68 replies to this topic

[Jetpilot]

Yes supercharged and whilst i wont disagree as i have no experience with a closed air box, my buddies Atom whines like a b*tch and he had 0 problems, bizarrely he was on the 98db static limit, there was also a whining charged mx5 there, 0 problems.

 

In fact the day was a total shambles, advertised as open pit and it was semi, track regularly closed to allow the db readings to average out, managed 4 sessions total before i gave up and came home at 3.30, my mate in his Atom stayed and got one more session in, spent more time sat in the car queuing than on track.

 

Anyway, lesson learned, i am going to gut a std back box, have a central inlet, split to two outlets, high temp steel wool and filling as recommended earlier in this thread and fire out through the diffuser and probably get a couple of 90 degree ish bends with some additional small slip on silencers sitting under the diffuser worse case scenario.

[MartinS]

Goodwood never does open pit lane, they just don't know how to word the set up they do. Its a total pain in the %rse with all the queing as even if your with mates, you never get to chat just permanently pushing your car up the line.and we only go there as for once its local.

My car always passes the sound check there but fails on drive by. For whatever reason our sc cars from what I've see, sound a lot worse than atoms  as they seem to have a high pitch whine whereas ours are often likened to like a jet engine, harsher.

I even surrounded the air box area with sound deadening material which helped,  but my enclosed box (pier vm7000 I think) just shuts it up totally).

Like you I am going to create an exhaust.

 

Martin S

 

 

[MartinS]

sorry, Piper VM7000 Viper enclosed air intake is what I have.

Martin S

 

[tibby]

 Foam 'type' filters absorb better sounds than cotton ones?

 

grtz

[Nev]

A metal airbox surrounding the cone itself and a metal 90 degree inlet pipe into that box will diminish the sound a lot I am sure. Some noise/resonance cancelling sticky matting on the metal of the airbox might help too. You could also try attaching some perforated exhaust pipe tubing to the 90 inlet bend and cap off the end of it, that will force the sounds waves to bounce around in the perforated pipe prior to being emitted.

 

Density and lack of large flat surfaces (or support ribbing/webbing to stop resonance) on the box is your friend when trying to reduce noise output.

 

It's not an insurmountable problem by any means, just a heavy solution.

Edited by Nev, 20 September 2016 - 04:14 PM.

[MartinS]

The piper is a plastic enclosed box that supposedly also helps keep the air cooler and it has a wide fee pipe that on mine sits right in the turbo vent ear so it gets a good solid cool air feed, better than it would from a  open cone just sitting in the wheel arch area.

 

Martin S

 

[dominik]

Milltek NA is definitely baffled. Dunno about turbo.

 

Milltek Turbo is not baffled.

A layer of steel-wool around the perforatetd tube.

The repacked acoustafill 900° stuffing has been blown away in 2 years and around 8000km without doing trackdays.

[Jetpilot]

Pretty much all cars will burn out packing over time Vx's just quicker i seem.

[Bargi]

Pretty much all cars will burn out packing over time Vx's just quicker i seem.

I'd guess it's the back box being such a short distance from the engine. More heat and maybe pressure than a front engined car.