4.0L performance upgrades? - JeepForum.com
 
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post #1 of 8 Old 08-06-2017, 07:05 PM Thread Starter
jjstrom
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4.0L performance upgrades?

So I thought the headgasket went on my 97 Grand Cherokee Laredo. I finally got the head off and found pistons #1&2 were cracked on the top. I found a replacement motor, but was thinking I might build a performance motor using the current block. So my question is how much can build one of these 4.0L motors and are there any good performance rebuild lots available. Thanks for you help and input.

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Last edited by jjstrom; 08-09-2017 at 08:43 AM.
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post #2 of 8 Old 08-07-2017, 01:51 PM
StanF
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There's no replacement for displacement:
http://www.jeepstrokers.com


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post #3 of 8 Old 08-09-2017, 06:10 AM
jeepdaddy2000
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Quote:
I finally got the head off and found cylinder #1&2 were cracked.
If the cylinders themselves are cracked, you're out of luck......

There are a ton of mods, ranging from mild to wild.
The first thing you need to determine is what application you are building for. A "drag" motor won't work worth a crap for DD'ing and mild wheeling, and a mild build won't perform as well if you are pulling or mud bogging.

You have to be realistic in you assessment.

Once you have figured out what you are building for, then you can look at putting together a build sheet of components that complement each other or choose a replacement engine.

Don't forget everybody's friend, the EPA.

bazinga
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post #4 of 8 Old 08-09-2017, 08:49 AM Thread Starter
jjstrom
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@ jeepdaddy2000 my Jeep will be a DD. It will also be my hunting rig, so it will also see logging roads and occasionally see light trail runs. I also had a typo in my original post. The top of piston 1&2 are cracked not the cylinder.

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post #5 of 8 Old 08-10-2017, 10:40 AM
jeepdaddy2000
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I owned a 95 GC with the 4.0 and felt it was more than adequate for my needs (DD + hunting and trips skiing).

I would suggest a mild (re)build. Try to keep close to stock with perhaps a small upgrade with the cam.

Your profile states a future lift, and I'm sure a corresponding tire size increase. Your money may be better spent on the gearing swap that will need to be done at that time.

If you are looking for some larger HP increases, you are going to need to spend some cash. I would suggest you peruse the ZJ section to see the different options, mow much they cost, the effort involved, and how the owners like them.

bazinga
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post #6 of 8 Old 08-10-2017, 10:46 AM Thread Starter
jjstrom
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@jeepdaddy2000 thank you this is the kind of info I'm looking for. I have a 17 ski/fishing boat I would like to possibly tow with it. Do you feel the stock motor would have enough umph to tow it fine. The lake is about 15/20 miles from the house, there are a few hills along the way and it's a 55 mph state Hwy. As for lift I'm only looking at a small 3".

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post #7 of 8 Old 08-11-2017, 06:13 AM
jeepdaddy2000
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The boat should be within the tow capacity of the rig (5000lbs).

The motor willpull it, however, as with anything, a 5.2 or the 5.7 are better choices for any heavier pulling. I have owned a 95 with the 4.0 and a 97 with the 5.2. I really liked the 6 over the 8 for just about everything, however when I towed (about 2500lbs), the larger engine made a difference. I live in southern Oregon and to get anywhere off the valley floor means a 2000 foot hill climb (going north means four passes). For me a 17 foot Ski boat would tax the 4.0 and wouldn't be my first option.

Some minor engine upgrades can help, but when looking at really pumping up the power, such as a stroker, personally, the money and effort is better spent on simply going to a V8.


If you decide to tow, I would suggest a complete transmission flush and cooler upgrade, as well as slapping some new oil in the rear diff.

bazinga
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post #8 of 8 Old 09-13-2017, 05:54 PM Thread Starter
jjstrom
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Ok so after some thinking I've decided that at this point I'm just going to put a used motor in it. I will rebuild the current motor, but will be a slight build staying mostly stock. Thanks for all you input
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