hi guys,im Rob from England and i love reading your posts on here,however i have a bit of a prob with my R53 JCW,if you look at the airbox on my car it has a very small hose coming out of the front l/h about 6/7 inches long,now i think this small hose operates the flap at the back of the airbox,but mine has dropped off where it is attached in the engine bay and i cannot find out where it goes anywhere??,can someone on here help me please,also i have heard i dont even need to run this hose and flap in the airbox as some people say just do away with the lot,is this true??..hope someone can help from across the pond......Rob

 

it goes on the back of the throttle body.

 

You don't need the hose at all but you do want to make sure that if you de-flap your box that you plug the hose or it will create a vacuum leak and lead to poor idle. I removed the flap and all its components from my box altogether, plugged that hose and have no issues at all.

 

hi,thanx for your reply,when you say you removed the flap in the airbox,do you leave it open or cover up the gap left by taking out the flap......Rob

 

Removed the flap altogether. If I remember correctly I also removed much of the mechanicals as well. Not sure of the gap you are referring to.

 

Hi there,the actual gap im referring to is the flap itself,so I just remove the flap and keave that gap open?,the flap is at the back of the airbox,is that right??...... ..Rob

 

Yes, that flap is designed to restrict air intake at lower rpm and open at higher rpm. Removing it increases air flow at all rpm, don't block that gap or it will defeat the purpose.

 

once again thanx,you have been most helpful,now all i gotta do is find the connector on the throttle body to block it...Rob

 

There's no need to do this flap removal at all, it gains noise only. JCW designed it to open at 4.5k because the engine doesn't need it open below there.


The airbox is described as a noise kit itself, and below the flap is a small rubber tube which sits against the bulkhead trim, and on the standard non JCW airbox it is open to draw air from the rear, as well as the front intake, but on the JCW, the same tube is present, but they block it off with a plastic disc.


As a consequence, some people miss the supercharger noise that then comes back when the flap opens, so only with a heavier foot. They then remove the flap for no real power gain, but a different sound.


The answer if you want the supercharger noise from a standard car, is to remove the disc from the tube and leave the flap alone in my humble opinion.


People just love chopping things about on these cars, when they don't need to be.


Reconnect the hose, maybe change the air filter for easier breathing.


The engine will take the air that it wants, opening a big hole will not help you in any way as there is enough air supply already. It may be nice to have it colder, but at less than 4.5k you most likely won't be reaping any benefit from it.


Only my 2p of course, but with 209whp (246chp) 176wtq, and it left well alone, but disc removed, on a non JCW 2005 MCS, (+ standard catback).