billabobprice

Just stuck an 57 Air Filter on the Forester,

At low revs-sounds like a real deep & loud tuba , - by putting my hand in the intake and manilulating the air it goes, also when given revs it goes. Basically as the valves open up etc the length of pipe changes, then it stops being an instument-i think.

So could i lengthen it at the throttle body-if so how??
or
Stick a baffle in filter end of pipe, would it de-feat the point of a free air intake? - if not, how 2 do it??

K&N say its natural - never had any probs with them when put on bikes-(aside the flat spots).

ta

The rookie

iTrader: (1)

Is this a turbo or an NA? I suspect an NA from what you say.

Nothing opens in a Forester to change the LENGTH of the intake at all!

I'm not clear how/eher its fitted, direct to throttle or on an intake pipe and back at the original airbox?

Simon

billabobprice

Urr right Simon N/A it is

All air box bits are out, Pipe comes straight off throttle body, filter ends up bottomleft bay, even with no filter or housing its sounds as bad.

Its sounds exaclty like blowing across the top of a beer bottle(but alot louder), as you drink the noise changes / therefore as the engine opens up so does the noise.(Well thats the theory from the pub)

Kinda think a panel like yours would been a better option!

The rookie

iTrader: (1)

OK its almost certain that the length of that pipe is going into resonance at that certain engine speed, if you can make it a bit longer (changing the resonant frequancy) then it will move the rpm at which its resonant lower and should stop it, only way I can think to make it longer is by cutting it and using some silicon hose to bridge the gap, just getting it an inch or two longer should do it, if making it longer, then shortening is will increase the resonant speed, but shorten it to much and you'll drive on that speed, so you need to shorten it slowly so you get it at a speed the engine doesn't sit at very often (a lot of manufacturers use about 1600rpm, its above idle but below the usual 1750+ rpm you drive at!)

Sounds like K&N just got the length wrong!

Simon

NorthDownsScooby

Welcome by the way...

...and say hi to us over at Forester.org (Europe section) too..