Air Filter Housing Restriction
 

I recently bought a stock air filter assembly with a K&N filter off of EBay to to see what I could do to modify it. I immediately noticed that just prior to the MAS, the housing has a built in, very fine, screen. I can just imagine the restriction this imposes, just as bad if not worst than the snorkel. I'm going to see what the best way to remove this is, then remove the one on my car and give it a "seat of the pants" check. Any suggestions?



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IS it sandwiched in between two sections that can be taken apart and reassembled without the screen?
If not, it looks like a very careful die grinder job. Don't try a hole saw, as it will grab the screen and probably tear up the whole thing.
You will have to cut through one wire at a time, far enough away from the throttle body to not damage it, then carefully grind each wire to flush with the inner bore.
Looks like a PITA, but I'd say your right about the restriction, it's hideous!
One question: is it doing something to the airflow so that the MAS works properly?

While watchin' the season premier of "The Office" I started messing around and found a couple of locking tabs. With a screwdriver I was able to pop the locks, squeeze my hand into the air filter hole and pull the "snorkel like" end with the screen attached!! This can be done with the filter housing on the car.

Yes Virginia, there is another free upgrade you can do to you car.

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With this piece removed, the screen can be removed more easily and the velocity stack can be reinstalled.

http://986forum.com/forums/attachmen...tid=9744&stc=1

I also took a picture of the snorkel that's removed through the left intake vent, just in case anyone was wondering what it looks like.

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Just remember Porsche didn't put that screen in there just to piss you off. It is there to prevent your motor from injesting large chunks that often fall into the bottom of the air box when changing the filter. Toolpants has some great pictures of nasty STUFF in the air box. Big bugs, ciggy butts, chunks-o-rubber etc.

As long as you clean around the filter box before you pull the filter tray out, you should be fine. If "Big bugs, ciggy butts, chunks-o-rubber etc." are getting past the air filter, what the hell is the air filter even there for? Sorry, but if ******************** like that is on the filtered side someone must be running with NO filter.

I know of no other company that has a screen to catch the big chunks. I'm cutting out this screen and replacing the one in my car.

Wow, there sure are a lot of restrictions in the airbox. Thanks for sharing.

I'll probably keep mine in because with my luck, when I remove my air filter to replace it, some crap will fall into that area before I even get a chance to stick my vacuum down the airbox. :D

Hey now. It's just this week's episode on "How I out smart Porsche engineers". :)

Boxtaboy,

I understand your concerns, but don't stop with the P car. As I said in my post, I don't know of any other car that has a screen aft of the air filter. So if you own other cars you should be just as careful not to leave any screws, paperclips or club sandwiches in your air box. :)

Ekam,

I'm not trying to outsmart the Porsche engineers, I'm just trying to free up the car from the federal mandates that are imposed on imports. You know the ones that limit performance in the name of the environment and keeping the neighbors happy. :cheers:

True, I doubt it would be a big deal either way. Let us know if you feel or hear any difference.

I certainly don't have those problems since I yanked out my stock air box and replaced it with an EVO Hi-Flow three years ago. Forget the fairytales of CEL and MAF problems; if you know how to properly oil a cone filter, those problems don't arise. You'll never get the sound an EVO produces with a modified stock box.

Jmatta,

I'm with ya on the properly serviced, cottom based, oil filter thing. Some people just soak the media to the point of it dripping. Just follow the directions!

I'd love to put an EVO on my car. But cost and the love of tinkering prohibit it at this time. I'll let the forum know after I swap out for the screenless stack.

I hear you...good luck on the swap. I truly believe Porsche purposely put all this stuff in our cars (baffles, screens, secondary cats) to keep them quiet for the EU restrictions. Our cars should have a nice sound, just as Dr. Porsche intended them to in the beginning.

Most of them do. In fact, every car I've worked on that had a MAF (as opposed to a MAP) had a screen like the one here.

Not only does it serve to keep out "large chunks", but it more importantly influences airflow over the sensor.

You can read more here: http://www.gmtips.com/3rd-degree/dox/tips/maf/maf-screen.htm

Ditto that. I've put in a couple of CAI (Cold Air Induction) kits in other cars, I haven't encountered one without the screen, domestic or import. Oh and BTW, there was always a seat of the pants difference felt with them, one verified a 13 HP increase on the dyno, these completely replaced the stock airboxes though.

OK, I'll post this to anyone out there that has an EVO intake installed. Does that intake have a screen just before the OEM Mass Airflow Sensor? I went to the site that sells them and could not see or read that it does. It does utilize the stock sensor so, if you guys are right, will have this screen installed. I checked my SUV, my wife's car and my Harley and none of then have a screen in front of the MAS. Everything else I own has a carburetor.

I can see where you think it should. In high RPM engines, the air flowing past the MAS will act like a wing on a high performance aircraft and will create a boundary layer of air giving false readings. The screen will act as vortex generator breaking up that boundary layer. On an aircraft wing it allows the flight controls to be more effective at high air speeds.

So with that said I need someone that knows first hand what the EVO intake has inside that pipe. Pictures would be nice also. Until then I'm swapping out for my screen-less stack (which only took an Exacto knife to cut out). If I get a CEL, I will post it and won't hide the fact that I was wrong in my assumption. :cheers:

I should just go ahead an get the EVO because the air in a stock air box takes no less than 4-90 degree turns in less than 12 inches!

You may not get a Change Engine Light, but it may run like crap or stumble at certain RPM ranges, etc.
I put a K&N ram tube, ot whatever they called it, on an RX8 and it used the original MAS and had no screen in it, but neither did the OEM airbox.
Made the car so loud on intake noise, I couldn't stand it.
Know anyone who wants one?

Swap out and 50 mile test drive complete. No CEL and I can swear that the intake noise is throatier, maybe the screen suppresses some noise. Driving the car through the twisty's does seem to run similar to a sexual molested primate. IMHO :cheers:

While sitting around this weekend I decided to do a little research on a couple of issues;

1. Over servicing of K&N air filters. That myth is settled here;
http://www.knfilters.com/MAF/massairfindings.htm

2. Removal of the intake screen (reason for the thread). I've visited sites, read posts and learned about the different mass air flow sensors. We utilize the hot wire type. The wire is maintained at a constant temp and the air flow moving across it will cause it to loose heat faster. The ECU will compensate by sending more current and measures this current flow and puts out a voltage signal. This wire is made of platinum (hence the $250+ replacement cost) and is susceptible to damage if a foreign object should come in contact with it, (the screen). So are the internals of our engines, so if this happens I think the MAF is the last thing I would worry about.

The wire is self cleaning, (from what I read) at engine shut down this wire is heated to 1800 degrees to clean itself, unlike a dog that can lick his balls. :rolleyes: A couple GM forums had CFM numbers with and W/O the screens but the 180CFM difference was based on their size and density of screen. I know ours is restrictive and the filter I use will keep out anything harmful. As I've said, I will continue to run without. If a CEL occurs and its determined to from the MAF I'll post the results.

Hi, Thanks and keep us posted and I like your :rolleyes:

:cheers:

Except that the Boxster doesn't use a Hot-wire sensor... it uses a Hot-film sensor similar to mylar, it is conductive and so can be heated. It is not however self-cleaning - at 1800 degrees, the film would simply melt.