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Old 03-04-2012, 09:05 PM   #1
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motor question

I am sure this has been brought up before. I have a 2011 jeep wrangler unlimited with the v6 I wanted the 2012 but I got such a good deal on the 11 , I could not see paying a extra 15,00 for the 12.
So my question is what is my best way to get more power and acceleration out the jeep ? If someone could list in order of importance that would be very helpful.
I do not understand how jeep could put such a dog motor in this thing its driving me mad
Thanks
Dave

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Old 03-04-2012, 09:12 PM   #2
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Best bang for your buck is going to be a supercharger.

Do you have a lift and larger tires/wheels or is it stock? Manual or automatic transmission?

If you are lifted with larger tires/wheels and especially with an automatic the best thing you can do to begin with is re-gear. In my opinion the automatic equiped JKs came from the factory with the wrong gearing.

Mike.

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Old 03-04-2012, 09:30 PM   #3
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Quote:
Originally Posted by krumby View Post
I am sure this has been brought up before. I have a 2011 jeep wrangler unlimited with the v6 I wanted the 2012 but I got such a good deal on the 11 , I could not see paying a extra 15,00 for the 12.
So my question is what is my best way to get more power and acceleration out the jeep ? If someone could list in order of importance that would be very helpful.
I do not understand how jeep could put such a dog motor in this thing its driving me mad
Thanks
Dave
It's not a dog of a motor, it's just under-geared. Your best option is probably to re-gear. Others who really know the subject will come along to help you more than I can.....
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Old 03-04-2012, 09:32 PM   #4
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Quote:
Originally Posted by Up Hill Bill

It's not a dog of a motor, it's just under-geared. Your best option is probably to re-gear. Others who really know the subject will come along to help you more than I can.....
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Old 03-04-2012, 09:50 PM   #5
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Quote:
Originally Posted by zmotorsports View Post
Best bang for your buck is going to be a supercharger.

Do you have a lift and larger tires/wheels or is it stock? Manual or automatic transmission?

If you are lifted with larger tires/wheels and especially with an automatic the best thing you can do to begin with is re-gear. In my opinion the automatic equiped JKs came from the factory with the wrong gearing.

Mike.
I'm with Z.

Here are some links to supercharger threads:

RIPP and tranny cooler installed!!!
Supercharger!! Anyone done it


RIPP is the most popular with Jeepers, but there are others. And the regearing is practically a must if you really want more oomph outta your rig.
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Old 03-04-2012, 09:55 PM   #6
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Should have paid the extra $1500, most likely cheaper than any other options.
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Old 03-04-2012, 09:58 PM   #7
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This will help give you an idea of what regearing can do for you.

Gear Ratio Calculator

NOTE: These are the input values for a 2008 jeep jk manual transmission. To use the calculator, input the values for your ’11 (manual or auto), and do the following:

(Put 6 in # of forward gears) then fill out the ratios as follows:

4.4 in first, 2.6 in second, 1.7 in third, 1.2 in fourth, 1.0 in fifth and 0.8 in sixth. (don’t need reverse for the chart.)

Transfer case is either NV241 or NV241OR (I tried both just a minute ago, and it hardly changed a thing in terms of the calculated mph/rpms.)...select either of these from the pull-down menu under 'Transfer Case Values'.

Fill in the gears you have, or are thinking of getting, etc.

Fill in the tire size in inches (fill in ACTUAL size, not what the mfr claims...i.e. my tires are 35’s, but are actually 34”).

Once you hit the "calculate" button, scroll all the way to the last fields, where it will give you your rpms @ a given speed, etc. Any time you change something on the chart (rpm, speed, etc) you need to hit calculate again.
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Old 03-05-2012, 07:13 AM   #8
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The 3.8 engine is not a bad engine. It is a little anemic for the 4-door especially when you start adding lift and weight. The 2-doors it seems to be a little snappier and more responsive in but then again there is about a thousand pounds difference between the two.

The 4.0 is one of the most beloved engines in the Jeep lineup and it was rated at 190 hp and 225 ft./lbs of torque compared to the 3.8 V6 that is 205 hp and 237 ft./lbs. of torque. It is merely a higher RPM where these numbers are obtained. I would say this engine probably needs to be roughly 750 RPM higher to "feel" the same as the I6 4.0.

The automatic version is definately not geared proplerly from the factory. Get that corrected and it is not bad.

I wish I had more HP but then again I have never had a vehicle where I had enough. That said, after re-gearing mine it felt like a different vehicle.

Mike.
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Old 03-05-2012, 07:17 AM   #9
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Quote:
Originally Posted by kbwwolf View Post
This will help give you an idea of what regearing can do for you.

Gear Ratio Calculator

NOTE: These are the input values for a 2008 jeep jk manual transmission. To use the calculator, input the values for your ’11 (manual or auto), and do the following:

(Put 6 in # of forward gears) then fill out the ratios as follows:

4.4 in first, 2.6 in second, 1.7 in third, 1.2 in fourth, 1.0 in fifth and 0.8 in sixth. (don’t need reverse for the chart.)

Transfer case is either NV241 or NV241OR (I tried both just a minute ago, and it hardly changed a thing in terms of the calculated mph/rpms.)...select either of these from the pull-down menu under 'Transfer Case Values'.

Fill in the gears you have, or are thinking of getting, etc.

Fill in the tire size in inches (fill in ACTUAL size, not what the mfr claims...i.e. my tires are 35’s, but are actually 34”).

Once you hit the "calculate" button, scroll all the way to the last fields, where it will give you your rpms @ a given speed, etc. Any time you change something on the chart (rpm, speed, etc) you need to hit calculate again.

That definately makes it slick. I still calculate mine the old fashioned way using the following formula:

MPH = (rpm x tire diameter) / (gear ratio x 336)

RPM = (mph x gear ratio x 336) / tire daimeter

The online calculators and the charts work great but I guess I am still old school.

Mike.
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Old 03-05-2012, 08:36 AM   #10
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Auto/manual/Sport/Ruby-it all makes a difference on the differential gearing--


Quote:
Originally Posted by krumby View Post
I am sure this has been brought up before. I have a 2011 jeep wrangler unlimited with the v6 I wanted the 2012 but I got such a good deal on the 11 , I could not see paying a extra 15,00 for the 12.
So my question is what is my best way to get more power and acceleration out the jeep ? If someone could list in order of importance that would be very helpful.
I do not understand how jeep could put such a dog motor in this thing its driving me mad
Thanks
Dave
If you just got the JKU--if you have a RIPP/AVENGER/Sprint SC involved--you'll lose 90% of any warranty you got--

If you regear at 1/3 the cost you'll get a 20/30% increase in APPLIED HORSEPOWER and increased throttle response--immediate passing power and better gas mileage-

Manual tranny-get 4.88 YUKON gears--

Auto tranny-get 5.13/5.38 YUKON gears--

Good luck-

JIMBO
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Old 03-05-2012, 11:59 AM   #11
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Motor question

THANK YOU FOR ALL YOUR ANSWERS EVERYONE. I meant 15,000 not 1500.00 i would have gotten the 12 then.
will a gearing change make that much of a difference to acceleration ? I have the stock tires for now I will upgrade to 33's when they are worn out. this is a 4 door too.
I love the idea of a supercharger but the cost etc is too much.there is no computer chip or anything else ?? does exhaust and a intake really make any difference ? My main complaint is acceleration its so sluggish in passing etc.
thank again for the help
dave
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Old 03-05-2012, 12:10 PM   #12
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You can try a "Superchip? for an interim increase in performance, but



Quote:
Originally Posted by krumby View Post
THANK YOU FOR ALL YOUR ANSWERS EVERYONE. I meant 15,000 not 1500.00 i would have gotten the 12 then.
will a gearing change make that much of a difference to acceleration ? I have the stock tires for now I will upgrade to 33's when they are worn out. this is a 4 door too.
I love the idea of a supercharger but the cost etc is too much.there is no computer chip or anything else ?? does exhaust and a intake really make any difference ? My main complaint is acceleration its so sluggish in passing etc.
thank again for the help
dave
Other than a regearing--nothing else will increase your JKU's performance and regearing will make a SUBSTANCIAL change-especially in acceleration, if you have an auto !

JIMBO
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Old 03-05-2012, 12:16 PM   #13
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Quote:
Originally Posted by JIMBOX View Post
Auto/manual/Sport/Ruby-it all makes a difference on the differential gearing--




If you just got the JKU--if you have a RIPP/AVENGER/Sprint SC involved--you'll lose 90% of any warranty you got--

If you regear at 1/3 the cost you'll get a 20/30% increase in APPLIED HORSEPOWER and increased throttle response--immediate passing power and better gas mileage-

Manual tranny-get 4.88 YUKON gears--

Auto tranny-get 5.13/5.38 YUKON gears--

Good luck-

JIMBO


^^^ This is the definitive answer from a Jeeper speaking from his own experience doing this with his own rig.

If you regear, you'll be telling others it's the answer for the 3.8L

If you do chips, exhaust, intake, etc., you'll be back asking the same question again.

JMO....
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Old 03-05-2012, 12:17 PM   #14
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Quote:
Originally Posted by kjeeper10

This X 100 +1 (JIMBOX)
And like I said lol

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Old 03-05-2012, 12:31 PM   #15
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Quote:
Originally Posted by krumby View Post
THANK YOU FOR ALL YOUR ANSWERS EVERYONE. I meant 15,000 not 1500.00 i would have gotten the 12 then.
will a gearing change make that much of a difference to acceleration ? I have the stock tires for now I will upgrade to 33's when they are worn out. this is a 4 door too.
I love the idea of a supercharger but the cost etc is too much.there is no computer chip or anything else ?? does exhaust and a intake really make any difference ? My main complaint is acceleration its so sluggish in passing etc.
thank again for the help
dave
If you have an auto transmission, the answer--as has been stated--is a regear. Figure $1200 to $2000. Don't waste your time with chips, exhausts, etc. If it's a manual transmission, you're just upshifting too soon. Keep it in a lower gear longer and you'll get more power to the wheels.
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Old 03-05-2012, 12:47 PM   #16
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Thanx guys, but

We gotta remember, that as great as out technology gets (ECM/CHIPS/Throttle-by-wire)--we still gotta mechanical connection to the ground !!

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Old 03-05-2012, 02:42 PM   #17
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Keep in mind a tuner is not available at the current time for the 2011 (or 2012) model years. As far as a cold air intake (CAI) and exhaust, they will help but I doubt you will feel anything as far as performance goes. The Jeep 3.8 engine is a speed/density system so you may see something on a dyno but seat of the pants feeling is not going to happen.

That said, I installed an AFE cold air intake and a MBRP exhaust system on mine but I did it knowing I would not get the gains of a MAF engine. I like getting more air in the engine and I wanted the throatier sounding exhaust.

Getting the proper gearing (mechanical leverage) is the best bang for your buck to start with.

Mike.

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