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Exhaust sound mod

Specific discussion about the E89 2009 Z4 (sDrive35is, sDrive35i, sDrive30i, sDrive23i)
HillWalker
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Exhaust sound mod

Post by HillWalker » Wed Jul 26, 2017 5:42 pm

On my 35is one thing I find very noticeable is that before I did the mod it would start up from cold with the flap open and be really rorty and then after 2/3 seconds as the flap closed it would quieten down and sound quite tame, also being a fairly steady driver, though not quite pipe and slippers yet !! I love to hear the extra growl you get pulling a high gear at low revs. One last thing I completely disagree with Maniac on the drone at motorway speeds because even as standard the flap would be fully open at speed, but I do appreciate the 35i/35is have different exhausts which may make a difference.

mcbutler
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Exhaust sound mod

Post by mcbutler » Wed Jul 26, 2017 5:54 pm

Is this flap fitted to all models of Zeee?
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HillWalker
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Exhaust sound mod

Post by HillWalker » Wed Jul 26, 2017 6:09 pm

On the 6 cyl models only on the 3litre turbo's, on the newer 4cyl turbo's I'm not sure, but someone will confirm

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Smartbear
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Exhaust sound mod

Post by Smartbear » Wed Jul 26, 2017 6:12 pm

HillWalker wrote: Wed Jul 26, 2017 6:09 pm On the 6 cyl models only on the 3litre turbo's, on the newer 4cyl turbo's I'm not sure, but someone will confirm
The 2 litre turbo engines have the exhaust flap as well :thumbsup:
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e89 Sdrive 20i, plenty of mumbo & good economy-the thinking bears z4
e89 Sdrive 30i, this ones busted, pass me another...
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Jasper ham
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Exhaust sound mod

Post by Jasper ham » Sat Jul 29, 2017 2:15 pm

I tried this and did not find a lot of difference. I have now had the secondary cats removed and replaced with a straight through pipe and left the exhaust flap as it is. The car now burbles at tick over, but under heavy throttle it sounds really nice, not too loud and no drone at motorway speeds. In sport mode it accentuates the pops and bangs which is really entertaining.
BMW Z4 e89 35i white, black roof, 296 wheels emap to 390 BHP and running Vredestein Ultras. Second cat delete and straight through pipes.

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bob4333
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Exhaust sound mod

Post by bob4333 » Sat Jul 29, 2017 3:19 pm

Do you have to put your secondary cats back on come MOT time....?

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Jasper ham
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Exhaust sound mod

Post by Jasper ham » Sun Jul 30, 2017 9:46 am

No, it's a permanent mod. I did the same on my SLK55 which did sound amazing. The secondary cats keep down the emissions for countries with very tight regs, it will and has passed an MOT with them removed. The lambda sensors are only on the first cats on the downpipes so they also don't through up any errors once removed. The car is not noisy, but rumbles nicer and no drone. Would highly recommend.
BMW Z4 e89 35i white, black roof, 296 wheels emap to 390 BHP and running Vredestein Ultras. Second cat delete and straight through pipes.

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benv6
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Exhaust sound mod

Post by benv6 » Sun Jul 30, 2017 1:41 pm

:evil: :oops:

Any effects on the MPG though ?
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Previous: 435D Coupe, BMW Z4 E89 35i, BMW Z4 E85 2.0, BMW E46 330CI

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Maniac
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Exhaust sound mod

Post by Maniac » Sun Jul 30, 2017 3:21 pm

HillWalker wrote: Wed Jul 26, 2017 5:42 pm On my 35is one thing I find very noticeable is that before I did the mod it would start up from cold with the flap open and be really rorty and then after 2/3 seconds as the flap closed it would quieten down and sound quite tame, also being a fairly steady driver, though not quite pipe and slippers yet !! I love to hear the extra growl you get pulling a high gear at low revs. One last thing I completely disagree with Maniac on the drone at motorway speeds because even as standard the flap would be fully open at speed, but I do appreciate the 35i/35is have different exhausts which may make a difference.
This is incorrect, the flap will close at moderate motorway speeds to reduce drone. It is intended to open and close at different criteria such as revs speed engine temp and so on hence why it is ECU controlled.

HillWalker
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Exhaust sound mod

Post by HillWalker » Sun Jul 30, 2017 6:30 pm

Maniac, first of all let me say that I personally don't get any drone at motorway speeds with the exhaust mod, but I do acknowledge your greater wisdom on all things Z4. So are we saying that if the flap is controlled by the ECU it affects the performance parameters more than just the little bit of extra noise on start up ? could it affect the torque figures due to reduced back pressure ? I certainly noticed a slight drop in fuel consumption figures after the mod, but put that down to me just giving it a few more beans to hear that sweet 6cyl sing.

As of this afternoon I've reconnected mine after 2years of running with it disconnected, as anyone else any thoughts on how it might affect driving characteristics other than the extra noise.

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Exhaust sound mod

Post by Pbondar » Sun Jul 30, 2017 7:12 pm

On almost all modern engines with free flowing well designed exhaust systems, the impact of changing the exhaust note will be negligible given where in the system the valve lies..its purely an emotion jerker.. :!: :thumbsdown:

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Jasper ham
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Exhaust sound mod

Post by Jasper ham » Mon Jul 31, 2017 4:47 pm

benv6 wrote: Sun Jul 30, 2017 1:41 pm :evil: :oops:

Any effects on the MPG though ?
No MPG still the same ...... poor with a lead foot lol
BMW Z4 e89 35i white, black roof, 296 wheels emap to 390 BHP and running Vredestein Ultras. Second cat delete and straight through pipes.

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