New air filter design, DIY

[Zendalar]

Last night I took off the air filter and took a test drive without it. What I noticed was way better torque and acceleration, and pretty mighty vacuum sounds =). I know I know, one should not drive without the filter but just had to try.

A thought came to my mind: "Why not design cabinet for filter of your own choosing?"

The freeflow filters are very expensive when bought separately, like 100$ a piece. And you have ot buy 6 of these. Different case, and there is only need for one bigger freeflow filter.

Here's what came up, tell me what you think. Planning to build it from stainless steel.


//Zen

[MIK911]

Good idea.I was thinking something similar myself ('86 Carrera), after seeing the latest Performance/Automotion catalog which sells an open airbox lid (similar to your drawing) for almost $200.
BTW, did you notice any change in the EXHAUST note from your car with the removal of the air filter? I've heard that this type of modification yields a nice vacuum/hiss sound (like you described), but also a change in the exhaust note.
thanks
mike

[Zendalar]

Dunno about exhaust sounds.
The vacuum sounds sure ain't hissing sounds, kinda similar to normal exhaust sounds and they appear only if you press gas =)

[911pcars]

Might the apparent increase in torque and horsepower be due to the fact you did this at night when the air is cooler and denser?

Your filter housing design looks interesting, but why do these "freeflow" filters cost $100? Can you describe them? Also, how would you prevent water infiltration from the exposed filter element?

Sherwood Lee
http:members.rennlist.org/911pcars

[Zendalar]

www.greenfilters.com , costs here 1150 marks. 150$
H&M filters 50$
www.itgairfilters.com 65$
www.jrfilters.com 65$
k&nfilters.com 110$
www.pipercross.com 100$
Twister (www.greenfilters.com) 110$

These are costs per piece and you would need six of these.

I have driven many times during the night, but never seen this much increase in torque. Here are test results.

Vapaavirtaussuodattimien vääntökäyrät= Freeflow filter's torque curves.

VAKIOSUODATIN+SUODATINKOTELO= Normal filter+casing








[This message has been edited by Zendalar (edited 09-26-2001).]

[Wayne 962]

Ok, take the Pepsi challenge. Have a friend take out the filter, and place it back in several times, and then go for a drive (without knowing if it's in there). Put the radio on loud if you think that you can 'hear' the difference.

I don't think that the air filter is any real point of restriction in the 911 engine (Bruce agrees with me on this. Actually he wrote that first, so I guess I have to say that I agree with him).

-Wayne

[Zendalar]

Soo, it might be that my air filter is just dirty and clogged? After all its..hmm..lets count, 12 years old =). Ok, it has not been used and it looks pretty clean, but I guess I have to change it and then check test it.