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Z4M exhaust upgrade project

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Mangozac
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Z4M exhaust upgrade project

Post by Mangozac » Sat Sep 16, 2017 5:49 am

Hi guys, I thought you might be interested in one of two current projects on my Zed. The other one I'll post about when it has progressed a little further ;)

When I bought the car it had RPi mufflers fitted. A week later I was able to swap with a mate for his OEM exhausts and I can confidently say that I absolutely hated the RPi mufflers. Why anybody would want to live with that level of noise and drone, even if tracking the car regularly, is beyond me! Still, after a year of ownership I was feeling that the stock exhaust was just a bit too quiet - this wasn't helped by going on runs with some of my M Club mates and listening to their S54 and S65 engines sing!

So I'm fortunate to be mates with a couple of professional BMW technicians and was able to nab a pair of mufflers that came off an F12 M6 that had received an upgrade. These, coupled with some electronic exhaust flap actuators from an M4 (the actuators on the M6 mufflers are vacuum controlled) combine to make a perfect setup for the Z4M!

So here's how it fits:
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Here we have all of the parts laid out:
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With regards to the tips, I wanted something really cool and double walled but still appropriate for the age of the car. The standard chrome M Performance Exhaust tips are perfect but I couldn't justify spending AU$150 each on them, so I decided to machine my own. The outer is a piece of 3" polished stainless tube. Into the end is press-fit a custom made aluminium ring which provides the detail and a seat for the 2.5"inner pipe (the pipe which will be welded to the muffler). A set screw on the bottom near the rear of the exhaust tip will clamp everything in place (please ignore the temporary socket head screws):
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This was supposed to be installed on Friday, but the exhaust shop was running behind schedule and knowing how perfect I want it they cancelled so they can dedicate the proper time to the project and not rush it. So we're rescheduled for the coming Wednesday!

I also custom designed a control board which monitors the sport button and send the signals to open and close the actuators. This wires quite nicely into the boot (trunk), with a wire threaded through the bulkhead and centre tunnel trim to the sport button. The cables to the actuators thread out through a grommet in the boot floor.

Can't wait to get this on and hear what it sounds like! Even better will the ability to have it quieter for normal driving and a bit louder when hanging with the guys ;)

Hopefully I'll have an update on Wednesday!
Current: 06 E85 M Silbergrau
Previous: E85 3.0si Silbergrau, 03 E85 2.5i Maldives Blue.
Mods: Gaptech OTH+R, Dension Gateway 300 with USB, CDV-, clear side indicators, euro tails, stubby, MFSW retrofit, OEM Bluetooth/VR

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Yorkie Z
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Z4M exhaust upgrade project

Post by Yorkie Z » Sat Sep 16, 2017 7:29 am

Wow that's quite a project, can't wait to hear the results :thumbsup:
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mr wilks
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Z4M exhaust upgrade project

Post by mr wilks » Sat Sep 16, 2017 7:47 am

Yorkie Z wrote: Sat Sep 16, 2017 7:29 am Wow that's quite a project, can't wait to hear the results :thumbsup:
Me too :) very bespoke system & look forward to seeing the end results :thumbsup:
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Z4M exhaust upgrade project

Post by FD3S » Sat Sep 16, 2017 8:19 am

Very interesting project! Please post some videos when it is finished.
From your experience can fit in our cars, mufflers from M3 and M4 ?
I have the same opinion with you, that the RPi is way beyond what my nerves can handle and the stock mufflers are too quite when I hear other M's.

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Z4M exhaust upgrade project

Post by Mangozac » Sat Sep 16, 2017 8:47 am

Thanks guys!
FD3S wrote: Sat Sep 16, 2017 8:19 am Very interesting project! Please post some videos when it is finished.
From your experience can fit in our cars, mufflers from M3 and M4 ?
Originally we were looking at trying to fit the muffler from an M3/M4, but because it's just a single, centrally mounted muffler it's too difficult to fit. Not only are the tips a lot closer together on the F8x, but the Z4M has a tension strut for the rear bumper mounting and the fuel tank carbon filter, etc. mounted in the area between the mufflers.

A friend wants my stock mufflers when this project is complete, as he wants to open them up and remove the "wool" filling. Will be interesting to see what difference that makes (but he didn't want to use his own pair of stock mufflers as the guinea pig!).
Current: 06 E85 M Silbergrau
Previous: E85 3.0si Silbergrau, 03 E85 2.5i Maldives Blue.
Mods: Gaptech OTH+R, Dension Gateway 300 with USB, CDV-, clear side indicators, euro tails, stubby, MFSW retrofit, OEM Bluetooth/VR

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Z4M exhaust upgrade project

Post by D4dawg » Sat Sep 16, 2017 12:36 pm

Haha nice mission you've taken on;)

Awaits final pics and maybe vids or at least a link to them

Nice work

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Z4M exhaust upgrade project

Post by MrPT » Sat Sep 16, 2017 12:44 pm

Awesome project.

What's the layout inside the muffler? Does the valve-actuated pipe run straight through with no silencing? Bypass pipes are popular here, but they do add weight, which this approach avoids.
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Z4M exhaust upgrade project

Post by Beedub » Sat Sep 16, 2017 1:00 pm

impressive!
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Mangozac
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Z4M exhaust upgrade project

Post by Mangozac » Sat Sep 16, 2017 1:12 pm

MrPT wrote: Sat Sep 16, 2017 12:44 pm What's the layout inside the muffler? Does the valve-actuated pipe run straight through with no silencing? Bypass pipes are popular here, but they do add weight, which this approach avoids.
It's bizarre - both pipes actually look like they go straight through, and there is some kind of fancy perforated pipe section which obviously provides the sound dampening. As best I can tell both paths through the muffler look identical!

Overall, I expect this solution to be pretty similar in weight to the stock mufflers. The M6 mufflers by themselves are surprisingly light, but by the time all the ancillaries are added on I'm sure it will add up quickly.
Current: 06 E85 M Silbergrau
Previous: E85 3.0si Silbergrau, 03 E85 2.5i Maldives Blue.
Mods: Gaptech OTH+R, Dension Gateway 300 with USB, CDV-, clear side indicators, euro tails, stubby, MFSW retrofit, OEM Bluetooth/VR

Mangozac
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Z4M exhaust upgrade project

Post by Mangozac » Sat Sep 16, 2017 1:23 pm

Here's a shot of the internals, looking from the inlet end:
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Current: 06 E85 M Silbergrau
Previous: E85 3.0si Silbergrau, 03 E85 2.5i Maldives Blue.
Mods: Gaptech OTH+R, Dension Gateway 300 with USB, CDV-, clear side indicators, euro tails, stubby, MFSW retrofit, OEM Bluetooth/VR

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Z4M exhaust upgrade project

Post by wspohn » Fri Sep 22, 2017 12:53 am

FWIW, I actually enjoy the RPI, but then I bought the car with mufflers fitted some time before and I gather they have a break in period after which they become quieter than they are initially. I was worried as a coupe is more sensitive to drone, but it sounds great.
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Mangozac
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Z4M exhaust upgrade project

Post by Mangozac » Fri Sep 22, 2017 10:16 pm

wspohn wrote: Fri Sep 22, 2017 12:53 am FWIW, I actually enjoy the RPI, but then I bought the car with mufflers fitted some time before and I gather they have a break in period after which they become quieter than they are initially. I was worried as a coupe is more sensitive to drone, but it sounds great.
I reckon you'd be in the minority with that opinion of the RPis, but there's certainly others out there who agree with you. Just not me ;)
I have heard suggestions of a break in period, but mine came with the car when I bought it so should have had sufficient break in.


As an update in my new exhaust, there have been some delays due to the constraints I had placed on the project (in that I wanted it fabbed to be a bolt on bolt off project). I've had to make some compromises though as to fit everything in we're going to have to cut back the mid pipes slightly. Hopefully can get it knocked over on the next attempt this week!
Current: 06 E85 M Silbergrau
Previous: E85 3.0si Silbergrau, 03 E85 2.5i Maldives Blue.
Mods: Gaptech OTH+R, Dension Gateway 300 with USB, CDV-, clear side indicators, euro tails, stubby, MFSW retrofit, OEM Bluetooth/VR

Mangozac
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Z4M exhaust upgrade project

Post by Mangozac » Mon Oct 16, 2017 12:10 pm

Well it has taken a lot of screwing around but we finally go there in the end. It ended up taking the exhaust shop a lot longer than they budgeted and required two further attempts to get a result I was happy with. They were good about it though and the workmanship of the finished result is great!
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So the big question everybody wants to know is what does it sound like? Well it's definitely loud but not like the horrendous noise of the RPis. Because these mufflers are off the twin turbo V8 M6, the turbos cut a lot of the high frequency noise, so these mufflers are designed to do a fantastic job of cutting the low frequencies. There is no drone to speak of.

It sounds like the titanium race exhaust a mate has on his E46 M3. The problem is that I've been using it only with the valves closed - opening them makes it even louder, but not in a particularly good way. I would like the current sound with the valves closed to be the sound with the valves open. So I'm going to research into how I can possibly silence it further, focusing on the mid to high frequencies.

I'll try to grab a video some time to stick on YouTube ;)
Current: 06 E85 M Silbergrau
Previous: E85 3.0si Silbergrau, 03 E85 2.5i Maldives Blue.
Mods: Gaptech OTH+R, Dension Gateway 300 with USB, CDV-, clear side indicators, euro tails, stubby, MFSW retrofit, OEM Bluetooth/VR

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Z4M exhaust upgrade project

Post by tomscott » Mon Oct 16, 2017 12:55 pm

Looks a great project people have been screaming for this type of exhaust for years!

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Fishy Dave
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Z4M exhaust upgrade project

Post by Fishy Dave » Mon Oct 16, 2017 1:29 pm

Excellent, looks like a much higher quality result of what I've achieved with mine. :thumbsup:
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