Rear muffler delete on 2.8 m52b28tu

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sviru
Joined: Wed 06 Apr, 2011 22:32
Posts: 99

  Z3 roadster 2.8

Rear muffler delete on 2.8 m52b28tu

Post by sviru » Sun 15 Feb, 2015 10:43

Has anyone tried this? There is a lot of youtube videos with such modification and it sounds really nice...

And... it resolves the problem with quad exhaust on non z3m, no more problems with tight space.

I'm planing on leaving the rest of the exhaust system intact. cats, middle - untouched.
I'm worried how loud it is gonna be in real life though.

https://www.youtube.com/watch?v=3hMJCKQMKww
https://www.youtube.com/watch?v=zMqR6otV8TE#t=28

Finally z3! https://www.youtube.com/watch?v=vJgNou6fYr8
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pingu
Joined: Fri 30 Apr, 2004 17:01
Posts: 3337

  M roadster S50

Re: Rear muffler delete on 2.8 m52b28tu

Post by pingu » Sun 15 Feb, 2015 10:57

Stage 3 of what I did would be to completely gut-out the inside of the rear silencer and join the in and out pipes with a section of tubing.

http://www.zroadster.net/forum/viewtopi ... 8&p=388131

I noticed that you are from Poland. You would need to do this in the UK, as a missing silencer would fail our annual vehicle check (MOT).
Pingu

sviru
Joined: Wed 06 Apr, 2011 22:32
Posts: 99

  Z3 roadster 2.8

Re: Rear muffler delete on 2.8 m52b28tu

Post by sviru » Sun 15 Feb, 2015 11:17

The same here when it comes to MOT... but I can manage that ;)
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Dino D
Joined: Fri 10 Feb, 2012 16:59
Posts: 376

  Z3 roadster 2.8

Re: Rear muffler delete on 2.8 m52b28tu

Post by Dino D » Sun 15 Feb, 2015 15:15

I like it but it's going to be loud.
These videos can't capture just how loud it is in real life...
You can easily reverse it though...
I would like one that I could easily switch myself (remove the rear box when the mood takes me...)

sviru
Joined: Wed 06 Apr, 2011 22:32
Posts: 99

  Z3 roadster 2.8

Re: Rear muffler delete on 2.8 m52b28tu

Post by sviru » Sun 15 Feb, 2015 20:37

Will try this week ;) Hope it works just fine :)
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sviru
Joined: Wed 06 Apr, 2011 22:32
Posts: 99

  Z3 roadster 2.8

Re: Rear muffler delete on 2.8 m52b28tu

Post by sviru » Mon 16 Feb, 2015 14:06

Ok. I have just removed backbox... it sounds better for sure when it comes to overal sound. A tad to loud for my taste. Will give it a try today. It is a temporary cut to see if I can live with such noise... the fact is when you accelerate you feel like you have 100hp more :D
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wassell
Joined: Fri 28 Mar, 2014 10:35
Posts: 18

  Z3 roadster 2.8

Re: Rear muffler delete on 2.8 m52b28tu

Post by wassell » Mon 23 Feb, 2015 15:11

Here's mine with a straight pipe. Just playing around a few weeks ago with a mates new camera, but got a nice vid for sound from it

BMW Z3 open exhaust in a Forest: http://youtu.be/kCIGcjwFVao

Dino D
Joined: Fri 10 Feb, 2012 16:59
Posts: 376

  Z3 roadster 2.8

Re: Rear muffler delete on 2.8 m52b28tu

Post by Dino D » Mon 23 Feb, 2015 22:35

Awesome looking car you have and I love the sound, very TVR like (so great for weekends but weekday mmmmm....)

Is that straight through from the cat back - ie no silencer or resonator?

wassell
Joined: Fri 28 Mar, 2014 10:35
Posts: 18

  Z3 roadster 2.8

Re: Rear muffler delete on 2.8 m52b28tu

Post by wassell » Mon 23 Feb, 2015 23:44

Cheers :)

Its decat and straight through with just the small resonator. Its a sneaky system as ive fitted an electronic valve to open/close the straight through section. So when i flick the switch the gasses flow through the stock exhaust and its quiet, open the valve and they dump out just before the backbox.

Dino D
Joined: Fri 10 Feb, 2012 16:59
Posts: 376

  Z3 roadster 2.8

Re: Rear muffler delete on 2.8 m52b28tu

Post by Dino D » Tue 24 Feb, 2015 16:03

wassell wrote:Cheers :)

Its decat and straight through with just the small resonator. Its a sneaky system as ive fitted an electronic valve to open/close the straight through section. So when i flick the switch the gasses flow through the stock exhaust and its quiet, open the valve and they dump out just before the backbox.
Now that's clever...

I have a Supersprint cat back which is perfect for general use but every now and then (like on a run with a TVR or similar) I find my car too civilized and which for something like that just for the weekend and then be able to switch back to the supersprint.

Is it something that can be made up and sold in kit form or something a competent exhaust place can make up?

wassell
Joined: Fri 28 Mar, 2014 10:35
Posts: 18

  Z3 roadster 2.8

Re: Rear muffler delete on 2.8 m52b28tu

Post by wassell » Tue 24 Feb, 2015 20:28

Its a relatively simple task if you have a welder and some patience to wire in the switch.

The kit is available from ebay, "2.5" exhaust cut out valve" should bring up the right style. There are 2 main types, and two types of operation (remote or switch). Theres not much room underneath so i had to reverse the mounting welding the "v band" section to the exhaust rather than the intended section.

Im having troubles inserting links and images on my phone unfortunately.

wassell
Joined: Fri 28 Mar, 2014 10:35
Posts: 18

  Z3 roadster 2.8

Re: Rear muffler delete on 2.8 m52b28tu

Post by wassell » Tue 24 Feb, 2015 20:40

Here is the kit i used

Image

And here is how i mounted it, please excuse the mud, i live on a farm haha.

Image

and heres the valve open

Image

wassell
Joined: Fri 28 Mar, 2014 10:35
Posts: 18

  Z3 roadster 2.8

Re: Rear muffler delete on 2.8 m52b28tu

Post by wassell » Tue 24 Feb, 2015 20:48

Oh ill also add i havent made the tailpipe yet haha, thats going to be a discrete section. Also, the valve never 100% fully closes so you do get a little hiss and rattle when its closed. Its no fuss to me mind as i keep it open most of the time, only keeping it closed when driving home at the early hours - no point in waking the locals up.

lmrdave
Joined: Tue 29 May, 2012 12:30
Posts: 55

  Z3 roadster 2.8
Location: Lincolnshire

Re: Rear muffler delete on 2.8 m52b28tu

Post by lmrdave » Wed 25 Feb, 2015 15:16

Nice, just how I want my z3 to sound! I had a similar idea, but never pulled my finger out! :dunce:

Just a thought, it might rattle while closed if the valve is handed (for direction of flow). From the bottom picture, it looks like there is a seat/stop for the butterfly, if that faced the flow it might well push the valve onto the seat, rather than pushing it away from the seat, might be worth a look?
1998 Z3 2.8 Arctic Silver
1991 Mazda MX5
1987 Nissan Silvia

wassell
Joined: Fri 28 Mar, 2014 10:35
Posts: 18

  Z3 roadster 2.8

Re: Rear muffler delete on 2.8 m52b28tu

Post by wassell » Wed 25 Feb, 2015 15:56

The butterfly seat is the same on both sides, tried it in both directions and makes no difference. Annoyingly the butterfly is about 1mm too small in diameter so never fully seals the hole, also when the motor reaches the end point it rewinds a tiny amount as a safe guard, meaning the valve never fully closes. Not too much of an issue mind :)

It is funny driving through town with it closed, then opening it up at the lights and letting it rip, before closing it again at the next set of lights haha. People cant work it out.

lmrdave
Joined: Tue 29 May, 2012 12:30
Posts: 55

  Z3 roadster 2.8
Location: Lincolnshire

Re: Rear muffler delete on 2.8 m52b28tu

Post by lmrdave » Thu 26 Feb, 2015 07:36

Well I'm suitable inspired to pull my finger out now, ebay here I come! :D
1998 Z3 2.8 Arctic Silver
1991 Mazda MX5
1987 Nissan Silvia

wassell
Joined: Fri 28 Mar, 2014 10:35
Posts: 18

  Z3 roadster 2.8

Re: Rear muffler delete on 2.8 m52b28tu

Post by wassell » Thu 26 Feb, 2015 21:39

Get on it ;) space is the only concern, the other design may be easier to fit in place, but i cant be sure.


To.any australian members theres a company called varex, they make exhausts and boxes, but one of their box brands has a valve built in. Beautiful design, where its either a straight through box, or directed to flow through 3 chambers. Unfortunately not available in the UK.

Dino D
Joined: Fri 10 Feb, 2012 16:59
Posts: 376

  Z3 roadster 2.8

Re: Rear muffler delete on 2.8 m52b28tu

Post by Dino D » Fri 27 Feb, 2015 18:23

What is the other design you refer to wassell?

How does the car drive when you bypass the backbox?

Could you make a video of how loud the hiss and rattle is?
I'm hopefully going to have a rattle free rear end soon as many bushes and bits get replaced by Lee so don't want to have new rattles!

Even thinking about putting one on our family bus - a Ford Galaxy V6 (has the 2.8 24v VR6 engine). Make for a fun school run!'

Dino D
Joined: Fri 10 Feb, 2012 16:59
Posts: 376

  Z3 roadster 2.8

Re: Rear muffler delete on 2.8 m52b28tu

Post by Dino D » Fri 27 Feb, 2015 18:36

Another question, can it be held open in variable positions or is it fully open/closed?
Just thinking would it be possible to tailor how loud you want it by adjusting the opening on the fly.

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pingu
Joined: Fri 30 Apr, 2004 17:01
Posts: 3337

  M roadster S50

Re: Rear muffler delete on 2.8 m52b28tu

Post by pingu » Fri 27 Feb, 2015 21:15

I'm liking this 8-) .

I just need to work out what the tuned length of the exhaust should be and then I can see another project. An open tuned exhaust :P .

It's a shame that the butterfly is in the way of the flow. The only other one that I have seen was a flap that acted like a set of railway points and closed the other exhaust as well. It was on a replica Mercedes W125 race car.
Pingu

wassell
Joined: Fri 28 Mar, 2014 10:35
Posts: 18

  Z3 roadster 2.8

Re: Rear muffler delete on 2.8 m52b28tu

Post by wassell » Fri 27 Feb, 2015 23:06

For what its worth, ive just done a db test on her at 4,500 revs. With the valve fully shut its 89db, fully open its 97db. So quite a difference. However, near the limiter its 121.7db! Its very loud when fully open.

When the valve is past 1/3 open it makes no difference to the volume tbh. The valve can be opened at any point too,as its just 12v being fed to the motor to turn the valve, flicking the switch the other way just reverses the polarity, making the valve spin the other direction. And Ill see if i can make a video of the hiss sound when fully closed - bit its not that bad.

The only niggle with this product is the bolts that secure the butterfly spindle to the motor spindle, they seem to come loose easily - even with better bolts and loctite. As the items only £80 i think im going to weld my spindles up rather than use bolts, then if it breaks ill buy another.

Performance wise there is very very little in it. If anything low end torque feels more pronounced with the valve shut (2-3k in 3rd for example). But ive also got an m50 manofold on there and havent had her remapped yet so may be different with the m52 manifold. Top end is nice and free though. Shall see how it goes after a remap :)

Ill also add that the decat made a big difference to power delivery. Much nicer without it.

wassell
Joined: Fri 28 Mar, 2014 10:35
Posts: 18

  Z3 roadster 2.8

Re: Rear muffler delete on 2.8 m52b28tu

Post by wassell » Fri 27 Feb, 2015 23:08


lmrdave
Joined: Tue 29 May, 2012 12:30
Posts: 55

  Z3 roadster 2.8
Location: Lincolnshire

Re: Rear muffler delete on 2.8 m52b28tu

Post by lmrdave » Mon 09 Mar, 2015 15:16

Popped mine on this weekend in a similar location, but valve mounted vertical.
Chopped the vee band flange off, then welded it to a profiled bit of tube, so the position of the valve can easily adjusted, then a dump pipe pointing down about 45 degrees from vertical. I was going to do a bit more pipe, but I wanted to go out and play :lol:
Cost £80 plus a small chunk of my thumb I ground off in the process.
Remote unit sit's in the battery well, so I just click a remote in the cabin.
1998 Z3 2.8 Arctic Silver
1991 Mazda MX5
1987 Nissan Silvia

wassell
Joined: Fri 28 Mar, 2014 10:35
Posts: 18

  Z3 roadster 2.8

Re: Rear muffler delete on 2.8 m52b28tu

Post by wassell » Mon 09 Mar, 2015 20:56

Same idea as mine then, allows lots of rotation as opposed to the bolts only :)

Get some pics up

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