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Looking to get more power out of my 99 XJ

Old 03-03-2019, 12:45 PM
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Default 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 iím 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 itís 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 Iím willing to put in the work and cash.
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Old 03-03-2019, 01:01 PM
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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.
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Old 03-03-2019, 01:12 PM
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LS swap it ... or whatís already been mentioned ... or 4.7 stroker .
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Old 03-03-2019, 01:25 PM
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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.
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Old 03-03-2019, 02:00 PM
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Buy a Grand Cherokee SRT, then the only work you'll have to do is climb inside and push "Start".

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Old 03-03-2019, 02:14 PM
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Originally Posted by Turbo X_J View Post
Buy a Grand Cherokee SRT, then the only work you'll have to do is climb inside and push "Start".
But then he would have something that is expensive, unreliable and not as good off-road.
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Old 03-03-2019, 05:54 PM
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Originally Posted by 00t444e View Post
But then he would have something that is expensive, unreliable and not as good off-road.
?
The kid next door bought an '18 and let me take it out for a romp, as far as smiles per mile it's a freakin winner.
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Old 03-04-2019, 10:45 AM
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Originally Posted by Turbo X_J View Post
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
why stop there.,.. just get a trackhawk. trust me.. makes a great tow vehicle :-)
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Old 03-04-2019, 11:10 AM
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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.
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Old 03-04-2019, 02:47 PM
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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!
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Old 03-04-2019, 05:59 PM
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Originally Posted by Battle View Post
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.
Its a bone stock except for a cheap CAI. No lift no nothing. Wondering how much horse boltons actually give, with a good tuner/programmer I donít think theyíre as bad as everyone says. Hoping for some extra input.
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Old 03-04-2019, 06:01 PM
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Originally Posted by 00t444e View Post
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.
Thatís only an extra 20-30? Even with only those things thatís looking like a good $500+...
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Old 03-04-2019, 07:16 PM
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Originally Posted by Turbo X_J View Post
?
The kid next door bought an '18 and let me take it out for a romp, as far as smiles per mile it's a freakin winner.
i'm not a fan of them either..good friend of mine works at the local dealer and they get constant reliability complaints.
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Old 03-04-2019, 09:53 PM
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Originally Posted by Martlor13 View Post
i'm not a fan of them either..good friend of mine works at the local dealer and they get constant reliability complaints.
Not sure I agree I owned a '14 srt GC, not a single problem. Only reason I got rid of it was to get a track hawk.. also no problem. And I actually do track mine once in a while. Liked it so much, got my wife a durango srt ... not a single issue other than a blown directional bulb.

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.
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Old 03-04-2019, 10:08 PM
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Originally Posted by Martlor13 View Post
i'm not a fan of them either..good friend of mine works at the local dealer and they get constant reliability complaints.
having been a dealer tech you have to remember that people donít 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 itís a 6.0 or 6.4 powerstroke weíre talking about haha in that case theyíre all pretty worthless !
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