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Airbox Intake Tube Mod

215K views 337 replies 122 participants last post by  BlueRAM46 
#1 ·
I took out the airbox to see how the intake tube fits at the fender and noticed that it's a really cramped area. So I decided to add another inlet tube to the bottom of the airbox by attaching 3" aluminum flex pipe using a modified 3" PVC drain grate (cut out the grate). I drilled a 3" hole in the front bottom corner of the airbox then put in the modified drain and slid on the 3" flex tube using a 3" hose clamp to secure it. Next the tubing is routed between the frame and the inner fender liner down to opening that allows
it to be positioned behind the bumper.

The original inlet tube inside diameter is 3.5"x4" or 14 sq inches, the new inlet inside diameter is 2.75" so that's a gain of 5.9 sq. inches. The more air you can feed the engine the better. I bought the materials at Lowes if anyone is interested.





 
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#2 ·
Nice job. Great report on DIY CAI tube. :rep:
 
#4 ·
Thats a cool DIY! Thanks for sharing that with everyone and giving a great idea!
 
#5 ·
Thanks. I did the same thing to my Avenger R/T only the hose is routed to pick up ram-air by the fog light.
 
#11 ·
thanks man:wavey:
I had $13 and half an hour to burn so I followed your diy to the T..... 15 min. of that was waiting for the 2 coats of black dry, very very easy mod. Lower OEM box just pulls right up from the studs, for the people that hasnt completely removed theres yet.
I can hear a deeper growl when I stab on the throttle at idle. Its definitely pulling more air, hoping to get gains where the AFE stage 11 failed with canned 93 tune.
project OEM box complete.. thanks again
 

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#8 ·
That's pretty cool, nice job on that! :smileup:

- Cajun
 
#13 · (Edited)
dont have part #s just go to the PVC pipe aisle in home depot or lowes.. pvc drains come in 2" 3" 4" etc... I used a 3" as jmr did
dryer/flex vents are close by, 3" also and get a 3"-4" hose clamp total cost materials $13
if you dont have a 3" holesaw you have to buy that $15, plus the matching mandrel bit $15
pvc drain pops in the hole snug where you just have to tap it in no glue needed, you have the option to take snips and snip around edges to open the drain completely or keep the screen on, your choice..very nice mod
 

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#14 · (Edited)
I used the 3" aluminum flex tube from Lowes plumbing dept along with a 3" PVC drain that is made to fit inside 3" pipe
so this fitting is actually 3" OD. Remove the drains grille work so that the air flows better then you'll have a way to attach
the flex pipe to the air box.

Here is another update I modifield the plastic filler panel in the bumper so that the grille work where the tow hooks
go is opened up (lots of small holes were drilled). Then I put a 3"x4" PVC pipe adapter on the end of the 3" flex tube
and mounted it where the tow hooks would fit behind the bumper so that air now flows through the Black filler panel into the tube.
If you notice in the upper picture on the left side is where the flex tube sits behind the grille.

I tested it with my portable wind tunnel (leaf blower) to verify that additional air is going into the airbox (and it does).
I'm not sure of any gains but it's cooler air going into the airbox now.

 
#15 · (Edited)
nice work man, Ill be all over that this week. This way I can snip the grate completely open in the box and the front bumper will filter the debris etc.. instead. I can feel the difference for sure especially rolling in the power from 60mph or so.. it seems to kick down to passing gear with less effort:4-dontknow:but I need to see it in my ET slips, only reference I have to go by
 

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#19 ·
Check out this web site---www.psmdiesel.com/. Although they are made specifically for diesels I see no reason that they won't work on out Hemi's. Had one on my 04 Cummins and was very pleased with the results.
Jay
 
#20 ·
I like how clean this install would be (even though more expensive than total DIY). Where would I route the loose end of the hose to? I haven't checked around the airbox yet...
 
#21 ·
As I recall the PSM's are 4" so I'd check your air box first to see if there is enough room to cut a 4" hole. The DYI system looks like they are using a 3" hole. I'd have to look under the front end to see where the appropriate place would be to run the down tube. You can call PSM and talk to them, they have always been very helpful to me when I have talked to them.
Jay
 
#23 · (Edited)
Finally I modified the lower grill and put a 3"x4" reducer on the end of the intake pipe and mounted it behind the lower grille.



I have since sold the '10 QC 4x4 and bought a '12 Express RC 4x2. I've already done this mod to my '12 Express but the intake pipe just sits behind the lower grill..it's not opened up yet.

Good job BackRamHemi you can probably find some grille material to match the upper grille.
 
#24 · (Edited)
This a great and innovative home mod for sure. No kidding on the apparent restriction in the fender well where the OEM box gets its cold air intake. I'm going to do something similar. While researching this, I noticed that Spectre Air Intakes...also carried by Summit Racing...has a good supply of 3" and 4" ductwork, flanges, reducers, and a bunch of other air plumbing parts for DIY setups. Don't really know or claim that those parts would be any more functional or effective than the hardware store items here, but it's another source of parts if one wants to take a different approach. I think I may have found my choice of cold air scoop to mount in the lower grill opening...once the proper hole is cut. The part pictured here came from a window exhaust kit for one of those DeLonghi room AC units...the kind you don't have to stick in the window. Looks like it was made for our lower grill panel...with the proper hole, of course. I'll have to shim the big round inlet hole a bit for a tight 4" fit, but that will be relativel easy. I'm sure there are other similar products for everything from dryer vent systems to other possible candidates. The nice 8" X 2" oval hole was handy on this part.

With a better flowing aftermarket filter, I'm thinking this airbox mod when coupled with a better flowing air tube over to the throttle body would probably give all the cfm that most people would need for trailer towing and more common uses short of just WOT, drag racing, high rpm performance. The stock air filter size is fairly huge. All of this coupled with a better flowing muffler should be a decent bang-for-the-buck approach that doesn't break the bank.
 

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#25 · (Edited)
View of fender opening from engine bay (after airbox removal)



view from the front on a friends Ram with headlight removed at the track to reveal the other side of the fender opening



Close up




The "limited" path the air has to take when the headlight is installed







I've rigged up twin 3" feeder tubes to my Volant Box (Lowes Hardware for less than $20)



Flex pipe extends from 12" up to 20" (I actually used three flex sections and 1 coupler)

First one directs air toward the stock fender port, the other two connected with a coupler to the Volants optional lower port.

Along with my Fastman Throttle Body I'm getting about as much air as possible.

(also have Magnaflow Y pipe and CatBack (no resonators) to free up exhaust flow)

My post from Sept 18/11

WOW!!!

I dont usually post "butt dyno" results, but I cant wait to get to the track!
I added my own lower Ram-Air tube to the Volant with excellent results!!!

Not being the patient type, I wasn't satisfied to wait for Volants release of their lower scoop in November
...besides our Track closes after the first week in Oct.

So off to Lowes for some more flex tube, so now I have Dual 3" feeder tubes to my air box,
one to the stock fender port and one directly to the bottom of the Volant box,
But BOTH force fed and Ram'd from the front bumper opening. ;)

I know a smooth tube would be better than the ribbed flex tube,
but for now this works and I'm out less than $20 total until the scoop is available.




View from the Bottom looking up (Left tube goes to the air box, Right goes up the fender)










View from below where the tube enters the lower port on the Volant box.

from the CAI thread : http://www.ramforumz.com/showthread.php?t=59630&page=29

She runs consistent 13's now even at high DA (2000'+)
...and would be a Beast at sea level in cooler weather






 
#26 ·
oh, BTW Metro Restyling has grill material to finish the look off and clean up the front end

available in 12" x 48" sheet

http://www.youtube.com/watch?v=XE4AL9dQ50Q

Just need to graft it onto the stock surround after cutting the center section out, like MGH did for his Twin Turbo intercooler
....



I wont be doing it until Spring though, race season is over here (Snow) and my stock "fake" grill is back in place for the Winter :(
 
#28 ·
That's basically a standard CAI like many already out there, isn't it? The quality and durability of the components might be debatable, but who knows. I think the neat thing about the OP's thread here is the cold air/ram air aspect of his mod and for very little money. The factory intake is already a cold air system, albeit probably less overall flow. Like I mentioned earlier, I think you're going to get some decent improvement with the OP's cold air, ram air mod and a better flowing OEM sized filter. I was looking at the size of the OEM filter in my '12 Express, and it has quite a few square inches of flow service. When the higher flow filter is coupled with a ram air inlet, and perhaps a more efficient air tube from the box to the throttle body, I'd bet that's all most people would need for trailer towing power and fuel economy. Put on a better flowing muffler and you're out the door with some effective mods and not a lot of money.

I can see the larger CAI systems being a benefit for an application where more exhaust mods are involved and higher rpm power is the priority. Let me ask a question here. Do the aftermarket CAI systems just use the existing fender opening or do they offer more intake volume somewhere in their intake design? If you don't get a bigger opening into the aftermarket box, it would seem that you're not taking full advantage of the what appears to be a bigger filter. For that matter, has anyone actually tried to calculate how much surface area there is on one of these aftermarket cone filters compared to the OEM surface area? I notice the Volant CAI seems to have an opening and an optional attachment for a cold air ram air addition much like the OP's mod on the OEM box here. And I guess one could add a ram air inlet like this one to just about any CAI box out there if they don't already have one.
 
#31 ·
Looking at pics with the headlight out the OEM air intake port really looks inefficient for feeding a 5.7L Hemi.

When I saw the size of the stock airbox along with using a drop in K&N air filter I felt compelled to enhance it with a 3" cold air intake tube. I've done this before on my 2010 Avenger and a 08 RAM, when I saw the clearance around the 4th Generation RAM's airbox it was a no brainer. lol

You could spend more by using a name brand system but really this will work just as well for allot less cash.
 
#32 ·
jmr, much credit to your digging into the OEM airbox and coming up with what I can't help but believe has some reasonable performance return. I'm going to do a similar mod to my '12 Express, and I would also like to swap the air tube from the box to the throttle body with a smoother, better flowing setup. Airaid has some of these for other models, and they told me they had no plans for the later Rams to provide these. There's apparently a change from some point at '09 or earlier. I may try their U-build-it kit like I saw another poster use but not sure if I want to go to the expense. The extra ram air inlet, higher flow filter, and a smoother throttle body tube should be sufficient for my need.

Your intake mod along with a performance muffler swap should be sufficient for my needs, and the price is right. Thanks.
 
#33 ·
Great job JMR

This thread just talked me right out of the Volant CAI that I had on my wishlist. I already have the K&N drop-in filter so with the Volant setup at roughly 375(with the Ram Scoop) and the DIY with the Airraid TB tube at 140... Its a no brainer. And leave me 200+ more bucks to do other neat things. Thanks again JMR!!!
 
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