Best filter to run in stock airbox?

**Morritse** · 07-26-2018 11:05 AM

I have a ported stock airbox and silicone inlet hose, but I'm not sure what the best/largest filter can fit in the stock airbox. Any suggestions?

**doughboy17** · 07-26-2018 12:10 PM

Just this week, my son and I installed an ECS silicone inlet hose and aFe filter (#11-10121). The #10-10121 aFe filter is oiled vs. the dry one we installed. I can certainly say that this filter is a tight fit. Make a search on "aFe" on the B8 S4 forum and conduct some research. I decided to go with this set up due to my goals (no stepping on a cat trapped under the hood noise and $).

When you say ported, I assume you are referring to holes cut/drilled in the stock box. With my set up and the Soundkator still on, it is hard to hear any additional whine from inside the car. I may be porting my box (a little) in the future to obtain a little more whine.

**jimrobbington** · 07-26-2018 02:24 PM

AFE dry Sflo hands down

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**Morritse** · 07-26-2018 02:29 PM

Originally Posted by jimrobbington

AFE dry Sflo hands down

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Can I get a link? According to their website there aren't any compatible filters for the s4

**jimrobbington** · 07-26-2018 02:49 PM

Originally Posted by Morritse

Can I get a link? According to their website there aren't any compatible filters for the s4

Hmmm, I don't have a link to one that fits the stock airbox as I'm running a CAI. I'm fairly certain however the right sized cone filter does fit. Hopefully someone can chime in on this. Worst case, pull your stock filter, measure come length/ width and inlet diameter and find an AFE filter of similar size.

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**doughboy17** · 07-26-2018 03:35 PM

I gave you the part number from aFe's website. It says it does not fit, but it does.

**Lbsigman** · 07-26-2018 05:41 PM

PSA: Don't overtighten the lock nuts or the nut and washer that come with the aFe filter as they can be pulled out of the silicone base material. It's a poor design as it's nothing more than a screw and washer embedded into the silicone rubber. I do like their dry filter media though, and previous used oil analysis I have done does confirm they filter the air well.

**TC_S4** · 07-26-2018 06:10 PM

This is the Afe filter I bought for my S4 2013 and it fits perfectly in my OEM box with the silicon tube. Although, many websites indicate it doesn’t fit, including Afe site.

https://afepower.com/afe-power-10-10...-5r-air-filter

**Morritse** · 07-26-2018 06:35 PM

Thanks guys. Picked one up on Amazon. Mounts look identical to a KN filter I was running previously

**LeadToRome** · 07-26-2018 07:38 PM

Is there really much of a bump from K&N to that Afe in terms of airflow?

**Morritse** · 07-26-2018 08:03 PM

Originally Posted by LeadToRome

Is there really much of a bump from K&N to that Afe in terms of airflow?

KN broke. Figured I might as well replace it with the best.

**LeadToRome** · 07-26-2018 08:26 PM

Yeah no I was just wondering. I have a K&N and it's time to do the whole wash and re-oil thing and I was sorta hoping for an excuse to skip that and just buy this one new.

**DufraineMK6** · 07-26-2018 11:59 PM

Afe seems to be the most popular, also the more surface area the filter has the better.

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**Loe** · 07-27-2018 03:29 AM

you'll be surprised to find that I run an OEM filter...the amount of pleats on the OEM filter = large surface area. But every once in awhile I swap for my oiled aFe one, but always seem to go back to my OEM one for the best filtration and maximum quietness.

**MSq5** · 07-27-2018 05:41 AM

Loe knows best.

Based on a thread here by another member, which I can't find readily at the moment, those flow studies suggested that the dual cone (inverted cone at the end, oiled aFe outflowed everything else. I'm running it. Part number is in my signature below and in this link. It's probably overkill at my modest power level. Maybe like my engine drinking from a firehose.

If Loe can run 10's with OEM filter, given his level of mods, flow restrictions are probably not significant enough in the filter, itself, to impede his power.

I just liked the reusability and long service intervals.

https://afepower.com/afe-power-10-10...-5r-air-filter

**JJI** · 07-27-2018 07:30 AM

Originally Posted by Loe

you'll be surprised to find that I run an OEM filter...the amount of pleats on the OEM filter = large surface area. But every once in awhile I swap for my oiled aFe one, but always seem to go back to my OEM one for the best filtration and maximum quietness.

Do you have any photos of your modified air box and scoop .I found this in one of your posts “modified OEM airbox (2.5" hole cut using the DIY airbox mod) + reinforced scoop” . But couldn’t find the process or photos. Just searching modified airbox I found ton of different designs but was hoping to see what you did

Thanks in advance for your time

**Tom Sawyer** · 07-29-2018 05:55 AM

FWIW, I've been quite happy with the Eurocode intake hose/filter combo, $160 when on sale. Bit more than a filter alone but I really like the approach of using the stock airbox and keeping as much hot air out as possible. I actually modded the airbox this weekend, (cut out intake hole at fender, removed extra plastic covering filter at inlet side and it's breathing nicely. Not major SC noise, but just enough for my tastes.

https://www.ecodetuning.com/EC0407-0...s4-s5-3-0.html

**Loe** · 07-29-2018 06:06 AM

here's a link for a photo that includes the 2.5" holes in the airbox and also the plastic rivots I used to reinforce the air scoop:

CLICK ME

**MSq5** · 07-29-2018 07:20 AM

Originally Posted by Loe

here's a link for a photo that includes the 2.5" holes in the airbox and also the plastic rivots I used to reinforce the air scoop:

CLICK ME

Wow! You put in two 2-1/2" holes. I just did one in that area with the circular molding facing the passenger headlight. I see I have a little more work to do!