Hello,

I just purchased my first jeep, its a 1999 Cherokee XJ with the 4.0. The guy i purchased this from swapped a Ford Supercoupe supercharger onto the engine, it is currently running 5psi boost, and the only supporting fuel mod is injectors from an LT1, should i swap it back to OEM, or should 5psi be safe? maybe i should add supporting mods?

 

If it ain't broke...

 

well, it spits and sputters some times, and just wanna know if i should just put it all back and sell off the kit, or just try to fix as is.

 

Fix it until it is?

 

The hardest part of doing a SC or turbo setup is tuning. I would say if it's working, leave it alone. If it isn't, and you'd like to keep it, better have a knowledgeable person, deep pockets and lots of time on your hands. Oh, and a spare vehicle if it's your daily.

Personally, I would take it off and sell it, and put that money towards other mods or maintenance that needs to be done. Less headaches. I personally have a stroker, and love it. If you want more ponies, a stroker or a swap is the way to go IMHO.

 

Bingo.

Good to see ya Wes...how's your wallet killer doing? Send me a PM...

 

That was kind of my thinking too, i do have a DD and this will only be used for trails and maybe sometimes hauling a small pop up camper, figure the more stock it is, the easier it is to fix things. Thanks for the input, it has a 6.5" lift so ill probably just sell off the SC kit to upgrade a few suspension parts because it rides like hell. PS. Any idea how much i should charge for the complete setup?

 

No idea, start looking at what components you have, make a list, then start looking around at some for sale to get a good idea on a price point. Just because somebody slapped a SC on your 4.0, doesn't mean it's worth anything. You have the right idea, though, KISS theory. Sounds like your time, effort, and money would be better spent on a suspension revamp anyways.

 

that air "filter" needs a revamp as well. Hate they hacked the hood up instead of doing a cowl intake.

looks like no intercooler either....

 

Also no a/c!!! Must not live in TX....lol

 

aint that the truth!!

 

Hey, hows your rig running out on 33s with the 3.55 gear set?

 

No hiway miles so its not that bad. I'm quick to drop it in 4-LO on the trail.

 

Only way to know if it's safe is to monitor FP to ensure it isn't dropping off and keep an eye on the A/F ratio. I think I read somewhere that the 4.0s like to run lean which isn't good for a FI set up.

In general, though, FI or nitrous on stock internals is a ticking time bomb.

I'll add that typically when going forced induction you would need a higher flowing fuel pump as well as bigger injectors and a custom tune

 

Jeep stock fuel pump is good to 325-350HP if it is not 'worn out'.

Stock internals are pretty stout.
-Head gasket good to 12 pounds boost
-pistons 14+ pounds boost if no detonation
-rods good to 450HP
-crank never seen one broken if not reved over 5100rpm

All is dependent on condition and wear/mileage of your stock parts.

4.0s do not run lean, 14.7AFR in closed loop, richer in open loop and WOT.