Uprated air filters

Guest · Jul 21, 2005

How many people are running uprated air filters i.e. non std air box type or cone type filters? Are there any noticeable advantages such as increased response, any more power, nicer induction noise?? It would be interesting to know. I did a lot of this kind of thing to my 200SX and it responded very well being a turbo car, not sure of the pros and cons with the 911. Any advice would be great and any recommended brands. Cheers

Kris

Guest · Jul 21, 2005

Kris,

I did put in a K&N panel filter but was told by JZ that this really wouldn't give any noticable advantage and indeed may allow more dirt into the engine.

I'm using standard filters with an open air box, and get a nice sound but JZ doubt any power increase. I did drill holes in my standard air box and it sounded ace, but I'd already got the open one on order and the company wouldn't accept a return. One of my needless purchases!

Cheers,
Simon

Andy Tims · Jul 21, 2005

Do a search (go back a year) & you'll find lots of past debate on filters / induction kits.

Guest · Jul 21, 2005

What Andy said.

Summary: zero horsepower, but lovely induction noise. They may even hurt hp because you are taking in more hot air (maybe but imho unlikely).

Independent lab studies show K&N type filters let more dirt into the engine.

ClubSport 911 · Jul 21, 2005

I know it's a different car but I had exactly the same symptoms on my 944.

Most of the sense has already been spoken, but I did obtain a trick from RUF (in writing) a couple of years back to improve the WOT air flow on the 3.2. Drill 4 x 25mm holes at the bottom of the airbox lid. Too many = lose torque...too few and no effect.

I have this upgrade on my airbox and can report that (thankfully) it doesn't sound like a Nova 1.1 coming down the High St. of your choice (as most induction kits can).

Effect ? Probably zero, but since I have another airbox lid (standard) I can say it has cost me nothing but time.

Follow up. Don't forget, that when you look @ the 3.2 inlet design you might notice the single biggest restriction - the moving vane AFM. (see 12 below) If you are operating on anything other than WOT, then the restriction is in fact this device ! (That's why the 964 people with larger engines need to move to hot film etc to help alleviate this effect)

The only time the air-filter etc comes into play is WOT, and max RPM (i.e. max air flow into the engine).