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Riffraff Diesel Performance Inc, Engines - Supplies, Equipment & Parts, Eagle Point, OR


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Donaldson Blue® 6637 Filter

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Part Number:

Donaldson Blue® 6637 Intake Filter for Ford 7.3L 94-03

Donaldson Blue® air filters with Ultra-Web® nanofiber technology protect engines by providing better initial and overall efficiency compared to conventional cellulose media. Donaldson invented air filters for heavy-duty diesel engines over 100 years ago and were the first to develop nanofiber air filter media for the diesel engines, with more than 20 years of proven performance. 

  • Longer Engine Life - Donaldson Blue™ air filters provided better engine protection by allowing much less contaminant to pass through than cellulose air filters but still maintaing a higher flow rate
  • Longer Filter Life - Smaller interfiber spaces of Ultra-Web® nanofiber technology hold more submicron contaminant than conventional filters with cellulose media, delivering longer filter life
  • Increased Flow - Utilizing the nanofiber Ultra-Web® media has allowed for a 37% increase in flow over the standard 6637 cellulose filter. It has also been tested to flow over 1300 CFM+.
Media Type
  • Ultra-Web® Nanofiber Technology -- Exclusively in Donaldson Blue air filters
    • Engineered to perform in extreme temperature and humidity conditions, unlike ordinary nanofibers and cellulose which aren't hydrophobic
    • Proven in the real world – used in diesel engines for nearly two decades
    • On-road applications are guaranteed to go twice the distance compared to standard cellulose filters

We suggest buying them in quantities of 2 as your shipping won't increase much and you will save money.

100% Made In The USA


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Product Reviews

Showing reviews 1-10 of 26 | Next

  1. 6637 Air filter 5 Star Review

    Posted by on Aug 18th 2017

    Worked great on my Ex 7.3

  2. 6637 upgrade 5 Star Review

    Posted by on Aug 7th 2017

    My old 6637 filter was looking a bit rough so I decided to try this blue one as a replacement.
    It is certainly a worthwhile option that anyone looking for more air should consider.
    This will be my go-to filter from now on.

  3. Donaldson blue 6637 5 Star Review

    Posted by on Aug 2nd 2017

    Flows way more air then the regular 6637

  4. Great filter! 5 Star Review

    Posted by on Aug 1st 2017

    I like this filter better than the original 6637. The filter seems to breathe better. The turbo also doesn't hesitate as much either. I would definitely recommend this filter.

  5. Go blue! 5 Star Review

    Posted by on Jul 6th 2017

    High quality, lots more turbo whistle. It's nice to know I'm not dusting my turbo. And Riffraff always has super fast delivery!

  6. Great filter 5 Star Review

    Posted by on Jul 3rd 2017

    I read the reviews about the regular 6637 with a large following, but knew the math doesn't add up for better breathing than stock filter. They report noisier turbo, but that is from starvation. This filter is quite like stock, but breaths so much better while stock or with upgrades. I'm very pleased with the product. Thanks riffraff for the great solution.

  7. Increased Flow 5 Star Review

    Posted by on Jun 13th 2017

    This filter looks and feels like a very high quality product. I replaced my K&N filter kit with this Donaldson Blue filter. I believe it breathes a lot better then either the stock filter or a K&N kit. I had to cut my battery tray on the driver side to fit this filter though. I recommend this product if you are looking for increased flow and protection.

  8. The new blue Donaldson filter looks sounds and a great product 5 Star Review

    Posted by on Jun 7th 2017

    I pick up a few mpgs on towing and all around driving in my 2003 f250 7.3 , the filter looks great under the hood and sounds great driving I'm very happy with my purchase !!

  9. WOW 5 Star Review

    Posted by on May 22nd 2017

    ordered this filter last week to replace my old k&n filter that seemed to rob my truck from power. Installed this filter today and went for a drive noticed a serious power difference along with a slight egt decrease and no longer blowels black smoke. Great job riff raff will definately be buying again and will come to you for my future mods

  10. great filter 5 Star Review

    Posted by on May 10th 2017

    I like this filter over the std filter.I feel their is better pick up off throttle.

Showing reviews 1-10 of 26 | Next