[tylerhart_21]

Looking at the US air box, behind the charcoal air filter there is a diviet. Would the flow be better if the hole was filled to smooth out that side of the airbox?

[jadams161]

Zero difference.. search eBay UK for the better Euro air box

[tylerhart_21]

Gotcha, however the euro airbox in my opinion is not worth it for dollar per hp. The US and Euro will flow the same since BMW will try to keep it even. With US airbox having the charcoal filter it does lose some power however but enough for someone to feel a difference. I would say get the euro airbox if you don’t want to deal with taking out the box just to change the air filter.

Not sure about the euro airbox but on the US there is a small hole at the bottom. I was thinking about plugging it up however not sure if it’s meant to drain water if it gets into the intake. Does anyone know what’s the purpose of the small hole?

[jadams161]

You kinda contradict yourself.. lol. Trying for more airflow with a mod to a highly restricted air box.
I found a good used Euro air box on eBay, it was under $100 us shipped and it arrived in a week. I can honestly say that removing the sulev air box (charcoal filter inside) and installing the Euro air box with a K&N filter and a silicone connector between the air box and throttle body, has greatly improved how my 328 runs and drives. While it may not improve HP a whole lot it revs better, sounds better and drives better. So for me well worth the $200 investment..

[The Nightman]

Do you have a photo of this hole? The airbox should be sealed as far as I know (other than the intake duct obviously).

And let's be honest, intakes are prone to bikeshedding but we're not going to outsmart the engineers that designed it. They're not leaving free performance on the table unless they have to (eg charcoal filter for emissions standards). The fins inside the air box are for noise control and have no affect on air flow, and whatever else you find in there is likely negligible.

Swap to the 3 stage manifold with the free Bimmerlabs tune if you haven't already, and be done with it.

[tylerhart_21]

Originally Posted by The Nightman

Do you have a photo of this hole? The airbox should be sealed as far as I know (other than the intake duct obviously).

And let's be honest, intakes are prone to bikeshedding but we're not going to outsmart the engineers that designed it. They're not leaving free performance on the table unless they have to (eg charcoal filter for emissions standards). The fins inside the air box are for noise control and have no affect on air flow, and whatever else you find in there is likely negligible.

Swap to the 3 stage manifold with the free Bimmerlabs tune if you haven't already, and be done with it.

I didn’t have a photo when I took it out but found one online. It’s at the bottom not sure the purpose but it’s there for a reason.

With my airbox I just removed the top fins and the divider where the air comes into the box. With the sound and feel there’s no difference but just did it since the m performance intake did the same thing but with a bigger snorkel and I am guessing from photos it’s smoothed out. I have looked at the McLaren 570s airbox and they have a smoothed airbox with I am guessing insulation inside to keep the sound down.

Going to get the manifold soon and rebuild the disas as well but have to get my werid battery problem fixed and get the intake vanos fixed. Probably will do the Dinan intake as well but I will have to see.

[chilledn52]

Originally Posted by tylerhart_21

I didn’t have a photo when I took it out but found one online. It’s at the bottom not sure the purpose but it’s there for a reason.

With my airbox I just removed the top fins and the divider where the air comes into the box. With the sound and feel there’s no difference but just did it since the m performance intake did the same thing but with a bigger snorkel and I am guessing from photos it’s smoothed out. I have looked at the McLaren 570s airbox and they have a smoothed airbox with I am guessing insulation inside to keep the sound down.

Going to get the manifold soon and rebuild the disas as well but have to get my werid battery problem fixed and get the intake vanos fixed. Probably will do the Dinan intake as well but I will have to see.

Wouldn't that be a drain port in case any water gets inside the airbox. I would leave that little hole but smooth the inside for some more sound