Air Box mod

kccherokees · Sep 7, 2003

Would it be a bad idea if on my 89 Cher I cut a hole in the bottom of the air box, below the air filter, to allow more air flow and a deeper tone?? A couple of my friends did it in their nissans. On my 89 though the egr valve is in the bottom of the air box, could I still do this?

Chris

juicexj24 · Sep 7, 2003

You can do it, but your just letting in more hot air from the engine. The big air filter intakes work better, but it's still a good idea to put up some type of shield to block the hot air and get cool air into the filter.
check out
www.xj-armor.com
Steve is a great guy with some really good products for air intakes and bored throttle bodies. Or you can go through
www.xjmotorsports.com to link to it. Juice

vintagespeed · Sep 8, 2003

If it's a street only rig it'd be ok to do. I dont know how much more 'sound' you're going to get out of it though. If you wheel it in water you're lowering your water-fording depth. I like to wheel mine & I really could give a sh*t what it sounds like.

azxjman · Sep 8, 2003

that bracket xj-armor sells seems kinda stupid I achecvied the same thing using PVC pipe and drilled a hole for the sensor

juicexj24 · Sep 8, 2003

Well the XJ Armor bracket is much the same as Rusty's. The only difference is the one vacuum sensor has a place to go, Rusty's doesn't. Juice

2xtreme · Sep 8, 2003

I just replaced my stock airbox with a custom large K&N cone and 3" exhaust tube. There is a huge difference in sound and quantity of air able to get into the intake quickly. Eventually I will mud and hot air insulate it.

I used to have the stock airbox and replaced filter with a flat K&N and did not notice any significant difference in performance or sound. My mother in laws xj had three large holes drilled on the outside of the airbox (between the air box and fender) and did not make any difference in sound at all and again would only allow more hot air in than without the holes.

I have cut holes into other airboxes with some noticeable imporvements but I do not think it is worth it on the jeep. Big cone filter is the way to go.

Michael

TOZOVR · Sep 8, 2003

2xtreme said:
I just replaced my stock airbox with a custom large K&N cone and 3" exhaust tube. There is a huge difference in sound and quantity of air able to get into the intake quickly. Eventually I will mud and hot air insulate it.

I used to have the stock airbox and replaced filter with a flat K&N and did not notice any significant difference in performance or sound. My mother in laws xj had three large holes drilled on the outside of the airbox (between the air box and fender) and did not make any difference in sound at all and again would only allow more hot air in than without the holes.

I have cut holes into other airboxes with some noticeable imporvements but I do not think it is worth it on the jeep. Big cone filter is the way to go.

Michael

I really have to say that I doubt (this is just opinion based on my experiences) that the XJ really needs a filter setup that flows more CFM....

When we did a FIPK on a '99 with a cat back and 60mm TB we got 1.8 hp on the Gtech...we then repeated the tests and got 1.5hp as a result at the drags.

Not a chassis dyno, no, but much more reliable than the ass-dyno.

It sounds neat but until you open up the engine it's my opinion that you're wasting time with intakes on the 4.0.

RJ

Brian Carpenter · Sep 8, 2003

you could.. I don't think it would give you that much though... Ii have taken my air box completely out. Some will say that this is overkill, and that the truck won't warm up properly, but I live in VT and the 4.0 works fine even in -20. The horsepower you are seeking would be found easier by taking out the air box, adding a Ram Air tube ( any 3.5 or 4" tube + a K&N filterthat fits it). But beware, the XJ wants to get rid of fasses more than it needs. Exhaust upgrades give you back more than intake can.
-bc

dave · Sep 8, 2003

uhm.. get a snorkel.. they are tre-chic and provide ram air like qualities on the road.. ( i really am going to be adding one as soon as i find the time to pick my design up off the garage floor and grow the sack to chop into my clean body and mangle my bushwhacker cutouts

)

juicexj24 · Sep 8, 2003

I have the ARB Snorkle an a K&N in the stock box with a bored throttle body. I can't say if I get more power out of it or not. It will get up and go, but I think that is more because of the gear swap and not the intake. I also have a Borla cat back and High flow cat. I think this made the most hp's and seat of the pants power. But without a dyno to really check it out, you never really know. Juice

Dr. Dyno · Sep 8, 2003

juicexj24 said:
The big air filter intakes work better, but it's still a good idea to put up some type of shield to block the hot air and get cool air into the filter.

Definitely! Take a look at my homebrew Powerstack FIPK:

http://www.jeep4.0performance.4mg.com/FIPK.html

I build a heatshield to isolate the filter from hot underhod air and I get a very good flow of cooler air from the grille. If you don't fancy making your own intake, take a look at my old insulated ram airbox set up instead:

http://www.jeep4.0performance.4mg.com/ramair.html

Xtreme Jeeper · Sep 9, 2003

If you are looking to get a couple of ponies.And not wanting to spend much money I know what you can do to do that. You won't get much sound though. If you take the air intake tube off right behind the air box you can see a little sleeve that Chrysler put in there to supposedly to take away air flow. Which therefore takes away horsepower. when you get in there you will find you can just clip it out. There is very little power diff, but you'll get about 2-3 horsepower.

XJTripp · Sep 9, 2003

Yea, I think this is a venturi. It lowers the air pressure at the point the charcoal canister hose connects to the snorkel. I think the idea is to induce fuel vapors from the canister into the intake. The pressure drop is of course a pressure loss to your intake. At Wide open Throttle it could cost you a little. I pulled mine and I think at WOT in passing gear I get a little more oomph. Nothing bad has happened that I can tell, but I guess I might be venting gasses. That's rude

Air Box mod

kccherokees

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juicexj24

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vintagespeed

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azxjman

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juicexj24

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2xtreme

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TOZOVR

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Brian Carpenter

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dave

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juicexj24

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Dr. Dyno

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Xtreme Jeeper

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XJTripp

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