air filter...

Eldorado · 08-15-2005, 12:37 PM

hey guys, I got a K&R air filter that i want to experiment with... mainly out of couriousity.
included with the filter package is the filter cone itself as well as the mounting bracket.

I went to take the stock filter out today and came across that rubber hose going into the top half of the filter... I didn't have time to follow it down because i had to get to work, but what is it for? and do I just ignore it when I install the K&R?

bryanthompson · bryanthompson's Garage

I think you mean the hose that goes into the top of the timing belt cover... I have no idea what its purpose is. Do the timing belts need the airflow? Why would they put a hose going to a filtered source, then give us a debris hole in the bottom??

Those Porsche knuckleheads, sometimes...

SoCal Driver · SoCal Driver's Garage

You can plug the fitting in the belt covers. Use a plastic cap that you find at the hardware store on the ends of hard pipes. Make sure you support the AFS. If you leave it on the rubber duct it will crack the rubber. Also the bouncing around will tweak the AFS.

I would be better to leave the stock filter unit on the car as you have to clean the cone filter every other week for it to be effective.

Eldorado · 08-15-2005, 03:19 PM

I'm not getting rid of the stock filter just for that reason, SoCal... Like I said, it was on a whim and it will just be an experiment...

so I can remove that hose and get a rubber plug to plug the hole? is the connection hard to get at? not near my car at the moment...

legion · 08-16-2005, 04:50 AM

I highly recomend the polypropylene filters...although I hear Hanes makes some nice cotton ones...

THE manning · 08-16-2005, 06:52 AM

Quote:

Originally posted by Eldorado
I'm not getting rid of the stock filter just for that reason, SoCal... Like I said, it was on a whim and it will just be an experiment...

so I can remove that hose and get a rubber plug to plug the hole? is the connection hard to get at? not near my car at the moment...

Turn off your ears when you first start using this thing. Your car will, maybe, sound more aggressive, but you probably won't get much in the way of measurable performance gains. If you ignore the more roarty intake note you will be more objective about it.

I used to run an MSDS cone filter setup, for about 3 years or so. I got tired of the claims that performance will drop because of the underhood temps, so I measured them and found that at speed the underhood temps aren't that much higher than ambient. Maybe enough to impact performance, but not much. So I decided to reinstall a factory airbox and test temps in the box. First thing I figured I would do was a back to back comparison of how the car would idle on a dead cold motor. What I found was that the car actually ran kind of crappy with the cone at idle, but ran great with the airbox. Remember, dead cold motor, so no chance of hot air under the hood. I also found I like the throttle response more with the stock aribox. I have never reinstalled the MSDS, in fact I actually gave it to somebody on Rennlist since I didn't need or want it anymore.

Der Rennwagen · 08-16-2005, 10:40 AM

Quote:

... cold motor. What I found was that the car actually ran kind of crappy with the cone at idle, but ran great with the airbox....

The key is retaining the Porsche designed velocity stack that is built into the lower part of the stock air box. It's been tuned for the engine. Porsche designed the top air box cover to comform to most conditions (all around performance, Swiss noise restrictions, max dust, water ingress, fit under the hood, etc.). Try running your stock air box with a paper filter (or K&N) and no air box top - remove it entirely. Just make sure it isn't raining if you use a paper filter... The difference is amazing.

What I've done is to cut the airbox top off but retain the lower portion to hold the filter in place (Carrera Cup style - hey why not Porsche Weissach did it.) and left the location for the belt cover vent to screw on to. I get a great idle, better throttle response, quicker revving engine, wonderful sound and I bet a slight gain of about 2-3 hp on top end right at about 5500-5800 rpms where you need it. Yes, I may have lost a little torque in the midrange but, the overall improvement in drivability and how the Porsche talks back to me more than makes up for any other loss. I did the temperature testing too and the findings were exacty as you discovered. When you drive, the air going into the engine at the filter is ambient.

Thompson
1985.1 944
Club Sport targa

Z-man · Z-man's Garage

I don't like K&N air filters. Sure, they let in more air, but the also don't filter out pollutants as well as the stock units.

My $0.42,
-Z.

Der Rennwagen · 08-16-2005, 11:22 AM

Agreed, when I cleaned my K&N this last weekend you could almost see through it! I like to find a severe service non-paper cleanable filter similar to the gauze and mesh construction but with more filtering capabilities.

TS

Dougster · 08-16-2005, 01:31 PM

This is always a interesting subject...
I was looking at the setup this morning myself.

schmedes1 · 08-16-2005, 08:28 PM

I am a long time K&N user... have one on all of my cars and believe they really do what they say. The key is to make sure you put the right amount of (red) oil on the mesh. You put the oil on and let it rest on the filter for a couple of days before installing it into the box. Since we all change our oil regularly and frequently (right?), dirt blow by has never been a factor...

SoCal Driver · SoCal Driver's Garage

"Red oil"... Wow! Just like the old VW air cleaners!

Wait!

We don't use them any more.

Slam · 08-17-2005, 01:48 PM

About the hose...

My best guess would be to provide positive air pressure to help blow debris out of the belt cover...?

Eldorado · 08-17-2005, 02:12 PM

does that hole *need* to be plugged?
and I would think those belts get damn hot.. maybe it's something as simple as air to blow over 'em to keep 'em frosty...

XxKHxX · 08-19-2005, 11:10 AM

Quote:

Originally posted by Der Rennwagen
The key is retaining the Porsche designed velocity stack that is built into the lower part of the stock air box. It's been tuned for the engine. Porsche designed the top air box cover to comform to most conditions (all around performance, Swiss noise restrictions, max dust, water ingress, fit under the hood, etc.). Try running your stock air box with a paper filter (or K&N) and no air box top - remove it entirely. Just make sure it isn't raining if you use a paper filter... The difference is amazing.

What I've done is to cut the airbox top off but retain the lower portion to hold the filter in place (Carrera Cup style - hey why not Porsche Weissach did it.) and left the location for the belt cover vent to screw on to. I get a great idle, better throttle response, quicker revving engine, wonderful sound and I bet a slight gain of about 2-3 hp on top end right at about 5500-5800 rpms where you need it. Yes, I may have lost a little torque in the midrange but, the overall improvement in drivability and how the Porsche talks back to me more than makes up for any other loss. I did the temperature testing too and the findings were exacty as you discovered. When you drive, the air going into the engine at the filter is ambient.

Thompson
1985.1 944
Club Sport targa

does water get into ur air filter element?

pokey · 08-19-2005, 02:46 PM

Quote:

Originally posted by Slam
About the hose...

My best guess would be to provide positive air pressure to help blow debris out of the belt cover...?

It would actually suck air past the belts, as the airbox is under vacuum.

Eldorado · 08-19-2005, 08:27 PM

that's a good point...
*sits and thinks*.....

hmm... i dunno - i'm stumped.. lol

XxKHxX · 08-19-2005, 08:56 PM

is it bad to plug up this whole. cuz if we do, it sounds like we prevent air from blowing across the belt covers.

Eldorado · 08-19-2005, 08:59 PM

or.. getting sucked across them...

if the air gets sucked through that line from the belt area, where is it's air supply coming from? is there another line that runs somewhere cooler than the engine bay?

Der Rennwagen · 08-20-2005, 05:57 AM

Quote:

Originally posted by XxKHxX
does water get into ur air filter element?

I guess it could that's why I suggested not using a paper filter. I don't think that water will get into the filter element but there is always that chance when you hit a huge puddle of water or driving in a torrential rain storm it could. Chances are that it won't, with the lower engine tray on and I've got an AIR lower front splitter that covers up similar to the bat wing under tray on the 951. With my stock air intake snorkel gone, the actual height of the air inlet is further up than the stock location than in the fender hole, where it was closer to exposed wheel, road and water spray.