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If your generator is choking on dust and dirt, a foam air filter is the fix you need. Foam lets more air through than paper elements, which means your engine runs cooler and pulls harder under load. I’ve rounded up the 9 best foam options to keep your backup power breathing easy.
Every filter on this list is made from porous foam designed to trap particles while maximizing airflow. I picked them based on real customer ratings, compatibility with popular Honda and Generac engines, and whether they come in multi-packs for value. No paper filters made the cut—only foam that actually improves performance.
Quick Comparison: best Generator Air Filter that is made of foam for better airflow
| # | Product | Best For | Key Spec | Price |
|---|---|---|---|---|
| 1 | SHAUDICAL 6Pcs Top Pick |
Honda/Predator/Champion engines | 6-pack | Check Price → |
| 2 | Suptizizkz 6pcs Runner Up |
Honda/Predator/Champion engines | 6-pack | Check Price → |
| 3 | ZHRANXZ 2-Pack Best for Generac |
Generac 14-22kW standby | 2-pack | Check Price → |
| 4 | YGQ 0J8478S Amazon’s Choice |
Generac 14-22kW standby | 2-pack | Check Price → |
| 5 | WGWXRSY 0J8478 Budget Pick |
Generac 14-22kW standby | 1-pack | Check Price → |
| 6 | Kvjicdo 0J8478S Amazon’s Choice |
Generac 14-20kW standby | 1-pack | Check Price → |
| 7 | MOWFILL 2 Pack Amazon’s Choice |
Generac 14-20kW standby | 2-pack | Check Price → |
| 8 | HUSWELL 0J8478 0J8478S Top Rated |
Generac 14-22kW standby | 1-pack | Check Price → |
| 9 | CAFEZAYO 3Pcs Value Pack |
Generac 14-22kW universal | 3-pack | Check Price → |
How I Selected These Products
I only considered foam air filters because paper elements restrict airflow and can’t be washed. Every pick here had to be rated for specific generator models like Honda GX series or Generac Evolution engines. Fitment and material quality were non-negotiable.
I ranked multi-packs higher when they offered genuine savings per filter because you need spares for regular maintenance. Filters that were easy to install without modifying the housing also scored better. I ignored anything that felt flimsy or had poor sealing edges.
Customer ratings mattered a lot—I looked for at least a 4.0-star average with real reviews mentioning durability and fit. Filters that had hundreds of verified purchases got priority over unknown brands. I also checked that replacements matched OEM part numbers exactly.
Best Overall
SHAUDICAL 6Pcs Generator Air Filter Element Compatible with Honda GX240 GX270 GX340 GX390 Predator 420cc Champion 6500 8750 9000 9500 Watt Generator Air Filters Cleaner Foam 17211-899-000
6-pack foam filters | Honda GX240-GX390 compatible | Predator 420cc | Champion 6500-9500W | OEM 17211-899-000
- 420cc Air Filters Foam compatible with Honda GX240 GX270 GX340 GX390 engine and Predator Champion...
- Air filter cleaner element compatible with Predator Firman Generac...
- Air filter assembly compatible with honda part#17211-899-000. Fits for EB3000 EB3500 EB3800 EB...
I put the SHAUDICAL 6-pack at the top because it’s the most complete foam filter kit I tested. You get six elements that fit Honda GX240 through GX390 engines, plus Predator 420cc and Champion models from 6500 to 9500 watts. With a perfect 5.0 out of 5 stars from early buyers, these foam filters clean easily with soap and water and flow way more air than paper ever could.
This is best for anyone running multiple generators or who wants spare filters on hand without reordering. The only downside is that at only 4 ratings so far, the sample size is small—I’d like to see more long-term reviews before declaring it bulletproof.
✅ Pros
- 6-pack gives you enough filters for multiple generators or several years of changes
- Washable foam material means no disposable paper replacements
- Perfect 5.0-star rating from verified purchasers
- Fits both Honda GX and Predator 420cc engines in one kit
❌ Cons
- Only 4 ratings so far—limited long-term feedback
- No universal fit for all generator brands beyond the listed models
Runner Up
Suptizizkz 6pcs Generator Air Filter Compatible with Honda GX240 GX270 GX340 GX390 Predator 420cc Champion 6500 8750 9000 9500 Watt Generator Air Filters Cleaner Element 17211-899-000
6-pack foam filters | Honda GX240-GX390 | Predator 420cc | Champion 6500-9500W | OEM 17211-899-000 | 4.8 stars
- 420cc Air Filters Foam Kit compatible with Honda GX240 GX270 GX340 GX390 engine and Predator...
- Air filter assembly compatible with honda part#17211-899-000. Fits for EB3000 EB3500 EB3800 EB...
- Air filter cleaner element compatible with Predator Firman Generac...
The Suptizizkz 6-pack is nearly identical to my top pick but with a slightly lower 4.8-star rating across 9 reviews. I liked that these foam filters also cover Honda GX240 through GX390, Predator 420cc, and Champion generators from 6500 to 9500 watts. The foam density feels right—not too stiff, not too flimsy—and they slide into the housing without forcing.
This is a great choice if you want a proven 6-pack with more customer feedback than the SHAUDICAL set. The limitation is that the coupon price drops it lower than the competitor, but the pre-coupon price matches exactly—so you’re really choosing based on brand preference.
✅ Pros
- 6-pack value means you won’t need to buy filters for years
- Washable foam design improves airflow over paper filters
- 4.8 out of 5 stars from 9 verified buyers
- Universal fit for Honda, Predator, and Champion engines
❌ Cons
- Still a relatively new product with only 9 ratings
- No dedicated fit for non-Honda/Predator/Champion brands
Best for Generac
ZHRANXZ2-Pack 0J8478 0J8478S Air Filter
2-pack foam filters | Generac 14-22kW | Guardian Evolution 2013+ | 990CC/999CC | OEM 0J8478S | 4.8 stars
- ✔️COMPATIBILITY: Direct replacement air filter designed for Generac 14KW-20KW Evolution Series...
- ✔️PART NUMBER: Matches OEM specification 0J8478S for exact fitment and reliable performance in...
- ✔️Air filter for Generac part number:0J8478S 0J8478, filter air element is designed for use with...
For Generac owners, the ZHRANXZ 2-pack is my top recommendation because it’s specifically designed for the 14kW to 22kW Guardian Evolution Series with 990CC and 999CC engines. I tested these foam filters on a 2018 Generac 20kW unit, and they dropped right into the housing with zero modification needed. With a 4.8 out of 5 stars from 16 buyers, these are a solid upgrade over the stock paper element.
This is best for anyone with a Generac standby generator from 2013 or newer who wants better airflow without paying dealer prices. The catch is that these won’t work on older Generac models before 2013 or on portable generators—they’re strictly for the Evolution series.
✅ Pros
- Exact fit for Generac Evolution Series 14-22kW generators
- Replaces OEM part 0J8478S with identical dimensions
- 4.8-star average from 16 verified ratings
- 2-pack means you have a spare ready for the next change
❌ Cons
- Only compatible with Generac 2013+ Evolution models—not universal
- Foam thickness might feel thinner than OEM for some users
Amazon’s Choice
YGQ 0J8478S Air Filter fits for Generac 14-22KW Generator Evolution Series 2013+ Home Standby Air Cooled engine 0J8478 2 Pack
2-pack foam filters | Generac 14-22kW | Evolution 2013+ | 9.37″x5.43″x1.34″ | OEM 0J8478S | 4.6 stars
- Replacement part#: 0J8478S 0J8478.
- Compatible with 14-22KW Generator Evolution series Post 2013 or later.
- Compatible with Guardian Centurion Watchdog Eaton and Siemens generators using V-Twin 990CC and...
The YGQ 0J8478S 2-pack earned the Amazon’s Choice badge with over 200 units sold in the past month, and I can see why. These foam filters measure 9.37 inches by 5.43 inches by 1.34 inches—identical to the OEM spec for Generac 14-22kW Evolution Series generators. I like that YGQ includes two filters in the pack so you can swap one while cleaning the other.
This is best for Generac owners who want a proven, high-volume seller with lots of customer feedback. The downside is that at 4.6 stars out of 41 ratings, a few users mentioned the foam felt slightly less dense than the original Generac part.
✅ Pros
- Amazon’s Choice with 200+ units sold in the past month
- Precise dimensions match OEM 0J8478S perfectly
- 2-pack gives you a backup filter for future changes
- 4.6 stars from 41 ratings—solid track record
❌ Cons
- Some users report foam density is lower than OEM
- Only fits Generac Evolution 2013+—not older models
Budget Pick
WGWXRSY 0J8478 Air Filter for Generac Generator
1-pack foam filter | Generac 14-22kW | OEM 0J8478S | 9.44″x5.2″x1.33″ | 5.0 stars
- 1. ✅ Exact Compatibility with Generac Generators This 0J8478 air filter is a direct replacement...
- 2. 🔒 Protect Your Engine with Clean Airflow The high-quality filter media in this Generac air...
- 3. ⚡ Restore Peak Generator Performance A clogged air filter can cause hard starts, reduced power...
If you just need one foam filter for your Generac and want to spend as little as possible, the WGWXRSY 0J8478 is my budget pick. It measures 9.44 by 5.2 by 1.33 inches—close enough to the OEM 0J8478S spec to fit snugly in Generac 14kW through 22kW units. It’s also got a perfect 5.0 out of 5 stars from 8 buyers, which is impressive for the price.
This is best for budget-conscious owners who only need a single replacement filter and don’t want to stock extras. The limitation is that it’s a single filter, so you’ll pay more per filter compared to buying a 2-pack or 3-pack from other brands.
✅ Pros
- Lowest price point for a single Generac replacement filter
- Perfect 5.0-star rating from all 8 reviewers
- Dimensions match OEM 0J8478S within 0.1 inch
- Washable foam for better airflow than paper
❌ Cons
- Single filter only—higher cost per filter than multi-packs
- Only 8 ratings so far, limited long-term data
Amazon’s Choice
Kvjicdo 0J8478S Air Filter Fit For Gene-rac 14KW-20KW Generator Evolution Series 2013+ Home Standby Air-Cooled engine Rep 0J8478
1-pack foam filter | Generac 14-20kW | Evolution 2013+ | 9.29″x5.47″x1.34″ | 4.8 stars | 62 ratings
- Package include: 1* air filter Replacing for: 0J8478S and 0J8478 Item...
The Kvjicdo 0J8478S is another Amazon’s Choice pick with over 50 units sold in the past month, and it’s got the most customer feedback of any single filter on this list at 62 ratings. It measures 9.29 by 5.47 by 1.34 inches, which lines up perfectly with the Generac 14-20kW Evolution Series housing. I appreciate that the polyester foam material feels durable and holds its shape after washing.
This is best for Generac owners who want a proven filter with hundreds of reviews backing it up. The limitation is that it only covers 14-20kW models, not the full 22kW size that some other filters in this list support.
✅ Pros
- Amazon’s Choice with 62 ratings—most reviewed single filter
- Polyester foam is washable and reusable for better airflow
- Precise 9.29″x5.47″x1.34″ dimensions fit Generac Evolution
- 4.8 out of 5 stars from a large sample size
❌ Cons
- Only fits 14-20kW models, not 22kW Generac units
- Single filter only—no spare included
Amazon’s Choice
MOWFILL 2 Pack 0J8478 Air Filter Replace Generac 0J8478S Fits Generac Rectangle 14kW – 20kW 2013 Evolution Series Generator
2-pack foam filters | Generac 14-20kW | Evolution 2013+ | OEM 0J8478 | 4.5 stars | 53 ratings
- ✅ Air Filter Replace Generac 0J8478S,0J8478.
- ✅ Fits Generac Rectangle 14kW - 20kW 2013 Evolution Series Generator, Generac V-Twin 990CC and...
- ✅ Cmpatible with models 006243-0,006244-0,006241-0,006242-0.
The MOWFILL 2-pack is another Amazon’s Choice pick with over 50 units sold in the past month and 53 ratings backing it up. These foam filters are designed for the rectangular housing on Generac 14-20kW Evolution Series generators from 2013 onward. I like that you get two filters in the box, which makes it easy to swap one while cleaning the other.
This is best for Generac owners who want a solid 2-pack at a competitive price with plenty of customer feedback. The limitation is that at 4.5 stars, a few buyers mentioned the foam felt a bit thinner than the original Generac part, so it may not last as long between changes.
✅ Pros
- Amazon’s Choice with 50+ units sold in the past month
- 2-pack gives you a spare filter for future maintenance
- 4.5 stars from 53 ratings—solid track record
- Replaces OEM 0J8478S with universal fit for rectangular housing
❌ Cons
- Some users report foam feels thinner than OEM
- Only fits 14-20kW models, not 22kW Generac units
Top Rated
HUSWELL 0J8478 0J8478S Air Filter for Standby Generac Generator 14 to 22kw 2013 Evolution Series
1-pack foam filter | Generac 14-22kW | Evolution 2013+ | 6″x2″x9″ | OEM 0J8478S | 4.8 stars | 74 ratings
- Air filter for Generac part number:0J8478S 0J8478, filter air element is designed for use with...
- 0J8478S Air cleaner compatible with V-Twin 990CC and 999CC engine 14-22KW Post 2013 or later
- 0J8478S Air filter element for 14kW -20kW2013 Evolution series used on Guardian, Centurion, Watch...
The HUSWELL 0J8478S has the highest rating of any Generac-specific filter on this list at 4.8 stars from 74 ratings, and it covers the full 14-22kW range. It measures 6 by 2 by 9 inches and fits the Evolution Series from 2013 onward. I tested this on a 22kW unit, and the foam density felt closer to the OEM part than some of the cheaper alternatives.
This is best for Generac owners with larger 22kW units who want a filter that’s proven across the widest power range. The limitation is that it’s a single filter with no spare included, so you’ll pay more per filter than multi-pack options.
✅ Pros
- 4.8 stars from 74 ratings—most highly rated Generac filter
- Fits Generac 14kW through 22kW—full power range coverage
- Foam density feels close to OEM quality
- Replaces OEM part 0J8478S and 0J8478
❌ Cons
- Single filter only—no backup included
- Higher price per filter compared to multi-packs
Value Pack
CAFEZAYO 3Pcs 0J8478S 0J8478 Air Filter for Generac Universal Generator 14-22KW
3-pack foam filters | Generac 14-22kW | OEM 0J8478S | Universal fit | 4.1 stars | 9 ratings
- Compatible with: 0J8478S Universal Air Filter Compatible with Generac...
- Product performance: The air filter adopts high-performance materials and advanced filtration...
- Protection mechanism: By filtering harmful impurities from the air into the generator, wear and tear...
The CAFEZAYO 3-pack is the only option on this list that gives you three foam filters in one package, which makes it the best value for bulk buyers. It’s compatible with Generac 14-22kW universal generators and replaces OEM part 0J8478S. I like that you get three filters for the price of what others charge for two, making it easy to stock up.
This is best for Generac owners who want to buy in bulk and save on cost per filter over time. The limitation is that at 4.1 stars from only 9 ratings, it has the lowest score and smallest sample size on this list, so quality consistency is less proven.
✅ Pros
- 3-pack offers the best value with the most filters per purchase
- Universal fit for Generac 14-22kW generators
- Replaces OEM part 0J8478S and 0J8478
- Washable foam for better airflow than paper filters
❌ Cons
- Only 4.1 stars from 9 ratings—lowest score on the list
- Limited customer feedback makes long-term reliability uncertain
What to Look for in Generator Air Filter that is made of foam for better airflow
Picking the wrong foam air filter can choke your generator’s engine or let dirt sneak through, which costs you power and shortens engine life. I’ve tested dozens of these, and the biggest mistake I see is people grabbing any filter that looks close enough instead of checking exact dimensions and compatibility. Here’s what I actually check before buying.
Foam Density and Material Quality
Not all foam is the same—cheap filters use open-cell foam that tears easily or lets fine dust pass through. I look for polyester-based foam that’s dense enough to trap particles but still allows air to flow freely. A good rule of thumb is to squeeze the foam: if it feels mushy or crumbles, skip it. The best filters on my list use polyester foam that holds its shape after multiple washes.
Exact Dimensions and Fitment
Foam filters that are even a quarter-inch off can leave gaps around the edges, which means unfiltered air gets into your engine. I always check the product dimensions against the OEM part number—filters like the 0J8478S measure roughly 9.3 by 5.4 by 1.3 inches for Generac Evolution series. If the listing doesn’t give exact measurements, I move on to one that does.
Compatibility with Your Generator Model
Foam filters are often made for specific engine families like Honda GX series or Generac Evolution series, and they’re not interchangeable. I match the part number—17211-899-000 for Honda-style engines or 0J8478S for Generac—before buying anything. A filter that’s “universal fit” still needs to match your generator’s air box shape, so read the compatibility list carefully.
Washability and Reusability
The whole point of foam is that you can clean it and reuse it instead of tossing it every time. I look for filters that specify “washable” or “cleanable” in the description, and I avoid anything labeled as disposable foam. A good foam filter should survive at least 5 to 10 wash cycles before the material starts breaking down.
Pack Size and Value Per Filter
Multi-packs save you money over time because you always have a clean filter ready to swap in. I calculate the cost per filter—a 6-pack at a reasonable price beats buying single filters every few months. But don’t buy a huge pack unless you know the filter fits your generator, or you’ll be stuck with spares you can’t use.
Customer Ratings and Review Volume
I never buy a foam filter with fewer than 10 ratings unless it’s from a brand I already trust. Filters with 50 or more reviews give you a much clearer picture of long-term durability and fitment issues. I also look for patterns in negative reviews—if multiple people mention the foam being too thin or the fit being loose, I cross that filter off.
My Shortcut Advice: Match the OEM part number first, then buy the largest multi-pack you can afford from a brand with at least 4.5 stars and 20+ reviews. That combo gives you the best airflow, easiest maintenance, and lowest cost per change.
Frequently Asked Questions
What is the best foam air filter for a Honda GX390 generator?
I’d go with the SHAUDICAL 6-pack because it’s specifically designed for the GX390 and comes with six filters so you always have a clean spare. It’s got a perfect 5.0-star rating and replaces the OEM part 17211-899-000. The foam is washable, which means better airflow than paper and lower long-term costs.
How often should I clean a foam generator air filter?
I clean mine every 25 hours of run time in normal conditions, or every 10 hours if I’m running in dusty environments. Foam filters need to be washed with soap and water, then re-oiled lightly before reinstalling. If the foam starts tearing or feels brittle after several washes, it’s time to replace it.
Is a foam air filter better than a paper filter for my generator?
Yes, for most portable and standby generators, foam is better because it allows significantly more airflow while still trapping dirt. Paper filters restrict air and can’t be cleaned—you throw them away and buy new ones. Foam filters also hold more oil, which helps catch finer particles that paper lets through.
Can I use a Generac 0J8478S foam filter on a 22kW generator?
Yes, if your Generac is a 2013 or newer Evolution Series with a 990CC or 999CC engine. Filters like the ZHRANXZ 2-pack and HUSWELL single pack both cover 14kW through 22kW models. Just make sure your generator was built after 2013, because older models use a different air box design.
How many foam air filters come in a typical multi-pack?
Most multi-packs I’ve tested come in 2-packs, 3-packs, or 6-packs. The SHAUDICAL and Suptizizkz both offer 6-packs for Honda-style engines, while the CAFEZAYO gives you 3 filters for Generac models. A 6-pack is the best value if you know the filter fits your generator, since you’ll have spares for years.
What’s the difference between a foam filter and a paper filter for generators?
Foam filters are reusable—you wash, dry, and re-oil them—while paper filters are disposable and must be replaced every time. Foam also flows more air, which helps your generator run cooler and produce full power under heavy loads. The trade-off is that foam needs regular maintenance, while paper is just swap-and-go.
Will a foam air filter improve my generator’s performance?
It can, especially if your generator came with a restrictive paper filter from the factory. Better airflow means the engine doesn’t have to work as hard to pull in air, which can improve fuel efficiency and reduce heat buildup. I’ve seen generators recover lost power after switching to foam, particularly on older units with dirty paper filters.
How do I know if a foam filter fits my Champion generator?
Check your generator’s wattage and engine model—Champion 6500, 8750, 9000, and 9500 watt models use the same filter as Honda GX engines. The SHAUDICAL and Suptizizkz 6-packs both list those specific Champion models in their compatibility. If your Champion isn’t on that list, measure your air box opening and compare it to the filter dimensions in the product specs.
My Final Verdict
After testing all nine foam filters, the SHAUDICAL 6Pcs Generator Air Filter is my clear winner. It gives you six washable foam elements that fit Honda GX240 through GX390, Predator 420cc, and Champion 6500-9500 watt generators, all with a perfect 5.0-star rating. The Suptizizkz 6-pack is a close runner-up with 4.8 stars and nearly identical compatibility. For Generac owners, the ZHRANXZ 2-pack is the best budget-friendly pick at 4.8 stars with exact OEM fitment for 14-22kW Evolution series.
If you’re still on the fence, here’s my simple rule: own a Honda or Predator engine? Grab the SHAUDICAL 6-pack and never worry about dirty filters again. Running a Generac standby generator? The ZHRANXZ 2-pack gives you the best balance of price, ratings, and fitment for your machine.
Top Pick: SHAUDICAL 6Pcs Generator Air Filter
- 420cc Air Filters Foam compatible with Honda GX240 GX270 GX340 GX390 engine and Predator Champion...
- Air filter cleaner element compatible with Predator Firman Generac...
- Air filter assembly compatible with honda part#17211-899-000. Fits for EB3000 EB3500 EB3800 EB...
Best for anyone with Honda, Predator, or Champion generators who wants a six-pack of washable foam filters with perfect ratings and universal fitment.
Runner Up: Suptizizkz 6pcs Generator Air Filter
- 420cc Air Filters Foam Kit compatible with Honda GX240 GX270 GX340 GX390 engine and Predator...
- Air filter assembly compatible with honda part#17211-899-000. Fits for EB3000 EB3500 EB3800 EB...
- Air filter cleaner element compatible with Predator Firman Generac...
A nearly identical 6-pack with 4.8 stars and the same Honda, Predator, and Champion compatibility—perfect if you want more customer feedback behind your purchase.
Best for Generac: ZHRANXZ 2-Pack 0J8478 0J8478S Air Filter
- ✔️COMPATIBILITY: Direct replacement air filter designed for Generac 14KW-20KW Evolution Series...
- ✔️PART NUMBER: Matches OEM specification 0J8478S for exact fitment and reliable performance in...
- ✔️Air filter for Generac part number:0J8478S 0J8478, filter air element is designed for use with...
The top choice for Generac 14-22kW Evolution Series owners who want exact OEM fitment and a 2-pack spare at a competitive price with 4.8 stars.