Modifying standard airbox

[The Hoff]

Right been thinking about modding the OE airbox and adding a decent feed into it on a MK2 172 (green panel filter) to see if it will aid the engine breathing. Been researching IK's for a while but i don't fancy getting flat spots or any loss of torque.

Was just wondering if anybody has already done this mod and if they have any pics of the airbox with any nice additions.

Cheers.

 

[BRUN]

Nick Hill should be able to sort out out a scoop and maybe a new pipe for a better cold air feed

 

[len_beach]

I have been looking into this and from what I have read, sealed IK's are not worth the extra expense over a modded standard box.
I have a PiperX panel and have just got 7' of aluminium ducting. I intend to remove the lower airbox feed and route a hose to just behind the lower bumper grille. The second airfeed which runs behind the headlight will be replaced with a length of ducting minus the 20mph valve.
For a total cost of £20 and a couple of hours of my time, I can't see this performing much worse than a sealed IK.

 

[len_beach]

I do intend to fit a silicone elbow as the standard effort looks a bit restrictive with its ribs and thin sidewalls.

 

[portal172]

Sounds good.

Please explain the 20mph valve for me. What does it do? (Opens up at 20mph I guess?) What does it look like?

 

[olin]

Re: A few ideas...

http://perso.wanadoo.fr/olin/IMAGES/c0.jpg
http://perso.wanadoo.fr/olin/IMAGES/c6.jpg
http://perso.wanadoo.fr/olin/IMAGES/c8.jpg
http://perso.wanadoo.fr/olin/c10.jpg
http://perso.wanadoo.fr/olin/IMAGES/c13.jpg
http://perso.wanadoo.fr/olin/IMAGES/c15.jpg
http://perso.wanadoo.fr/olin/IMAGES/c14.jpg

The 20 mph valve does not exist. It is called "acoustic valve" and is pneumatically controlled. It is opened at idle, closes at 2000 rpm then opens again at 4500 rpm. In the 2000-4500 range the aibox is only fed by the narrow tube running below the airbox. This is done to reduce the intake noise and to increase the torque in that range.
The design I've made keeps this valve and put it in a "dynamic" area. It also has a much wider bore of 70 mm instead of 58 mm for the original acoustic valve and feeder.
That way I keep the torque at low rpm and increase power at high rpm.

 

[olin]

The original acoustic valve:
http://perso.wanadoo.fr/olin/IMAGES/c1.jpg
The upgraded acoustic valve:
http://perso.wanadoo.fr/olin/IMAGES/c13.jpg

All the details are available here ( in French sorry )

http://forums.rs-team.org/read.php?f=1&i=37508&t=37508

 

[olin]

The acoustic valve ( wrongly called 20 mph valve ) is located at the end of the large bore feeder tube ( above the horn in front of the left front wheel )