Looking to get more power out of my 99 XJ
03-03-2019, 12:45 PM
#1
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Model: Cherokee (XJ)
Looking to get more power out of my 99 XJ
I have a 99 Classic Xj with about 180 on the odometer. It still runs amazing and is almost completely stock but i’m wanting to get a huge power boost out of it, trying to get to somewhere in the 250-300 horse range (not adding 250 horse, but having that as the final product.) What options do i have? I know it’s hard to add power to the straight 6s without boosting or stroking, but i may be willing to do those if i have to. I know this may sound absurd, but I’m willing to put in the work and cash.
03-03-2019, 01:01 PM
#2
CF Veteran
For bolt on mods you can get the 4 or 12 hole injectors, 62 mm throttle body, an air intake, high flow header, and a 2.5" exhaust with a high flow muffler and cat delete if you don't have inspections where you live. Those mods may get you an extra 25-30 HP, anything beyond that will require a turbo or stroker build.
03-03-2019, 01:25 PM
#4
CF Veteran
I've done the 4.0 supercharged with an m90 and turbocharged. Turbo is the way to go. PM me if you want to go that route.
03-03-2019, 02:14 PM
#6
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03-04-2019, 10:45 AM
#8
Buy a Grand Cherokee SRT, then the only work you'll have to do is climb inside and push "Start".
https://www.youtube.com/watch?v=tk8h_rC-fVI
https://www.youtube.com/watch?v=tk8h_rC-fVI
03-04-2019, 11:10 AM
#9
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Join Date: May 2013
Location: Asheville, NC
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Year: 1999
Engine: 4.0
By almost completely stock, what do you mean? What size tire are you running? Do you need to regear?
My 99 has a somewhat decent amount of bolt ons (62mm throttle body, 784 injectors, gibsom header, 2.5" exhaust) and it pulls pretty hard for what it is. It's not fast, but it feels faster than it was when it was actually stock with much less miles. 4.11 gears, a manual trans, and skinny, light weight 33s help too. It will white-smoke 31s if desired...
If you want 250-300 crank horsepower, you'll need headwork at the least. I bet a 4.7 liter with an aluminum head and a 93 octane tune could make that much.
My 99 has a somewhat decent amount of bolt ons (62mm throttle body, 784 injectors, gibsom header, 2.5" exhaust) and it pulls pretty hard for what it is. It's not fast, but it feels faster than it was when it was actually stock with much less miles. 4.11 gears, a manual trans, and skinny, light weight 33s help too. It will white-smoke 31s if desired...
If you want 250-300 crank horsepower, you'll need headwork at the least. I bet a 4.7 liter with an aluminum head and a 93 octane tune could make that much.
03-04-2019, 02:47 PM
#10
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Join Date: Feb 2012
Location: Arlington, Texas
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Year: 1998
Model: Cherokee
Engine: 4.0
I'd love it if Mopar offered a crate 3.6 Pentastar and a 5-speed auto to put in an XJ. I have that combo in my '11 WK2 and it's great!
03-04-2019, 05:59 PM
#11
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Model: Cherokee (XJ)
By almost completely stock, what do you mean? What size tire are you running? Do you need to regear?
My 99 has a somewhat decent amount of bolt ons (62mm throttle body, 784 injectors, gibsom header, 2.5" exhaust) and it pulls pretty hard for what it is. It's not fast, but it feels faster than it was when it was actually stock with much less miles. 4.11 gears, a manual trans, and skinny, light weight 33s help too. It will white-smoke 31s if desired...
If you want 250-300 crank horsepower, you'll need headwork at the least. I bet a 4.7 liter with an aluminum head and a 93 octane tune could make that much.
My 99 has a somewhat decent amount of bolt ons (62mm throttle body, 784 injectors, gibsom header, 2.5" exhaust) and it pulls pretty hard for what it is. It's not fast, but it feels faster than it was when it was actually stock with much less miles. 4.11 gears, a manual trans, and skinny, light weight 33s help too. It will white-smoke 31s if desired...
If you want 250-300 crank horsepower, you'll need headwork at the least. I bet a 4.7 liter with an aluminum head and a 93 octane tune could make that much.
03-04-2019, 06:01 PM
#12
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Model: Cherokee (XJ)
For bolt on mods you can get the 4 or 12 hole injectors, 62 mm throttle body, an air intake, high flow header, and a 2.5" exhaust with a high flow muffler and cat delete if you don't have inspections where you live. Those mods may get you an extra 25-30 HP, anything beyond that will require a turbo or stroker build.
03-04-2019, 09:53 PM
#14
My guess is that the complaints are due to people beating the he!! out of them and then not properly maintaining them. There's nothing any more unreliable about them or the trackhawk over the typical GC.
03-04-2019, 10:08 PM
#15
Senior Member
having been a dealer tech you have to remember that people don’t bring their vehicles to you to brag how great they are .. they bring them to complain or get them repaired . The few that come in typically are far outweighed by the ones without issues . Unless it’s a 6.0 or 6.4 powerstroke we’re talking about haha in that case they’re all pretty worthless !
