What effect might an air filter with 27k miles/5 years on it have on my engine?

[OllieVRS]

Pretty much just the post title, wonder if I'm losing a few hp, mpgs etc.

I'm gonna replace it this weekend anyway. Any recommendation for brand, Bosch, Mann, Genuine etc?

I also recently noticed some quiet turbo flutter/chatter ('stoo-tu-tu') after flooring it in second and lifting off at 3500-4000rpm, it's satisfying to hear, but is it normal? When lifting off the accelerator at any other rpms it's more of a 'woosh' I hear. For reference the turbo was rebuilt with a new core 2k miles ago but with the original DV. No loss of power nor check engine light.

[pudding]

Yeah that's probably in need of replacement.  I would just go with an OEM replacement personally.

The pigeon cooing noise is basically wasted boost travelling backwards and hitting the compressor blades.  Some people think it's cool, but it's actually harmful to the turbo, hence the need for a DV.  Maybe yours is a bit tired and not bleeding the boost off properly.

[LC5F]

27k is definitely overdue a change.
VW use a few suppliers, you would be fine with either Hengst or Mann.

If air filter has been neglected, you may also look into how old the fuel filter is, this also can reduce performance.
Usually it's a straight forward job to replace...not wishing to foreshadow... but if you are unlucky, one of the fuel line clips may jam on and not release.

[ald1717]

its good practice and cheap to change, although you wont feel any gains in performance, there will be but it will likely be 1-2hp if your lucky, ive seen different types of filters tested and the oem ones performed better than cotton or foam, when swapping an old paper one for a fresh one it was 1.5 hp gain.    this was on a stock car though so may make bigger difference on a tuned car

[LC5F]

its good practice and cheap to change, although you wont feel any gains in performance, there will be but it will likely be 1-2hp if your lucky, i've seen different types of filters tested and the oem ones performed better than cotton or foam, when swapping an old paper one for a fresh one it was 1.5 hp gain.    this was on a stock car though so may make bigger difference on a tuned car

With 27k miles worth of dirt strangling the current filter, I suspect the OP will feel a noticeable change.

[OllieVRS]

Thanks for the replies guys.

The turbo sound isn't something I'm that worried about for now as the turbo is basically new, especially as some people even debate whether it's harmful or not, and the flutter is quite minimal. I'm not going to worry about it for now as the engine is stock, so the boost pressure shouldn't be that high.

If I do get it mapped in the future however, I'll replace the DV with a revision D or G.

27k is definitely overdue a change.
VW use a few suppliers, you would be fine with either Hengst or Mann.

If air filter has been neglected, you may also look into how old the fuel filter is, this also can reduce performance.
Usually it's a straight forward job to replace...not wishing to foreshadow... but if you are unlucky, one of the fuel line clips may jam on and not release.

Fuel filter was replaced at 102k miles, car is now on 119k. VW say 30k mile interval, and I haven't had at fuel related error codes other than a purge evap error one a few months ago, that I cleared and never came back (I replaced the fuel cap and stopped brimming the tank since).

I may look into replacing it over the summer during my annual service though, thanks for the advice 

EDIT: Only seen your last message now, I hope so too @LC5F , I'm still looking for an excuse as to why my friend's 184hp DSG GTD was faster than my Octy

[OllieVRS]

Little update, here's the new and old filter.




I got a WIX branded filter as that was the only brand that was in stock in the parts store (VW didn't have air filters in stock either). Coincidentally the same brand as the one that was already in there. Old one was much cleaner than I expected.

Also unrelated but here's a pic of the OEM battery that VW supplied, a calcium 72AH EXIDE Battery with dimensions 278x175x190.




I had no idea EXIDE was the OEM brand, It was €121.77 with a 2 year warranty so I guess that's alright. It's also kinda funky the way you see the acid splashing around as the casing is translucent.

Also unrelated again, but I did a cheap little mod to get some more engine noise since my exhaust is stock. I removed the sound deadening material under the bonnet.

Sounds great with the windows down, maybe 20-40% louder induction noises (with the stock engine cover too). 

[LC5F]

That doesn't look like a filter that has done 27k.
VW love to swing around with suppliers, but I would have thought Varta would have still been their goto.

[pudding]

I think Hengst is the current brand for filters.