Question for the JK peeps: Is the 3.8 good, bad or ugly?

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AZKJ

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With the 6-speed = BAD. My 4 cyl 5 speed '99 TJ was better.
 

ThunderbirdJunkie

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Don't listen to the 4.0 fanboys, the 3.8 is a fantastic engine. Perhaps a bit underpowered, but so have all the 6 cylinder Jeeps of the past...what...30 years?

Have seen plenty minivans where it served 200,000+ miles with soccer-mom-type (aka zero) maintenance with lackadaisical oil change intervals, and have seen a TON of them with 300k+ that are awesome.

ITBJHO, the KJ would have been better with the 3.8 than the 3.7. He is a 3.8 Mopar fanboy.
Also, valve cover gaskets...that's about it. Nice thing about the JK, unlike the minivans, is you don't have to pull the friggin plenum to do them :D
 

sharpy

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i love my libby!! i think the 3.8 has great power. and based on the number of libby;s i see around here i am not alone!!!(attn)
 

Inc

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The 3.8 is underpowered to say the least, but AEV sells a programmer and it is supposed to be amazing. It will never be a hotrod, at least without doing a Hemi swap, but with the AEV setup, it turns it into what it should have been from the factory. Otherwise, it is underpowered just like the previous I6s out there, but maybe a bit more so because of the extra weight in the JK.
 

sharpy

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lol!! ok then.. i luve the 3.7 it has great power!!
sory i had a brain fartpeepwall.gif

jk jkj cj kk whatevaaaa!!!:D
 

J-Thompson

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my .02 not enough power
why I say it
my TJ with the TF999 and I6 and 3.73's with 32's locked front and rear
climbed the hill with ease ,all be it spinning all 4 tires most of the way up I still made it and did not stall
2 door JK running oem size MT's ,sport with Rubi rims and tires
auto and 3.73's ,also only 2wd as it has 1 front and 1 rear to spin
the wonderful 3.8 could hardly get the wheels to spin after it stalled under load
and yes it was in 4wd low
now when it would make enough power it was cranking out 5000 rpms making the thing bounce off of the trees

so I will never be a fan
unless you could run 4.88's with 33 in them because the top gear was so big
 

ATXKJ

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There's a reason that Hemi swaps are popular - even if they are expensive
 

benny

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With the correct gearing for your tire and suspension setup, and a 6 speed ****** like I have, you will find you have enough power to get the job done.
The 3.8 is a fine motor. The people that do the HEMI swaps will be spending more money on broken parts along the way as well. This alone makes the HEMI swap pointless.
You put a stock JK and a stock TJ (x vs x) or (rubi. vs rubi.) and the TJ will never out climb or out crawl the JK. It's as simple as that.
 

benny

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my .02 not enough power
why I say it
my TJ with the TF999 and I6 and 3.73's with 32's locked front and rear
climbed the hill with ease ,all be it spinning all 4 tires most of the way up I still made it and did not stall
2 door JK running oem size MT's ,sport with Rubi rims and tires
auto and 3.73's ,also only 2wd as it has 1 front and 1 rear to spin
the wonderful 3.8 could hardly get the wheels to spin after it stalled under load
and yes it was in 4wd low
now when it would make enough power it was cranking out 5000 rpms making the thing bounce off of the trees

so I will never be a fan
unless you could run 4.88's with 33 in them because the top gear was so big

You are comparing a Jeep with lockers vs. one without. Equal equipment vs. equal equipment and the outcome will be different.
There are too many videos showing stock JKs climbing very steep hills without any problems. Sometimes you have to blame the driver and not the JEEP. my.02
 

incommando

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This is kind of funny. My '81 350/auto C30 Crew Cab Chevy had 145 hp. I pulled a 4,300# car on a 2,000# trailer. GCVW was probably around 12,000 #'s.

Most V8's for 10-15 years had 50 less hp than the 3.8. Check out an early 80's vette, Z28, or Mustang.

Yes, torque is the more important # that must people ignore, but still......

I think that some of the "feel" of less power is 1.) engine controls altering the power delivery and 2.) people not realizing that different power curves , like from an I6 to a V6, will require different gearing or at least different driving styles to optimize.
 

JTPhotoJK

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I guess it depends on what you are use to. It certainly is not a sportscar but then thats not what I bought it for. I run the Sahara Unlimited A/T with 3:73 and 35's and have no power issues during my commute 60-70 miles a day on the highway. I've had no problems and have been trouble free for + 50K.. Its just that any 6cyl is not going to have the torque to pull hills like an 8cyl.
The only thing minivan about the 3.8 is the design. The block is cast not aluminum and the powerband is totally different.
The ultimate set up if you want more power for the 3.8 is Superchips Flashpaq programmer and 5:13 gears( for 35" ), a Supercharger, or a Hemi conversion.
General consensus is that cold air intakes and throttlebody spacers are a waste of money.
If you plan on staying with 33" tires 4:88 gears will be best.
It is important to note that you must reprogram the computer to compensate for gear and tire size changes or the engine will feel sluggish.

If you were to compare the power/torque curves between the I6 and the 3.8v6 you would see hoe the 3.8 totally outperforms the 4.0L I6.
 
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