Maybe The Best Modification I've Ever Made!

[Fishy Dave]

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

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.



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 thankfully it's not visible.


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!

Updated to add a short video:

https://youtu.be/c4sV0p3FPqs
[youtube]c4sV0p3FPqs[/youtube]

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
[youtube]0LBgj12dREM[/youtube]

 

[bmwaddict]

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!

 

[Leesfarm07]

So it's an open pipe before the rear silencers ?

 

[Fishy Dave]

So it's an open pipe before the rear silencers ?

Yes, that's right and you control how open the pipe is.

 

[Fishy Dave]

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?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

[bmwaddict]

Cheers! Enjoy!

 

[Roundozo]

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.

 

[Ducklakeview]

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

 

[Jollyjoiner]

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 :driving:

 

[lordgrover]

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.

 

[Fishy Dave]

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

 

[Fishy Dave]

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.

 

[srhutch]

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.

 

[Ducklakeview]

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..

Mike

 

[FD3S]

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-Products/JEGS-Electric-Exhaust-Cutouts/1231909/10002/-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.php?t=854018&highlight=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.

 

[Fishy Dave]

I've been out for a drive this evening and with the help of my wife I have a short video to try to show the difference in sound.

https://youtu.be/c4sV0p3FPqs
[youtube]c4sV0p3FPqs[/youtube]

As always it never quite captures the sound perfectly but gives a fair idea of the change in tone if not the volume. The drive by picks up on the Eventuri as the car drives towards the camera. The pops and bangs on the overrun can be provoked with the lightest of throttles. Childish but fun. The conditions were cold and slippery so I felt that 2nd and 3rd gear were plenty with occasional use of 4th. The drive bys are actually on a dual carriageway with central reservation (70 limit) with my wife in a safe location.

 

[Rally]

It's a great mod haters going hate lol, mine is a bit more aggressive than yours but I didn't want to cut into my miltech cat back exhaust and planned that it would be easily reversed.
Mine aren't perfect and rattle sometimes and blow a little but all is forgiven everytime I find a tunnel.

 

[dannytheduck1985]

Sounds awesome. My car sounds like the slightly open as stock lol. Think I'm going to look into having this fitted for the times I want more noise

 

[BMWZ4MC]

Sounds great on the video. I'd be interested to hear it in the metal and compare it with my Remus back boxes. I get no drone at cruising speeds but I would like the option of a straight through exhaust at the flick of a switch when having fun!
Do you know how reliable they M3 guy's have found them to be?

 

[TomK]

In between doing my valve clearances yesterday with Dave (big up that man!) we had need of a correction to my parts order. Perfect opportunity to hear what this sounds like in person while off to BMW Bath. Where to start, hmmm. It's OBSCENELY LOUD :lol: and then back to standard at a touch of a button. 8) For the outlay I'd have to agree with Dave that's it's one of the best things you can do. It also doesn't have to be that loud as he has explained, it's a cool system.
The actual noise, hmmm, well it's how do I put it, perhaps not the most cultured of sounds but if it's aggression you're after on a spirited drive then it certainly ticks that box.
The ability to go back to a stock noise when required is really cool though and something I wish I could do with my SS sometimes.