99+ Intake manifold

[JeepSpeed]

Hi all,

Alright, before I even start this I have to say I am not a newbie, I performed a search, had trouble with it because of the number 99 for some reason, and couldn't find it. So anyway,what's this I hear about the 99+ intake manifold. I know they changed them, but are peeps switching them in older rigs for performance? Is that where the 4.0 picked up those three or so ponies? I'm looking to open up the intake and exhaust as much as possible, and I like the way a better breathing manifold sounds. If this is true, does it just bolt right up, or is there trouble with the ODBII and ODBIII matching up? (I have a 94') Also, if all other answers are lookin good, where can I get one? Seems like the stealership would charge me a large one for every nut and bolt, I'd rather there was somewhere else. (Plz don't say boneyard, Ive never once seen a 4.0L XJ in any by me, especially not a 99+) And finally, thanks for reading my long ass post and answering my barrage of questions. :D

[5-90]

You'll find more information on the boards at the "strokers' egroup (link below.)

As the 4.0 evolved, the intake runners in the head were gradually and slightly straightened out, which increased airflow efficiency and THAT is where the extra power came from. Remember that an engine is little more than a self-powered air pump that makes more power than it needs to run. Increasing the extra power made is a matter of increasing the efficiency with which the air enters and exits the engine (which is the targetted result of most mods, if you look at it.)

Swapping just the manifold isn't the key, tho. You will want to think about switching the entire head assembly to get the full effect of the airflow increase. If you have an HO already, it will be easier than switching heads on the Renix (87-90) due to electronic changes carried out by ChryCo.

Strokers E-group (http://groups.yahoo.com/group/strokers)

5-90

[JeepSpeed]

Kay, thanks. I havent looked at the link yet, but just asking real fast, do you think i will realize any gains form it? I do have the HO,with a bored TB, K&n, opened up intake, and cat'n'back. Im also planning on a port 'n' polish for the head in the future. So, now or later, will this do me any good?:confused:

[XJ Saga]

Ironically Jeepspeed, you're question would best be answered by the guys out on the Jeepspeed forum. Several of them have swapped out to the newer intake manifold on their racer cherokee's and they have noticed significant gains with it. There is a Cherokee race team out there called Ajax Auto who runs a stock post 99 XJ and wins quite a bit. I emailed the guy (John Kearney) some days ago about this very question and he told me that every year from 97-up the XJ has gotten noticeably faster and he noticed this especially when the new exhaust and intake manifolds were introduced and secondary to that was the coil-on-plug ignition, he states that that may have helped a bit as well. Now I've been doing some research myself on the newer intake manifolds and this is what I've found: this is from JP magazine from March of 2003- March 2003 issue of JP magazine....article titled "Excellent XJ",page 28 "John Kearney of Ajax auto parts( driver of Billy Bunch's Jeepspeed XJ), swears the new intake is good for 25 hp, due to the equal length runners, where as the squared off intake has unequal length runners" shows the difference with two pics.
Here is another individual report where someone swapped out the intake manifold to the newer style: "I just wanted to tell you guys about the updated '99+ 4.0L Jeep intake manifold I installed with a self-bored-out throttlebody. I felt a slight power loss off the line but once the engine hits around 1,500 rpm, it comes alive and hits the redline much, much faster. Now, since I don't have access to a horsepower dyno I just relied on my "ass-o-meter" and felt a noticeable gain in horsepower. I installed the intake on a '96 XJ 4.0L with a K&N filter and a Flowmaster muffler. I would definitely recommend the upgrade, but I have been asked many times what the actual horsepower gain is and I can only say that another magazine rated the gains at 25 hp."
--Bryan Cloward

I'm here to tell you that with the newer intake and exhaust manifold and 2.5" S pipe the post 99 XJ's can cover some ground in a hurry especially with alot of modifications. Yes Jeep had to make the 4.0 less polluting but all they could manage was a LEV status (low emission status) with the EPA and LEV does not hamper any type of power gains in any way. HTH

[XJ Saga]

Let me add that the article in my previous post: "Excellent XJ" was researced painstakingly by "Awsum98xj" I'd like to give him credit for helping me with the search but I cant remember his screen name.

[JeepSpeed]

Wow, Saga, thanks alot. Man, that really got me excited. 25 horses obviously sounds a little exaggerated, but the guy from the quote you included sounded happy none the less. So, now that I won't be able to sleep until I know I can get one, does anyone know where I can? I don't wanna have to start selling drugs to buy one from the dealership, and like I said, junkyards are a bust. Is there an oem parts supplier or anything like that I can order one from? Or is someone parting out their late model XJ for some wierd reason? Again, thx for everyones help. :)

[XJ Saga]

http://www.ajaxauto.com/Jeep.htm

[Dr. Dyno]

Originally posted by JeepSpeed
[B]...25 horses obviously sounds a little exaggerated.....

That's putting it mildly! If the new manifold really did produce a 25hp gain :nono: , the '99 and later XJ 4.0's should have been rated at 215hp. Since they're rated at 193hp/231lbft as opposed to 190hp/225lbft for the earlier HO's, either 22hp has disappeared down the plug hole or, more likely, the new manifold is only good for an extra 3hp/6lbft.
I'd like to see a dyno comparo of the two manifolds instead of overinflated hype.

[czb83]

so is the 99+ intake manifold a direct bolt up to a 91-98 head?

[REDXJ4FUN]

I think everyone is taking that quote in the wroung way. I belive when he said that he was talking about a built race motor not what kinda gains you can get just by bolting it on a stock motor. Its just like alot of mods if you keep the stoock renix exaust manifold on and stroke it and everyother mod then putting it on a dyno then change to a good header you'll see a crap load of HP come out of nowhere. Is it a better intake hell ya but don't hope for a 25hp gain.

[XJ Saga]

Originally posted by REDXJ4FUN
I think everyone is taking that quote in the wroung way. I belive when he said that he was talking about a built race motor not what kinda gains you can get just by bolting it on a stock motor. Its just like alot of mods if you keep the stoock renix exaust manifold on and stroke it and everyother mod then putting it on a dyno then change to a good header you'll see a crap load of HP come out of nowhere. Is it a better intake hell ya but don't hope for a 25hp gain.

John Kearney of Ajax Auto runs a stock XJ in the races. It would be nice to read the entire article but it's not available on JP's website. His comment is a comparison between the older manifold and the newer version.

[XJ Saga]

http://www.apexmodified.ca/phpbb2/viewtopic.php?t=425

Now someone prove to me otherwise that DC does NOT lowball the hp figures for either EPA and/or insurance reasons. This is a case in point only because more often than not have I seen DC undercut the hp figures for specific purposes. Another example would be the new Hemi that is going into several platforms within the next year, it is underrated in hp @ 345 in several instances. Now what does this have to do with this thread? Simple, I am almost certain this is what DC did with Jeep vehicles as well. So what if the rating of 25hp was exaggerated for the new manifold? Say the newer Cherokee is rated at 210bhp, nobody can argue that it is NOT out of the realm of possibility solely based on all the "upgrades" done to the 4.0

[MassbayXJ]

"Jeepspeed, the mach 5 is not ready for that much horsepower, haha" "you'll have to use the cherokee, haha"

sorry, couldn't resist.

[JeepSpeed]

First off, sorry everyone, I prolly shouldnt be posting right now, cuz im wasted. but Maasbay, I sorry, i had no idea what u just said. If it was an insult to supin up a jeep, ford sucks man, and what's wrong with makin a 2900lb sleeper with 50/50 weight distribution? If you didnt mean anything like that, sorry. But either way, I'd still like to throw a newer manifold on, if it gets me 3 horsepower or 50. ALso, before I hit the bars=, does anyone know another place i could snatch one? I've checked Ajax multiple times, and it always says there are no matching parts. Any input(even negative) is appreciated. Muchos gracias.

[JeepSpeed]

Oh, yeah, and Saga, thats 100% right. One of the reasons i love DC is because they almost alway deflate thier hp and torque numbers. Most other makes inflate 'em, but jeeps and dodges almost always dyno higher. Understated champions. :D

[Dr. Dyno]

Originally posted by JeepSpeed
One of the reasons i love DC is because they almost always deflate thier hp and torque numbers.

DC correctly rated the HP numbers of the 4.0 but they did underrate the torque by about 15lbft. The early HO 4.0 XJ should have been rated at 190hp/240lbft and the later one slightly higher, but definitely not 210hp. A '00 XJ is not quicker than a '92 XJ so I think the 210hp claim is just wishful thinking.
As for other Jeep engines, DC correctly rated the 4.7 V8 for HP and underrated it for torque, underrated the 5.9 V8 for both, and correctly rated the 5.2 V8 for both.
They didn't underrate every engine though. They somehow managed to grossly overrate the 3.5 V6 in the Chrysler 300M. They rated that one at 253hp but the performance suggests that it has about 30hp less than that.

[XJ Saga]

Originally posted by JeepSpeed
First off, sorry everyone, I prolly shouldnt be posting right now, cuz im wasted. but Maasbay, I sorry, i had no idea what u just said. If it was an insult to supin up a jeep, ford sucks man, and what's wrong with makin a 2900lb sleeper with 50/50 weight distribution? If you didnt mean anything like that, sorry. But either way, I'd still like to throw a newer manifold on, if it gets me 3 horsepower or 50. ALso, before I hit the bars=, does anyone know another place i could snatch one? I've checked Ajax multiple times, and it always says there are no matching parts. Any input(even negative) is appreciated. Muchos gracias.

JeepSpeed, I'd at least send ajax an email they'll be able to assist from there. BTW, that 3-5 extra hp that Jeep claims is from a newer H20 pump and coil on plug ignition, there is no mention of addt'l hp from the new intake/exhaust manifold but here is a quote from their literature: The new intake and exhaust manifolds enhance the sound quality of the engine and produce a lower, "throaty" sound preferred by customers.

You be the judge on what that last statement meant to indicate. ;)

Semi OT: 300hp on the SRT-4 !! (outrageous)!:D :D Plus it's 300lbs lighter than a WRX STi. That is insane amount of power.

[REDXJ4FUN]

i'd deffinatly change out intakes just for the heck off it. and have fun.heres where i found some here http://car-part.com/ for about 35 bucks.

[CW]

I don't think the exhaust manifold would give any benefit since they switched from a tube stlye headerish manifold to a cast manifold.

[XJ Saga]

Originally posted by CW.
I don't think the exhaust manifold would give any benefit since they switched from a tube stlye headerish manifold to a cast manifold.

The newer manifold resembles a shorty header version of the Borla header for the 4.0's. Matter of fact I know a fellow street jeep enthusiast who installed a banks header on his 00 XJ and noticed very little to no improvement. He still ran a 14.7 @ englishtown raceway a few months back. :cool:

[rsalemi]

Have sold several - contact me rsalemi@hotmail.com

[Karlm]

I can vouch for rsalemi. He sold me a 99+ intake and gave me a good price too. Unfortunatly its still sitting in a box waiting to get hot-dipped and installed. What I'm really waiting for is a header so that I only have to mess with that junk once. I can't wait to get it on though.

[hjeepxj]

Originally posted by rsalemi
Have sold several - contact me rsalemi@hotmail.com

how much $?

[ryurabbit]

If you want one I can get them for $157.55 + shipping! This is for a brand new never used factory manifold!

We put one on my buddies jeep and we noticed the low end kinda went away but the 1500-4000 put you in your seat abit. He runs 35" with lockers and 4.88 gears. We didn't like the low end going away but what can you do. Also we installed the banks header at the same time so that may effect the results too.

Rabbit

[XJ Saga]

Originally posted by ryurabbit
If you want one I can get them for $157.55 + shipping! This is for a brand new never used factory manifold!

We put one on my buddies jeep and we noticed the low end kinda went away but the 1500-4000 put you in your seat abit. He runs 35" with lockers and 4.88 gears. We didn't like the low end going away but what can you do. Also we installed the banks header at the same time so that may effect the results too.

Rabbit

Hmm, I've read that before about losing power down in the low rpms but I dont have that problem. I wonder if it has something to do with your header install or just something that occurs when you install one on an older 4.0

Irregardless you are still gaining hp in the optimum rpm range, and I'd wager it's a bit more than 3hp. ;)

[REDXJ4FUN]

I happen to be thinkin about our debate here today when one posibliity. DC may have detunde other parts of the motor to help emissions. and since they made gains in the intake they could back off the fuel and reduce emmisions.

[jack SF]

to answer czb83. the 99 intake bolts up directly to the 91-98 head. but you need the steering pump and belt tensioner out of a 95 or newer jeep. wrangler inake and pump set up works in xj too. i got a whole set up from a 2000 tj.

[czb83]

Wow, I was just about to ask about the steering pump. I went and looked intake and saw it was connected to the power steering pump.

Thanks jack SF

Maybe I'll try a junkyard for the pump and tensioner. Maybe I can find a new manifold there too. *crosses his fingers*

[Ed A. Stevens]

Originally posted by REDXJ4FUN
I happen to be thinkin about our debate here today when one posibliity. DC may have detunde other parts of the motor to help emissions. and since they made gains in the intake they could back off the fuel and reduce emmisions.

The later 4.0L HO heads have smaller exhaust ports (rumored to improve emissions), and possibly the intake and coil on plug ignition (water pump, revised exhaust, etc.) are measures to retain the power output?

The guys at Edelbrock have never designed an I6 intake (except for a manufacturer) and offer that if enough interest is communicated, they would consider a design. "Enough interest" is a few thousand requests.

[REDXJ4FUN]

An eddy intake would be nice but like you said it would take thousands of people to get them to do one. but then again they still make AMC V8 intakes and just released a new airgap intake.the only way we are going to know if the newer intake is better is to do a good soild test.

[Bryan C.]

Originally posted by XJ Saga

Here is another individual report where someone swapped out the intake manifold to the newer style: "I just wanted to tell you guys about the updated '99+ 4.0L Jeep intake manifold I installed with a self-bored-out throttlebody. I felt a slight power loss off the line but once the engine hits around 1,500 rpm, it comes alive and hits the redline much, much faster. Now, since I don't have access to a horsepower dyno I just relied on my "ass-o-meter" and felt a noticeable gain in horsepower. I installed the intake on a '96 XJ 4.0L with a K&N filter and a Flowmaster muffler. I would definitely recommend the upgrade, but I have been asked many times what the actual horsepower gain is and I can only say that another magazine rated the gains at 25 hp."
--Bryan Cloward



It is interesting to find yourself being quoted in a post. I'm coming in late to this thread, but I thought I would like to say I saw the HP increase quote in 4wd&su in the 4word column. I do not agree with the claim, but that was the only "number" that I heard of.

I work at a Jeep dealer as a tech and have the oppertunity to dive alot of XJ's. I would have to say the fastest XJ is the 99 4.0l. 99 is the first year of the intake, but with the old tube style header, and distributor ignition. I also drove a bone stock 96 and felt it had more power than mine with all the modifications, I just blamed it on the gearing change to make myself feel better.:D

Once the coil on plug came out on the 00, DC also changed the exhaust manifolds, and in California, stuffed two small cat converters in place of the old header. I think the 00, and 01 models are underpowered, compared to previous years. I haven't driven the 49 state model 00 or 01 XJ yet, so I cannot comment on its performance.

As far as rated HP numbers being low, I agree with that. I recently heard at the local DC training center that the new Dodge Neon SRT4 HP ratings were about 30 HP higher than what DC had published, also mentioned was the new hemi 5.7l.

The power steering/tensioner mounting to the intake manifold changed in 96, so the intake is a direct swap in for 96 to 98 XJs. 95 and later will need to upgrade to the new style tensioner system, and more than likely need a new power steering pump and belt too.

Bryan Cloward

[XJ Saga]

Good deal. I like to see positive response from individuals quoted in magazines.

I agree with just about everything you have stated with one exception: the 00-01 4.0's are very likely not underpowered, I'm running 0-60 in the mid 6's with all of my bolt ons. In stock form it was already an 8 second XJ. The precats are too small to provide any restriction and the new exhaust manifold resembles a good aftermarket header.

[Dr. Dyno]

Originally posted by Bryan C.
[B]As far as rated HP numbers being low, I agree with that. I recently heard at the local DC training center that the new Dodge Neon SRT4 HP ratings were about 30 HP higher than what DC had published, also mentioned was the new hemi 5.7l.


Almost correct.
Stock High Output 4.0 Jeep Cherokees with an automatic transmission produce 150-155hp/190-195lbft at the rear wheels in 2nd gear. Assuming a 20% drivetrain loss, that equates to 188-194hp/238-244lbft at the flywheel. It appears that the factory correctly rated the horsepower output but slightly underrated the torque.
You're right about the SRT4's. They were rated at 215hp (flywheel) by the factory but most of them are producing more than that at the front wheels. The true flywheel output is more like 240-250hp.
The Hemi, on the other hand, appears to be overrated. A 5.7 Hemi Ram produces about 240rwhp so even allowing for a 22% drivetrain loss, that amounts to 308hp (flywheel), well short of the 345hp quoted by the factory

[Dr. Dyno]

I think that might have been an underpowered version of the Hemi that wasn't yet broken in. I found a dyno sheet of another stock Hemi in a Ram, and the nos. were 269rwhp @ 5500rpm / 288rwtq @ 4250rpm.
Assuming a 20% drivetrain loss for a RWD automatic, that's 336hp/360lbft at the flywheel. If we use the 22% figure, the flywheel nos. are 345hp/369lbft. That's much closer to the factory quoted 345hp/375lbft.

[Bryan C.]

My observation regarding the 00 and 01 was just just that, an observation. Maybe I'll take better notice the next time I drive 00 and 01 XJs. I still think a stock 99 will beat a stock 00, or 01. I have no doubt that 99 to 01 XJs are all faster than my 96.:D

Dr. Dyno, you seem to be much more knowledgeable than I about the HP ratings. Thanks for the correction.

I often wonder how my mods have helped or hurt the performance of my Jeep. I guess you just keep going till you get it all dialed in and working together correctly. Oh the joys of Jeeps.

Bryan

[lunghd]

Originally posted by jack SF
to answer czb83. the 99 intake bolts up directly to the 91-98 head. but you need the steering pump and belt tensioner out of a 95 or newer jeep. wrangler inake and pump set up works in xj too. i got a whole set up from a 2000 tj.

(edited)
Quick clarification, if possible:
Does this apply to non HO / 'Renix' motor accessories (incl. power steering pump) as well?

My stroker has a '90 block, '93 head and a y2k intake.

I'm trying to retain my old non HO / Renix accessories if possible with this new intake.
I don't have a problem w/ swapping to the later power steering pump, belt & tensioner but dunno if the tensioner will work w/ my existing a.c. compressor & alternator?

Any input would be appreciated.

:anon:

[jack SF]

the 91 and newer dont have an egr port like the pre 91, so you wont pass visual smog.

the throttle body and all sensors are different, but i have seen an adapter for sale that would take care of that.

i am not sure about this one, but i think that the 91 and newer heads are a little different. the intake might not line up axactly with your old head, maybe you could just put on a head from a 91 or newer. double check on this.

it does not seem that its worth doing after all those problems. jack

[lunghd]

Originally posted by jack SF
the 91 and newer dont have an egr port like the pre 91, so you wont pass visual smog.

the throttle body and all sensors are different, but i have seen an adapter for sale that would take care of that.

i am not sure about this one, but i think that the 91 and newer heads are a little different. the intake might not line up axactly with your old head, maybe you could just put on a head from a 91 or newer. double check on this.

it does not seem that its worth doing after all those problems. jack

Not sure if ya was posting in response to me or not, but here's some additional info I left out:

By "renix motor" I was referring to my donor block.
I'm building a stroker from the ground up - non-HO block, HO head, HO intake, HO throttle body w/ Renix TPS, HO header with the non-HO EGR tossed just as far as gravity & my arm will allow.

Got all that covered either in the garage, at the machinist or on the way... what I'm trying to figure is what kind of power steering pump I'll have to run - My old one if I can keep the old bracket w/ the y2k intake; or a new pump set up if the belt & tensioner will work w/ my old 'renix' accessories.
:anon:

[jack SF]

yes lunghd i was replying to you. you should just get the whole set up from the donor jeep. the pump, bracket, tensioner pulley, hoses and all the bolts. if i remember right than the pump bracket and tensioner bracket are 1 piece. i think it might be possible to reuse your existing pump with a little work but i did not want to waste my time with a pump thats over 10 years old. just get the whole thing from the donor jeep. jack

[lunghd]

Originally posted by jack SF
yes lunghd i was replying to you. you should just get the whole set up from the donor jeep. the pump, bracket, tensioner pulley, hoses and all the bolts. if i remember right than the pump bracket and tensioner bracket are 1 piece. i think it might be possible to reuse your existing pump with a little work but i did not want to waste my time with a pump thats over 10 years old. just get the whole thing from the donor jeep. jack

Gettin' parts from all points of the compass so there's not a 'donor Heep' to eyeball the setup on or to rob all the parts together from. (New pump goes in regardless - just trying to get the right one the first time.)

Thanks!
:anon: