There seems to be a scarcity of aftermarket performance air filters for the XJR. My "new" XJR is not in my hands yet so I'm asking all of you this: What is the outer diamater of the MAF (mass airflow sensor) inlet? My goal is to use a high performance cone air filter on it with a heat shield, ducting or something. 3", 4"?

I know all about the concerns around the efficiency of gauze (i.e., K&N) filters, underhood heat soak, etc., but feel free to discuss anyway. One of the things I want to achieve is to let some of the supercharger noise out. Perhaps I'll get sick of it in time. For now I want to hear my car!

Mike
2004 XJR

 

I have the Mina cold air intake that I will sell if you are interested. My XJ8 didn't like it after I added the Mina Performance exhaust, so I switched back to the OEM intake system. I think I even have a couple of new replacement filters for it too.

 

If he doesn't want it im interested.

 

check the for sale/classifieds section, i've had one for sale for a month now. Only used it for maybe 1k miles. $85 shipped

 

I'm more into making my own stuff. I can't even remember how many cold air intakes (not to mention custom turbo and supercharger intakes) I've made over the years.

Mike

 

Mike when u finish your custom intake post pic please.

 

I separated the MAF sensor from the airbox lid so that it could be mounted to the filter. The jumbo filter is made by Spectre, P/N 9738. It's a beauty. I plan on putting a polyurethane foam pre-filter over it because I don't trust cotton gauze filters on their own to provide adequate dirt removal (do a web search on the topic).

I found it easiest to cut the MAF from the lid by using a small diameter drill bit and making a zillion holes around it. I left enough of the original bell mouth (i.e., the tapered opening to the airbox) so that the airflow regime into the MAF should not be much different from stock.

More pics to follow after I make the heat shield and install everything. One more thing... I blocked off the opening to the dead-end noise cancellation tube on the inlet snorkel. AFAIK it is supposed to cancel some of the "offensive" engine sounds. One possibility that I thought of afterwards is that perhaps this particular snorkel is supposed to *enhance* desirable sounds. Whatever.

Some other observations:
- There was some molding flash around the inner circumference of the MAF that I trimmed off. It was clearly an artifact from the manufacturing process and had no benefit and looked sloppy.
- The airbox has a fancy solenoid-activated flap door that is designed to provide additional air under high load (and/or stifle noise when closed at low load). Normally the door remains closed to keep hot engine bay air out. The early 2000s Audi RS4 had this gizmo in the airbox as well. I don't know if it's a case of good engineering or over-engineering.

Mike
'04 XJR

 

Hi Mike, what do you hope to gain from this upgrade? I've read in past threads where these high-flow filters cause check engine lights and other error messages on the XJ's. I like the looks of what you are doing, I did something very similar in 1987 on a Buick Grand National with a K&N cone.....wow, that's a long time ago, and seems like yesterday.

 

Part of me likes to tinker. Okay, all of me likes to tinker. I also want to be able to hear the (hopefully) nice sounding noises from the intake. More horsepower would be nice too. Besides, the paper filter I had looked like it dated back to G. W. Bush's first term in office; it was full of dirt and dark (see attached).

I really don't expect to get any CELs -- the XJR intake is pretty much the same as that in 90% of the cars on the road.

Mike

 

Wow thats a dirty filter right there.

 

Let us know how it runs Mike!

And I am interested to see if blocking off the silencers makes a big difference in noise...I've been contemplating doing that.

 

I took off the engine cover and saw four more silencers!!! That's six in total! It's practically a project in itself to block these off! I'll have to think of a cost-effective method to do this.

I made a open cel foam pre-filter for my cone filter. It has similar porosity and thickness to the widely available K&N pre-cleaner filters. I added some ghetto-fabulous decoration as well! The embossing is with silicone so it should last forever.

I just mounted the filter in the car and <gasp!> the hood/bonnet wouldn't close completely! Fortunately, I shifted the filter a quarter inch and everything was fine.

Mike

 

Hahaha that factory intake tract is something else. I was blown away by how many silencers there are on that thing when I removed it to install my supercharger pulley!

The filter setup looks great! How does it feel and sound? Perhaps you could upload a sound clip or video clip?