M939 air filter mod

The Wix 46664 is rated at 950 CFM
WIX - Air Filter
Line: WIX | Part # 46664

• 1 year limited warranty
• UPC: 765809466647
• WIX Radial Seal Outer Air
• Height (In): 15.515 Inch
• Inside Diameter (In): 5.796 Inch
• Filter Media: Cellulose

Detailed Description
WIX HD Air Filters feature a cellulose/poly media with skip-a-pleat media stabilization and hot melt stabilization beads for contaminant holding capacity that out performs many of our top competitors with a minimum efficiency of 99.9% contaminant removal.
Additional Details

• Bottom Outside Diameter (In): 10.875 Inch
• CFM Rating: 950 cfm
• Style: Radial Seal Outer
• Top Outside Diameter (In): 10.965 Inch

So I managed to borrow a Donaldson intake cap from a brand new Oshkosh fmtv. (It's huge) Have to get an adapter to reduce to the 939 intake. The new fmtv intake stacks apparently are much larger.
Once set up I'll post what happens. Trucks enough of pig with out getting dirt in air intake! I'll try this before I mod it to
the marine set up.

Still thinking of modifying my stock one, and maybe looking at relocation and or different housing

sent from my decrepit fingers

Sorry I'm late to the party. I hope to soon have time to quantify all of this. I will connect a MAP sensor from a gasoline fuel injection system into the filter minder line, and be able to record the restriction of each component on a scale with good resolution, since MAP sensors inherently do that anyway. First suspects are stock filter, TMG filter, and mushroom cap. When we get a brand new Kenworth truck to test, even with the big Cummins ISX 15L engine, it's filter minder is on total zero even after a full throttle pull on the dyno or road. Something else I don't like is the turbo inlet boot. It has a funky squish to it. I can see what they were trying to do, but again, looking at 2015 model year big rigs, they just use a conventional 90 degree adapter with no flattened area to it. I understand this is after the filter minder port, but this was another potential restriction part I never felt fuzzy about.

74M35A2 said:

Sorry I'm late to the party. I hope to soon have time to quantify all of this. I will connect a MAP sensor from a gasoline fuel injection system into the filter minder line, and be able to record the restriction of each component on a scale with good resolution, since MAP sensors inherently do that anyway. First suspects are stock filter, TMG filter, and mushroom cap. When we get a brand new Kenworth truck to test, even with the big Cummins ISX 15L engine, it's filter minder is on total zero even after a full throttle pull on the dyno or road.

Click to expand...

Any thoughts on why our M925A2's minder reads around 50% when there is no filter installed?

Not yet. Try filter out and no mushroom cap next. That leaves just all open pipe, and if still restricted, then it is just likely a pipe diameter issue. I don't think bends should play as large of part as the pipe diameter (flow velocity). Also try filter out and filter can lid off.

The filter minders they used are junk. that's the problem mine has the old style and it never pulls up but my buddies truck has the style as you're referring to and his truck has identical mods as mine and his will suck the filter minder right up.

K+n makes a higher flow filter to fit the trucks to, it is washable and re-oilable.

I am doing this mod. It is a mockup. I am hoping to have it done tomorrow. 8 inch hole where the blackout light would be with expanded metal over it. I will run 8" ducting with a 90 degree elbow to dump it into the top of the filter. Same setup as the air inlet for the heater box. I am also going to do the same thing across the engine running off the passengers inlet for the heater box. I do not even use my heater so not much since in not rerouting that. Hopefully I have the clearance over the engine . The metal inlets are 8' wide and have a seal on one end and have 4 holes for self tapping screws.

I will use a long piece of steel to secure it to the metal supports on the inner fender wells and secure the box to it. I used a box for irrigation that goes in the ground the 46664 filter fit right in it. 6" pipe to the 6" T . I did have to trim the band on the intake down some to allow the piping to be tucked into the original pipe area. It allowed me to have no hood clearance issues on closing nor on the box. I believe also I will add the same filter into the stock air box for additional flow. I am going to spray the flex seal stuff all over the piping on it at the moment to seat it up and give it solid texture perhaps. I do not use my truck to hit the mud anything but light stuff. In the event I want to do anything serious I will install the factory pipe.

Did not get any miles put on it today. I did idle it up to 1,700 rpms and let it run for a few mins. with the hood closed it did suck a sheet of paper directly over the inlet up flush. I do plan to double line the intake tube or wrap it with a head wrapping. it is quite fragile. I could not find the expandable solid dryer duct kind So I had to use an insulated type and just remove the insulation. I am going to work on my passengers side one this next week. I think I am going to cut that hole with a plasma cutter. With the air box setup though the two 8 inch pipes will fit fine. I think I will have to route it around the front of the hood. Not sure how much air flow it will actually have then. WORK IN PROGRESS.

Took it out yesterday and towed my other 923 home about 30miles away. A huge noticeable difference on towing especially from a stop on a gradual incline (on ramp) I manual shift up but very very smooth pulling and no bogging. I don't notice a big change when I am empty unless I am up to highway speed and she will haul pretty good from bout 52 on up and quick to jump to 70mph. Noticeable on pulling on hills empty as well.

Pulled around the empty M322 today for a bit and it did very well with it also. At about 1900rpms ( my best power rpm) you can hear it pulling in the air with no headphones on. I will be adding a second intake tube this week. both 8" hoses coming in with completely engulf the box. I also have to make some mods to block off any from the engine getting in. I do have the filter raised off the bottom of the box so the air can get around to all sides.

This was a 200 hour test filter for the modified air cleaner box. That this post refers to. Not my ram air box. This 931 is used extensively offroad and does a lot of idle time in dusty environments. I think it used pretty much all the filter. Did not have any noticeable loss in power with this filter.

Just some info so it can be found easily by others. The WIX airfilter 546664 (smaller filter used in the aftermarket kit) is rated for 949.42 CFM[FONT=HelveticaNeue, Helvetica Neue, Helvetica, Arial, sans-serif].

Can't find the requirements on the NHC 250 but for the more powerful NTC 270 it calls for 825 cfm at 2100rpm, NTC 335 calls for 850 cfm at 2100rpm NTC 350 calls for 986 cfm at 2100rpm, and the NTC 400 calls for 1165 cfm at 2100rpm.


Going off of this chart from Donaldson [/FONT]https://drive.google.com/file/d/0B54l5h8VOG0QMUxqc2RqYk1kRFk/view