The sound of ///M

The sound of ///M

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Output Flange

Original Poster:

16,793 posts

210 months

Sunday 19th March 2017
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Was listening to some videos of GrpA E30 M3s, M1 Procars and the like.

All of them had the distinctive metallic rasp as they were being ragged mercilessly. But what is is that gives them that noise? The air boxes?

By contrast, the GrpA 635CSi doesn't sound anywhere near as good to me. So maybe it's the ITBs?

What's the thoughts, chaps?

johnny m3

75 posts

193 months

Sunday 19th March 2017
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It is the airbox I've got a carbon airbox fitted to my e30 m3 track car and sounds mega.

Deptford Draylons

10,480 posts

242 months

Sunday 19th March 2017
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johnny m3 said:
It is the airbox I've got a carbon airbox fitted to my e30 m3 track car and sounds mega.
Yep. You can turn a stock 195bhp E30 M3 into sounding like a full on DTM with a carbon airbox. Look for some dyno videos of street cars fitted and its quite a transformation

AW10

4,422 posts

248 months

Monday 20th March 2017
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If this photo http://www.ultimatecarpage.com/img/BMW-635-CSi-Gro... is to be believed the 635CSi group A cars ran a stock looking intake plenum. ITBs allow the "bark" from each cylinder's intake stroke to be clearly heard while the plenum blends all the "barks" into a more continuous noise.

SebringMan

1,773 posts

185 months

Monday 20th March 2017
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You have to love ITBs! It's one of the main reasons I bought my E46 M3. Now to look away from the carbon airbox.

bennyboysvuk

3,491 posts

247 months

Tuesday 21st March 2017
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SebringMan said:
You have to love ITBs! It's one of the main reasons I bought my E46 M3. Now to look away from the carbon airbox.
I started googling pics and found this oddity! I bet it sounds wonderful though.


Cactussed

5,292 posts

212 months

Tuesday 21st March 2017
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Dan
I've got the carbon airbox on the M3 which you're welcome to come round and drive.
You definitely get the induction noise effect, which is epic, but it's not the metallic rasp you refer to.

The e36 M3 has ITB's and doesn't really have the rasp.

The e46 does for some reason, but different back boxes either seem to enhance it or eliminate it.

Not sure that really answers your question but my money is on exhaust material type, thickness and no and type of resonators etc

ETA: Take this at face value. http://www.custom-performance.net/productcart/pc/v...


Edited by Cactussed on Tuesday 21st March 16:51

bennyboysvuk

3,491 posts

247 months

Wednesday 22nd March 2017
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Cactussed said:
Dan
The e46 does for some reason, but different back boxes either seem to enhance it or eliminate it.

Not sure that really answers your question but my money is on exhaust material type, thickness and no and type of resonators etc
This is true, the S54 in the M3 and the Z4 sound very different in those applications. Installed in the Z4, it's much more bassy and doesn't have that tinnier, thrashier sound, but both sound fantastic regardless.

robbiekhan

1,466 posts

176 months

Wednesday 22nd March 2017
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johnny m3 said:
It is the airbox I've got a carbon airbox fitted to my e30 m3 track car and sounds mega.
Combo of box and exhaust system as a whole.

The airbox adds induction roar (I have the Eventuri in my E46 and it sounds c;lose to a CSL, just not quite there yet due to the lack of CF plenum and additonal sound deadening), whilst the exhaust system covers the remainde with rasp and metallic sounds. E46 in particular as it has to flaps or valves in the exhaust, just pure engineering and plumbing! Worth noting that later model E46s have the CSL exhaust manifold as standard, so have an additional element in the noise.

Edit+
Forgot to add that ITBs as mentioned need to be the baseline for the combo to work so well!

Edited by robbiekhan on Sunday 26th March 23:02

doclip

349 posts

222 months

Sunday 26th March 2017
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My S54 sounds just fine umodified -especially when the roof is down

Edited by doclip on Monday 27th March 13:11

InductionRoar

2,001 posts

131 months

Sunday 26th March 2017
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robbiekhan said:
induction roar
byebye

e21Mark

16,205 posts

172 months

Monday 17th April 2017
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ARM BMW's Grp A spec was kicked off Donnington as induction was making 106dcb at full chat. As said previously, even a tired 2.3 can sound special with a carbon air box.

https://www.youtube.com/watch?v=5jqogfgHHPU

Sadface

104 posts

122 months

Sunday 7th May 2017
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Output Flange said:
Was listening to some videos of GrpA E30 M3s, M1 Procars and the like.

All of them had the distinctive metallic rasp as they were being ragged mercilessly. But what is is that gives them that noise? The air boxes?

By contrast, the GrpA 635CSi doesn't sound anywhere near as good to me. So maybe it's the ITBs?

What's the thoughts, chaps?
enjoy it why you can...new m cars play it thru the speakers wtf

e21Mark

16,205 posts

172 months

Monday 8th May 2017
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weeping