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99-up 4.0 intake

H

HogWash

NAXJA Forum User
Location
Murfreesboro, TN
Earlier 4.0L engines used more squared-off, log-style intake manifold that hampared flow to the outer ports,especially the #1 and #6 cylinders. Beginning in '99 Chrysler employed this horseshoe-shaped, high-flow manifold with individual runners.It's said to be worth anywhere from 10-25HP over the log-type manifold.You may need to convert to the later powersteering brackets and move a few vaccume lines, but the manifold bolts to all 4.0 engines. You can also use this manifold as a way of converting from the earlier Renix-style injection.
 
Hello hogwash:

Several people here are running the 99+ intake, I have one on my 97. It's a simple install. No modification other than pluging a port and switching around hose barbs, there are a couple bolts under the manifold that are a PITA to get in and torqued. I installed it at the same time I did the header so I can't say exactly how much improvement it made, definatly worth it though. I got the manifold plus theTB and sensors on the net from car-parts.com for $125, great website for locating used parts.
 
indianaXJ said:
Hello hogwash:

Several people here are running the 99+ intake, I have one on my 97. It's a simple install. No modification other than pluging a port and switching around hose barbs, there are a couple bolts under the manifold that are a PITA to get in and torqued. I installed it at the same time I did the header so I can't say exactly how much improvement it made, definatly worth it though. I got the manifold plus theTB and sensors on the net from car-parts.com for $125, great website for locating used parts.
Click to expand...
Would be worth getting one from the junk yard and then getting it polished or bored I would think thats pretty cheap.Oh ya what part of IN are you from?
 
I checked local junkyards, all wanted from $200 to $250 for just manifold - TB and sensors. Mine cleaned up and looks pretty good, polishing would be a prefrence thing, or are you talking about polishing the inside? No nead to bore, it will already take a 42mm TB.

living in Indy moving to Putnam county.

You should probably do the exaust first, air won't go in unless it can flow out. I did the Kolak exaust, not the cheapest but definatly a high quality setup. It will hook up to the original hangers and be very sturdy.

Have you tried doing a serch on this stuff?
 
indianaXJ said:
I checked local junkyards, all wanted from $200 to $250 for just manifold - TB and sensors. Mine cleaned up and looks pretty good, polishing would be a prefrence thing, or are you talking about polishing the inside? No nead to bore, it will already take a 42mm TB.

living in Indy moving to Putnam county.

You should probably do the exaust first, air won't go in unless it can flow out. I did the Kolak exaust, not the cheapest but definatly a high quality setup. It will hook up to the original hangers and be very sturdy.

Have you tried doing a serch on this stuff?
Click to expand...
I have flows dual on now.....DUALS yes duals.why I DONT KNOW yes I had them put on.
 
well this is great news, course its not really news as it has been info on this board for a while.
many have done this conversion with great results, me included.
do a search you'll find much more than this little tidbit of information, write ups, pictures can be found rather easily with a simple seach.

granted its good for people who didn't know about this upgrade, its a well covered topic on here.
 
HogWash said:
It's said to be worth anywhere from 10-25HP over the log-type manifold.
Click to expand...

So I keep hearing but I haven't seen any direct dyno comparison between the two manifolds to prove it. If it was true, why are the '00+ XJ 4.0's rated at the same 190hp/225lbft as the earlier engines?
I think the true gain is more like 0-5hp.
 
Dr. Dyno said:
So I keep hearing but I haven't seen any direct dyno comparison between the two manifolds to prove it. If it was true, why are the '00+ XJ 4.0's rated at the same 190hp/225lbft as the earlier engines?
I think the true gain is more like 0-5hp.
Click to expand...

http://www.mallcrawlin.com/forum/showthread.php?t=6355

This guy did the swap. He got 27 hp and 20 lb-ft of torque from it.

Quite an impressive gain for such a simple bolt on.

I think Jeep kept the 4.0's true horsepower/torque numbers underrated so that it wouldn't look as good as the new 3.7 V6 that they were developing at the time, or hell, the 4.7 V8 for that matter.

But that damn 0331 head could have very well cost them what the new intake gained them, leaving the output the same overall. But like they say "the dyno doesn't lie".

Even if it costs a little low end that is a good gain in power. Believe me, I was skeptical of those numbers, but a 50% error would still yield about 14 hp and 10 lb-ft of torque which is still fantastic in my eyes.
 
Dr. Dyno said:
So I keep hearing but I haven't seen any direct dyno comparison between the two manifolds to prove it. If it was true, why are the '00+ XJ 4.0's rated at the same 190hp/225lbft as the earlier engines?
I think the true gain is more like 0-5hp.
Click to expand...

If I remember correctly they designed this new manifold to get back some of the HP lost when they had to restrict exhuast flow or something along those lines. I believe there were new smog laws that had to be followed and to get back some of the ponies lost to the newly designed header (which went to 2 cats possibly?) they found the ponies with this manifold. So for those with the older header design, and less restrictive exhuast the intake manifold definitely helped with the air flow in. As the stats above show, I can't say I feel 27 more HP or 20lbs of torque (butt dyno that is), but there was more pep in my step after the install.
 
Dr. Dyno said:
So I keep hearing but I haven't seen any direct dyno comparison between the two manifolds to prove it. If it was true, why are the '00+ XJ 4.0's rated at the same 190hp/225lbft as the earlier engines?
I think the true gain is more like 0-5hp.
Click to expand...

yeah, and with all the volume low end should suffer from low intake velocity. I think it's an over-rated mod. Imho, of course.....
 
SCW said:
yeah, and with all the volume low end should suffer from low intake velocity. I think it's an over-rated mod. Imho, of course.....
Click to expand...

I think the 99+ intake is a good intake. It's looks as if someone actually put some thought into designing it.

In my opinion, if you truly care about engine performance, you need a 99 intake.



It's your decision.
 
j99xj said:
http://www.mallcrawlin.com/forum/showthread.php?t=6355

This guy did the swap. He got 27 hp and 20 lb-ft of torque from it.

Quite an impressive gain for such a simple bolt on.

I think Jeep kept the 4.0's true horsepower/torque numbers underrated so that it wouldn't look as good as the new 3.7 V6 that they were developing at the time, or hell, the 4.7 V8 for that matter.

But that damn 0331 head could have very well cost them what the new intake gained them, leaving the output the same overall. But like they say "the dyno doesn't lie".

Even if it costs a little low end that is a good gain in power. Believe me, I was skeptical of those numbers, but a 50% error would still yield about 14 hp and 10 lb-ft of torque which is still fantastic in my eyes.
Click to expand...

I saw that write-up by DJJordache but remember that he also changed injectors as well as the manifold. The HP/TQ numbers before the manifold/injector swap were way down on normal stock 4.0 chassis dyno results so I think his old injectors might have been clogged up. Therefore the 27hp/20lbft gain is an overoptimistic representation of what the newer manifold can achieve.
Jeep DIDN'T underrate the 4.0's HP even in later years. It still made 150-155rwhp on the chassis dyno as it did on early HO models.
The 0331 head cost about 5-6hp compared to the 7120 and 0630 heads, but they regained 2hp of that with the new water pump and another 4hp with the camshaft.
Almost everyone who's done the manifold swap has reported either a very small performance improvement (usually a gain in low rev torque due to the smaller diameter runners) or no improvement at all, so I still say that at best it'll yield 5hp.
 
Dr. Dyno said:
The 0331 head cost about 5-6hp compared to the 7120 and 0630 heads, but they regained 2hp of that with the new water pump and another 4hp with the camshaft.
Click to expand...

I have a 99 with a 0630 head and the new manifold. It feels better than my 96 with the 0630 and old intake and my 01 Grand with the 0331 and new intake. It really responds better to the throttle that the other two.
 
falcon556 said:
I have a 99 with a 0630 head and the new manifold. It feels better than my 96 with the 0630 and old intake and my 01 Grand with the 0331 and new intake. It really responds better to the throttle that the other two.
Click to expand...

Thats exactly what I have.
 
j99xj said:
Thats exactly what I have.
Click to expand...

One more reason I am convinced that the 99 with the high pinion D30 and engine improvements is the best XJ. Has all the improvements without the screw ups.
 
falcon556 said:
One more reason I am convinced that the 99 with the high pinion D30 and engine improvements is the best XJ. Has all the improvements without the screw ups.
Click to expand...
Oh hell yes dude. Exactly what I have again.

I have a "classic" model with all the options. So its basically a "limited" without leather seats. Runs like a champ, even up here in the sky at 5000 feet above sea level.
 
Dr. Dyno said:
I saw that write-up by DJJordache but remember that he also changed injectors as well as the manifold. The HP/TQ numbers before the manifold/injector swap were way down on normal stock 4.0 chassis dyno results so I think his old injectors might have been clogged up. Therefore the 27hp/20lbft gain is an overoptimistic representation of what the newer manifold can achieve.
Jeep DIDN'T underrate the 4.0's HP even in later years. It still made 150-155rwhp on the chassis dyno as it did on early HO models.
The 0331 head cost about 5-6hp compared to the 7120 and 0630 heads, but they regained 2hp of that with the new water pump and another 4hp with the camshaft.
Almost everyone who's done the manifold swap has reported either a very small performance improvement (usually a gain in low rev torque due to the smaller diameter runners) or no improvement at all, so I still say that at best it'll yield 5hp.
Click to expand...

Wow. I didn't consider that. That would certainly explain such a huge gain. :doh:

Thanks for enlightening me.

But 5 hp is 5 hp more than before. I'm suprised you haven't done the swap....yet. But I'm sure the temptation to do so will eventually overcome you....
 
Has anybody done this with a non H.O. motor?
 
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