Air Intake Help Needed!

[doctorcherokee]

1074658

I want to put an intake with a K&N cone filter on my 1998 4.0I Cherokee Sport. I have a few questions and propositions. Please, whoever reads this, feel free to give me your opinions.

First of all, there is the (I think) the PCV valve that runs from the crankcase to the air filter housing. Other than the main intake tube, that's the only hose running to the housing. My question is...would it be too detrimental if the PCV valve had its own filter and didn't come from the main airbox housing? Would there no longer be a sufficient VACUUM? It would make putting on a new intake MUCH easier. If it would be okay, where would I get such a PCV filter (perhaps K&N) and what's the part number?

Secondly, I'd like to use a cheap, easy to work-with material for the tube that attaches to the intake and the cone filter. Is there a cheap, high-temperature PVC pipe that works well? What's the best length and width? I've heard 3" diameter. Would high-temp paint do very well to resist the high temperatures?

Also, what would be the best way to secure the tube and the filter? Some sort of large hose clamps could connect the intake to the tube and the tube to the filter, could it not? Would zip ties be good to secure the whole setup?

Perhaps most importantly, what's the BEST K&N cone filter for this project in y'alls opinions? I promise if I get a lot of opinions I'll take pictures and post my results! Thanks for any INPUT you can give me about my air INPUT.

edited by: doctorcherokee, Jul 04, 2003 - 10:09 PM[addsig]

 

[dingus]

1074682

First of all, there is the (I think) the PCV valve that runs from the crankcase to the air filter housing. Other than the main intake tube, that's the only hose running to the housing. My question is...would it be too detrimental if the PCV valve had its own filter and didn't come from the main airbox housing? Would there no longer be a sufficient VACUUM? It would make putting on a new intake MUCH easier. If it would be okay, where would I get such a PCV filter (perhaps K&N) and what's the part number?

The pcv hose actually is breathing DIRTY air INTO the airbox, this is an emissions component, you don't even actually need that hose going into your airbox, but your rig will produce less environmentally harmful bi-products... you can just vent that hose to the atmosphere if you want, or get a breather filter like i did on my old civic...

Secondly, I'd like to use a cheap, easy to work-with material for the tube that attaches to the intake and the cone filter. Is there a cheap, high-temperature PVC pipe that works well? What's the best length and width? I've heard 3" diameter. Would high-temp paint do very well to resist the high temperatures?

pvc is fine, but painting pvc is another story... paint DOES NOT LIKE TO STICK TO ITS SURFACE. i have found that sandpapering the PVC pipe to roughen it up a good bit helps, but it will never be perfect. i would suggest an aluminum tube/pipe... automotive shops or a home depot should have something that works.

Also, what would be the best way to secure the tube and the filter? Some sort of large hose clamps could connect the intake to the tube and the tube to the filter, could it not? Would zip ties be good to secure the whole setup?

once again, pepboys or the like should have hose clamps and stiff rubber that will make this work...

Perhaps most importantly, what's the BEST K&N cone filter for this project in y'alls opinions? I promise if I get a lot of opinions I'll take pictures and post my results!

just get the biggest cone filter that will fit...[addsig]

 

[doctorcherokee]

1074683

Dingus,

Thanks for all that great info.

Anyone else care to add to it? [addsig]

 

[woody-wagon]

1074686

How do you plan to connect the tube that runs from near the engine oil cap to the rubber intake tube? I want to make my own intake but I can't figure out how I would connect that to PVC pipe.[addsig]

 

[dingus]

1074694

most people just weld/screw/epoxy a little 'nipple' for that tube to reattatch to... (for lack of a better term)[addsig]

 

[doctorcherokee]

1074743

Dingus,

Is that rubber tube near the engine oil cap not the PCV valve tube that you said does not have to be connected? (I'm a little confused since I know little about engines.) Does it have to be connected to the air filter on the "nipple" or can it just be left disconnected?[addsig]

 

[dingus]

1074747

in a nutshell, the PCV system evacuates the engine of excess crap vapors that hang out in the valvetrain and such... because of emissions, they come from the factory set up to reroute those crap vapors into the air intake to go back into the engine to be burnt up instead of into the atmosphere. when building your own intake, you have the option whether or not to hook it back up. keep in mind that local emissions laws may fail your rig if you don't have it hooked back up to your intake...[addsig]

 

[doctorcherokee]

1074765

Aha, now I get it. Doesn't hurt the engine or the engine performance but could be illegal. Now I've gotta decide whether I "nipple" the intake or not!

Thanks for the great help, dingus! [addsig]

 

[woody-wagon]

1074785

I don't know about your engine but my 4.0L L6 1991 Cherokee has 2 nipples and hoses that connect above the filter. One tube I can't follow because it ends up behind my dash, the second connects just forward of the engine oil cap. Are both tubes not important?

Matt[addsig]

 

[dingus]

1074808

those two little hoses are vacuum lines for something... i'm not sure... [addsig]

 

[dingus]

1074810

all the aftermarket air intakes are designed for '92 + cherokees, nobody makes one for earlier models probably because of those 2 stupid vacuum lines...[addsig]