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Maybe The Best Modification I've Ever Made!

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Fishy Dave
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Maybe The Best Modification I've Ever Made!

Post by Fishy Dave » Wed Feb 08, 2017 6:58 pm

It's a bold statement that requires me to wear a flame suit and risks ridicule from you all. :oops:

Let me explain.....

I love my Z with it's Eventuri and near standard exhaust (3/4" bypass pipes) but have often said that I have noise envy whenever I've been in Toms Coupe. To increase the volume I have looked at a CSL airbox with remap but cost is a barrier. Supersprint or Stromung back boxes (or having internals modified) would be more affordable but longer journeys would be more uncomfortable plus my car only just passes noise limits at Thruxton.
So, today I have gone down the slightly chavvy route of an electronic cutout (remote exhaust valve), fitted just behind the right hand back box (so post Lambdas, cats and crossover). It was probably the hardest decision I've made with regard to a modification as I hate the way they look (not that they are visible once fitted), it adds another few kg and means cutting a chunk out of the BMW mid pipe. I did a lot of research on M3 forums and listened to various clips on Youtube before spending the princely sum of £55 on Chinas finest 2.5" remote control kit. I had assumed that a pair of valves would be needed, but E46 guys who have had these fitted opted for just one, stating that the meeting of the gasses in the cross over pipe ensures even pressure from each cylinder and a proper 6 cylinder soundtrack. Rolling road figures seem to suggest a tiny gain up to 20bhp, I'm sceptical but will get this and the fuelling checked shortly.
On Sunday I spent the day tracing the wire through the car, neatly wiring into the fusebox. This morning I had it fitted at Infinity Exhausts, Chipping Sodbury, following my request of not cutting the mid pipe through, instead making a hole and welding the spur to the stock pipe. This way I could remove the appendage and have a patch placed over it if I change my mind, or I can get a custom made X pipe from Infinity for £350.
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The result? Absolutely superb! I drove away with the valve closed with the same level of trackday/village friendly volume. A quick press on the remote control and the volume increased slightly with the valve open a fraction. A second press and things got more exciting, maybe the volume of a sports exhaust, whilst a full 3 second press gives OMG loud volume (more than your Supersprint race exhaust Tom)! Whilst fully open there is a loud drone at low revs and steady throttle as you would expect, but at high revs it sings. I just love that i can go back to being quiet and under the radar with the press of a button.

Overall it's a cost effective (£55 plus £160 fitting) way of adding volume and tone and is completely reversible. I just don't like the thought of the chunk of cheap chinese chavvy gadget under the car :oops: thankfully it's not visible.
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This thread is worthless without video which I will try to oblige with shortly. Tom will have the pleasure (!) of being a passenger on Saturday....

Right off home now, giggling like a girl as I go, whilst I hold the remote button down for 3 seconds. I will read your insults in a while! :cry: :D

Updated to add a short video:

https://youtu.be/c4sV0p3FPqs


Video of the exhaust cutout used on a trackday, at first it is closed then for the rest of the clip it is fully open.
https://youtu.be/0LBgj12dREM
Last edited by Fishy Dave on Sun Aug 06, 2017 1:18 am, edited 2 times in total.
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Maybe The Best Modification I've Ever Made!

Post by bmwaddict » Wed Feb 08, 2017 7:04 pm

I love this mod, best of both world's imo. I want a Eisenmann back box but they're bloody expensive. Rally did this to his zed, and I really liked the results, and being able to quieten it down really appeals to me as I live in a quiet village and my car is my daily. Link to the one you bought? I've seen them for circa £155 so that's cheap.
Video soon please!
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Post by Leesfarm07 » Wed Feb 08, 2017 7:06 pm

So it's an open pipe before the rear silencers ?
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Maybe The Best Modification I've Ever Made!

Post by Fishy Dave » Wed Feb 08, 2017 7:11 pm

Leesfarm07 wrote:So it's an open pipe before the rear silencers ?
Yes, that's right and you control how open the pipe is.
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Post by Fishy Dave » Wed Feb 08, 2017 7:18 pm

bmwaddict wrote: Link to the one you bought? I've seen them for circa £155 so that's cheap.
Video soon please!
They've gone up to £57.99 delivered now. Oh and it arrived boxed and from the UK in just a few days.

http://www.ebay.co.uk/itm/311697913574? ... EBIDX%3AIT
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Maybe The Best Modification I've Ever Made!

Post by bmwaddict » Wed Feb 08, 2017 7:22 pm

Cheers! Enjoy!
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Post by Roundozo » Wed Feb 08, 2017 8:14 pm

Interesting. Surely only on one pipe this would cause some sort of odd waveform (or whatever it's called) to the exhaust flow? One manifold expelling gas quicker than the other however all 6 cylinders expelling at the same time. To get any gain (if there is any bhp gain not just sound), it would need to be on both pipes. Then the whole engine can get rid of exhaust gasses quicker. I still want my coupe to sound better so this is a potential.
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Post by Ducklakeview » Wed Feb 08, 2017 8:19 pm

A customer of our shop has one of these on his Mk2 RS, not my cup of tea.

However, I'd be a tad concerned about the proximity of your OSR rear tyre to all that hot exhaust gas, surely that can't be good for the rubber?

Mike

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Post by Jollyjoiner » Wed Feb 08, 2017 8:25 pm

I've seen this mod done on these American car programs and always thought thats a mod I wouldn't mind doing at some point and now the parts seem to be available It's time to start thinking about it more :thumbsup: :driving:
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Maybe The Best Modification I've Ever Made!

Post by lordgrover » Wed Feb 08, 2017 9:09 pm

Slight aside, I've used Infinity several times and he's always been superb. A real enthusiast who can deliver pretty much exactly what you want. Highly recommended.

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Post by Fishy Dave » Wed Feb 08, 2017 9:09 pm

Roundozo wrote:Interesting. Surely only on one pipe this would cause some sort of odd waveform (or whatever it's called) to the exhaust flow? One manifold expelling gas quicker than the other however all 6 cylinders expelling at the same time. To get any gain (if there is any bhp gain not just sound), it would need to be on both pipes. Then the whole engine can get rid of exhaust gasses quicker. I still want my coupe to sound better so this is a potential.
My thinking: The gases travel from the manifold in two pipes, through the cats and then join in the H/X pipe before splitting back out into two. As standard (or with the valve closed) the gases flow approximately 50/50 between the two tail pipes as both provide similar lengths and resistance. By adding the exhaust cut out the same process takes place but the gases favour one tail pipe after mixing in the H/X pipe. At idle I can still feel gases come out the left and right back boxes with the valve open. Waveforms I'm uncertain about, but due to the gases still mixing, combined with reading about the experiences of others I was happy enough to give it a try. Worst case I will add another cut out on the other side. :)
I doubt the back boxes are very restrictive so I'd be surprised if there were much or any bhp gains, I did it purely for the noise :)

http://www.m3forum.net/m3forum/showthread.php?t=470210
Last edited by Fishy Dave on Wed Feb 08, 2017 9:21 pm, edited 1 time in total.
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Post by Fishy Dave » Wed Feb 08, 2017 9:12 pm

Ducklakeview wrote:A customer of our shop has one of these on his Mk2 RS, not my cup of tea.

However, I'd be a tad concerned about the proximity of your OSR rear tyre to all that hot exhaust gas, surely that can't be good for the rubber?

Mike
Hi Mike, not your cup of tea for the same reasons as me (appearance and iffy image)?
Don't worry, at that point they were still fitting the curved tail pipe when I wanted a pic. The pipe points downwards, no danger of overheating anything. :)
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Post by srhutch » Wed Feb 08, 2017 9:17 pm

What I find interesting is that when I fitted only one modified back box I was told be a couple of members on here the balance would be out and it would cause problems. I pointed at the same as the m3 guys though that dues to the crossover pressure would be equalised.
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Post by Ducklakeview » Wed Feb 08, 2017 9:19 pm

Fishy Dave wrote:
Ducklakeview wrote:A customer of our shop has one of these on his Mk2 RS, not my cup of tea.

However, I'd be a tad concerned about the proximity of your OSR rear tyre to all that hot exhaust gas, surely that can't be good for the rubber?

Mike
Hi Mike, not your cup of tea for the same reasons as me (appearance and iffy image)?
Don't worry, at that point they were still fitting the curved tail pipe when I wanted a pic. The pipe points downwards, no danger of overheating anything. :)
Yup, just a bit erm, "Corsa-ish" imo.. :)

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Post by FD3S » Wed Feb 08, 2017 11:04 pm

I was reading about this mod a lot the last days.
There are some vendors for this mod:
http://www.dmhperformance.com
http://www.jegs.com/p/JEGS-Performance- ... 9/10002/-1
https://www.quicktimeperformance.com
http://www.badlanzhpe.com/collections/kits


On zpost it has some relevant post. There is a guy on the zpost that has done this mod also:
https://www.youtube.com/watch?v=5DVX7XtxHr4
https://www.youtube.com/watch?v=yLw0n9qet5E
http://www.zpost.com/forums/showthread. ... hlight=dmh


Those valves not the specific ones, have been reported with some problems of leakage and also that they need to be replaced often. But for 57.99 you can change them twice a year for 5 years.

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