Hi all,
For some time I have been deliberating over fitting a stainless steel cat back i.e. the Supersprint. What is putting me off is chopping the factory exhaust which I've never been keen on and I'm thinking should the Cat ever fail it could be a pain to sort out. I think the factory Cat and Eaxhaust is all once piece. I've recently found a local exhaust place that do custom exhausts so I could have a system made up to the exact spec as the factory exhaust but with the Cat and remainder of the exhaust in 2 pieces. If I went for a tailor made system should I go for normal steel or stainless? I've heard stainless systems can be noisier and have a tendency to expand much more than steel when hot giving problems with the tailpipes going off centre. Is this true? Should I go for normal steel or stainless off the shelf or a custom made system?
Cheers,
Tim.
Off the shelf or custom exhaust
Off the shelf or custom exhaust
2001 Z3 1.9 Roadster Sport - 2012 Z4 sDrive 2.0 M Sport
Re: Off the shelf or custom exhaust
Hi Tim
I replaced the exhaust on my 1998 1.9 M44 in September. My catalytic converter broke up inside and was rattling like a bag of nails and the rear section was looking quite rusted in places. The original BMW stuff is fine quality but is very expensive to replace – front and rear sections totalled around £1,000, plus any fitting costs, plus new Lambda sensor.
I went for a Longlife stainless steel, bespoke system. The chap who did it had 15-years experience and the welds are superb. They say that the OE front part of the front section will last indefinitely and so they cut downstream of the Lambda sensor and weld in new stainless pipework. They retain two sections and clamp a new, completely stainless section at the rear. It cost less than what Kwikfit quoted for their cheap after market system. I went for the most quiet option meant to replicate the OE (2 silencers) but it is definitely louder than the OE. As you say there is also some expansion when hot which makes my oval tailpipe shift off-centre slightly to the nearside.
A nice exhaust noise is definitely part of the driving experience with a sports car. The OE sound on the 4 cylinder cars is rather conservative. I’m still getting used to mine, the deep low burble at tick-over sounds great but sometimes under some conditions I think it is a bit noisy (roof down). However, my teenage son thinks it sounds great and not too noisy at all.
Perhaps I should force myself to take a more youthful view and fit a K&N filter to make a sporty noise upfront as well.
I replaced the exhaust on my 1998 1.9 M44 in September. My catalytic converter broke up inside and was rattling like a bag of nails and the rear section was looking quite rusted in places. The original BMW stuff is fine quality but is very expensive to replace – front and rear sections totalled around £1,000, plus any fitting costs, plus new Lambda sensor.
I went for a Longlife stainless steel, bespoke system. The chap who did it had 15-years experience and the welds are superb. They say that the OE front part of the front section will last indefinitely and so they cut downstream of the Lambda sensor and weld in new stainless pipework. They retain two sections and clamp a new, completely stainless section at the rear. It cost less than what Kwikfit quoted for their cheap after market system. I went for the most quiet option meant to replicate the OE (2 silencers) but it is definitely louder than the OE. As you say there is also some expansion when hot which makes my oval tailpipe shift off-centre slightly to the nearside.
A nice exhaust noise is definitely part of the driving experience with a sports car. The OE sound on the 4 cylinder cars is rather conservative. I’m still getting used to mine, the deep low burble at tick-over sounds great but sometimes under some conditions I think it is a bit noisy (roof down). However, my teenage son thinks it sounds great and not too noisy at all.
Perhaps I should force myself to take a more youthful view and fit a K&N filter to make a sporty noise upfront as well.
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Southernboy
- Joined: Thu 07 Oct, 2010 12:39
- Posts: 6437
- Location: Johannesburg
Re: Off the shelf or custom exhaust
Hi Tim
as you may have read, I converted my boot floor - moved the battery to the center of the boot, and did away with the "old" battery recess. The reason was I fitted a dual system aka M style exhaust system. The shop that did the mod fitted stainless front box just aft of the cat, and stainless all the way back including the two rear boxes. Apart from the excellent work they did in terms of welding etc, the result has been great. The noise level is acceptable. One aspect that you might consider is that the sound increases as the system gets hotter. I have found that if I go on a "quick" run and cruise at around 180kph for an extended time, the noise level increases - due to heat - even when I subsequently drive at 60kph. In conclusion, I would say the stainless is noisier than the mild steel systems, it's more durable, and if maintained will outlast the mild steel.
The exhaust shoppe guy told me that the major cause of corrosion in exhaust boxes was caused by using the car to go a mile or two vs getting the exhaust up to temp. Apparently, after driving, the exhaust in the process of cooling collects condensation in the pipes and boxes, and if this isn't "burnt off" in the subsequent outing, it combines with with the carbon deposits in the exhaust system to make carbonic acids, which corrode the metals. The answer is that if you want to "pop up to the local" either walk, or take the "scenic" route and drive harder to get the condensation out...
as you may have read, I converted my boot floor - moved the battery to the center of the boot, and did away with the "old" battery recess. The reason was I fitted a dual system aka M style exhaust system. The shop that did the mod fitted stainless front box just aft of the cat, and stainless all the way back including the two rear boxes. Apart from the excellent work they did in terms of welding etc, the result has been great. The noise level is acceptable. One aspect that you might consider is that the sound increases as the system gets hotter. I have found that if I go on a "quick" run and cruise at around 180kph for an extended time, the noise level increases - due to heat - even when I subsequently drive at 60kph. In conclusion, I would say the stainless is noisier than the mild steel systems, it's more durable, and if maintained will outlast the mild steel.
The exhaust shoppe guy told me that the major cause of corrosion in exhaust boxes was caused by using the car to go a mile or two vs getting the exhaust up to temp. Apparently, after driving, the exhaust in the process of cooling collects condensation in the pipes and boxes, and if this isn't "burnt off" in the subsequent outing, it combines with with the carbon deposits in the exhaust system to make carbonic acids, which corrode the metals. The answer is that if you want to "pop up to the local" either walk, or take the "scenic" route and drive harder to get the condensation out...
Re: Off the shelf or custom exhaust
Burning fuel creates water vapour, which will condense on any cold surface, so don't use car for short journeys!
Stainless steel systems can be made from thinner gauge simply because of corrosion resistance over standard steel systems, this equates to more noise.
Stainless steel systems can be made from thinner gauge simply because of corrosion resistance over standard steel systems, this equates to more noise.
2000 Topaz 2.8 Individual.
Youth would be more useful if it came later in life!
Re: Off the shelf or custom exhaust
And also a saving in weight, the standard exhaust is very heavy due to the metal used.Frank.A wrote:Burning fuel creates water vapour, which will condense on any cold surface, so don't use car for short journeys!
Stainless steel systems can be made from thinner gauge simply because of corrosion resistance over standard steel systems, this equates to more noise.
Sent from my HTC Desire
Re: Off the shelf or custom exhaust
Captain wrote:And also a saving in weight, the standard exhaust is very heavy due to the metal used.Frank.A wrote:Burning fuel creates water vapour, which will condense on any cold surface, so don't use car for short journeys!
Stainless steel systems can be made from thinner gauge simply because of corrosion resistance over standard steel systems, this equates to more noise.
Sent from my HTC Desire
I am sure that is the case with many custom systems (figures due to guage reduction) but surprisingly the Supersprint back box I bought as a future fit is extremely heavy.
2000 Topaz 2.8 Individual.
Youth would be more useful if it came later in life!
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Mike Fishwick
- Joined: Fri 19 Jun, 2009 10:27
- Posts: 2094
- Location: Daglan, France
Re: Off the shelf or custom exhaust
I would not worry about cutting the original exhaust system - in the event that your car fails, just take the new cat and car to your favoured exhaust specialist, and leave it tothem - no problem.
Stainless is the only answer - it would be foolish to have a mild steel system made up. a stainless system has a different resonant frequency than mild steel, probably due to the stainless system being of thinner material - it does not have be thick enough to allow for it gradually rusting away! In some conditions this produces a rather different note.
There is however no real problem with it being noisier - that depends on the silencer specification.
I had a cat-back system made up during 2011 by MIJ Exhausts of Walsall, and specified that I wanated the lowest noise level possible - like a 316 saloon. They used single-outlet silencers, the rear section bolting on, with a cosmetic twin tailpipe which looks fine. It seems that the ration of silencer volume to pipe volume is important where low noise is concerned.
When the engine is hot and idling I can stand about 20 feet behind the car without being able to hear the exhaust. Exhaust noise being part of driving a sports car? You must be joking - it's the driving which counts, not making people look up to see where the noise is coming from!
Performance and fuel consumption are unchanged - or at least no worse - than standard, but the car is effectively a lot quicker because I can now put my foot down without being emabrassed by the noise! It also has a slight warble at idle, such as a six is supposed to make, but which the original system masked with an anonymous drone. When cruising at 80-plus withthe roof down the main noise comes fom the tyres and road surface, so after a full day's drive I do not have ringing in my ears. Noisey exhausts are for the immature and the deaf . . .
Stainless is the only answer - it would be foolish to have a mild steel system made up. a stainless system has a different resonant frequency than mild steel, probably due to the stainless system being of thinner material - it does not have be thick enough to allow for it gradually rusting away! In some conditions this produces a rather different note.
There is however no real problem with it being noisier - that depends on the silencer specification.
I had a cat-back system made up during 2011 by MIJ Exhausts of Walsall, and specified that I wanated the lowest noise level possible - like a 316 saloon. They used single-outlet silencers, the rear section bolting on, with a cosmetic twin tailpipe which looks fine. It seems that the ration of silencer volume to pipe volume is important where low noise is concerned.
When the engine is hot and idling I can stand about 20 feet behind the car without being able to hear the exhaust. Exhaust noise being part of driving a sports car? You must be joking - it's the driving which counts, not making people look up to see where the noise is coming from!
Performance and fuel consumption are unchanged - or at least no worse - than standard, but the car is effectively a lot quicker because I can now put my foot down without being emabrassed by the noise! It also has a slight warble at idle, such as a six is supposed to make, but which the original system masked with an anonymous drone. When cruising at 80-plus withthe roof down the main noise comes fom the tyres and road surface, so after a full day's drive I do not have ringing in my ears. Noisey exhausts are for the immature and the deaf . . .
A Z3 is not just for Christmas - it's for life!
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Mike Fishwick
- Joined: Fri 19 Jun, 2009 10:27
- Posts: 2094
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- Location: Daglan, France
Re: Off the shelf or custom exhaust
As they say in pantomimes - 'Oh no I don't!' Lots of people want noise, thinking that it is part of the image they want to display, or in the mistaken belief that noise equals power. I'm not worried about what people think - otherwise I would not drive a Z3! I suppose that back in the dark ages after WW2 we were brought up to consider other people, and I just dislike unnecessary noise anyway.
I guess that means I'm not a real sports car driver, but I've always been the same . . .
About forty years ago I was tired of the exhaust noise on my Austin-Healey Sprite, so cut the one and only silencer open, stuffed it full of Brillo pads, and closed it with a curved copper plate and self-tapping screws. I could them drive around in deathly silence, pursued by a smell of hot soap! I had to replace the Brillo pads about every couple of months, when their fine wire construction fell to bits and was ejected through the tail pipe.
I later fitted a resonator (two small sausage-shaped silencers from a Cooper S) into the exaust pipe, and stuffed the silencer with stainless steel turnings, which had the strength to last indefinitely.
Apart from anything else, my hearing has been damaged sufficiently by large diesel engines, so I prefer to hang on to what I still have!
I guess that means I'm not a real sports car driver, but I've always been the same . . .
About forty years ago I was tired of the exhaust noise on my Austin-Healey Sprite, so cut the one and only silencer open, stuffed it full of Brillo pads, and closed it with a curved copper plate and self-tapping screws. I could them drive around in deathly silence, pursued by a smell of hot soap! I had to replace the Brillo pads about every couple of months, when their fine wire construction fell to bits and was ejected through the tail pipe.
I later fitted a resonator (two small sausage-shaped silencers from a Cooper S) into the exaust pipe, and stuffed the silencer with stainless steel turnings, which had the strength to last indefinitely.
Apart from anything else, my hearing has been damaged sufficiently by large diesel engines, so I prefer to hang on to what I still have!
A Z3 is not just for Christmas - it's for life!
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geminimustang
- Joined: Mon 11 Jun, 2012 21:06
- Posts: 487
- Location: Wirral
Re: Off the shelf or custom exhaust
Much as I love the zed,sports car? I don't think so,more of an open top cruiser.I accept I've a screw loose but I actually like driving to the speed limit with gentle acceleration,both myself and the zed don't fit the boy racer image.exhaust sound or noise? I'm not worried about how quiet or how loud,it's a particular sound I like,difficult to describe but you know what you like when you hear it.Cutting exhausts,welding,altering floors? life's too short! Off the peg,reasonably original,well maintained,driven with care,that's the way to do it!
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geminimustang
- Joined: Mon 11 Jun, 2012 21:06
- Posts: 487
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- Location: Wirral
Re: Off the shelf or custom exhaust
Rich been on the red wine again!!
Re: Off the shelf or custom exhaust
Thanks for all the replies
Afraid I'm with Mike F thanks for posting the pic Mike, any system I have fitted would have to be as quiet as possible or as quiet as stock, I don't mind a slight burble at idle but anything that drones on the move is a definate no no as would spoil the car for me.
Talking of stainless steel Vs steel am I right in thinking the stock BMW system is mild steel? As mine probably has the original system, has done short trips it seems as good as new at 11 years old
so they do last. As I've been bitten in the past fitting an Eisenmann to a MINI Cooper S which was nothing but trouble I'm still feeling a little hesitant although thinking a custom made system would be the route to take. Still worry about the tail pipes moving around once upto temperature, can this be sorted by ensuring the exhaust is clamped into position than allowed to move around on the hangers?
Cheers,
Tim.
Afraid I'm with Mike F thanks for posting the pic Mike, any system I have fitted would have to be as quiet as possible or as quiet as stock, I don't mind a slight burble at idle but anything that drones on the move is a definate no no as would spoil the car for me.
Talking of stainless steel Vs steel am I right in thinking the stock BMW system is mild steel? As mine probably has the original system, has done short trips it seems as good as new at 11 years old
so they do last. As I've been bitten in the past fitting an Eisenmann to a MINI Cooper S which was nothing but trouble I'm still feeling a little hesitant although thinking a custom made system would be the route to take. Still worry about the tail pipes moving around once upto temperature, can this be sorted by ensuring the exhaust is clamped into position than allowed to move around on the hangers?Cheers,
Tim.
2001 Z3 1.9 Roadster Sport - 2012 Z4 sDrive 2.0 M Sport
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Mike Fishwick
- Joined: Fri 19 Jun, 2009 10:27
- Posts: 2094
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- Location: Daglan, France
Re: Off the shelf or custom exhaust
BMW use stainless steel for the pipe, but mild steel for the silencers.
My front silencer was rattling for a couple of years before I went stainless, even when going over bumpy roads, after its internas rotted out, and the rear was starting to go when I bought an Eisenmann - which was very well made, but far too noisey, even though I ordered the quietest model.
My front silencer was rattling for a couple of years before I went stainless, even when going over bumpy roads, after its internas rotted out, and the rear was starting to go when I bought an Eisenmann - which was very well made, but far too noisey, even though I ordered the quietest model.
A Z3 is not just for Christmas - it's for life!
Re: Off the shelf or custom exhaust
Gazza
"Understeer is when you hit the wall with the front of the car, oversteer is when you hit the wall with the rear of the car. Horsepower is how fast you hit the wall and torque is how far you take the wall with you"
Z3 S54 M roadster
, BMW Z1, BMW M3 CSL, Z4M Coupe
"Understeer is when you hit the wall with the front of the car, oversteer is when you hit the wall with the rear of the car. Horsepower is how fast you hit the wall and torque is how far you take the wall with you"
Z3 S54 M roadster
, BMW Z1, BMW M3 CSL, Z4M Coupe-
geminimustang
- Joined: Mon 11 Jun, 2012 21:06
- Posts: 487
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- Location: Wirral
Re: Off the shelf or custom exhaust
Cobra make stainless exhausts and beer,sorted !
Re: Off the shelf or custom exhaust
I'll hopefully be collecting a lot of such empty tins over the next week or so in an effort to try out which one is best on my Z3.
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geminimustang
- Joined: Mon 11 Jun, 2012 21:06
- Posts: 487
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- Location: Wirral
Re: Off the shelf or custom exhaust
I was suggesting a cobra stainless exhaust and a cobra beer to celebrate not a glass exhaust. If you did that,all the guys who've lowered their cars would have a smashing time with sleeping policeman.
