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Bored Throttle Body and TB Spacer for '99+

2

2001XJ-32

NAXJA Forum User
Location
Southern California
I have read through a number of threads discussing the subject and it seams that boring the TB to 62mm is the way to go for any 4.0.

Someone also mentioned that because of the 99+ Manifold, the TB spacer is a good mod.

Can anyone with a 99+ manifold confirm or deny this? Anyone Dyno it? Thoughts on grinding out the helix or not?

:cheers:
 
Skip the spacer they are too expensive for what you get, it increases the volume by a very small amount. You will notice a difference with the bored throttle body. Check the opening in your intake you may be able to use a 63mm.
 
Hey 2001xj-32,

I am also in a 2001 and picked up a TB spacer last night for $30... cheap enough to play with for fun right?

I think that its a pretty good mod. Changes the power band in a nice way and suprisingly, I havent noticed much of a whistle, just an increase in power. I will check back in with gas mileage results when I have them...

Those people must have been right about the 99+ intake adapting well with the TB Spacer.

Thank you for those who differentiated pre and post 99 efficiencies in other threads!

Watch out if your running an ARB Air intake as there is little room available for the spacer so you will have to trim up the intake to fit.

Enjoy!

2001xj-32
 
Why is it that the TBS would be good on the 99+, but not worth much otherwise? I ran one on my stock intake for a while, and all I really noticed was a whistle at part throttle- no change in mileage or power. I yanked it when I put the newer intake on.
 
I was under the impression that the whistle came from the IAC sensor holes. I just for the most part grabbed a sanding wheel and bored out the taper at the bottom and smoothed out the edges where the idle control sensor sits. I have no whistle to speak of after that.
 
In this case, I'm speaking about the TBS only. I haven't bored the TB yet.

And why is that guy talking to himself in the third person? How does adding a few CCs of volume (some fraction of a percent of the total?) move the power band noticeably or add power with an MPFI system? I'm more skeptical after noticing that.
 
NAXJA friend put the bored TB on his 2001, thought it was a waste of money.
I put one on my old YJ, 4cyl and did notice some jump in acceleration.
 
It seams peppier at lower RPM's now on my 01 with an ARB intake and high flow exhaust... Definatly not the 15-20 hp that they advertise, but it feels like more than 1 for sure...

For $30, I am happy with it. Not reccomending one per say, just that I like it.

:cheers:
 
2001XJ-32 said:
It seams peppier at lower RPM's now on my 01 with an ARB intake and high flow exhaust... Definatly not the 15-20 hp that they advertise, but it feels like more than 1 for sure...

For $30, I am happy with it. Not reccomending one per say, just that I like it.

:cheers:
Click to expand...


you added more then 1 component at a time, so you dont know if one or a combination of all of them is the reason for the improvement. the spacer may not be doing anything, but if the combination is working, dont mess with it.

but if you want to give a more accurate result, take off the specer and report your findings.
 
I bored mine out to 64 MM and it only made a slight difference. It would likely work well on a stroker or an engine with a cam and other intake and exhaust mods. A spacer could be a plus for pre 99 intakes but won't make a huge difference.
 
I don't feel it's as much of a "power" increaser, as it is a sensitivity increaser. I did a 62mm on mine, and felt a big difference, but like said not power. More like, control. The pedal felt "crisper", I wish someone would find a way to make a homebrew TBW setup :(
 
2001XJ-32 said:
It seams peppier at lower RPM's now on my 01 with an ARB intake and high flow exhaust... Definatly not the 15-20 hp that they advertise, but it feels like more than 1 for sure...

For $30, I am happy with it. Not reccomending one per say, just that I like it.

:cheers:
Click to expand...
ARB intake? You mean snorkel?
 
I dunno, my gf's IsF seems pretty responsive? But I'm willing to be there's a number of other factors to that ;)

Another question though, how would you go about port matching the head and manifold holes?
 
Abrasives rolls. Standard Abrasives sells a deluxe porting kit. You want the intake manifold ports to the head smaller or no larger than the head ports. Opposite on the exhaust manifold.
 
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