Ebay Exhaust!

[Liam22]

Would this system fit a N52/3.0si? Or is it M54 only?

I was thinking about this for my 3.0si so did a little research.

Short answer: it won't fit N52.

Long answer:

N52 exhaust manifold to mid-pipe flanges are aligned in a 'V' shape:
http://www.realoem.com/bmw/enUS/showpar ... Id=18_0653

M54 exhaust manifold to mid-pipe flanges are parallel:
http://www.realoem.com/bmw/enUS/showpar ... Id=18_0498

The eBay advert clearly shows parallel flanges:
https://www.ebay.co.uk/itm/153004754976

[Rakey78]

Would this system fit a N52/3.0si? Or is it M54 only?

I was thinking about this for my 3.0si so did a little research.

Short answer: it won't fit N52.

Long answer:

N52 exhaust manifold to mid-pipe flanges are aligned in a 'V' shape:
http://www.realoem.com/bmw/enUS/showpar ... Id=18_0653

M54 exhaust manifold to mid-pipe flanges are parallel:
http://www.realoem.com/bmw/enUS/showpar ... Id=18_0498

The eBay advert clearly shows parallel flanges:
https://www.ebay.co.uk/itm/153004754976

This one appears to be for the M54:
https://www.ebay.co.uk/itm/3-STAINLESS- ... 0005.m1851

[JamieZ4C]

Would this system fit a N52/3.0si? Or is it M54 only?

I was thinking about this for my 3.0si so did a little research.

Short answer: it won't fit N52.

Long answer:

N52 exhaust manifold to mid-pipe flanges are aligned in a 'V' shape:
http://www.realoem.com/bmw/enUS/showpar ... Id=18_0653

M54 exhaust manifold to mid-pipe flanges are parallel:
http://www.realoem.com/bmw/enUS/showpar ... Id=18_0498

The eBay advert clearly shows parallel flanges:
https://www.ebay.co.uk/itm/153004754976

Took me a minute to work out what you were talking about (my stupidity, not your explanation!)

But you are right. The eBay ad states E86 in the description, as well as 2.5 and 3.0 (which could be the SI N52's), so I hope no unsuspecting buyers have made a duff purchase.

Exhaust N52 vs M54.png (12.57 KiB) Viewed 1773 times

[Haro]

It looks like they have picked up a job lot of exhausts from somewhere and don't really know what application they are for, even the box wasn't marked as to which vehicle it was intended.

This is for the M54, the one I have

https://www.ebay.co.uk/itm/2-25-STAINLE ... ctupt=true

This I suspect is the one they have for the N52

https://www.ebay.co.uk/itm/3-STAINLESS- ... rk:55:pf:0

[Sgub]

Anyone game enough to try the n52 exhaust?
I'm quite curious as it's not much money for an exhaust, but don't have the guts myself to see how if fits and if its any good

[Jamie25]

Been nosing on the forum for a while and just thought I’d add my experience.

I was very unsure when I saw the listing, the price put me right off but I eventually bought it whilst under the influence, however the exhaust is indeed excellent quality for the money, unreal tbh. Fitment again is straight forward with zero problems with all gaskets and bolts included.

The noise however is something I think some people may not really understand and should think about. Some people may want and like the idea of a louder exhaust, but then when they get it they don’t because they are used to the standard sound and think its overbearing or “droning”. All straight through exhausts drone/resonate under load, the only thing that can/may alter it is where the boxes are situated or potentially the size, I think it also really depends on whether you have had modified cars in the past as to what you perceive as loud/droning/annoying. The exhaust to me is not too loud, definitely nowhere near the straight pipes I’ve heard and did contemplate at first and compared to say an Impreza or indeed a lot of the hot hatch stuff it's pretty tame. Its deep and grumbles low down but eases off over 3k and crackles/pops on occasion when coasting in gear. The biggest problem I suspect is that with the centre box on the system being more or less bang underneath the seats that could be the problem for some, as just like a sound generator you can hear it inside when you prod the accelerator pedal at lower/under load rpm, but that is the price/fun of noisy exhausts and if you don’t want to hear it then I would have to ask, why do you want one? For me a roadster with the top down should have a sense of theatre which the Z really doesn't have as standard, it gives it a much better soundtrack and was a proper bargain, but that is just in my opinion.

How would you say this sound compares to sound generator mod with both pieces of foam taken out. I know that's a tricky question to answer but it'd be interesting to know how they compare from the drivers seat in use.

[Haro]

It's deeper than the sound generator, hard to describe. The sound generator is pumping induction sound into the cabin at higher rpm, whereas the exhaust is sitting underneath with a deep tone at lower rpm. It sounds like a bigger engine, more aggressive. The clip of that dlv exhaust is kind of it but without the "farting" sound at the end and slightly more grumble. It's hard to tell in a video.

The exhaust sounds great from outside, it's really whether people worry about noise inside they are not used to. The sound clip I put up is more or less how it sounds inside the car if you listen through decent speakers. If you take out the foam in the generator, then you are looking for the kind of sound the exhaust will probably with give you and everyone else will hear it. As I've said it doesn't bother me, but I've had exhaust on various cars before and it's a lot less than some, maybe deeper than others. If you're not used to it it may be a different kettle of fish.

[Jamie25]

Sounds very tempting. Having only just taken the second piece of foam out of the sound generator I'm loving it but could see me possibly putting it back in for any very long trips. I guess the exhaust wouldn't be quite as 'in your face' at high revs as it's not in the cabin. However not as easy to adjust as the sound generator, thus my hesitance.
Leaning towards getting one at this price though.

[Russblade]

Has anyone got one of these for sale still, the car is just to dam quiet!

[Russblade]

Mine's still sat in my cupboard. Had it months now

For sale?

[Davz]

I have doubts about the design of this system. The standard system has two 50mm pipes running all the way to the backbox, this will have been designed to allow the gas to flow at a certain velocity to ensure a good spread of power across the rev range. The ebay system is two pipes to the centre silencer and then only one pipe to the backbox. This will restrict the gas flow, to maintain the gas flow the pipe diameter will have to be increased but by doing this the velocity of the gas will be compromised. The scavenging of the exhaust gas may also be effected, the net result is going to be less hp and torque.
I wouldn't trust some unknown company working out the maths correctly if you just want sound this may be perfect.

[Sgub]

The ebay system is two pipes to the centre silencer and then only one pipe to the backbox. This will restrict the gas flow, to maintain the gas flow the pipe diameter will have to be increased but by doing this the velocity of the gas will be compromised.

I'm a little bit fuzzy on bernoullie's principal of gasses. However, I would assume, going from 2 pipes to 1 does not per se, give a decrease, as long as the surface area of the second (only pipe) equals the (approximate) circumference of the first 2 pipes combined.

[Davz]

I think that is correct, but won't the velocity decrease with one large pipe? I'm reading up on this at the mo, trying to understand as much as I can before I get a custom made system made this summer.
Certainly going to have a crossover system but double into single is not what I had thought about.

[Sgub]

Hmm, I'm not an expert either (obviously), and it's been quite a few years since I've studied about the flow of gasses, so I might be talking complete b*llshit..

I'm not sure how much energy gets lost in the silencer itself, however most likely quite a lot of velocity does get lost there, due to turbulent flow, and well silencing..

With regards to velocity aspect.
The total pressure should remain largely the same between the two smaller tubes and the after single bigger tube, as total pressure is made out of static pressure and dynamic pressure (velocity). I'd reckon as long as the surface area comparing before (2 tubes) and after (1 tube) doesn't change by too much, there shouldn't be a big change. One could however say, if the diameter of the one bigger tube, was slightly smaller, than the two smaller tubes combined, that would increase the velocity of the gas and maybe even counteract the cooling down of it, whilst it vacates the exhaust. Obviously spit balling here.

On the other hand, if the surface area of the big tube is bigger than the two small tubes combined, the dynamic pressure would drop (velocity) and the static pressure would rise. Which is not perse what we want. That's enough thinking for me, for now, before my brain explodes

[IAcKI]

Mine's still sat in my cupboard. Had it months now

For sale?

It will be now as I'm selling my Z4 before I got a chance to put it one