Interesting conversation going here. I, too, would like to see some testing results if they ever become available.

Barry is right... the prefilter is not disposable unless you damage or destroy it. They are 100% polyester knit and easily washable and re-usable. That goes for not only my covers, but also for those from AFE and Outerwears.

Regarding the restriction issue in terms of performance, my own personal experience is this, and pelase forgive the subjective nature of what I'm about to say... it's just my own observations. With the stock air filter, I would get black smoke from punching the accelerator moderately.

With a new 6637, no cover, I had to slam the throttle hard to get black smoke, and it was only momentary in comparison to the sotck filter.

With the cover on the new filter, no noticeable difference in SOTP (seat of the pants) acceleration or smoke generation under any conditions.

At 10K miles when the cover was really dirty, there had been no indication of performance loss due to either SOTP, smoke, or mileage (which I hand calculate and track meticulously).

Washed the cover and reinstalled. Before it got as dirty as previously when washed, I started seeing mileage drop off. Shined a light through the air filter, adn light would not shine through it due to filter pluggage - not cover pluggage.

I've run this cycle twice now and the cover appears to make no difference on performance. Remeber this... the 6637 has nearly twice the surface area of the stock filter element which means that the pressure on the surface is going to be roughly one half, which means less tendency to have stuff drilled into the fabric for pluggage. Furthermore, if you hold the fabric up to the light, you can see that the holes are large enough such that only things like wet leaves or straw will actually plug the cover... the fabric knit is simply too "open".

Just for a little more context, folks. I made my first cover because it would keep things like leaves and bugs out, and I put graphics on just for the fun of it. I hear from different people about how the cover is actually extending their filter life, and I do not doubt that it does, to some degree at least. How much difference it will make will depend on your driving style, ambient conditions (dry and dusty versus wet and not dusty, etc.), etc.

Now, as for price versus value... every individual has to make that decision based on their own set of personal goals, values, and finances.

The quoted price of $25 for a new 6637 sounds great, but I'd bet that that is either before taxes and/or before shipping, otherwise, it's a good deal because Fleetfilter.com's price in closer to $28 or $29 each before S&H. If anyone wants to talk with me about my own pricing, you'll have to email me because I cannot discuss that here in FTE. Just send me an email.

Motoman... if you want to test one of my covers, I'd be happy to send you one free for testing, complete with graphics on it so the comparison would be real world. I would, though, like to hear more details about the flow bench test equipment you have so I can understand how comparable it is to the application on our engines. We can discuss that offline through our own personal email, though.

Regarding the Filter Minder, I personally believe that it isn't useful or meaningful. Something like a low pressure gauge using inches of water vacuum from (0-30 inches) would be perfect, but it would only be most effective if installed in the cab where you can see it's performance while the engine is under load and pulling more air through the filter. I know that Navistar recommends changing the filter elements when they start pulling 15 inches of water vacuum under load.

 

You said it best.

When i put the 6637 on my truck i could feel and hear that it was getting more air. The feeling in "SOTP" welcomed. I feel the same way about the Filter Minder. I just recall talk about that issue before. I think all comes down to taking care of your stuff. If you wash Pete's cover as it is needed and change the 6637 out as needed. It is the Best filter out there.

 

Pete has said it well and made the offer for testing along with wanting to see offical results. Not that I need it, below is enough proof for me.
1st is the filter after around 7k, still looks good
2nd is the outside of filter with about 3k since last wash
3rd is the inside of same cover.

 

Well, motoman620 must be out-of-pocket since his last post. I've even PM'd him to talk more about the bench testing, but no response yet.

 

Sorry I dont check this site daily, I sent you a PM about bench testing.

 

Got it, Curt... thanks.