engine upgrades

[amcamx]

I bought a used 2000 XJ for my daughter to use in college. After she graduated and had kids she decided the old XJ was too small so she was going to trade it in but I liked driving it so much I bought it from her. I've done a few upgrades to it but now the rear main oil seal is leaking so I'm going to pull the motor. While it is out I intend to rebuild it. What are the most common minor upgrades you can do to the 4.0? We don't have emission testing here so does removing the emission equipment from the motor help? Thanks

 

[dan1977p]

No need to pull the motor for a RMS replacement. Drop the oil pan, remove bearing cap, punch old seal out, punch new seal in, bolt up oil pan with new gasket. Check the oil pump pickup while its out.

 

[Anak]

The man to ask is Russ Pottenger:

Russ Pottenger
Bishop-Buehl Racing Engines
531 N. Lyall Avenue
West Covina, California 91790
Shop (626) 967-1000
Fax (626) 967-7836

The major upgrade is a stroker, but I expect Russ can tell you what is worth doing on a minor rebuild as well. He is the engine guru for these 4.0L tractor motors.

 

[smokeyyank]

The 4.0 really isn't a power builder platform with bolt on's, but the basics would be about the same with any NA engine. Here's some ideas.....

-4 pin fuel injectors are an easy swap, don't really net any HP but may help throttle response (did for me).
-Headers, since you don't have emissions you can ditch the stupid CA manifold with double cats.
-Replace the head as the 00-01 have problems with cracking. Can't remember everything off the top of my head but plenty of info on here.
-Get a more aggressive cam
-Get a intake manifold from a 99

 

[VAhasnoWAVES]

rear main is 2 piece, you can do it just by dropping the pan.

personally... i would do some diagnosis to see what kind of condition the motor is in. a leak down and compression test can tell you a lot. if the numbers look good, i wouldnt bother pulling it and tearing it into it. as said, the 4.slow isnt a giant power maker with bolt on stuff.

 

[RCP Phx]

Define your meaning of "up-grades"? There are several things that add reliability but net no value in performance!

 

[cherokeefan_1]

Edelbrock aluminum head

 

[Russ Pottenger]

rear main is 2 piece, you can do it just by dropping the pan.

personally... i would do some diagnosis to see what kind of condition the motor is in. a leak down and compression test can tell you a lot. if the numbers look good, i wouldnt bother pulling it and tearing it into it. as said, the 4.slow isnt a giant power maker with bolt on stuff.

X2,

If it passes a compression test I'd drop the pan and just do a rear main seal in the Jeep.
If you decide you want to go through the engine and not do a full Stroker 4.6/4.7 build there's a "Mini" stroker option utilizing a 3.500 stroke 232 crank.
That's based off of a low-cost cast piston 4.0 kit.

Feel free to call me if you have any questions or would like more information.

Russ

 

[ehall]

There isn't that much emission stuff on the 91-01 engines (no EGR or anything). You could replace the upstream O2 sensors with dummy plugs and open a wider selection of exhaust setups, that's about it for emissions.

Most of the performance mods are bolt-on, like bored throttle body, high-flow cat converter (eg Magnaflow), four-hole injectors, higher-voltage ignition coils, etc. That stuff will all make the car more responsive and feel stronger. There are also some aftermarket internals available, like roller rockers, performance cams, etc. Beyond that, there's no replacement for displacement

 

[cherokeefan_1]

There is a replacement for displacement, it's called boost.

 

[ehall]

boost is just another form of increased displacement

 

[blakews2217]

There is a replacement for displacement, it's called boost.

If he adds boost to it stock I see broken pistons and bent/ broke rods in the very near future. I'd love to get all my ducks in a row and find a forged rod/crank/ piston combo for my 4.7 stroker. I've herd they can take about 7 pounds stock but idk about it. Maybe Russ can point me to the forged stuff if he still looks here. I have plans for an eaton m90 and a hacked manifold and a hail tech. Maybe make more than 300ft/lbs at the crank and more like 450.


Sent from my iPhone using Tapatalk

 

[SolarBell]

I realize there are probably 1,001 folks that will disagree, but it's the internet so I'll say my piece and you can ignore or debate at will.

These are what I think helps power that are super simple and bolt-on for a 4.0, in my opinion of order. I believe they all work the best when used together versus one or two, since you want to increase efficiency all the way through.
- Cat-back exhaust. Magnaflow or such.
- Bored throttle body
- Cold air intake
- Air/Oil separator (not eBay, get Moroso)
- Option: Exhaust header (depending on year and emission requirements)

What I think doesn't help:
- Throttle body spacer
- Injectors
- 'Chips'

 

[VAhasnoWAVES]

I realize there are probably 1,001 folks that will disagree, but it's the internet so I'll say my piece and you can ignore or debate at will.

These are what I think helps power that are super simple and bolt-on for a 4.0, in my opinion of order. I believe they all work the best when used together versus one or two, since you want to increase efficiency all the way through.
- Cat-back exhaust. Magnaflow or such.
- Bored throttle body
- Cold air intake
- Air/Oil separator (not eBay, get Moroso)
- Option: Exhaust header (depending on year and emission requirements)

What I think doesn't help:
- Throttle body spacer
- Injectors
- 'Chips'

so, kind of my thinking... i would agree that these things make a difference, especially together, rather than alone, as you said. many i see as a must to get top performance out of a stroker build.

but HP per dollar? i feel like its a lot of money to put into a 4.0 for very little gain.

 

[SolarBell]

I guess. I could see a savvy shopper getting the top 4 items for under $500, and I would would be of the opinion they would get someone 20-30 HP (and some folks have done item-by-item research to reasonably back that up). Sure it's not stroker power, but it's still 1/4 of the cost for the common bolt-on mortal man. Someone could build a stroker for cheap money but that's not bolt-on.