Hey Guys. I keep reading about this mod to my 2004 XJR air box. I searched high and low, but can't find anything about how it is done or how it affects performance. Can anyone that has done this let me know more about it?

 

Open the airbox and take out the air filter
You will now see the flap
Remove the screw then the flap, leaving the actuator in place
Replace the screw
Put the filter back in and close the airbox.

there is also a video on this here


The plus side of the mod is more blower noise and more air.
The minus side is the air is very hot when you are not moving

You may also notice a hole, in line with and the same shape as the flap, that goes through the radiator support panel.
This leads to the void behind the headlight. This is a good source of cold air but does not benefit much from positive pressure when moving.
A good further mod is to connect the hole in the radiator support to the hole from the removed flap.
Even better is to keep going and route air from the blanking panel that divides this area from the grill. If you take off the plastic cover over the radiator you will see this.
As part of the Grill mod I am working on I am also looking at making a duct for this from abs plastic that will include a replacement divider

Cheers
34by151

 

Thank you very much for the informative post. Does anyone else out there with a X350 XJR recommend this mod? Is it worth it? Does it make much difference?

 

I did it to mine, along with a K&N panel filter & an intake elbow.

I honestly doubt it gives more power, in fact as mentioned it might actually cost a bit since hot air is coming in at idle.

But the blower whine at part throttle, worth it!

 

I already have the K&N filter. I am still considering this mod though. I'm not sure I'm sold on the benefits yet.

 

Does anyone else have an experience with this mod to share?

 

I finally did this. I really can't tell if there is more power now, but I think the SC whine is more obvious at all speeds.