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Old 08-27-2017, 07:14 PM
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3.8L power upgrade

Have a 2011 wrangler, all stock, with the 3.8L engine. Does OK at highway speed but seems to lack low-end torque. I do most 4-wheeling in sand and it bogs down pretty bad particulary in 2WD when the tires start digging. I've read quite a bit about upgrades and it seems a programmer may be the best option. Any opinions? I'd like to eventually put bigger tires on but not until I get some better low end power.

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Old 08-27-2017, 07:37 PM   #2
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It really depends on what you can afford and what your goals are for the change.

On the low end, are programmers. They can help you get a small amount more power by changing things like requiring premium unleaded. (Diablosport inTune seems to be the current programmer everyone is using from my experience.)

You can do things like change the axel ratio. While it doesn't give you more performance, it can dramatically change the performance to the wheels.

Then you start getting up to power adders. (Ignore the cold air intakes, they're junk IMHO). What I'm referring to are superchargers or other forced induction. Prices seem to be from about $3500 to about $6000 depending on manufacturer and options.

Then on the high end is an engine swap. This starts at about $15k and goes up from there. (Some claim to have done it cheaper then $15k, but I've not found anything 'easy' for less.)

(I have a 2011 as well, and just added a Sprintex Supercharger myself.)

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Old 08-27-2017, 08:19 PM   #3
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I wouldn't put money into a 3.8l unless you've got some other upgrades you want to keep... the 3.8 is a dog... that's just the hard facts of it...
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Old 08-27-2017, 09:12 PM   #4
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3.8 JK's need gearing. There's no way around it. If a 3.8 JK has 3.21's and an auto trans., that's a perfect storm for lack of performance.
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Old 08-27-2017, 09:58 PM   #5
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3.8L power upgrade

The 3.8L is a torquey engine but it is poorly geared right from the factory. There are NO 3.21 gears on a 3.8L auto.
For comparison, your 3.8L auto would require 4.10 gears just to match a 3.6L with 3.21 gears on factory tires.
So what does this tell us? You need gears first, then the programmer to dial it in.


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Old 08-28-2017, 06:43 AM   #6
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Yes, my mistake, manual only for 3.21 3.8's. With the old auto gearing is important as stated above.
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Old 08-28-2017, 12:55 PM
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Thanks for the input. Is the regearing only ring and pinion front and rear or spiders as well? I tore down the rear end in my 97 TJ and replaced bearings and seals so I have some knowledge of the gearing but have never messed with anything with traction control. Any advice?
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Old 08-28-2017, 03:13 PM   #8
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This thread should help: https://www.wranglerforum.com/f274/wh...ar-177534.html Traction control operates electronically through the braking system, including engine torque control.
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Old 08-29-2017, 09:24 PM   #9
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I went through the same conversation 8 months ago and decided to install a supercharger. As of today my jeep is still not running right but it looks like the dealership was able to figure it out.
First thing I would do is to regar. What size tires do you have?
I went to 4.88 with 35"s.
I have dumped enough money in my jeep to justify a LS swap so I would be extremely cautious about going the SC route.

Here are details on my project:
https://www.wranglerforum.com/f202/sp...l#post31218169
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Old 08-29-2017, 10:04 PM   #10
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Nmdriver, how much power did you get with the sprintex and in hindsight would it have been more cost effective to sell your rig and pick up a '12+ with the 3.6?
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Old 08-29-2017, 10:31 PM   #11
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Quote:
Originally Posted by Bbear17 View Post
Nmdriver, how much power did you get with the sprintex and in hindsight would it have been more cost effective to sell your rig and pick up a '12+ with the 3.6?
(I know I'm not Nmdriver... but I figured I'd respond with a positive story and not a horror story...)

I just installed a Sprintex w/o and w/ intercooler on my 2011 JKU Sahara w/ 6 Speed MT and 3.73 gearing.

W/o is makes a noticable difference.. w/ the intercooler wow.. I can accelerate up-hill at 80 MPH on the freeway in 6th gear! I was never able to do this before.

It took me about 6 hours to install the supercharger w/o intercooler.. then another 3 to install the intercooler. (I ended up doing it this way because they were shipped to me separately...)

My engine is fairly new though, I installed a reman engine in early July -- so I was already familiar with the parts and pieces and when I did this install I made sure I had an upgraded clutch since I was going to supercharger it.

So far I've had it a bit over a week and I'm -very- happy with the setup. Feels like a completely new Jeep!

Link to my install thread... https://www.wranglerforum.com/f202/sp...l-2121425.html
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Old 08-30-2017, 09:37 AM   #12
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Quote:
Originally Posted by Bbear17 View Post
Nmdriver, how much power did you get with the sprintex and in hindsight would it have been more cost effective to sell your rig and pick up a '12+ with the 3.6?
Hello.

I am still working through issues and the SC has since been removed. I really am hopeful that the faulty PCM will resolve my random engine misfire engine and then I will be able to tell a good story like mtahle.

Looking back I would not have sold and bought a 3.6 JK. The power difference is noticeable but for the money, I would have been better ahead with a entire engine conversion.

I would have wanted to buy new which would have put me at a difference of 20k and I am a bit skeptical to buy used not knowing the history.

I'll keep you posted on once I get the sprintex SC back on though!

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