Does any one know the reason why the early Freelander 2's have the 4 tube sections sticking out the pipe which goes form the air box to the turbo inlet like below :-

Click image to enlarge

Click image to enlarge

I know they updated the part as when I had my smokey session in the lakes they replaced it with the updated one

I haven't noticed if it lost the 4 tubes though, only that it's not fix together with a jubilee clip

they are supposed to catch the resonance of the air intake piping and capture/equalise the noises.

john deere fit some odd speaker type grills inside tractor cabs, these apparently to a similar thing and capture equalise noises At work
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It was a "too much desire" to reduce the NVH (noise, vibration and harshness) on the engine.
It has to do with the "organ pipe theory" because the intake air is generating specific sound based on its velocity. The pipes are there to generate the opposite/inverse wave in order to nullify the sound, for specific RPMs.

Something that relates with this is found on the link below.
See that the fact that putting the metronomes on the "free moving" support allow the metronomes to propagate their movement momentum to the plank and to the others and finally synchronize themselves.


Last edited by alex_pescaru on 4th Dec 2012 8:43 pm. Edited 1 time in total

Very interesting video Alex. I thought it would more than likely be because of noise dueto the different lengths.

As later cars didn't have this, does it mean it proved they didn't work, or have they found a different solution.

The reason I ask, is that I have one of the newer pipes off a facelift and was wondering if it would be a backward step by fitting it. Freelander 2 HSE Lux 2013MY - Barolo Black with Ivory Leather. Alpine DVD - Privacy -Evoque 20" Dynamic Wheels and more to come.........

The original material here: http://physicsbuzz.physicscentral.com/2009...rgans.html

And anyhow, I believe that it applies only on constant engine RPM, like when running on the highway, where at a specific speed/RPM some noise could become resonant and intrusive.

I don't know how it will affect the noise the new pipe... It's only one way to find out...

I believe they've been dropped because, as you know, every engine has its own sound / resonance points / etc. given by different tolerances and so on and therefore also the length of the pipes should be modified accordingly in order to work properly. Too much trouble, so better they've dropped them all altogether. Cheaper anyhow....

New engines have a new turbo, so the intake air is disrupted differently to our pre-fl models so that could explain the reason for dropping it. If leave it as it is, if you're changing the way the air enters, who knows what errors it may flag up! Mine: 2012 Golf GTI Edition 35
Family's: 2009 Freelander 2 HSE TD4 Auto, Stornoway

Yorkshire - God's County

Unnecessary quote removed


Hi Dave,

I can't see this effecting the air intake of the turbo in anyway. A turbo draw's air in, then forces it out, so the way it flows in to it won't make a difference. The smoother the track into the turbo is always beneficial.

You will find that if you removed this pipe all together and fitted a cone filter directly onto the turbo inlet pipe, it would still run perfectly well, but you would hear alot more turbo noise.

Unnecessary quote removed


The bit I was getting at was that newer turbo's may reduce the noise sufficiently, hence the need for the 4 tubes is reduced on the later cars.

I asked ages ago when they were servicing mine what they were for and they didnt have a clue.

I love my 4 tubes

Iain

Its just a tunned baffel, I think the 4 pipe thing looks cool

superspark wrote:

I think the 4 pipe thing looks cool

Looks a bit like organ pipes, maybe in the the snowy weather it plays "I'll take the high road and you take the low road" to the other vehicles

New turbo ?? Ooo is it better ? When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car

The technical name is "quarter wave resonators" Each different length tunes out a different resonant frequency (wavelength 4x length of the stub) in the induction tract. Despite the presence of a turbo, the intake still sees the pressure fluctuations of the induction strokes of each cylinder. A positive pressure pulse in the intake travels up the little tube, bounces off the end and travels back so that when this positive pressure gets back to the main pipe, it arrives at the same time as negative pulse from the next wave, thus partially cancelling it out.

I conclude that the different turbo innards on newer models bring the amplitude of the intake resonances down to an acceptable level, removing the need for the more complex (and therefore more costly) intake pipe moulding. Looks neater too! Gone... 2013 XS TD4 Manual Firenze Red
Gone... 2008 (09MY) XS Td4 Manual Stornaway Grey
Prior... 2003 G4 Discovery 2, 1998 Disco 1 and 1997 Disco 1 Company car before that
Also gone in Nov'13, after 7.5 yrs, to new owners with time for more TLC - 1980 Series III 88
Current 2015 Discovery Sport HSE 2.0