Recently bought a 2011 wrangler sahara 2 door manual trans. stock 18inch wheels and tires. I am disapointed in the performance ,the engine seems to run out of power around 3500 rpm, this is most noticeable on acceleration not much there after 3500 rpm. Have 2 other jeeps one 4.0 runs great to around 4800/5000 rpm,one 4 cyl will pull good to the rev limiter(not a lot of power anywhere). Is this typical for the 3.8 engine. thanks
Well the 3.8 isn't known for its power from the get go. The other jeeps were 1k lighter. However not knowing the mileage and condition of your jeep I would recommend a tune up and fluid change. May add a little pep and mpgs. Also depends on your gearing as well. You may have the 3.21s which didn't help acceleration. Good luck.
Peak torque is 4k and peak hp is 5k. Most performance complaints come from 4door automatics, I never felt the need for more power on stock wheels with 3.73.
If you have 3.21's that's the problem. Having the manual trans. is a plus when you have a 3.8. If you have 3.73's there shouldn't be much of an issue unless it's some other mechanical problem, ie. tune up, etc. I have a 2 dr. 3.8 with a manual trans. and 4.10's and I have no complaints, primarily due to the gearing. If you had a 4 dr. JK with a 3.8, auto trans and 3.21's, you would have a perfect storm for lack of performance.
Thanks for the quick replys.I will check into the gearing, it has 65000 aprox miles.Is the ratio on a tag or stamped on the axel tubes or where should I look? Thanks
I have a 2008 2DR JK with the 3.8L. I use a Superchips performance tuner on 91 octane tune with stock throttle response. It improves the performance and low end torque a little bit. I also have 4.10 gears (rubicon edition) so I'm sure that helps too. I rarely if ever go above 4k rpm and usually always stay below 3.5k rpm. The 3.8L just doesn't have much above 3.5k rpm.
Thanks for info,will check out site.Green Rubi's comments on how his jeep runs sounds a lot like the way mine runs. Why would Chrysler build a modern engine that runs no better than this?
You have a good set-up. Other than having a 2010 2dr. manual Rubicon with 4.10's, you have the next best stock set-up having a 2dr. manual as far as getting as much performance out of a 3.8.
I have basically the same in a 2010. I do have 3.73's with stock size 17" wheels. Same overall size as stock 18's. I've had the older 4.0's in the past and wouldn't go back. The 3.8 has more power than the 4.0, but is in a vehicle almost 1,000 lbs heavier. The newer 3.6 does a better job of compensating for the extra weight, but I have no power issues with mine staying with 32-33" tires. I feel the power is about the same as the 3.6 when using 35" tires all else being equal.
Both the 3.8 and 3.6 get their torque at much higher rpm's than the 4.0. This is a disadvantage with both, but is less noticeable with automatic transmissions and can be compensated for once you get used to it with a manual.
Why do you need 4000-5000 rpm? I rarely get over 2500 rpm and 3000 is about as much as I've ever needed.
I have basically the same in a 2010. I do have 3.73's with stock size 17" wheels. Same overall size as stock 18's. I've had the older 4.0's in the past and wouldn't go back. The 3.8 has more power than the 4.0, but is in a vehicle almost 1,000 lbs heavier. The newer 3.6 does a better job of compensating for the extra weight, but I have no power issues with mine staying with 32-33" tires. I feel the power is about the same as the 3.6 when using 35" tires all else being equal. Both the 3.8 and 3.6 get their torque at much higher rpm's than the 4.0. This is a disadvantage with both, but is less noticeable with automatic transmissions and can be compensated for once you get used to it with a manual. Why do you need 4000-5000 rpm? I rarely get over 2500 rpm and 3000 is about as much as I've ever needed.
Thanks for the input.I do most of my offroading in soft sand on the NC coast,most any 4x4 can dig its way along in 4low but speed works to help things.So the need for higher rpms, I normaly run in 4high,the jeep runs out of power around 3000/3500 in 1st gear not fast enough to shift to 2nd this is why I would like a little more useable rpms.
You really should be using 4L and airing down your tires, especially since you're running stock tires. On sand, speed doesn't work as well. Slow and steady works best. You can only get so much out of any JK engine, whether it's a 3.8 or 3.6. Do a search and check how other Jk owners run in sand. There might be some helpful tips that will solve your problem. Good luck.
That could be the issue, unfamiliarity with modern vehicles. I agree with 4H in sand. Wheel speed and momentum are your friend's. Are you aware oh how the ESC system works? That is what is killing your power in 4H. You need to turn it off. With the engine running and TC in 4H, hold the button for 5 seconds until you hear the ding and see the readout on your dash say ESC OFF. It is automatically off in 4L and that is why most people will recommend 4L. The system will sense a spinning wheel and thinking you are sliding, will aply the brake to that wheel, transferring power to the other. When the other spins you will simply bog down and it will feel like all your power is being sapped.
I have a 3.8 with 35's on my Jeep and have tons of power, no complaints on the engine. I do have a Rubi so I have 4.10 gears with a manual transmission so that probably makes a huge difference. The 3.8 loves to run at about 2300 RPM when cruising. I'm confused why you are at 3,500 + RPM, that's way to high, you should be shifting at 3000 RPM
I think we have moved away from the original question (,power output of the 3.8)and have moved to my driving.Thanks for all the info and opinions. In driving it seems the 3.8 power falls off above 3500 rpm, don't understand this in a modern engine with a max torque output at 4000 rpm,it should pull strong to the max horse power output around 5000. I think the off road problems are traction control caused and the other performance issues from the computer controled throtle .Will continue to research these ideas.
You should consider a performance upgrade. Have you looked at turbo or supercharger as an option? Turbos have more HP and torque than the SC's and work awesome with the manual transmission. A Jeep buddy put on a Prodigy turbo on his 2010 4 dr manual and the difference was unbelievable. Costly, but solves the issue of lack of power. Can't get over the performance difference on the highway.
I have been researching this lack of power in the 3.8,I think it is a computer caused problem. The 3.8 will never be a power house but it should work better than it does.The computer controls everything on this engine ,throtle opening,timing,fuel mixture so it controls power out put.So this would explain the 3500 rpm power falloff.The 3.8 should pull strong at least to the torque peak and really on to the horse power power peak.This seems to be a more advanced type of torque management used on some of the earlier chryslers.I have no answers or fixes for this,wish I did . Thanks
I have been researching this lack of power in the 3.8,I think it is a computer caused problem. The 3.8 will never be a power house but it should work better than it does.The computer controls everything on this engine ,throtle opening,timing,fuel mixture so it controls power out put.So this would explain the 3500 rpm power falloff.The 3.8 should pull strong at least to the torque peak and really on to the horse power power peak.This seems to be a more advanced type of torque management used on some of the earlier chryslers.I have no answers or fixes for this,wish I did . Thanks
I use the superchip flashpak on my 2010 jk rubi. The 93 tune makes a very noticeable difference to me. I get better gas mileage on the highway to more than make up the difference in extra cost of premium fuel. Least expensive solution.
Thanks,I understand how the traction control works,and I agree with you,the traction control makes deep sand almost impossible.With it off does the engine still tend to run out of power around 3000 /3500 rpms or does it fix that also. I am looking in to turning it off using the method in the owners manual(turn steering,hold button etc). I will try your way and see how it works.
Before I put the Hemi in my 07 Rubi, I used the Bullydog tuner. It lets you turn your ESC off with the touch of a button. It also gives more power out of the 3.8. I was satisfided with the power off road. But I drive on the hyway alot and even with the Bullydog the 3.8 didn't have the power I wanted.
If you just stuff a Hemi in there you will have power to spare.:iamhappy:
I would love to,but over budget,the engine they should have came with. Thanks
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
Ask a question
Ask a question
Jeep Wrangler Forum
9M posts
468K members
Since 2005
A forum community dedicated to Jeep Wrangler owners and enthusiasts. Come join the discussion about reviews, performance, trail riding, gear, suspension, tires, classifieds, troubleshooting, maintenance, for all JL, JT, JK, TJ, YJ, and CJ models!