4.0 or 4.7 - JeepForum.com
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post #1 of 18 Old 01-13-2020, 07:13 PM Thread Starter
Byron30
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4.0 or 4.7

Shopping for new jeep wj. can’t decide if I should get one with the 4.0 or the 4.7 was hoping you guys can help me choose one.

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post #2 of 18 Old 01-13-2020, 07:32 PM
retrvrtrainer
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What do you have planned for it, daily driver...off road?

Matt 7:7-11
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post #3 of 18 Old 01-13-2020, 07:37 PM
paulvon
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The 4.0 had a reputation to go on forever.

At the same time the 4.7 is sensitive to abuse and has a reputation for dropping valve seat. Read up on this issue.

If you need extra power look at the 4.7, but not then the 4.0



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post #4 of 18 Old 01-13-2020, 08:34 PM
smokeyyank
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4.7HO or a 4.0 with a plan to swap axles and gears. 4.0 better engine but not my first choice for a lifted rig. 4.7 tons more power but not the best from a longevity/neediness standpoint.

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3" IRO lift, fastman TB, 32s, lunchbox rear 242HD, 3" exhaust
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post #5 of 18 Old 01-13-2020, 09:17 PM Thread Starter
Byron30
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Both but mostly daily driving
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post #6 of 18 Old 01-14-2020, 09:01 AM
Mattyjm
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I would recommend that you do plenty of research on your own and don't follow recommendations of opinionated people before making a choice.

If you don't know much about either engine, or complete powertrain packages offered with their respective engines, an opinionated forum thread is NOT the place to start your research.

2004 Special Edition WJ. LOADED!
2004 Rocky Mountain Edition. Froggy Bandit. Wife's Daily Driver. PRISTINE! Stock height and may stay that way.....
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post #7 of 18 Old 01-14-2020, 09:31 AM Thread Starter
Byron30
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I have 4.0 and have had a 4.7 I really like the 4.0. it is way more reliable but it doesn’t have enough power for me. do you know a simple and cheap way to get more power out of the 4.0?
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post #8 of 18 Old 01-14-2020, 11:35 AM
VNT
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I would buy whatever you find in decent condition
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post #9 of 18 Old 01-14-2020, 12:12 PM
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I chose to buy a wj with a "low" miles (100k) 4.0 because of the longevity/durability/reliability factor of that motor. My wheeling consists of rough forest service roads, so nothing hardcore for me.

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post #10 of 18 Old 01-14-2020, 02:39 PM
smokeyyank
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Quote:
Originally Posted by Byron30 View Post
I have 4.0 and have had a 4.7 I really like the 4.0. it is way more reliable but it doesn’t have enough power for me. do you know a simple and cheap way to get more power out of the 4.0?
Gears is the only way to cure the 4.slow in the WJ. Otherwise cheap and easy...... nitrous but that's not a good choice.......

04 WJ, 4.7HO
3" IRO lift, fastman TB, 32s, lunchbox rear 242HD, 3" exhaust
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post #11 of 18 Old 01-14-2020, 03:25 PM Thread Starter
Byron30
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What gear ratio should I change to?
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post #12 of 18 Old 01-14-2020, 03:45 PM
Wheelin98TJ
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I prefer the 4.7.

Quote:
Originally Posted by Byron30 View Post
What gear ratio should I change to?
Depends on the tire size.
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post #13 of 18 Old 01-14-2020, 04:56 PM
AVR2
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The 4.0 and 4.7 have almost the same awful MPG, but the 4.7 is way more fun to drive.

4.0 much more tolerant of abuse and easy to work on, but the 4.7 isn't as unreliable as often claimed. However, if you *do* get valve seat issues on the 4.7, then you can be looking at a complex and expensive fix.
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post #14 of 18 Old 01-14-2020, 06:08 PM Thread Starter
Byron30
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32 inch tires
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post #15 of 18 Old 01-14-2020, 09:44 PM
smokeyyank
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Check out the grimmjeeper.com. he had a great ratio calculator. Just going off my XJ I'd sy 4.56 or 4.11s. Will depend on what you need. I had 4.11s in my XJ with 33s and wish I had 4.56. I'm also at 7k+ elevation so that does make a difference.

04 WJ, 4.7HO
3" IRO lift, fastman TB, 32s, lunchbox rear 242HD, 3" exhaust
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