If you’re doing the classic 7.3 Powerstroke 6637/BHAF intake mod, the filter is the whole point: big surface area, less restriction, built for work. The 6637 style has lived forever in the heavy-duty world (semi trucks, ag equipment, etc.), which is exactly why it became the go-to “stop choking the turbo” move on 7.3s.

 

What makes our 6637 different

The Riffraff Diesel 6637 Dry Washable Filter (RDP-080172) uses proprietary blue dry synthetic media and was built to do two things at once: flow more and filter extremely well. We’ve tested it against a Donaldson 6637 and it flows 10.53% more air while maintaining 99.98% efficiency using ISO A2 Fine Dust criteria.

It’s also 100% Made in the USA.

Check It Out: https://www.riffraffdiesel.com/riffraff-diesel-6637-dry-washable-filter/

Why a dry washable 6637 is a win for 7.3 owners

Most 7.3 guys want the BHAF benefits (less restriction + more filter area), but they don’t want to sacrifice filtration for “turbo noise.” This is a dry filter (no oiling step), and it’s designed to be washed and reused up to 5 times, which keeps the long-term cost down.

That lines up with how customers actually use it—reviews call it a direct replacement for NAPA/WIX 6637 filters and mention it “paid for itself” after the first wash, plus noticeable improvements like less smoke and better airflow.

 

 

Cleaning it the right way (don’t overthink it)

Rinse it with a garden hose, lightly blow it dry with shop air, then let it air dry (repeatable up to 5 cleanings).

General dry-filter best practices still apply: rinse from the inside out, avoid high-pressure water that can damage the media, and let it fully air dry (no heat).

Bottom line: clean it gently, dry it completely, and don’t oil it (it’s dry media).

 

Fitment and install options

If you’re running a 6637 intake on a 1994–2003 7.3, our Riffraff Diesel 6637 Filter Kit (RDP6637) lets you choose the RDP Dry Washable option, plus the correct adapter tube (45° for 94–early ’99, straight for late ’99–’03) and an optional pre-filter cover.

And yes—some trucks have a fuse box under the airbox; trimming tabs or “nestling” the filter for hood clearance is a real thing (our instructions call it out).

 

If you want a 6637 filter for your 7.3 that’s built around measured airflow + real filtration efficiency (not vibes), RDP-080172 is the one.