1995 XJ with 98+ Intake Manifold
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Joined: Oct 2011
Posts: 689
Likes: 2
From: Longview, TX
Year: 1998
Model: Cherokee
Engine: 4.0L
Cons: cost for little gain.
Don't get me wrong, I have done all of these, but they don't really help unless you open up the exhaust as well. I put in an APN header, full 2.5" exhaust, magnaflow with mine and it does FEEL more responsive. Not sure of there is any real gain, but I like working on my Jeep so I don't mind anything I can do that may help or teach me something new.
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Joined: Jan 2015
Posts: 2,152
Likes: 7
From: Minnesota
Year: 1999
Model: Cherokee
Engine: 4.0L
Pros: better spray pattern injectors, more airflow, possibly better flow with the manifold, better throttle response. Cons: cost for little gain. Don't get me wrong, I have done all of these, but they don't really help unless you open up the exhaust as well. I put in an APN header, full 2.5" exhaust, magnaflow with mine and it does FEEL more responsive. Not sure of there is any real gain, but I like working on my Jeep so I don't mind anything I can do that may help or teach me something new.
Senior Member
Joined: Oct 2011
Posts: 689
Likes: 2
From: Longview, TX
Year: 1998
Model: Cherokee
Engine: 4.0L
I'm sure there is a small gain, but my butt dyno is out of calibration.
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CF Veteran
Joined: Jan 2015
Posts: 2,152
Likes: 7
From: Minnesota
Year: 1999
Model: Cherokee
Engine: 4.0L
I saw a website online said the swap gave an extra 15hp when they used a dyno with just the intake swap.. That sounds a bit high to me..
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Joined: Jun 2014
Posts: 925
Likes: 6
From: Eagle River, Alaska
Year: 1999
Model: Cherokee (XJ)
'99-Up Horseshoe Intake
Myth: According to that great wealth of information that is never wrong, the Internet says you'll get a 5-30hp gain thanks to the '99-up 4.0L's swooped, equal length runners and larger plenum volume.
Our Thoughts: While a free-flow intake manifold can deliver more power, it's only going to allow as much air to flow as the cylinder head and camshaft will call for. Upping the intake runner volume too much will cause the intake charge to lose velocity, killing low- and mid-speed power and torque. On a '98-earlier engine running a stock camshaft and unported cylinder head, it's wasted effort.
Claimed Gains: 5-30hp
Actual Gains: 5hp loss on Trasborg's '98 XJ (Project Mileage Master)
Myth: According to that great wealth of information that is never wrong, the Internet says you'll get a 5-30hp gain thanks to the '99-up 4.0L's swooped, equal length runners and larger plenum volume.
Our Thoughts: While a free-flow intake manifold can deliver more power, it's only going to allow as much air to flow as the cylinder head and camshaft will call for. Upping the intake runner volume too much will cause the intake charge to lose velocity, killing low- and mid-speed power and torque. On a '98-earlier engine running a stock camshaft and unported cylinder head, it's wasted effort.
Claimed Gains: 5-30hp
Actual Gains: 5hp loss on Trasborg's '98 XJ (Project Mileage Master)
Senior Member
Joined: Oct 2011
Posts: 689
Likes: 2
From: Longview, TX
Year: 1998
Model: Cherokee
Engine: 4.0L
But again, if you have the parts and they didn't cost anything, go for it.
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Joined: Jan 2015
Posts: 2,152
Likes: 7
From: Minnesota
Year: 1999
Model: Cherokee
Engine: 4.0L
I've seen that article referenced many times. It's nice that someone actually did the tests, but I wish they would list the result of all of them together (minus a "cold air" intake. I'd be interested to see what the result was. But again, if you have the parts and they didn't cost anything, go for it.
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Joined: Feb 2010
Posts: 12,367
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From: Oroville, CA
Year: 1995
Model: Grand Cherokee
Engine: 4.0 with all of the noise and clatter
I have done the intake swap on my 95. My butt dyno senses no loss of power and no real gain either. The only difference I can feel is that the engine will pull harder higher up in the RPM range instead of falling on its face at 4000 RPM. I only had about 75 bucks into the swap, so no big deal. The best thing about the swap on a 95 and older is that it is much easier to adjust the belt tension because of the improved power steering pump brackets.
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Joined: Oct 2011
Posts: 689
Likes: 2
From: Longview, TX
Year: 1998
Model: Cherokee
Engine: 4.0L
I'm not sure either, but I should mention that mine is a trail only rig. I only drove it on the street a few times after doing that swap. I couldn't say what impact the intake alone had, but the combination of that with the injectors, TB, headers, exhaust did make it feel like a different Jeep. Just a tap of the throttle would kick you in the butt and slap you with the headrest.
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CF Veteran
Joined: Jan 2015
Posts: 2,152
Likes: 7
From: Minnesota
Year: 1999
Model: Cherokee
Engine: 4.0L
I'm not sure either, but I should mention that mine is a trail only rig. I only drove it on the street a few times after doing that swap. I couldn't say what impact the intake alone had, but the combination of that with the injectors, TB, headers, exhaust did make it feel like a different Jeep. Just a tap of the throttle would kick you in the butt and slap you with the headrest.
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