'99+ Intake

There was a post a few weeks ago concerning the '99+ intake compared to earlier years as far as flow goes. Does that also include '97's? i'm just wondering if it's worth swapping in a '99+ intake to my '97? Wondering what king of performance gains will I get. Thanks

There was a post a few weeks ago concerning the '99+ intake compared to earlier years as far as flow goes. Does that also include '97's? i'm just wondering if it's worth swapping in a '99+ intake to my '97? Wondering what king of performance gains will I get. Thanks. I posted in OEM Form also

The 99's and up have a higher intake plenum (sort of the concept of an extended throttle body plate), and the manifold is more curved as opposed to squarish in shape, for better flow. There's a quote (and some pics) on page 28 of the March '03 issue of JP magazine, in which supposively the newer intake manifold is good for 25 hp.

Ivan

i've heard that too. but if so, why wouldn't jeep have advertised that gain for the 99+ models? shouldn't it have gone from 190hp to 215?

Jeep had to do something for their 4.0s getting choked down by emissions laws, it seems like power output was in a steady decline from 96 to 98 (although the specs don't readily show it). The manifold first appeared on 99 WJs, which coincided with the vehicle redesign. I think the engineers had to do something about the lack of power with the 4.0 when compared to the new 4.7L V8.

As far as installing it, I have one on my 96 XJ and I could tell a big difference in power (my ass-ometer hit the redline). My setup has the K+N FIPK, bored out throttle body, updated intake and a Flowmaster muffler. It was pretty much a bolt in replacement except for extending a vacuum line and a sensor lead, everything else just bolted up. Your 97 should be the same as mine.

The only drawback that I have had is I lost a little bit of low RPM torque, but it really pulls like hell in the mid RPM ranges(1500-2500).

I got my manifold brand new from the dealer as they are hard to come by in my area, list price is over $200(I work at a Jeep dealer so I paid $170w/tax for the manifold, gasket, and replacement injector o-rings with the employee discount) but it can be bought used for much, much less if you can find one.

Well worth the time, effort, and money for me.

Bryan

FJH97XJ said:

There was a post a few weeks ago concerning the '99+ intake compared to earlier years as far as flow goes. Does that also include '97's? i'm just wondering if it's worth swapping in a '99+ intake to my '97? Wondering what king of performance gains will I get. Thanks. I posted in OEM Form also

Click to expand...

Here's the thread from several weeks back. As you'll see, I never did get answer if it was a direct swap with all the sensors and such.

http://www.naxja.org/forum/showthread.php?s=&threadid=2745

I answered this guys post in the OEM forum but it makes more sense in this forum. Here is the other thread:
http://www.naxja.org/forum/showthread.php?s=&threadid=3165

The 99+ intake is pretty much a bolt in replacement on 96-98 XJs with the 4.0L. The only real mods required are to extend the IAT sensor wiring and extend a vacuum line. The new manifold has all the same ports and fittings, but in a slightly different location for some.The manifold will fit earlier models 91-95 but need the newer style power steering pump mount/tensioner assy and belt.

Part numbers for 96+ conversion:

99+ WJ 4.0L intake manifold #04854197AB list price $227.00
Intake manifold gasket #53010238 $13.20
Injector O-ring replacement kit #8350367 or #4897125AA $9.70
The other parts needed are, t-body gasket, exhaust manifold studs, a bolt for the fuel line support bracket(forgot what pitch), 18 ga wire for the sensor lead, and about a foot of 3/16 vacuum line.

I have the updated intake on my 96 and I must say I am impressed. Well worth the time and effort.

Bryan

Thanks for the much needed info Bryan.

Are the WJ and 99+ XJ manifolds the same? Which should I check for in the boneyards?

The manifolds started showing up in the 99 model year on the WJ, XJ, and TJ 4.0s. All are the same part number.

i put one on my 91. i am very happy with it. i think they started in the grands in 99 and xj and tj started in 2000. i got the intake and power steering pump from a junk yard for a $175 and than another $50 for the belt tnsioner and misc. from the dealer. jack

Thanks guys. Now I know what to look for at the junk yards.

jack SF, hows the TR bumper holding up? I got tired of the wait for TR, AEV & Hansen and decided to try something else.

Can this mod be done to a 1990 jeep with the Renix system if you adapt the sensors?

XmikeJ said:

Can this mod be done to a 1990 jeep with the Renix system if you adapt the sensors?

Click to expand...

The big problem you will have with the swap is the ports on the Renix era head are slightly different than on the HO models and will cause airflow problems. Another issue is the t-body bolt pattern, although you can swap on a HO style t-body and adapt your renix TPS to it. Then there is the lack of an EGR port on the new manifold, so emissions testing and inspection would be an problem depending on where you live.

I'm not going to say it can't be done but it may not be worth the effort on the 87-90 4.0s.

Bryan

Sounds like just another reason to buy a 1991 to 1995 Cherokee.

jeepzz, the trail ready bumper is still ok. it does not rattle. i do see some rust from corners where the powder caot did not reach.
i spoke to hanson on friday and he still has not made a rear bumper. he says that maybe another 6 months.

xmikej, its can be done. someone makes a spacer for the throttle body to adapt the older tbody to a 91 or newer intake. but than its smog illeagal because of the missing egr. like some one said, its just not worth doing for a few horspower.

I did it on my '98-

Yep, missed the year by one that this would have been on mine standard. However, got one from my local 'yard located by their 'net. Paid $125 complete with 3k miles AND all injectors, sensors, and T/B!! Believe i made out like a bandit!! Had to swap the previous injectors due to connector differences. Kept the old T/B for a stand-by.

My butt dyno felt the serious difference in pull above 2000 rpm and especially 2500. One can see that at speed this one has got to flow more efficiently- does not have to be proven by specific dyno specifications. Also this intake provides additional help when the exhaust system is upgraded as i did. Has helped to turn this little 4.0 into a rev monster. Yes, low end torque was negatively affected, but is normal at 1500.

I consider this one of the best mods on my '98.

Don't want to dissappoint, but it all got started in "4 wheel drive and sport utility" magazine. They did an article about T&J Performance's Jeepspeed racer. They went to HESCO enineering to get help on getting more performance from there 4.0 liter inline. HESCO said told T&J they could get 20 lbs more torque across the range, not the 25 hp that the guy said writing the article. I talked with HESCO, and that is what they told me. They said it was just a mistake that the writer made about using the 99 and up intake manifold. The also said that it was a combination of exhaust, modified throttle body, along with the manifold that gave the 20 ft lbs of torque.

GWS

Bryan C. said:

The big problem you will have with the swap is the ports on the Renix era head are slightly different than on the HO models and will cause airflow problems. Another issue is the t-body bolt pattern, although you can swap on a HO style t-body and adapt your renix TPS to it. Then there is the lack of an EGR port on the new manifold, so emissions testing and inspection would be an problem depending on where you live.

I'm not going to say it can't be done but it may not be worth the effort on the 87-90 4.0s.

Bryan

Click to expand...

this is all to gain top-end horsepower at the expense of low-end grunt.

to make this work effectively, you would need to swap an HO head along with the later manifold and throttle body. you'd also need the newer throttle cable and linkage.

the HO cam takes care of EGR function with valve duration overlap. if you need EGR function, you need to swap the cam. you WILL need to leave the EGR solenoid hooked up because it also controls EEC purge. most states allow swapping to a newer year engine as long as all emissions equipment related to that engine is retained.

this of course, all depends if you want low end grunt or top end HP. I prefer low-end grunt. I don't drive my XJ like a sports car