Removing exhaust. Yes or no?

[soupapes]

The BX 16v have 3 exhaust boxes.

Would i get any advantage in removing one of the exhaust (maybe the second one)?

And if i remove the second one, will the car make too much noise?

[thanuttiscotsman]

hi mate,
i think for sure your exhaust will become louder by removing a box and personally i would recommend the centre box for the one to be removed. you would prolly gain a little power if your modification involves making the gas flow run in a more straight line then theoretically yes you could gain a little power but prolly more noise lol.


cheers rossco

[AlanS]

I did it on mine one day just for the hell of it.
It seems to cause the car to drum at a bit of speed and the exhaust blowing out the back was shooting out so fast even at idle, it sounded like a gunshot and was almost strong enough to blow your hat off.

I couldn't get mine back on quick enough.
My best investment was a rear straight through muffler.
Modern straight through systems work on the back pressure pushing the exhaust outwards through the baffles thereby keeping it nice and quiet around town, but when you put the foot down, you get a nice free breathing system and the sporty burble as a bonus. That's the way I went and might be your solution.


Alan S

[thanuttiscotsman]

yeah ok my bad! but why remove the back box? it would just roar like a rally car with a blown exhaust.??

rossco

[Vanny]

roscco, you where talking about taking the middle box out, alan is talking about taking the REAR silencer and replacing it with a straight through box.

I've gone the straight through rear box method, and it's not made too much noticeable noise difference until on cam. Don't remove the front box, its important!

[AlanS]

roscco, you where talking about taking the middle box out, alan is talking about taking the REAR silencer and replacing it with a straight through box.

I've gone the straight through rear box method, and it's not made too much noticeable noise difference until on cam. Don't remove the front box, its important!

That's correct, however, it was the removal of the centre box that made it drum like you couldn't imagine, so much so, it literally made your head ache.
I have a straight pipe style centre box as opposed to the sideways version, but it made little difference, but the rear straight through was the one which really did it for mine.
If you go this way, don't go the cheap route though, as it needs to be the modern type with clean cut holes to the baffle, not the old style straight through with the holes raised when you look through the tail pipe as they just sound carp, a bit like a tractor (for which they were originally drsigned I understand).



Alan S

[Toddman]

I spent a lot of time on this issue and found the best sound and performance compromise is to go for a 2 box system.
Remove the first box that sits under the gear lever area abd then fit a decent cross box such as Sebring or Scorpion with a similar tailbox - the result is a nice sound that doesn't upset people in the back seat and a decent freeflowing exhaust.
Removal of the cross box even is accompanied by a larger front box just results in a nasty drummiong inside the car (as mentioned)

Cheers
Luke

[Vanny]

Remove the first box that sits under the gear lever area

surely that totally destroys the reflected pressure wave? Probably not noticed when the car is non standard (particulalry changed cams) but it would significantly impact performance and economy on a standard setup.

hmmm, is it worth making a CAD model of the exhaust and testing it? Probably not and i'm no good at FEA either.

[Timmo]

i used to run mine with the cross box removed but the resonater and back box as they are, used to sound great freed up the top rev range but lost torque lower down as you would expect, had it like that for 3 years until i caught the resonater box on the driveway lip at the inlaws and split the box to pipe join, removed and sleved it and had it like that for approximately 6 months before gatting a std system back on but with only 2 box's (cross and back box) which is how it is now! i would get a headache from it with just a straight through to backbox on a half an hour run and with impending littlun i thought it best to go sensible!
have to say as luke suggestion although mine is std box's rather than tasty ones it does make a very nice driveable car with a slightly nicer noise than std!
economy wise i didnt see any deterioration in figuers mpg wise with any of the different pipe connotations! 20ish around town and 32-34 ona run!

[docchevron1472]

economy wise i didnt see any deterioration in figuers mpg wise with any of the different pipe connotations! 20ish around town and 32-34 on a run!

I'd be fairly upset if I only managed 20 ish round town I have to say.
I've never yet had less than 27MPG round town, and tend to get mid to high thirties on the combined cycle.

If I'm on a steady run and don't clog it too much I can get 42MPG. Well chuffed with that!

As for the exhaust, I tried mine with a sidewinder replacing the middle box, but it was just unbearable on a run, so I tried a Scorpion middle box and back box, and found it sounded muffled and strangled at lower revs.

At the moment it's got a standard (splitter) Bosal front pipe, scorpion mis box and genuine PSA back box, and Inreckon it sounds spot on. Noisey but not too intrusive and burbles nicely at idle.
Or at least it did, it's been a few months since it ran....

[Timmo]

doc, i get around the 20's ish on mine partly because i dont do massive miles any more and like to excersie the ol' girl a bit too much!;)
last run i did i tried cruising at 70-75 but found it made no difference at all to fuel at that than at 80, and was quieter at 80 than lower! odd really!
one thing i never really worry about mpg though as its not the reason for why i drive the car!

[Toddman]

Remove the first box that sits under the gear lever area

surely that totally destroys the reflected pressure wave? Probably not noticed when the car is non standard (particulalry changed cams) but it would significantly impact performance and economy on a standard setup.

hmmm, is it worth making a CAD model of the exhaust and testing it? Probably not and i'm no good at FEA either.

Possibly ?
A few overseas owners are adamant that they have seen improvements on the rolling road with this box removed and I never found any ill effects after numerous rolling road sessions, some of them before headwork and cans were employed.
I don't know anyone who has removed this resonator and then rushed to put it back.

Cheers
Luke

[kriskarrera]

How come you've got 3 boxes then? 405 Mi16 only has 2.

[docchevron1472]

doc, i get around the 20's ish on mine partly because i dont do massive miles any more and like to excersie the ol' girl a bit too much!;)
last run i did i tried cruising at 70-75 but found it made no difference at all to fuel at that than at 80, and was quieter at 80 than lower! odd really!
one thing i never really worry about mpg though as its not the reason for why i drive the car!

I know exactley what you mean mate, I find it impossibly hard to have a "steady run" in mine, it just begs to go faster.
I find mine is more economical at 80mph than 65 actually, but 56 is as good as it gets on the economy front.
I dont get too anal about fuel consumption TBH, but I always keep a check on it (force of habit now) as it can be a good indicator of how the engines running.

Really shoulmd get on with the welding, I miss the old girl a lot.