husky Liners and Daystar Hood Wranglers. Pine Stripes.
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post #6 of 8 Old 11-14-2008, 08:00 PM Thread Starter
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Quote:
Originally Posted by TEEJ View Post
YES, As I said, anything under the redline is good...that's what its for...to tell you how high is too high.

That's why I mentioned the MPG...in case you cared, which you don't.



Obviously, the more rpm, the more wear and tear on the engine...but, in the mid-rpm range, you should be witin reason anyway.

Are you using a GPS to get the speed, or did you already recalibrate the speedometer?
I'm using a GPS and a Scanguage II set from the GPS

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post #7 of 8 Old 11-14-2008, 10:00 PM
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3500 RPM will be just fine with the 3.8 motor. My old TJ with a 4.0 3 speed auto (no overdrive) with 5.13s and 40" MTRs was turning 3200 RPM all the time on the highway.

To a point, higher RPMs are easier on an engine than low or idle. Better lubrication.

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post #8 of 8 Old 11-15-2008, 04:42 AM Thread Starter
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Thanks for the info guys, sounds like 3500 will be fine just get worse mileage.

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