The truth about cold air intakes
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DirtDawg
TJ Enthusiast
Showing removed from mine from the PO as that headed to landfill. Also, TB butterfly (subsequently cleaned along with several cans of Sea Foam consumed). A used 2005/2006 OEM airbox / tube, along with fresh Fram filter panel and Autolite XP985 Iridium installed ~1k miles ago. Um, right - dirty air filters work better...
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I ran an AFE CAI for many years. I will say that the efficiency issue was not something I experienced, as I was able to hit over 300k withe the original 4.0l. I went back to stock due to the obvious benefits in high water scenarios - and my 300K 4.0l mill was not going to blow anybody away with any amount of increased airflow 
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When the Tornado intake insert first appeared on the market I tested one on my '98 XJ 4.0L.
I believe the original Tornado was released about 25 years ago by Turbo City in California.
After testing the Tornado for approximately 3 weeks; the conclusion I came to was....
There was a noticeable loss in engine performance at least on my Jeep.
Shortly after removing the part and resetting the ECU; performance returned.
I returned the product for my money back.
I believe the original Tornado was released about 25 years ago by Turbo City in California.
After testing the Tornado for approximately 3 weeks; the conclusion I came to was....
There was a noticeable loss in engine performance at least on my Jeep.
Shortly after removing the part and resetting the ECU; performance returned.
I returned the product for my money back.
I'm generally pretty anti-CAI mostly because it seems like a poor ROI. I like that guy's videos and the fact that he often emphasizes - maybe.
@Jezza has done testing that has shown consistently that the TJ 4.0 benefits around 10WHP max from an aftermarket CAI setup whether it is the windstar cowl mod (with factory filter) or a more traditional CAI. That's about 14hp at the crank assuming a 30% loss and an unusual pickup for something with this low power. I intend to do a little dyno testing of my Jeep when I can find the time as it currently stands to check on some things I've done. One of the things I wanted to try in my hour on the pony tester was my current aFE Momentum GT, vs my factory intake with factory media, vs factory intake with no filter. I think there is a problem with the design of the factory intake tubing, while some think it's restriction from the size of the filter. The dyno will tell the truth. Maybe.
In the 20+ years I've owned my Jeep, I've put less than 80k on it. I want to get as much power from it as I can to keep up with traffic in the mountains and I'm OK with this tradeoff. On the other hand I really don't love how loud the aFe intake is on WOT and I knew a cowl intake would almost certainly be louder. YMMV
The K&N filter media is notoriously bad. My dad's LJR has one just like this courtesy of it's prior owner. I shared a couple photos from the thread below and convinced him to change it to the AFE dry media which is a direct replacement for the K&N filter. I really wish all these companies would publish their data and that aFe Power provided their filter test numbers themselves. The tests I've seen (incl this video) don't clearly indicate which version of their air filter was tested, but they're always miles better than K&N.
https://afepower.com/afe-power-21-90072-magnum-flow-pro-dry-s-air-filter
And added one of these covers over it to catch the big chunks
https://afepower.com/afe-power-28-10213-magnum-shield-pre-filters
I think our own @Coalcracker18 can attest to the filter media's "efficiency" over the long haul
@Jezza has done testing that has shown consistently that the TJ 4.0 benefits around 10WHP max from an aftermarket CAI setup whether it is the windstar cowl mod (with factory filter) or a more traditional CAI. That's about 14hp at the crank assuming a 30% loss and an unusual pickup for something with this low power. I intend to do a little dyno testing of my Jeep when I can find the time as it currently stands to check on some things I've done. One of the things I wanted to try in my hour on the pony tester was my current aFE Momentum GT, vs my factory intake with factory media, vs factory intake with no filter. I think there is a problem with the design of the factory intake tubing, while some think it's restriction from the size of the filter. The dyno will tell the truth. Maybe.
In the 20+ years I've owned my Jeep, I've put less than 80k on it. I want to get as much power from it as I can to keep up with traffic in the mountains and I'm OK with this tradeoff. On the other hand I really don't love how loud the aFe intake is on WOT and I knew a cowl intake would almost certainly be louder. YMMV
The K&N filter media is notoriously bad. My dad's LJR has one just like this courtesy of it's prior owner. I shared a couple photos from the thread below and convinced him to change it to the AFE dry media which is a direct replacement for the K&N filter. I really wish all these companies would publish their data and that aFe Power provided their filter test numbers themselves. The tests I've seen (incl this video) don't clearly indicate which version of their air filter was tested, but they're always miles better than K&N.
https://afepower.com/afe-power-21-90072-magnum-flow-pro-dry-s-air-filter
And added one of these covers over it to catch the big chunks
https://afepower.com/afe-power-28-10213-magnum-shield-pre-filters
I think our own @Coalcracker18 can attest to the filter media's "efficiency" over the long haul
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