4 cyl performance upgrades

[voudoux]

I have a 1998 XJ 4 cyl ,5 speed ,4.10 gears,31.10.50 tires; what can be done to upgrade the power,other than an engine swap? Can the throtle body be changed, I have improved the air cleaner,not much inprovement only sounds better. Thanks

 

[Talyn]

IIRC a 4.0L throttle body fits.

 

[voudoux]

Does the 4.0 throttle body make a noticeable improvement in performance ?

 

[gradon]

You will notice it. I'd get a 62-3mm bored one from theFastman.com or strokedjeep.com. They want a 4.0l TB as a core, so if you don't provide one, fastman charges $30 and Jeff Leigh charges $70. I see Jeff can get 64mm out of them now(sure the walls are thin). I have the Fastman 62mm TB with the half shaft.

 

[REDXJ4FUN]

The stock intake on the 2.5 dosen't have a large enough hole stock to handle even a 60mm TB. It is actually just a hair smaller than a stock 4.0. A good header and a 4.0 TB with the intake cleaned up works well along with a good tune up.

 

[h-townxj]

505 performance has stroked and turbo kits for 4 cyl hesco has cams. Port polish valve job high compression. It's just like any other engine there's parts for it. Go as crazy as you want with it

 

[NorCalChris]

Port polish valve job high compression. It's just like any other engine there's parts for it. Go as crazy as you want with it

Kinda along the lines of what I was gonna say. Bore over, tb, port matching, higher compression. Good tune up, injectors, ignition control like the msd 6a box.