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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 14 | Next

  1. Donaldson Blue 5 Star Review

    Posted by on Mar 2nd 2017

    Great filter. Turbo spools faster and lower egt's up long hills. Fits nice under the hood with factory air box removed.

  2. 1999 F250 Super Duty 7.3 liter 5 Star Review

    Posted by on Feb 26th 2017

    Just fits behind the battery area. Installed a Filterwears pre-filter over it. Fits on the existing K/N intake tube. Had to remove what was left of the stock air box to fit it. Seems a little peppier to me, like it's getting more air flow. It's much larger than the K/N filter. Happy with it so far. Pre-filter is a nice bright yellow, looks good.

  3. Red Line! 5 Star Review

    Posted by on Feb 12th 2017

    After installing truck revved very fast 2800-3200rpm is not laggy. Turbo blow is also noticeable now.

  4. 7.3 powerstroke must have 5 Star Review

    Posted by on Jan 18th 2017

    One of the best and cheapest mods to do. Truck will breathe and run better without compromising air filtering. Riffraff offers different versions of the filter at great prices. Riffraff as always best place to turn for your 7.3.

  5. Air filter 5 Star Review

    Posted by on Jan 1st 2017

    I love this thing it looks so good under the hood and it works awesome !

  6. Donaldson Blue 6637 replacement filter 5 Star Review

    Posted by on Dec 8th 2016

    This product shipped fast, arrived at my home in Canada within a week. This filter is a direct replacement for a Napa 6637 or similar set up and takes about a minute to swap in (if you've already done the 6637 mod) and looks great!

  7. Filter you cant beat 5 Star Review

    Posted by on Nov 18th 2016

    For the low price and high quality of the filter it doesnt get any better

  8. Waiting to see 5 Star Review

    Posted by on Nov 12th 2016

    I like it fine but I'm not sure I can tell much difference for normal everyday use between the Donaldson Blue & just the standard 6637 that I've used for years. But it's only been a week. I have the TSI 6 position chip and right now it seems to smooth out some of the hard shifting of gears when I have the 100hp mode

  9. Great Quality and Flows Great! 5 Star Review

    Posted by on Sep 22nd 2016

    I purchased this filter for a custom air intake I built for a Cummins and I will not recommend any other air filter. This is by the far the best quality air filter I've used and I will definitely buy more!

  10. Best filter on the market 5 Star Review

    Posted by on Sep 1st 2016

    Donaldson teamed with Riffraff to bring this to the table, and there is no going back. This filter will handle whatever is thrown at it and pass the white glove intake test! Very competitive price, and worth every penny. Don't second guess, buy the best! Hats off to Riffraff for the efforts.

Showing reviews 1-10 of 14 | Next