actually, this probably applies to all S airboxes. I just replaced the filter in my JCW intake and removed the upper flap, but also noticed a lower hole with a rubber gasket connecting it to the partition. It had a circular plastic "blank" inside to block it closed, but I pulled this out also. I'm assuming it's all good, but wanted to see whether there was any obscure reason one would want to leave this lower hole closed. Thoughts?

Thanks!

 

I lot of others have removed it as well. I removed the blank from my JCW intake and didn't notice any difference at all in performance, mileage, noise, responsiveness.

 

But it's cool knowing you did.

 

When I installled my JCW intake I could see no reason for it being there. I gave it the boot. I'm sure I gained mega power by removing it. NOT!

 

Don't forget about the weight savings.

 

Mine was more than 2 grams! Colin Chapman is smiling down upon me.

 

My question to this was WHY??

Why have it? I figure the Stupid Engineers at BMW must have put it there for some Stupid reason beyond my 5 grade education so I left it there.

 

And why put the hole and gasket there at all if you were just going to close it off?

I like the fact that the hole is aimed straight down the barrel of my new Madness filter.

 

In the MCS it's just a noisemaker that's there for all the people who need to be constantly reminded that they bought a "sporty" car. I'm sure lots of development time went into fine tuning its location and size after the focus groups indicated their preference. And I've heard speculation that it was probably blocked off so the JCW could still meet all drive-by sound regulations worldwide (the JCW exhaust is definitely louder outside the car even though it sounds a bit quieter inside), yet allow the customer who prefers to hear the engine more to remove it. That's the same reason factory scoops and cowl induction hoods on some old musclecars were blocked off too (though at least those were functional when opened).

My sample JCW flap did not seal completely anyway so it would have made no difference if I hadn't fixed that. Now it is quieter than a MCS (since the hole is blocked off) until the flap opens.

There won't be any difference in performance for the simple reason that each of the two intake paths to the airbox are already larger than the area of the throttle body. And OT: it's probably the front intake that allows the MCS to hydrolock, given the MC can hydrolock too and has no little hole in the cowl (unless equipped with JCW "Sound kit" for MC).

 

I just popped mine out for feces and giggles

I swear I'm getting about 5 more HP now..

Just kidding..

I do hear the SC a bit more in the 3,000 to 4,500 range now. BTW I wrote JCW in GB and e-mail for their take on this debate. If they reply I'll post.