Hi Guys, I installed the K&N FPIK kit, after reading posts here I am scared to keep the damn K&N filter on there so I ordered a 6637 from NAPA online.
What if anything do I need to adapt the 6637 to my K&N intake kit? The NAPA filter seems stiff at the end, doesnt seem that a hose clamp will seal this filter, what do you guys use to seal the filter to the tube?

 

a 4" exhaust pipe or a coupler for 3" PVC pipe...then just clamp it down..

 

What's the diameter of your adapter opening on the K&N intake side?

 

Not sure on the diameter yet, plan to get into it this weekend, I was just curious about clamping the filter to the tube..... seems like some hard material to try and clamp.
P.S. F-250 Pete, I ordered one of your filter covers for the 6637 filter, looking forward to receiving it.....

 

The 6637 will slip over and clamp to the K&N intake tube. Thats what I did.

 

I didn't use a clamp,I used a piece of 4"exhaust pipe and pushed it into the filter as far as it would go,then I used silicon(pretty heavily actually)and let it set and cure,it is definitely sealed and tight too. I can raise the filter up for inspection and it still holds fine,by the way, this is the second filter I've done this way.Just my .02 worth...

 

Thank you. Very much appreciated.

 

my filter came in, looks like I need to pick up an adapter from the larger diameter to the smaller. I've read PVC is bad for use in the engine compartment, is this true?

 

Not necessarily. What are you working with? a 4" OD piece of exhaust works perfectly. I ran mine for almost a year with just the tube over the neck of the filter. Down side is that filter neck collapses over time, loosening the connection. I had to keep an eye on it and keep clamping it down. When I finally got my piece of exhaust it was a real bear to get it opened up enough again to go over the pipe. When I ordered a new one and replaced it, it went right on no problem. And you can definitely clamp the 6637 filter neck -- no problems here with that at all:

 

The K&N intake tube on my "Aircharger" model was a cheap plastic that would distort its shape and possibly crack if you tightened a worm clamp tight enough to make a good seal with the stiff rubber neck on a 6637. Donaldson makes a special clamp which they recommend to avoid air leaks.

 

I don't understand the reason for this mod. The stock air filter gets cold air from the scoop next to the grill, this mod has the engine breathing hot engine compartment air. I can't believe the stock filter is a flow restriction, according to CFM charts a 444 ci engine at 3500 RPM with 115% efficiency (due to turbo) can only flow 450 cfm. The stock filter should flow 500CFM easy, no?

 

there is an issue with the stock box not sealing properly

 

Poor fitment and the stock box warping allowing dust by the filter is main reason. Extra air is just a by product.

 

Finally a voice of reason!!!

The sealing issue occurred with the older OEM filter and especially with inferior 3rd party replacement filters. Ford fixed that issue many years ago by introducing a revised OEM air filter part # FA-1750. The newer stock FA-1750 is a very good filter that works for most users in the stock air filter box. The Motorcraft FA-1750 has a 496 gram dirt capacity, and is strong enough to hold dirt & not warp.

A better filter setup for the 7.3L PSD is the even newer Motorcraft Severe Duty filter kit FA-1759. It uses a Donaldson Powercore filter media and has 1300 gram dirt capacity. An even better setup is to adapt the 6.0L Donaldson Powercore filter to the 7.3L like is shown in post #10 here... https://www.ford-trucks.com/forums/8...r-intakes.html

See post #88 here... https://www.ford-trucks.com/forums/8...n-turbo-6.html for how to calculate the detrimental effects of ingesting hot under the hood air from an "open element" filter.

These are my top 4 reasons for not using any type of under the hood "open element" air filter...

1) It lets in too much hot air which makes the turbo work harder trying to flow more CFM to make up the difference in the lower MAF due to the lower air density. If you tow hot and heavy you definitely will be better off using a cold air intake versus an open element filter. Measurements, computer models, and my 10 years as a fulltime RVer which included several years towing with an open element filter have demonstrated conclusively that ingesting hotter than necessary under the hood air is detrimental to towing performance.

2) Without an air box and an inlet snorkel leading to a Zoodad hole not only do you give up the benefit of the cooler ambient air but you also give up the benefit of 2" H20 or more of RAM air pressure which helps force cooler outside air past the filter and into the turbo inlet tube. This might not sound like much but when you're struggling to get to the top of the Grapevine on a hot day every little bit helps if only a little bit.

3) An open element filter is subjected to all the fumes and dust that gets into the engine compartment. It gets coated with oil fumes, dirt, and grime just like everything else in a typical engine compartment. A filter in an air box with an inlet leading directly to ambient air only has to deal with the dust that's in the air actually being used by the engine. I can wipe the top of my air box clean, and after 2 or 3 hours of towing pull into a rest stop and the air box is dirty again. The way I see it that's an extra amount of dust that would've wound coating my filter if it hadn't been protected by an air box.

4) Condensation! Yes I mean inside the engine compartment as well as all over the outside of the truck and RV. It's happened to me many times when camped out near the ocean and gulf. This might not be a big problem for an oiled type open element filter but it's not good for a paper one. Even high humidity has made papers inside my RV so limp that I've had to hold them with both hands to read them!

 

what is so bad about the K&N filter. i am have an afe intake with the seven layer filter.i works like the K&N meaning the oil on the element. should i change it to something else?