Standard airbox versus aftermarket

[TonyHayers]

Yes I agree Tony. From what I have read on here I will just be going for a decent cold air feed to standard airbox with some nice heat insulating material around the box.

I still can't see the gains in removing the flap though?

One reason you might want to do it is they can be prone to sticking, and if you fit a cold air feed, you're probably going to be bringing even more dust through it.

You might get some nicer sound at sub 5k rpm or whenever the flap normally opens too.

[Rick_RS4]

The problem is that the open intake which allows you to hear more induction noise than the standard airbox also allows more hot air in than the standard airbox.

I kinda like the idea of heavily modifying the standard airbox by putting a huge cold air feed in. Basically, making a rectangular trumpet shape which fits almost the entire aux rad position so giving you plenty of cool air but also acting a bit like a loudspeaker for induction noise. SAI would need to come out to make space though.

I have done exactly this Tony. It's a custom fiberglass one straight to the underside maybe 5 or 6 inch coming up through from the aux rad. I butchered the bottom of the OEM filter to suit but couldn't resist the carbon

[frank]

Whats the chances of a picture rick?

[TonyHayers]

The problem is that the open intake which allows you to hear more induction noise than the standard airbox also allows more hot air in than the standard airbox.

I kinda like the idea of heavily modifying the standard airbox by putting a huge cold air feed in. Basically, making a rectangular trumpet shape which fits almost the entire aux rad position so giving you plenty of cool air but also acting a bit like a loudspeaker for induction noise. SAI would need to come out to make space though.

I have done exactly this Tony. It's a custom fiberglass one straight to the underside maybe 5 or 6 inch coming up through from the aux rad. I butchered the bottom of the OEM filter to suit but couldn't resist the carbon

Ooh. Come on Rick, we need photos of this!

[Rick_RS4]

Don't think I took any. I'll take some tonight when I swap the filters over

[docurley]

Interesting read if you have never seen it.

http://www.europeancarweb.com/tech/prov ... n_drop_in/

[adsgreen]

I don't think there was much doubt that it would have an effect (although their 12hp jump at 8300 is a bit suspect looking at the graph).
The issue that it quickly heat soaks compared to the plastic unit and then you end up in a worse position.
IIRC Sonny tried everything from gold heat wrap and physical heat shields to try to keep the IAT down but it couldn't be done.

[dogtanion]

from the article:

The trick with dyno testing an RS4 is in monitoring fluid, ambient and intake air temperatures, which have to be the consistent from run to run

Most rolling roads I have been to have the bonnet up and there's a big fan blowing air into the radiator.

The result is that comparative air filter results might be an interesting academic exercise, but they don't really recreate the real world hot engine bay and heat soak problems under the bonnet.

[docurley]

Good point

[Rick_RS4]

My bonnet was down and I got 415ps with the Revo filter

[frank]

Thanks for the replies gentemen, it helped me make up my mind so I went for the CAF and panel filter.

[RossDagley]

Thanks for the replies gentemen, it helped me make up my mind so I went for the CAF and panel filter.

This is the best option. I've had ... some problems... since going with an aftermarket intake. If I lose another MAF sensor then I'll be returning to the stock airbox.

I make good power on the aftermarket one but there's probably a fraction more to come from a standard airbox if I refit that.

[Rick_RS4]

I did 2 runs in mine with each filter on and still averaged the same readings. It put doubts in my mind about the filter so I was going to revert to stock. After testing I found no difference. (I do have massive CAF )So I'm sticking with the sexy carbon.

Your maf problem is worrying tho Ross is it the new style filter.? And it's not vibrating about, with the maf set between 10 and 2?

[RossDagley]

I did 2 runs in mine with each filter on and still averaged the same readings. It put doubts in my mind about the filter so I was going to revert to stock. After testing I found no difference. (I do have massive CAF )So I'm sticking with the sexy carbon.

Your maf problem is worrying tho Ross is it the new style filter.? And it's not vibrating about, with the maf set between 10 and 2?

Glenn has kindly sent me a new filter but I haven't changed to using it yet (I've not used the car or even had much time with it) but will do ASAP. The new style filter looks much better really - the inside of the current one I have looks like it has the *potential* to have issues. Either it's not filtering properly and dust is getting into the MAF or parts of the filter foam itself are coming away (which I think is less likely). If I get chance I'll take photos of both and post here and you will clearly see the difference. New filter looks much better IMO.

I can't remember the angle of the MAF (I'll photo it later) but it was setup by MRC so hopefully in the correct place/angle

[adsgreen]

Wasn't the old maf oiled and this was becoming detached and clogging the maf. Given that the maf is just a heated wire with a known temperature that simply measures how much it's cooled by to give the mass of the air, then it's going to be incredibly sensitive to oil type residue.