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"Ram air" inlet hose for stock airbox


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I did a writeup on replacing the stock paper air filter with a Uni dual stage foam filter. As part of that process, I drilled a 2" hole in the bottom of the airbox. This is the completion of that part. I connected a hose from the hole I drilled in the bottom of the airbox to that plastic trim piece that’s right under the front bumper.

 

Here’s the starting point, the 2” hole I drilled in the bottom of the stock airbox:

 

The parts that I used, 2” X 36” pre-heater hose, and the 2” hole saw:

 

I cut the hole in the lower bumper piece where there was more “meat” to support the hose:

 

I stretched the hose to its full length, then fed the hose thru the lower bumper piece up into the airbox, then cut the end off, leaving about ½” of hose at either end:

 

This is what it looked like when I was done, as viewed from the front:

 

I didn’t like how this looked, it looked too “ghetto”, so I went to Lowe’s and got this black plastic drain part, it’s a 1.5” angled thing of some kind:

 

The new and improved look from the front. I put a hose clamp on the back side of this black plastic drain piece, and put some black RTV around the opening:

 

Cost for parts as follows: 2” hole saw ($0, I already had this), 2” x 36” pre-heater hose ($7 at Advance Auto), black plastic drain piece ($2 at Lowe’s). I’ve done this to other vehicles I’ve owned, and never had any issues with crap getting into the airbox. The way I look at it, for water or debris to enter the hose, travel up into the airbox, get past the two foam filter elements and into the intake system, would be the 8th wonder of the world, lol! If someone’s paranoid that will happen, they can put some type of screen at the bumper inlet and airbox outlet, to give them piece of mind. But I think it’s good to go as is. As you can see, there’s nothing blocking the inlet under the bumper, and it’s a fairly straight shot up into the airbox from there. So this setup should get a good amount of air being forced up into the airbox, at least when the vehicle is moving. Should get a LOT more air into the airbox than from behind the headlight!

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Looks like it should work well. Do you notice a performance increase with that? ive been thinking about putting a cool air intake on mine but i like your idea really well because its not in the way.

 

Well, it's difficult to say if the hose alone had any performance increase, since I did it right after installing the Uni dual stage foam filter. The Uni by itself made some performance improvements, so it's hard to tell how much more, if any, the hose did. But at least the airbox has an unobstructed source of cold outside air, which is a good thing. If you have the time, I'd suggest the following. Do this hose mod first, leaving the air filter/airbox alone, and see if you notice any changes. Then swap out the filter, to either a Uni like I did, or to a pleated gauze filter like a K&N. You should definitely notice something then.

 

But like someone mentioned in another thread, most of these "cold" air intakes are drawing in heated air from the engine compartment, which is worse than the stock airbox, which is sealed from the heat of the engine compartment. Doing these two mods with the stock airbox will give you a more free-flowing air filter, plus a direct source of cold outside air. At around $50 for these two mods, it most likely is less expensive than a cold air intake kit, and should be more effective.

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Looks good , you should get allot more eng. response . Let me know how it effected you gas mileage .

 

You get good use out of that hole saw , don't you . :thumbsup:

 

Yeah, I bought that hole saw when I drilled out a section of the lower grills on my Saturn Sky, and ran some 3" flex ducting up to the dual Unis I had on the Fujita intake system. Also notice I drilled out all the little honeycombs on the grills, to let more air inside the engine compartment:

 

I even took this setup one step farther, and ran a fully enclosed system, using smaller Uni foam filters that I squeezed into the ends of the intake tubes, then ran the flex ducting up to the tubes and clamped them over the ends:

 

For now, I'm back to the "open" system on my Sky, like in the first picture...

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Lol...I don't drive my Sky in the rain, or if there's standing water on the roads, so I'm not too worried about the upside down snorkel effect. But again, for water to travel from the lower bumper, up the hose, past the foam filter, and into the intake system, would take some doing, so I'm not too worried. From what I remember, even though the engine wasn't throwing codes, it seemed to run better with the "open" intake system versus the "closed" one. Since I had more money invested in the "open" system, I just went back to that one, and it's been running fine since.

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Lol...I don't drive my Sky in the rain, or if there's standing water on the roads, so I'm not too worried about the upside down snorkel effect. But again, for water to travel from the lower bumper, up the hose, past the foam filter, and into the intake system, would take some doing, so I'm not too worried. From what I remember, even though the engine wasn't throwing codes, it seemed to run better with the "open" intake system versus the "closed" one. Since I had more money invested in the "open" system, I just went back to that one, and it's been running fine since.

 

 

it would take almost zero effort to get water up there. I bet I could smoke a 4.0 in a matter of a second or two with that setup...with just one bad rain storm, a bit of stupid driving, maybe a ditch that's full of water...

 

 

you get where I'm going at...a simple drizzle is unlikely to effect it, but then again you also need to take into account the car in front of you in the rain will be throwing up water...and most cars throw it just about right in the area of that lower valance.

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Lol...I don't drive my Sky in the rain, or if there's standing water on the roads, so I'm not too worried about the upside down snorkel effect. But again, for water to travel from the lower bumper, up the hose, past the foam filter, and into the intake system, would take some doing, so I'm not too worried. From what I remember, even though the engine wasn't throwing codes, it seemed to run better with the "open" intake system versus the "closed" one. Since I had more money invested in the "open" system, I just went back to that one, and it's been running fine since.

 

 

it would take almost zero effort to get water up there. I bet I could smoke a 4.0 in a matter of a second or two with that setup...with just one bad rain storm, a bit of stupid driving, maybe a ditch that's full of water...

 

 

you get where I'm going at...a simple drizzle is unlikely to effect it, but then again you also need to take into account the car in front of you in the rain will be throwing up water...and most cars throw it just about right in the area of that lower valance.

 

Yeah i really like your idea though it still looks nice and seems like it would work nice. Just not something i would be comforable putting on my old farm truck =p I know as soon as i try something like that my amazing luck will show itself and i'll need to drive through a friggin creek or something, which does happen around here alot. It might be interesting to look into putting a big ball pivot on it like in a hose pipe splitter. Where you can turn a valve and change it to take in air under the hood during rain or any various scenario.

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Good discussion, both pros and cons...

 

I just went out and measured the distance above the ground of those inlet hoses. On my Sky, it's roughly 12" above ground, and on the MJ it's about 19" above ground. As I said, I don't drive the Sky in the rain, so I'm not too worried about sucking up any significant amount of water thru that hose. On the MJ, the hose inlet sits pretty high above ground, so it shouldn't be ingesting a lot of water directly either.

 

However, the points are well taken about vehicles in front shooting up water, and the hose being located in an area where secondary water spray could make it inside. I'm still okay with it though, because the corrugated hose has all those ridges on the inside, so the surface isn't smooth, and I still think it would take a LOT of effort for any significant amount of outside water to make it all the way up the hose, into the airbox, past the two layers of foam filter, and into the intake system. I'm sure someone could take a garden hose with a spray nozzle, turn it on, spray water into the hose inlet, which would simulate the vehicle moving, and water would get up into the airbox and eventually soak the filter. This sounds like something those guys on "Myth Busters" should experiment with, lol!

 

I'm from the west coast, so maybe it's a southern California thing, since it doesn't rain a whole lot back there, and I've never really worried about water ingestion into the intake system. I put the hose opening under the bumper because it looked like the easiest and most direct way to connect to the bottom of the airbox. Maybe if I drilled the hole into the side of the airbox, I could've positioned the hose inlet in the grill area somewhere. I still think it's good to go as is, and I'm not tempting the fates to grenade my engine any time soon. Only time will tell...

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Yeah if it doesnt rain much and your not planning on floating your jeep across a river like a covered wagon i wouldn't worry about it. But were I live i couldnt do that. I thought about your ram air system as soon as i took off from my driveway this morning. It had poured rain all night and water was standing several inches high in some places on the road and the guy in front of me was dousing me with water. Not to mention the roads around here that cross creeks. There aren't many of those left what with the marvel of bridges but there are still a few and i wouldn't want to be too limited to cross them in my pickup. i may look into piping it to the grill like you said. that would work fairly well but still may cause problems.

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Don't forget that the rain doesn't "splash" its way up that tube, the engine is actively sucking it up the tube. Have a similar issue with the stock airbox of our Liberty (which is kinda similar to the stock MJ box). We swapped it out for the v6 version (has an extra bit of tube that pulls air from higher up) and now we don't go through airfilters practically every oil change. :banana:

 

But, I guess if it never rains, there's not much rain to get sucked up. :D Still dirt/dust though.

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...But, I guess if it never rains, there's not much rain to get sucked up. :D Still dirt/dust though.

 

That's what window screen mesh is good for...put a little piece on the backside of the inlet adapter, slip the hose over it, should serve as a good "pre-filter" for anything making it's way up the hose...

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There are allot of manufacture's that do this from the factory . Honda is one of them , the stock air box is all the way

down by the front bumper , just behind the fog lights , if it has them .

 

I used to run a ram air injection , on my 72" GTO . There was nothing but the filter to stop water from getting in there .

 

However I never had a problem . It was the double scoop version , right in front of the hood .

I don't think you will have any problems with water spray . Its going to take allot of water to get up that pipe .

 

I wouldn't be driving through any streams or lakes though . :ack:

 

A small dust filter will help get rid of any major particles , But you still have the filter in the box as well .

That will stop everything .

 

But your going to test it out for us . he he he :D

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But you still have the filter in the box as well .

That will stop everything .

 

Yes it does. and the libby's filter filled up and started to lose power after a while. Owners in raining areas have had issues with water clogging up and collapsing the filter too. :( Of course, it is a turbo. maybe that's why there's more problems with that Jeep in particular. :doh: Either way we haven't had any issues since installing the v6 airbox parts. very happy about that :D

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  • 2 weeks later...
what about deep mud or water holes/creeks/etc? is there a bypass system to dump the water if you suck it in or is it hydro lock city?

 

If my MJ were in that kind of environment, I'd invest in a snorkel. But, growing up in So Cal, and being stuck here in Norfolk (VA), my MJ doesn't go thru deep mud or water, so I'm fine with the inlet hose under the bumper.

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what about deep mud or water holes/creeks/etc? is there a bypass system to dump the water if you suck it in or is it hydro lock city?

 

If my MJ were in that kind of environment, I'd invest in a snorkel. But, growing up in So Cal, and being stuck here in Norfolk (VA), my MJ doesn't go thru deep mud or water, so I'm fine with the inlet hose under the bumper.

 

Yeah man it's highly usefull and works well for your purposes, so good job bro :thumbsup:

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For those of you who do 4 wheel in warm to hot climates, back in the 1960's my brother and I drag raced a 57 chevy with a 327 in "cheater stock" and took eliminator once with it. We ran the fuel line through a coffee can with ice in it as close to the carb as possible to cool and condense the fuel. Learned that from other racers. Don't know it it would work on injected engines, and if we only "thought" it helped, but it seemed to improve performance. I am sure it would bring mileage down a bit, but, hey, when you are mashing to the floor for a quarter mile the throttle of an engine that already only got about 10 mpg, didn't matter a bunch!

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For those of you who do 4 wheel in warm to hot climates, back in the 1960's my brother and I drag raced a 57 chevy with a 327 in "cheater stock" and took eliminator once with it. We ran the fuel line through a coffee can with ice in it as close to the carb as possible to cool and condense the fuel. Learned that from other racers. Don't know it it would work on injected engines, and if we only "thought" it helped, but it seemed to improve performance. I am sure it would bring mileage down a bit, but, hey, when you are mashing to the floor for a quarter mile the throttle of an engine that already only got about 10 mpg, didn't matter a bunch!

 

haha thats great. did you pop two holes in the can so you could leave the fuel line in there and just fill it up with ice? it would be interesting to get alot of extra fuel line and run it through a coffee can from the bottom to top all coiled against the wall (like the coil from a moonshine destilery) and then put the ice in it. it would just be cool lol

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haha thats great. did you pop two holes in the can so you could leave the fuel line in there and just fill it up with ice? it would be interesting to get alot of extra fuel line and run it through a coffee can from the bottom to top all coiled against the wall (like the coil from a moonshine destilery) and then put the ice in it. it would just be cool lol

 

2 holes in the can to have the gas line go through the can and filled it with ice. Didn't coil it. We were unsure if it would cause and condensation in the line if it was in the ice too long.

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