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Unread 07-20-2010, 05:22 AM   #1
KJNewbs
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What's the right RPM?

The last manual trans I owned was an 87 Celica GT, which I could run to red on every gear and no worries. Last car I ownded before getting the Jeep was on '07 G35, auto - which had plenty of get up and go....

Now onto the JK, manual....I feel like if I go above 4k RPMs that I'm going to blow my engine up (even though it doesn't red line for awhile).

Question: Where are you all shifting at in your JK? Any advice or lesssons learned on shifting in general?

Cheers.

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Unread 07-20-2010, 05:27 AM   #2
RAZORBILL
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I guess I'm just an old slow guy, I shift between 2500-3000 rpms.
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Unread 07-20-2010, 05:31 AM   #3
Vin
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What have I learned?

1) If I keep my shifts around 2.5k I get around 20 mpg

2) She sounds really nice after 3k

3) If I'm shifting past 4k, I can watch my gas gauge move like my Tach in the opposite direction.

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Unread 07-20-2010, 06:41 AM   #4
Ravik
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The 3.8 seems to make the most torque at around 4k rpm - so when you shift really depends on what you're trying to do.

I agree completely with Vin - shifting at 2.5-3k seems to get the best mileage and shifting at the top of the torque band while heaps of fun, is much like pouring gas on the ground.

I have a 2dr Rubi manual, and I do a lot of up and down here in the mountains, so the 'lesson learned' from me would be - don't be afraid of RPM, going up a 6-7% grade, you'll be in 4th and hovering around 3.5-4k for the duration and getting about 16-18mpg.

The same is true going down hill, if you put it in 5th and set the cruise at 60, it'll just hang out at that speed due to compression without really using any gas. I can get 22-23mpg average (calculating the 16-18mpg to get to the top in the first place) on the down-hill sides of Vail or Loveland pass.
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Unread 07-20-2010, 07:22 AM   #5
KJNewbs
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Cool - yeah, i've been shifting right around 3k for my day-to-day driving. As I get up close to 4k, I guess I've just got to get used to the sound of the engine. Coming off of a rice burner with 306hp is a huge difference with the sound of the growl. Thanks guys.....
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Unread 07-20-2010, 07:57 AM   #6
Armycop
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http://www.hypertech.com/PerformanceGraphs/Dodge/52001_2007_2010_Jeep_Wrangler_3_8L_V6.pdf

According to the Hypertech Dyno results, looks like peak horsepower is in the 4500-5000 rpm range and peak torque is in the 3500-4000 rpm range.
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Unread 07-20-2010, 08:27 AM   #7
Chuck_Bullitt
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FWIW - normal around town driving, I shift between 3000 - 3500. Getting on the highway, I do 4000 - 4500, unless I really need to scoot...then I'll take it past 5000.
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Unread 07-20-2010, 08:48 AM   #8
fernjack
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If I'm just driving around with no particular place to go I generally shift at about 2500-3000 . If I have to get somewhere or enter traffic I'll shift anywhere up to about 5000 . It actually does growl a bit after 3000 and up but you can feel a bit of power after the 3000 mark .
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Unread 07-20-2010, 03:13 PM   #9
95Cherokee-
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So what do you guys figure the optimal RPM is for shifting to ensure the best MPG? Sitting in traffic when theres no rush, I might as well try and save some gas
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Unread 07-20-2010, 03:26 PM   #10
yukonmuscle
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2500 rpm i would say as long as its flat road
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Unread 07-20-2010, 09:26 PM   #11
fernjack
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Quote:
Originally Posted by yukonmuscle View Post
2500 rpm i would say as long as its flat road
Yup X2 on that ......get my best milage there .
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Unread 07-20-2010, 11:05 PM   #12
MilitaryJK4455
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So it really doesnt hurt to rev to motor close to the red line?
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Unread 07-20-2010, 11:14 PM   #13
fernjack
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Quote:
Originally Posted by MilitaryJK4455 View Post
So it really doesnt hurt to rev to motor close to the red line?
I can honestly say I have many times and with 65,000km+ on the clock my Rubi still runs smooth and quiet . I do over kill on my oil changes trying never to exceed 3000km even though I use synthetic oil and the Fram synthetic filtre . I was one time driving north for a job and had the tunes going had the JK in 5th at 4000rpm for about an hour before I realized what I was doing ....that was about two years ago ....still no ticking and smooth .....Just sayin' and that was about half way through a 9hr. drive north of Winnipeg past Thompson ........
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Unread 07-20-2010, 11:38 PM   #14
tennistom1
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It has a governor to prevent it from being over-reved doesn't it?
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6 speed , JK Wrangler , manual transmission , shift points , shifting , wrangler

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