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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 44 | Next

  1. Great filter 5 Star Review

    Posted by on Apr 19th 2018

    Great filter! RiffRaff is great as well!

  2. Good price, fast delivery 5 Star Review

    Posted by on Apr 13th 2018

    I usually run the std Donaldson but decided to give this a try. My truck sees allot of dirt roads during hunting season, and the extra protection is worth the small price increase since i change the filter once a year or 10000 miles. I did notice 2 mpg improvement!

  3. Nice filter 5 Star Review

    Posted by on Apr 11th 2018

    I have always had good luck with RiffRaff. Products arrive on time and the quality is excellent.

  4. Replaced K & N filter & used cold air intake tube. 5 Star Review

    Posted by on Mar 29th 2018

    I was hesitant to purchase the filter because I wasn’t sure it would work with my existing K&N cold air intake system on my 01 7.3L F-250. It worked with the intake tube, I had to remove the fire wall though ...simply zip tied the sensor out of the way.

  5. Great product 5 Star Review

    Posted by on Mar 19th 2018

    Definitely feels like it increased my acceleration and improved fuel mileage.

  6. open element a lot more surface area 4 Star Review

    Posted by on Mar 17th 2018

    this appears to be the same kind of filter element material thats in heavy industrial air filtration.
    they should work way better than a stock filter and if you get close you can actually hear it sucking air over a clattering diesel.
    one other thing is the stock piping doesnt put the filter all the into the old housing location.
    you will also need bigger hose clamps.
    you would have to get some exaust tube bent to have a clean and functional install.
    the filter takes the place of the entire housing which is great because by now your stock housing most likely rotten and its expensive to replace.

  7. What a difference 5 Star Review

    Posted by on Mar 6th 2018

    Outstanding. Big improvement over the standard 6637. Noticeable immediately my turbo (s364.5sxe) sounds and feels much happier.

  8. Filter upgrade amazing!! 5 Star Review

    Posted by on Feb 28th 2018

    Replace my k&n with Donaldson blue, You really feel the difference on my truck’sPerformance. Love the way my turbo sounds and the acceleration responds is great. 2003 F250, 7.3 powerstroke.

  9. 6637 5 Star Review

    Posted by on Feb 7th 2018

    Replaced my original 6637 with the new Donald blue lowed the egt more flow and better throttle response

  10. Amazing Flow! 5 Star Review

    Posted by on Dec 25th 2017

    Swapped my wix 6637 filter out for Riffraff’s Donaldson blue 6637 and what a difference! 250cc/100% injectors, T4 turbo and I ran 587hp and 1176ft tq. Thank you guys for this awesome well priced filter option.

Showing reviews 1-10 of 44 | Next