I would definitely not use an oiled media for the reasons you mentioned.

Yes, I'd like to experiment with some foam media as well. Even if it's designed to be used with oil it may still work well as a filter. I have some different UNI stuff I may play with in the future.

Looking forwards to what your research points you too.
I agree that a cabin filter is a pita to work with. Then again no doubting people who has one do have less dust to wipe when cleaning the interior of the 4r.
Thanks for taking on this.

I'm assuming merv4 filters more than a merv1 lowes has Merv1's washable 20x30x1 cut to size $7.00.
If understanding design the 1" thickness would compress when two halves screwed together.
If moisture is not of concern not sure on Runners many cabin filters are paper.
I'd try what my filter testing for house hvac worked out for cfm filtration low noise flowing 1600 cfm in pic.
Could be a bit of a challenge retaining pleats when fitting to filter housing.

Filter in pic handles 3rd coast humidity fine, what are chances of rain getting to it in Runner?

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Love to see the progress on this! I'm still sitting on a few of the Russian filters. Going to use some of my industry contacts to get in touch with AFE and a few other manufacturers. I think this product could be viable, if someone puts in the time. I am just waiting to sign some NDA's and agreements to move forward with the design phase for a commercially produced version.

I think there will still be a market for the 3d printed, cleanable versions. My biggest move is to use the same type of Charcoal media as the Russian filters. They have a much higher filter rating than the MERV4 foams.

That's great to hear! Obviously the simple flat-style filter has a key disadvantage to the canister style in the lower surface area. If we can get a canister style one with high quality media *and* no noise issues then that's 1st prize!

Wow nice work. Since the air flow rate is decreased with the cabin air filter installed, have you noticed a difference in cooling efficiency on hot days?

Sure, when the cabin is super hot it takes a bit longer to cool it down since it just can't pump as much cold air in. But after a few minutes it has more than enough power to keep it cool and not even at the highest setting.

I don't have any data to back up this claim though

Had a little fun with foam filter media.

I had some UNI 60ppi (fine) stuff sitting around so I tried it out:





Also got some UNI 30ppi (coarse), which is obviously too coarse to be much more than a big ol' chunk filter



The two foams stacked up vs. the Merv4 media



I just focused on the airflow since they all had about the same sound



The fine foam worked about the same as the Merv4 stuff. The coarse foam actually provided noticeable more airflow but it not a very good filter. This could be a good compromise if someone doesn't really want dust/pollen filtration but just to keep out leaves and stuff.

I'm all out of ideas for now!

I'll weigh in on this from my perspective as a HERS inspector (I inspect homes for energy efficiency measures and a big part of that is the HVAC equipment). The noise peak with the Russia filter is possibly strain being put on the bearing(s) for the blower fan. If speed is dropping off by half that tells me that these things are jacking up the static pressure of the system (basically there is a larger pressure differential between the downstream and upstream sides of the fan) which will decrease the life span of the fan. The flat filter though definitely has an issue with surface area and thus you can't get really useful filtration out of that without also having static pressure issues. The ideal would be the Russian style but with a lower MERV media but something still good enough to reduce dust and other large particulate. The most ideal situation would be some heavy fabrication to create a filter box like you see in most modern vehicles where the filter slot is much larger cross sectional area than the rest of the ductwork but that would probably run into numerous packaging issues. Sucks to see this as I've been wanting a filter for my truck but for some reason never applied my professional knowledge to the situation. The crappy thing though is dust will also kill your fan over time so I'm not sure if the filter is actually possibly killing it slower.

I'll say that I have been running 2 different versions of the Russian filter since 2021. My fan is always on Med or High. I don't think it drops the pressure enough to matter. My fan is still fine after 2 years of running these.

Same. I think the noise is due to the small clearance between the fan blades and the filter. Some sort of turbulence.

Considering how coarse that 30ppi filter is, I was expecting it would be closer to the no filter readings. Makes me wonder if the Tommy filter sans filter would read...might be that a significant amount of the restriction is due to the design of the filter housing?

Thanks for all the tests + sharing this filter with the community, just got mine in the mail, going to install now!

Good idea, next time I mess around with the filter I'll run it empty and see. There's not a lot of surface area blocked so I expect it to just be a minor drop. The coarse filter may let a lot of light through but it's still a meaningful restriction to airflow.

I just picked up two filters from Tommy, great guy! I've been looking for this mod for so long, thanks for posting all info on where to get it.