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intake swap + tb + tb spacer .....

Purple

Purple

NAXJA Forum User
Location
Mississauga, Ontario, Canada
Hey Guys, just have a quick question... i will be doing my 99+ intake swap onto my 98 XJ ... also a 62mm Throttle body and a spacer for it ...what gains do you think should i expect with all these?
I will not be changing my exhaust YET... i know it does not make sense to do all these without an exhaust...but exhaust will have to wait another month...
anyway... what do you think ... ? with and without exhaust?
 
It's hard to give an accurate number. Unless you have access to a dyno they don't mean too much. Do the swap then use the trusty seat-of-your-pants dyno to figure if your happy with it.
 
I just did a K&N FIPK II and Fastman 62mm throttle body, I am impressed by the gains and can't keep my foot off the skinny pedal because of it. But I cannot fit a TB spacer with my set-up... nor do I want to after reading about them on this site.

I can't wait until my exhaust is on this weekend... the skinny pedal will become the stupid pedal. haha Oh well, I'm just happy the Jeep has some kick in her step again.
 
8hp... hmmm... will i even notice that? when i bought my 98 xj the cat was shot, they said everything fell apart inside of it, when they installed a new one, for emissions etc... i have noticed a lot of power lost.. .. it ran better with the broken cat:) i figured i need a free flow cat now? that 8 HP was that without the exhaust or with everything bolted on.....
if thats with all these mods on my engine, im starting to think if thats even worth it...
 
From what I have heard, the stock cat. is fairly free flowing to begin with. Obviously it isn't as free flowing as a completely rusted out cat. like you had before, but you probably wont be able to find one that is much better. The main problem with the stock exhaust system on XJ's is the factory pinch on the header. Get a new header, and you should get some hp gain.
 
Like with most intake/exhaust upgrades, increasing one will be hampered by inefficiencies in the other. With the intake mods alone, you may get only 8 hp. With exhaust mods alone, maybe only 5. With a header, maybe only 5. This is because the exhaust cannot fully handle the intake upgrade, or the intake cannot handle the exhaust upgrade. Upgrading your intake now will help you yield more significant gains when you add a header, cat-back, etc. The 8 hp gain now may be a 15 hp gain in the future.
 
Purple said:
8hp... hmmm... will i even notice that? when i bought my 98 xj the cat was shot, they said everything fell apart inside of it, when they installed a new one, for emissions etc... i have noticed a lot of power lost.. .. it ran better with the broken cat:) i figured i need a free flow cat now? that 8 HP was that without the exhaust or with everything bolted on.....
if thats with all these mods on my engine, im starting to think if thats even worth it...
Click to expand...

If you're planning on doing more mods then go for it. 8-10 hp isn't a whole lot, but remember torque is far more important under 5000rpm than hp. I think that the swap will raise the motors powerband across the range. The 99+ intake and the TB will provide a nice platform to start squeezing more power out of the motor as other mods come. I wouldn't throw down the cash for the spacer unless you can get one cheap. Along with a better exhaust you should be very happy with the results:) Good luck

FUNKYTEE5
 
lol... you see....with the spacer i was going to install just that and the tb... but then a tb with an intake and sensors from a 99 xj came up on ebay... bought that for 100$ .... few days ago i have noticed that my exhaust is starting to have more than one outlet.... thats why i decided to get a full exhaust and a header, my only other concern is which type of header to get. Yes i did search and i followed couple of posts etc... and basicaly none of the poeople who installed headers on their 97+ 4L were "thrilled" about it, most said that they did not feel any difference... or maybe noitce some difference which was marginal... the only guy that said he fealt difference was an owner of Doug Throrley header - that was the only one i was considering.

i have a k&n filter now and i felt the difference when i installed and floored it for the first time. I run 31s with stock 3.55 gears. Im not yet ready to do gears.
 
Purple said:
lol... you see....with the spacer i was going to install just that and the tb... but then a tb with an intake and sensors from a 99 xj came up on ebay... bought that for 100$ .... few days ago i have noticed that my exhaust is starting to have more than one outlet.... thats why i decided to get a full exhaust and a header, my only other concern is which type of header to get. Yes i did search and i followed couple of posts etc... and basicaly none of the poeople who installed headers on their 97+ 4L were "thrilled" about it, most said that they did not feel any difference... or maybe noitce some difference which was marginal... the only guy that said he fealt difference was an owner of Doug Throrley header - that was the only one i was considering.

i have a k&n filter now and i felt the difference when i installed and floored it for the first time. I run 31s with stock 3.55 gears. Im not yet ready to do gears.
Click to expand...

Late model XJ's seem to have very good flowing factory headers. You could probably get by without the header and throw some of that cash towards other mods that'll make gains (fuel, intake,headwork, cam? etc...). I personally didn't feel much between stock header/Borla header on my 93. The older style exhaust manifold probably flows worse than yours too. But again the only thing i noticed was a different exhaust note and maybe a tiny bit on the top end. By the way i have 2.5 mandrel bent from header out:)

FUNKYTEE5
 
Where is a good place to order these mike Leach headers? from looking at the pic, these could also work for dual exhaust, right? but then two cats two mufflers etc..
 
xj_chris said:
I just did a K&N FIPK II and Fastman 62mm throttle body, I am impressed by the gains and can't keep my foot off the skinny pedal because of it. But I cannot fit a TB spacer with my set-up... nor do I want to after reading about them on this site.

I can't wait until my exhaust is on this weekend... the skinny pedal will become the stupid pedal. haha Oh well, I'm just happy the Jeep has some kick in her step again.
Click to expand...

Excellent. I love my fastman-62 and fipk as well.
 
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