Acoustic Valve... The Truth

[nelson182]

Yeah see my pics on page two of where I have put my air feed down past the passenger headlight. The acoustic valve and tubing gets in the way otherwise!

 

[ant]

My best guess is that it is to do with drive by noise, particularly for Switzerland

interesting. Isn't Switzerland the only other place they are imported?

or did I dream it lol

 

[ant]

Just would be good to have some definatice proof that removing this actually improves the running of the car.

as i keep saying - the car feels ABSOLUTELY THE SAME without it.

plus now with the viper and larger air feed a re-map will yield better results.

 

[rich[182]]

lol - take a look at the overhead view of the valve and tell me it's not restrictive, it results in a sub 50mm hole being reduced further by the valve even when fully open, if it doesnt affect airflow why dont we all put one in our zorst

 

[nelson182]

Its suffocating the poor car!! Out of interest does anyone know if this piece of kit (or similar) has been fitted to the 197??

 

[jayxx83]

lol - take a look at the overhead view of the valve and tell me it's not restrictive, it results in a sub 50mm hole being reduced further by the valve even when fully open, if it doesnt affect airflow why dont we all put one in our zorst

I believe, the latest ferraris and lambos actually do have these in the exhaust to meet relavant noise regulations.

 

[clidge]

can anyone draft together a really good easy to follow how to guide on this please as i want to do this asap

 

[ant]

remove n/s/f wheel
remove arch liner
remove a. valve [its attached with the horn]
block pipe
tape up electrical gubbins.

refit horn
refit arch liner
put wheel back on



thats from memory btw!

 

[TrophyDan]

If you do this (remove valve, put in proper air feed)
What do you tell the insurance company? and would they charge you for it.

 

[ant]

with elephant it just states "non-standard air filter" on my policy.

and they charged, others might not.

 

[nelson182]

with elephant it just states "non-standard air filter" on my policy.

and they charged, others might not.

Well becuase I already had open cone on mine, I declared it, so since modifying the air feed, it makes no difference
Personally I dont think it is even worth telling insurance co if you remove the valve and change air feed. At the end of the day it was an air feed, and still is (only bigger!)

 

[Neil G]

lol - take a look at the overhead view of the valve and tell me it's not restrictive, it results in a sub 50mm hole being reduced further by the valve even when fully open, if it doesnt affect airflow why dont we all put one in our zorst

The airbox has two feeds though, the other with no valve in.

The result it the filter can easily flow enough air.

 

[MarkM]

Heres a good thread about air filters

http://www.cliosport.net/forum/showthread.php?t=100940&highlight=bmc+test

It demonstrates how effective the standard setup is I think. Take off the acoustic valve, I have, but it wont make any difference IMO 1bhp maybe, you wont notice that.

 

[nelson182]

^^^ excellent thanks Mark

 

[Neil G]

Interesting read Mark

 

[clidge]

so are the horn and acoustic valves joined together? why do you have to block a pipe up and what with cheers

 

[ant]

so are the horn and acoustic valves joined together? why do you have to block a pipe up and what with cheers

no they just use the same bolt.

block the pipe with a screw.

 

[powello9]

why what does the pipe do?

 

[BenR]

Runs to the inlet manifold and if you dont block it then you will have an air leak and high idle.

 

[Nik]

Out of interest does anyone know if this piece of kit (or similar) has been fitted to the 197??

Yep, i believe so:

 

[Neil G]

Ah yes..I see the good old acoustic valve there

I wonder how many people are going to rip it out of their brand new 197 to be replaced by some washer drier hose lol

 

[Fred@BTM]

its bloody worse on the 197 (by the way we've got the cup racer airbox's in already for them!)

 

[powello9]

What does the cup racer use as a cold air feed? and does the megane 225 use this valve?

 

[Fred@BTM]

cup racer uses a big feed pipe

megane i'm not sure on

 

[powello9]

Just a thought on te use of the valve, Smeone said the valve was open when the engine was idling, that means it closes when the engine is worked hard, would that not cause the engine to pull the air through at higher pressure from the second air feed in the box? Could highier air pressure increase torque?

 

[Giles-172]

That is one theory, but again it is flawed.

The basic of variable length inlet system is nice, and the use of a smaller intake diameter at slow rpm is also nice. BUT, they cannot occur in the manner you speak sadly.

1) The issue with intake velocity is that the valve is upstream of the air filter. This air filter will destroy andy difference in velocity upstream from it, i.e. the filter laminitaes the flow as it passes through it. An engine consuming 1000ltrs of air a second constant will lead to differing velocities through one 50mm pipe or 2. BUT, when that velocity meets the airfilter it has to pass through it at the same rate as 2 supply ducts would, its laminated (laminar flow generated) and enters a constant volume intake system where velocity will not change irrespective of what you do pre air filter. Velocity changes only really take effect post throttle body, mainly the intake runners, ports and valve bowls/seats.

2) the notion of changed the tuned lenths is also flawed for the same reason. The paper type air filter does not allow accurate and constant passing of intake pulses, especially as they change all the time passing through a plenum, depending on throttle angle and RPM. If renault were actually concered with such phenomenons in a greater manner than the fixed induction system, they would be running a helmholtz resonator or similar.

So that is why i say none of the theories present me as true.

1000 L/second thats a 24L engine at 5000rpm or a 2L at 60000rpm

 

[BenR]

touche.............minute.

 

[WayneG]

Is this the truth? From panel of experts on renaultsport site.......

'Acoustic Valve on Clio Trophy's Induction Cold Air Feed'

'Can someone with an intimate knowledge of the design and manafacture of the 182 please explain exactly why there is an electronically operated valve in one of the two air feeds to the air box? It is creating a lot of interest on certain forums and I'm sure there is a valid reason for it's presence but it would be useful to know what it is doing as removing it seems to improve pick-up and engine response without any obvious detrimental effects elsewhere.'

Allen Collen responds.... 'The indution noise will be different if you remove it - there could be some marginal improvement in performance but only if there was not enough air available when the butterfly was open. It is controled by the ECU and its objective was to reduce induction noise in line with an EU directive.'

 

[powello9]

Awesome, That Sticks The Nail In The Acoustic Valve Coffin. Thank You Evrybody For Your Comments. Im Glad We Finally Got To The Bottom Of This.

 

[dannyboy172]

Interesting read on this thread.

I'll be removing that then lol...Not going to sacarfice the foglight tho, just get some done low down on the bumper.

Edit: Surely this doesn't affect insurance by removing the valve and replacing it with a new air feed?? :S

 

[ant]

well i dont want to say i told you so, but.............................................

 

[nelson182]

Interesting read on this thread.

I'll be removing that then lol...Not going to sacarfice the foglight tho, just get some done low down on the bumper.

Edit: Surely this doesn't affect insurance by removing the valve and replacing it with a new air feed?? :S

Go for the route I did here mate:

Car is slightly louder, although was already loud due to open induction kit :evil:

http://www.cliosport.net/forum/showthread.php?t=152583

 

[haitch]

the trouble with this mod is that unless you have your caf as straight as possible (the opening facing front & minimal or slight bend in the ducting) you wont see the full benefit, best off using the foglight area.

 

[ant]

but not if you want 2 foglights.

i could feel a breeze coming through my caf when the car was stood still!!

i imagine at 40 its plenty.

 

[dannyboy172]

Got tomorrow off work, so i'm gonna give this a go.

Just need to source some ducting from somewhere.

 

[haitch]

fair enough if you want to keep your fogs, many have to compromise, all im saying is for best results use the foglight area as the caf will have minimal bending & a direct opening. we cant all take out the headlight like a cup racer eh.

 

[nelson182]

Agree that fog light area is more direct. But as a subtle alternative I thought I'd do this. Plus I slash cut the pipe so avoided a 45degree bend in it. I tested it with a hairdryer and it was pushing nice amounts of air up through to it. I would guess the hairdryer would imitate a 10-15mph wind

 

[Neil G]

Would text that but I don't own a hairdrier