Air Filters: Tested

OEM vs Generic vs High Performance air filters – What’s really best for your engine?
We combine a leaf blower with talcum power to find the best type of air filter for your 4WD… SCIENCE!

Unless you are a drag racer chasing the maximum amount of power before rebuilding your engine every few weeks, you need an air filter. And a good one at that! As you are reading a four-wheel drive publication, it is safe to say you are a four-wheel driver (not a drag racer), and as such you would understand that we place our vehicles under insane amounts of stress. Dirt/sand/mud/snow/water… fun to explore, but these gifts of nature are trying their hardest to kill your engine. So what is the best option for off-road tourers? Genuine OEM parts, a cheaper aftermarket replacement or a high-flow pod filter? And what will actually be the best option for four-wheel drivers in Australia?



Hi, my name is Evan and I’m an off-road journalist, lover of unsavoury T-shirts and a terrible comedian. One thing I am not, however, is a scientist; I just want to get that out in the open. We don’t have a science-type-lab-for-science-stuff here at Unsealed 4X4 HQ, but we do have plenty of parts lying around the workshop and the ability to conduct this experiment surrounding the effectiveness of air filters. First up, we poached the snorkel and air filter housing from my Suzuki Sierra – as it uses a nice round inlet and outlet to allow for an easy sealed fit. We bought a leaf blower, and the entire supply of talcum powder in the lower Blue Mountains – because talcum powder has a similar consistency to bulldust. Next, it was time to drive to as many auto parts stores as possible and purchase a wide cross-section of air filters. With our leaf blower hooked up to the air filter assembly, and the same amount of talcum powder poured down the snorkel (600g; and yes, this felt so wrong), we were able to see how much powder each filter trapped by weighing them before and after. So while this test might not win a Nobel Peace Prize, it is 100% consistent, informative and (hopefully) entertaining in a sick sort of way. Now then, the results!



Looking at the genuine filter compared to the cheaper generic filter, it is easy to see there is more material in the genuine article. At over twice the price, is this filter a better performer?

COST: $44.99





This filter was the cheapest we could find over the counter, and at first glance you can see there are larger gaps between each fin of the filter. Now to determine if this allows more flow, or if it traps more powder.

COST: $18.49





Pod filters are a more common sight on drift cars than on 4X4s, but we wanted to take a look at the filtering ability of ‘high performance’ filters. We couldn’t fit the pod into our air filter casing, so it was attached to the top of the snorkel with a box to catch any debris. As pod filters aren’t encased in filter housings, this was a more realistic interpretation anyway.

COST: $29.99





There is a theory that a dirty filter will actually trap more contaminants than a fresh clean one. So as an exercise in conducting our experiment, we decided to run the old filter (found in the housing first) to determine if there was any merit to this claim.

COST: NA (it was in the vehicle)





These are just our findings from our little experiment. Straight up, pod filters do not belong on 4X4s. Old filters were only slightly better at filtering talcum powder than new filters. And the biggest surprise? The cheapest filter we tested kept the most powder out. Personally, I will stick with genuine filters and regular changes. Draw your own conclusion from the test below… but can we all agree on one thing? No more pod filters on off-road vehicles, okay!


This article was originally posted by Unsealed 4×4.

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Comments 8

  1. did you test a K&N type filter?? does that mean the rest of the talcum powder got through the filter into the filter housing/motor? I have a dmax with an K&N filter, should I go back to the factory option? I have one year left on factory warranty. BOB

    1. Pod filter is a K & N design 🙂
      WEIGHT BEFORE TEST: 560 grams
      WEIGHT AFTER TEST: 670 grams so caught only 110 grams of powder.

      Even the dirty old filter retained 347 grams by comparison, which is more than 3 times the amount of powder trapped by the “pod” style filter
      WEIGHT BEFORE TEST: 410 grams
      WEIGHT AFTER TEST: 757 grams

      As the test states the pod type filter should not be used on a 4X4 and it’s possibly because of the smaller amount of fabric used in the make-up of the filter.

    2. I have used K@N filters waste of money and uni filter also a waste best filter on vehicles I have owned have always been genuine. The K@N I was always checking and oiling it to try and keep the dust out but to avail, the uni filter when tested on dyno dropped 10hp of engine and I was always rotating filter to keep oil from going to the bottom of it.

  2. I am burying a Mazda CX-5 TOURING DIESEL. As i am a member can i get insurance through the club? I wrote off my prado and now i am only aloud (wife) to use dirt roads.

  3. Ian Bennetts
    I found these results interesting but the real question is how much airflow do you have between OEM and aftermarket filters when full of dust.
    There is a lot of science used in filter manufacture to determine the best amount of filter media to use and still be able to achieve maximum airflow and dust retention.
    For my money and piece of mind, I would only use genuine air filters as they are manufactured to suit vehicle manufacturers specifications.
    Most aftermarket filters will do the job ,but are only a “will fit” option with no back up from the supplier if they fail.There are a lot that do fail.

  4. Hi There,

    I found an interesting youtube channel (see link below) that tested a range of air filters on an engine dyno.

    Note – test did not measure captured debris volume – rather horsepower differential between original filter, foam filters, and importantly housing type.

    It seemed the filter material wasn’t particularly critical – rather a housing that promotes top down draw through – rather than peripheral entry – created good boost in horsepower.

    So – my take – use a standard OEM filter – but try and have the airflow direction drawing straight down into the carb or throttle body. Air velocity is the key – and stick with OEM filter for good filtration properties.

    Enjoy the vid.


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