Easy “Cold Air” Air Box Mod

[yxmj]

Here is an easy mod to help any Jeep breath better.

 

Having Yj’s Xj’s and now my first Mj, I have always wondered about the air box set up (used on both the 2.5 as well as the 4.0). Take a look at your air filter….it is +/- 13” x 6” or 78 inch² of breathable surface. Now take a look at the “Air intake hole it is +/-  4” x 4” or 16 inch² ( a little less that 1/5 the size of the filter)………Come on…….Lets let this thing have some air!!!!!

 

 

Here is my quick mod.

 

Years ago I worked at a plant that fabricated and assembled large farm equipment, One of the things we built was the grill that covered the rad on large tractors and earth moving equipment. This grill was made out of a thin gauge steel sheet perforated with holes, the slang name for it was 50% (I guess because half of the surface area was holes) So to make the grill we would run a sheet of this material through a “corrugator” so that it got a tight curving wave (like corrugated cardboard or roofing) The Idea being is that if you had a hole 1’ x1’ to cover and you took a piece of 50% 1’ x 2’ corrugated it down to 1’x1’ you have the protection of the steel grate but because you have equaled the surface area for all intensive purposes you have not restricted the air flow……Make sense??

 

Anyway enough rambling…..year ago I had picked as much of the 50% out of the scrap pile as I could and set it on the shelf hoping someday I would find a use for it…..Here it is

 

I use K&N in all my Jeeps……Find or fabricate a perforated piece of steel as seen in my picture ( The smaller the holes the better…..and every hole is going to ad air flow.) Try scrap yards or old implement dealers??

 

Remove the air box and cut out as much of the side against the fender as you like (remember trying to get cool air so my thinking is that fender side is cooler than motor side) Cut and fasten your (rivet / screw /or even silicon) your mesh in place, maybe a fast shot of paint to make it look “factory” and reinstall the box.

 

Just a cheap easy mod that you can do (in less time than it took to read this :laughin: ) it helps with the airflow, but still gives protection and a stock look.

 

You can see in the picture…..I could go bigger yet…..but I easily doubled my available intake air. :thumbsup:

 

[jpdriver1]

interesting --- another reason to place it on the fender side, if you live in a smog nazi state, they may not see the "modified air box"

[danbyrambler]

LOL - From 10 months ago - In for sale & then like I edited  "Poor attempt at humor"  - - Should've put in the PUB - - - Anyway - It works same way - Doesn't look as slick as yours - - didn't notice any increase in noise  - - Don't forget the restrictor - - Its removals been covered here on CC IIRC & If not here then on NAXJA

:thumbsup:

 

 

 

Posted 27 October 2012 - 02:23 PM

 

COLD AIR INTAKE & HEAT SHIELD - RETAINS STOCK APPEARANCE PLUS USES STANDARD AIR FILTER - - - REQUIRES REMOVAL OF OUTPUT RESTRICTOR & DRILLING OF A FEW 3/8 DIAMETER HOLES - - - OUTPUT INCREASED TO 7.1 SQ. INCHES & INTAKE INCREASED TO A HUGE 11.5 SQ. INCHES COMBINED - A WHOPPING 92% INCREASE! - - -MORE HORSE POWER PLUS INCREASED MPG! - - - - - $5 for one set of standard plans plus s&h - $6.75+s&h DeLUX set or 2 sets standard or delux only $12.95 & free s&h - - -HURRY - LIMITED TIME OFFER - -


POOR ATTEMPT AT HUMOR - - NOTHING IS FOR SALE - - -RM

[yxmj]

Well drilling the holes would do the same job as far as air flow for sure. Up here I don't need to worry about passing an emissions test but my real goal in putting on the 50% mesh was to try to keep out as many of the flying critters as I could while still maintaining max air. :thumbsup:

And yes the restriction plate was removed (on the 87 it is a plate operated by a vacuum pod that closes to let warm air in off the manifold during colder months)

(On my YJ the screen is larger and covers as much area as your hole pattern)

 

Noise was never a concern to me this 2.5 is quieter that all my 4.0's ( especially the one with a header and a straight pipe...... :brows: )

[danbyrambler]

Your type mod would'a been it if I'da thought things out a little more - just for the aesthetics even though that side of the AB is a somewhat obscured view - - My inspiration came from a post somewhere about removing the AB restrictor & I did it to my 87 4.0  - The round insert that's in the AB lid - It's a semi rigid plastic pressed in thing & pretty much has to be cut out - Anyway, when doing the same to my 91 4.0 it occurred to me to relieve the box beyond the 2x3 or so front opening - 3/8 r 10mm hole size to prevent easy access for the occasional mouse that sometimes slips into my shop - Ran the numbers for how many holes needed & Bam! - Fast & dirty mod - Looks like it too, LOL, but it works & was cheap - beyond inexpensive - cheap! - - - - - - Same here for emissions - No bother on older stuff - - I feel it for the folks in California - Tough regs are one thing, but you mix strict with the all too common  inspection zealot & wow - their horror stories are legion.

:wrench:

[gogmorgo]

That looks pretty slick... but I don't know how much you'd be benefiting from it. You've got less than 5in² at the throttle body, vs the six or so at the airbox inlet, so opening up the airbox doesn't really mean much, just changes where the air comes in. Whether the air from beside the fender is cooler than the air behind the headlights is anyone's guess.

 

But still cool to see another member from 'Toba  . :MJ 1: .

[yxmj]

That looks pretty slick... but I don't know how much you'd be benefiting from it. You've got less than 5in² at the throttle body, vs the six or so at the airbox inlet, so opening up the airbox doesn't really mean much, just changes where the air comes in. Whether the air from beside the fender is cooler than the air behind the headlights is anyone's guess.

 

But still cool to see another member from 'Toba  . :MJ 1: .

Well send your info to K&N and all the other companies that at selling the cone style cold air intakes for $250 + i am sure that it would have the same effect it had on me. :thumbsup:

[comanchedude]

just don't get in deep water ...but if its a street rig its fine

[gogmorgo]

 

That looks pretty slick... but I don't know how much you'd be benefiting from it. You've got less than 5in² at the throttle body, vs the six or so at the airbox inlet, so opening up the airbox doesn't really mean much, just changes where the air comes in. Whether the air from beside the fender is cooler than the air behind the headlights is anyone's guess.

 

But still cool to see another member from 'Toba  . :MJ 1: .

Well send your info to K&N and all the other companies that at selling the cone style cold air intakes for $250 + i am sure that it would have the same effect it had on me. :thumbsup:

Cone shaped air filters & smoother intake ducting reduce turbulence, leading to better flow. Not so noticeable at lower revs (<6000rpm). K&N's $250 kit adds a whopping seven horse above 4,000 rpm, and that's mostly down to the duct. My 4.0 doesn't spend all that much time above 4k, don't know about yours. Who knows, maybe you net a couple horse, maybe you didn't. But don't listen to me. It sure don't bother me none.

[yxmj]

I guess you missed the point of the post

every pony counts........especially ones you get cheap and easy  :thumbsup:

[ParadiseMJ]

I've had a K&N cone filter on my XJ for years,  Never had a problem with smoggers.  I gave Jeep to my son last year, he tried to smog it, but it failed because it needed an O2 sensor...it failed with high numbers...they tagged it as a "gross polluter" and so they take the smog AND engine inspection to a higher level.  Because of the lack of an air box, it also failed that part of the inspection. 

 

We put the box old back on, with all the appropriate vac lines.  Surprisingly, it didn't affect anything...except he got less noise. Not super noticeable while driving, but under the hood it was much quieter. After seeing this I'll be looking for another airbox for the MJ.  I never thought the cone filter did that much good anyway.

[yxmj]

I guess I can count myself lucky....up here all we have to get passed is a "safety" right at initial registration.

 

No smog concerns at all, the only real emission concern is if you have an intact operational muffler. Any engine mod (intake or otherwise) is of no concern as long as it poses no risk to the list of requirements for the Safety.

 

I guess that is the trade off you have to pay for the beautiful sights and sunshine down there.

 

We get off easy.....but in return we have to worry about negotiating 4' high snow drifts (no worry.. . :MJ 1: . ...hammer down)....and if the Jeep will start at -50 :thumbsup:

 

As a side,  in making this post, I was just trying to help out other MJ owners in a positive way....if this simple "Free" mod even adds 1/2 a HP or 1/3 of a MPG......too me it is worth it, successful and priceless  :thumbsup:

[ParadiseMJ]

 .

 

We get off easy.....but in return we have to worry about negotiating 4' high snow drifts...

 

LOL...I don't live at the beach...

 

 

[yxmj]

Fair enough :thumbsup:

 

Still looks like some nice scenery to me........

 

Google Winnipeg......I don't have to go to a mountain to find that kind of snow.......just to the driveway.... . :MJ 1: .

[desertmike]

Put a 2-3 inch hole in the fender side of the air box about 25 years ago. Don;t now if it helped but from my drag racing background more air is good.

[benjy_26]

^^^This. More air is always better. So what if your engine doesn't use all of it. There's no reason to restrict it.

[desertmike]

Not trying to restrict the air, just giving it all it can use. Breathing through a straw is no fun.

[benjy_26]

Not trying to restrict the air, just giving it all it can use. Breathing through a straw is no fun.

I'm with you on that. I guess my post was directed towards the guys that always come up and say that Jeeps don't need freer breathing.

[yxmj]

Put a 2-3 inch hole in the fender side of the air box about 25 years ago. Don;t now if it helped but from my drag racing background more air is good.

 

Yes....I don't think i said that when i posted this originally ......but with the Mj and the XJ's i took a 2" hole saw and put about 3 holes through the rad cradle behind and around the headlight.......more easily available air that the engine does not have to work hard to get.......it's a good thing. :thumbsup:

[Incommando]

Another vote for using caution if you do any play in water. The factory air box let's enough water in that hydrolocking an engine is a real concern without adding more ways for water to get in.

[yxmj]

Another vote for using caution if you do any play in water. The factory air box let's enough water in that hydrolocking an engine is a real concern without adding more ways for water to get in.

 

Well deep water crossings are always a problem.......but with reference to the original theme of this thread.....the original factory air intake is positioned lower that the mod so any water let in would have already come through the factory location.

 

And realistically how often are you driving around in 32" of water? The benefits you would receive the other 99.99% of the time would be worth it.... :thumbsup:

[Incommando]

Most cold air intakes, TB spacers, and gee gaws turn out to be snake oil. Not saying this one is but without verified before and after testing any actual improvement felt may just be self fulfilling prophecy. Who knows? But increasing potential airflow is worthless unless there is a proven defeciency. Unless thw engine requires it increasing the potential does nothing.

 

I am assuming some only wheel in dry conditions or their truck is kept on the pavement. That is fine but not all use their truck that way. You do not need to be in water as high as the inlet to get water in the box. When entering water it gets pushed higher than the water depth in many cases. Same when driving in water. Every seen a snow plow? Notice how the snow against the plow is higher than what it is plowing?

 

Going beyond actual rivers,ponds,etc... consider the far more common water-filled mud hole. You go in 18" of standing water and sink through 12" of mud. Any forward motion causes the wave effect mentioned above. Now what do you have? I have personally seen 3 4.0 XJ's hydro locked over the years. You can find plenty of incidents online as well. Your actual mileage may vary but if you wheel and if you do it in any of the above conditions I suggest that you should consider that. I never said to not do this mod but an informed decision is a better decision.

 

As to K&N filters for off-roaders that is another topic with varying opinions that one can research for themselves.

[yxmj]

Ha....if we all had your hot air......we would not need extra air for our motors we would all be super charged......you start emailing all the tubo companies blower companies air filter and hood scoop companies and tell them to shut the doors......cuz your wisdom has determined that extra air is not good for an internal combustion motor.....

 

and I have been a bit of a hillbilly in my time but.......your big argument.....(that you pulled from another thread not this one) is about getting in water and hydrolocking the motor.....here is a tip Billy bob....drive on the trail or on the street/highway/road......were 99.999% of the trucks on this site spend most of there time.......not everybody( thank you Jesus ) lives in your little world.

 

How about this Jethro........you provide us with YOUR facts on how allowing more air.... to any type of internal combustion motor is detrimental (that means bad) in any way..... :bowdown:

[Incommando]

Pulled from another thread? It is a fact. A turbo STUFFS air into a cylander. A metal screen does not :)

 

It is sad that you cannot tolerate someone not agreeing with you. I hope you get help with that.

[Incommando]

Ha....if we all had your hot air......we would not need extra air for our motors we would all be super charged......you start emailing all the tubo companies blower companies air filter and hood scoop companies and tell them to shut the doors......cuz your wisdom has determined that extra air is not good for an internal combustion motor.....

 

and I have been a bit of a hillbilly in my time but.......your big argument.....(that you pulled from another thread not this one) is about getting in water and hydrolocking the motor.....here is a tip Billy bob....drive on the trail or on the street/highway/road......were 99.999% of the trucks on this site spend most of there time.......not everybody( thank you Jesus ) lives in your little world.

 

How about this Jethro........you provide us with YOUR facts on how allowing more air.... to any type of internal combustion motor is detrimental (that means bad) in any way..... :bowdown:

;)