Air Filter Housing Restriction

[Quickurt]

Originally Posted by Jaxonalden

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.

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?

[Jaxonalden]

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

[Jaxonalden]

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. 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.

[Franco]

Hi, Thanks and keep us posted and I like your

[Lil bastard]

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.

[blue2000s]

Those screens have no discernible effect on the airflow through the intake. Removing it may make you feel like you've done a free mod, but really, it had no effect on the engine that you will ever notice. Send it to me and I'll put it on my flow bench to prove it to you.

This type of screen also is not used as any kind of a "flow conditioner" for feeding into the MAF. Screens that serve that purpose need to have "depth" in the direction of flow like a honeycomb-type screen.

My only guess is that this screen was added to prevent large particles from being ingested by the intake. I agree, that it's impossible for something to make it that far into the intake if the rest of the system is intact, but there must have been some significant "what if?" scenario that Porsche saw fit to protect from.

Send me a PM and I'll send you my address. You can put it in an envelope and I'll bench test it.

[Jaxonalden]

Will do, but first...I have my stack with the screen removed in now. You want to use the stack with the screen? Or do you just want the screen I removed so you can just wrap it around a tube that you already have base-lined?

LB,

I just compared the pictures of the OEM and the one in the article I read. Seemed the same one to me...I use the E-Gas model...especially after eating Mexican food.