Intake and header upgrade do I need anything else

[P1atinum]

I am in the process of doing some performance upgrades on my 97’ I have a 99 intake, a 62mm TB, a K&N filter and an APN header. The jeep already has new exhaust from the cat back with a flowmaster 40 muffler.

To install what I already have do I need anything else? I have read different opinions on injectors and if I need a down pipe for the header.

After these upgrades what is reasonable for a next step on performance.

 

[j99xj]

Your injectors should be fine but I would suggest a larger head pipe. 2.25 inch is about right for your setup. You don't NEED the head pipe though, the APN hooks up to the old one fine.

 

[Beej]

Depending on your mileage, you might want to replace your sensors...

 

[beakie]

I have a 97, K&N, bored TB, 99 intake, Banks header and FM50 cat bak... each made a difference for the better. But the Banks didn't do much on its own, it needed the new head pipe to flow properly, I would say after putting this much time and effort into your new parts, get the head pipe and be done with it. Maybe $200 at Midas or a local shop, and it will make a dif, atleast it did in my case.

 

[Jack-U]

IMO, not adding a Hi-Flow Cat leaves a bottle neck in the middle of your exhaust system. I went Hi-Flow from the front to the back (except for the TB) and, latter, added a Cold Air Intake. I felt the biggest improvement, by far, with the CAI. I will, soon, add a bored TB and see what difference that makes. Besides sounding like having a 4 Barrel under the hood (which isn't all that bad), it seens to take less throttle curising on the hi-way and much better acceleration.

 

[beakie]

from past reading the stock cat on our rigs is rather hi-flow anyway, so any replacement shoudl be pretty hi-flow too, granted you'll want to make sure it is, but paying extra money for something that says "hi-flow" but doesn't flow anymore than a stock replacement isn't a grand idea either. just something to look into when doing this work.
one thing I forgot to mention before tho, if you get a new head pipe fabbed, be sure they take into account flexxing of the vehicle and drivetrain and such. when mine was first made they had it on a frame lift, so everything sagged, and when it was on the ground and I hit a bump the O2 sensor would rub on the front drive shaft because of how they put it on. bonus was a replacement 2 weeks after I got it... bad part was it was such a hack job, looks like something I put together, and if you knew me you'd know thats not good.

 

[P1atinum]

thanks all,

I will be doing everything but the down pipe this weekend, and next week drop it off at the muffler shop. The same place that did my muffler also told me the stock Cat was pretty high flowing and I wouldn't see much improvment by changing to a "highflow" cat and 2.5 exhaust. But that was with the stock intake and stock header. I'll have them check it and let me know with the improved intake and exhuast.

 

[Clean Racing]

thanks all,

I will be doing everything but the down pipe this weekend, and next week drop it off at the muffler shop. The same place that did my muffler also told me the stock Cat was pretty high flowing and I wouldn't see much improvment by changing to a "highflow" cat and 2.5 exhaust. But that was with the stock intake and stock header. I'll have them check it and let me know with the improved intake and exhuast.

Have them install a small flex pipe somewhere before the cat... This will help with not cracking the new header..

 

[Jack-U]

from past reading the stock cat on our rigs is rather hi-flow anyway,

My Cat was rattling so loud that people sitting next to me at a red light had to start yelling at each other (and they were all in the same car!!!:shocked: ) so I had to get it replaced anyhow. I also had the dreaded Header Crack so I decided to go from the Header-Back with Hi-Flow. Seeing that I have an HO engine I can see why I didn't see much improvement with the exhaust changes, but I did see/feel a big improvement when I added the CAI. I've been checking on eBay and found a sourse for a Bored TB, 63mm.

Question... What is the size of the opening (TB seat) on the Intake Manifold? I have a '96 4.0
One seller says it's (TB seat) is 62mm and another is Boring the TB to 63mm:confused1

Thanks, Jack

 

[Hellbent]

i have an "ebay" 63mm tb on my '96, it fits the intake opening exactly. in fact, it's so close that i had to leave the bolts loose and center the tb around the intake opening before tightening them down.

 

[Jack-U]

i have an "ebay" 63mm tb on my '96, it fits the intake opening exactly. in fact, it's so close that i had to leave the bolts loose and center the tb around the intake opening before tightening them down.

Thanks for the fast reply. Did the "New" TB make a difference? The eBay seller/Borer is "Extreme_fi", the cost of getting one is $89 + $15 S&H (plus Core Exchange). I was thinking of getting an eBay TB for Core Exchange so I'll still have my old one.

Jack

 

[xjh3]

Don't buy one, if your at all mechanically inclined it's easy to do yourself.

I did mine myself following Go-Jeep's Write-Up and was pleased with the results.

 

[Jack-U]

Don't buy one, if your at all mechanically inclined it's easy to do yourself.

I did mine myself following Go-Jeep's Write-Up and was pleased with the results.

Thanks for that info! I read the article about Boring (and his article about exhaust) and have found them both very interesting. I will also try "resetting" the computer as he stated and see if I get rid of that flat spot I got after installing a CAI. I might try changing the Header to the specs he suggested, but right now though, I need Rocker Sliders (which will be ordered in a day or so) from "Bullet13" on eBay. They're made in Colorado and are set up the way I want. Check him out. I pushed one of mine in (drivers side) :doh: this weekend wheeling at Rausch Creek Park in PA. WOW... I had a great time! and got lucky that the Rocker was only "pushed in" slightly and not "BENT UP", so no door problems :clap:

Thanks again... Jack

 

[xjh3]

No problem. TONS of good info on that site.

Some of the best mods are the ones you can do yourself for little to no money and some good old elbow grease.

 

[Hellbent]

i bought mine from that extreme_fi guy. it definitely made a difference in throttle response. for 89.00, and considering my lack of machining tools and skill, i consider it an excellent deal. the guy does a really nice job with his tb's.

 

[P1atinum]

I bought the same TB from E-bay, works great plus the DIY way you still have the stock butterfly plate, not a huge deal but deffinatly worth the money $89.00 vs Jeep down time to bore my own. The only issue I had with it was changing over my stock sensors to the bored TB, the "screws" were the torx type with the hole in the middle. since I didn't have one of these I had to make my own by taking a Torx bit and driling a hole in the center. I actually had to make two since I snapped the first one removing the screws. Loctite is a bitch.


Thanks for everyone input,
Everything went together without to many problems, the TB sensor issue being the bigest and it was really a matter of not having the right tool. Removing the manifolds was not an issue, all the bolts came out easy and were not as hard to reach as others have made it out to be. had to re-route some Vac lines with the 99 intake and extend the wires to one sensor.

Throttle responce seams to be much quicker, I still need to have a new head pipe installed and play around to notice the rest of the benfit.. What is the Est HP increase by these mods assuming the head pipe being done.

 

[jimgrms]

IMO, not adding a Hi-Flow Cat leaves a bottle neck in the middle of your exhaust system. I went Hi-Flow from the front to the back (except for the TB) and, latter, added a Cold Air Intake. I felt the biggest improvement, by far, with the CAI. I will, soon, add a bored TB and see what difference that makes. Besides sounding like having a 4 Barrel under the hood (which isn't all that bad), it seens to take less throttle curising on the hi-way and much better acceleration.

where would you get cold air from a eng comp in a xj

 

[Beej]

where would you get cold air from a eng comp in a xj

Like this:

http://www.jeep4.0performance.4mg.com/FIPK.html

 

[Dr. Dyno]

Ha ha, you haven't seen the latest version of my homebrew FIPK. Feast your eyes on these pics:

 

[Beej]

Angelfire doesn't like hotlinking...



If you put up the links to the page the pics are on, I can put them up for you...