Hey guys im new here and to the Ford world. Picked up a 00 F250 4WD 7.3 Powerstroke the other day. Joined a couple other forums to learn more about these trucks as I work through them.

Now this is not meant to offend anyone, but im looking for the facts on this subject, and all I can seem to find is peoples thoughts. One of the other forums im a part of now seems to be pretty much like lemmings as they seem to just follow what the others do and not question anything. That is not the way I work, thats why im joining multiple sites to figure things out.

Alright for the CAI system the truck I bought had the full K&N air system already on it. This included the tubing, heat shield, and cone filter. Another forum this was a no no, completely horrible and will destroy the motor because its crap. So I changed out the filter to a 6637 and kept the heat shild and tubing. Well again this is a no no because the heat shield causes to much turbulance for the 6637. Now this is where im really starting to question everyone knowledge on this subject. No one can show proof that the 6637 flows, or filters better, its just what there saying.

So this brings me here.

K&N
Fits so much better
More turbo whine
Seems to be a little more power

6637
Very tight fit
No turbo whine
And I cant see how it can flow better due to how crammed it is in there.

Does anyone have any proof that the 6637 is better? Or any proof that the K&N system is as crappy as they say?

Thanks.

 

I believe most knocks against the K&N are the drop-in filters used in the stock box.... From what I,ve read, they don't seal correctly. That said, I have a MAC CAI which was on the Ex when I bought it.... Cone filter, tubing, etc. similar to your K&N. I don't think you'll have any issues with it. That, of course, is JMHO...that and $4.00 will get you a cup of coffee....(geez, I remember when it was a quarter....)

 

See opionions, I dont have a problem with them. I just hate hearing how I have it setup is wrong with no proof of anything, just there hear say. Thanks.

 

Like Don said, it's mostly the drop in K&N filter that are a little different from the OEM filter. They can let some dust/small particals to get by if not sealing right. No problem with the cone type filters. I have the 6637 and I am happy with this cheaper setup. I'm pushing mid 400 RWHP with no problems with breathing.

 

There was an air filter study done several years ago which indicated that the K&N has accomplished its high air flow capability by "opening up" the filter surface area... that means that it passes more dirt along with the increased air flow, which is not a problem with non-turbo engines except for the increased silica in the engine oil.

You see, there are two techniques to get more flow through a filter... more "open area" or "more surface area", and most filter manufacturers use a combination of the two when pursuing higher flow capacity. Apparently, K&N has focused more heavily on the "open area" technique.

I have a customer of mine who has run the 6637 on a flow bench unit and been able to achieve as much as 1,000 cfm without sucking in the element. Your 7.3L engine will not ever need anything even remotely close to that unless you are pushing well over 500 HP. Your stock element is rated at roughly 250 cfm while the 6637 is rated at 400 cfm... not sure what the rating is for the K&N you have. The point is that even when jammed into position, there is plenty of open area around even the 6637 to receive more air than your engine will require (remember, we're not trying to shove bulk items through that region under your hood... just air).

Just for clarification, I do not claim that the 6637 is the best approach for everyone, but it is more than adequate and provides excess air flow capacity while also providing very good filtration efficiency to keep your turbo and engine oil clean.

Here's a link to the study... Air Filter Test Report

 

I run the K&N cone with a pre filter cover, no dusting problem's, i have a sleeve in the hole on the fender and holes drilled in front grill, trying to get as much cold air as possible, the filters behind the battery, open like they are, are not as good at getting cold air like the newer designed closed boxes that relocate the battery, and draw cold air from the front, and fender. They also keep engine heat out. There are about 5 company's or so that make them.

 

See now theres some good stuff right there. Some proof of something instead of just bashing what I do since you dont do it.

Reading through all that its an entirely different truck there testing for, but the facts are still the same on the filters. What im seeing in there is pretty much taking it to the max to see how it works, right? And even with that I wont ever be at max for any of these filters. So with such the small numbers it was showing on the difference on the 6637 and the K&N, if the K&N is kept at peak operation (basically staying clean and not over oiled) theres really no reason that filter should hurt anything. Now if it gets really dirty I can see problems coming along with it, but how much of a perfectionist I am (engine bay you can basically eat off of) the K&N should not give me any problems.

Does this sound about right?

 

Where does this come from? Please show where this happened.

 

Where does the bashing come from? Its not on this forum, another one im on since im trying to learn on these trucks.

Thats why im thinking I found a new place im going to visit a lot more often than the other.

 

And the reason I brought this entire subject up is because I do like the K&N better for a couple reasons.

I like the sound of it better, and to me and the way my vehicles are it looks a lot more clean and in place under the hood.

But I had to make sure it wasnt going to kill the motor, because just buying the truck I dont really want to dump that kind of money in it right away

Thanks for all the replies.

 

Not really. You generally get better filtration with a dirty filter because the filter-plugging contaminants reduce the amount and size of open pores through which the air will flow. Smaller openings means better filtration, but along with that comes higher pressure drop (the turbo has to work harder for the same volume of air). Therefore, given that reality, a perpetually cleaned air filter will probably end up passing more dirt than one which is left to run for longer periods between cleanings (to a point). Also, keep in mind that you have a filter element which is capable of passing far more air than you need anyway, so a somewhat dirty filter will not significantly compromise performance for your truck.

Now, you can only get away from the pressure drop problem if you increase the surface area of the filter media because there will be more pore openings. The pressure drop is a direct result of velocity, and the more openings you have the less air you'll have going through each pore.

The REAL question now becomes this... if you have a partially plugged filter with a combination of completely and partially plugged pore openings, will the increased air velocity through the partially plugged pores cause some of the contamination to be forced loose into your turbo intake? I can see the theoretical possibility for this, but have no hard data to say whether or not this is a real problem for us... it's just one of those "wonderment" questions I have, and I would think that the real answer is, "It depends on how high the velocity is through the pore openings".

Personally, I am willing to sacrifice the sounds of both turbo whistle and "whoosh" for cleaner air entering my turbo... especially if the cleaner air comes at a significantly lower cost. But that is MY choice for MY reasons, and I am perfectly happy letting everyone else make their own choices for their own reasons.

The only thing I will challenge someone on is an issue over scientific principles and real world physics. Even then, I won't push anything on anyone because we're all adults in here and I can rarely help someone see something they don't want to see.

Nothing I said in the immediately previous paragraph is targeted at anyone in this discussion... it's based solely on my experience in threads in the past with other individuals.

 

I do like the sound but thats not the major reason I like the other better. Looks are a lot to me, and popping the hood and seeing the 6637 crammed in there just looks so half assed even with all the trimming ive done to make the K&N heat shield work with it. Where as the K&N filter fits perfectly centered in the space between the battery and heat shield. Looks more neat and professional.

This is not supposed to offend anyone that has the 6637 setup, my personal taste is smooth and clean look, hence no emblems or anything on the truck. Hell im still wondering about taking the foil off because that looks like crap under the hood to.

 

I don't have any opinion of the 6637 filter since I've never used one on any of my trucks.

I have nearly 1/4 million miles on my K&N drop in filter and each oil sample comes back looking pretty good. I will say the OEM box is NOT the most foolproof design so it's very possible to install a drop in filter in such a way as to allow unfiltered air to the engine. In my opinion, it's most likely the box design that has caused dusted engine problems since the problem is exaggerated when using a K&N drop in vs a OEM filter element (due the thickness of the filter seal around the perimeter of the element). I have actually performed a test on an OEM filter box which proves they can allow unfiltered air directly to the engine.

Most every cone style filter that I've seen does a much better job sealing itself to the intake tube including the K&N brand. My trucks run at stock or just slightly modified power levels (50 hp increase) and the K&N filter media seems to perform just fine for me. I do clean and re-oil every 15k miles, which is the same interval I've been using for fuel filter changes, EBP sensor cleaning etc...

Hope this info helps...

 

Thanks again for the personal opionions.

And I got to say im going to be sticking around this forum more than the others. You guys are easier to discuss things with and get actual input besides the "no thats wrong" or "that will kill your motor" answeres I have been getting elsewhere.

 

Welcome to FTE.

Most folks here have the same interest as you....we love our trucks and enjoy learning about how they work. Some like to modify heavily, some mildly and some not at all. It's all good.

Lots of great information here and lots of folks willing to help when possible. If you are able, please support the site and our vendors when the opportunity allows.