E30 S50 exhaust silencing - EDIT - temp solution

[Reeeedish]

What have you guys done for silencing the E30 S50's?

I have the BTB manifolds and X-pipe installed and now need to build from that backwards.

My problem/concern is that it needs to be around 100db to pass sound checks at most tracks.

The other slight problem is i'm trying to get this ready for Saturday 6th @ Castle Combe so a quick fix is certainly needed.

I've looked at building my own, by buying sections but its the silencing that i would struggle with. I.e; how many should I use and what size etc.

Any help appreciated.
Cheers, James

[e30_Turbo]

Try Jetex

They do all the pipes, joiners, reducers backboxes and decibel inserts, in 1 to 3.5 inch dia's!

Mines 3 inch all the way but my lump does breath well I suppose, needs extra capacity, whats the stock bore size used on a S50? I'd go a little bigger and be happy.

They do Stainless and ali steel, I used ali steel and it's been fine for well over a year, did paint it tho, def helps.

HTH, Fozz.

[Karan]

use mild steel to keep the noise down if you are concerned

i have 2 huge silencers on my s38 with twin 2.5in pipes but i reckon it would still be too loud for track....

[tomson]

E30 M3 exhaust butchered to fit would be a good option I'd imagine...

[ian332isport]

E30 M3 exhaust butchered to fit would be a good option I'd imagine...

Probably a bit restrictive for an S50.

[Jhonno]

I have 2x2" with a single rear silencer on an M50.. it is loud as fook

[tomson]

E30 M3 exhaust butchered to fit would be a good option I'd imagine...

Probably a bit restrictive for an S50.

Really, looks like I'll be selling the one I have for my conversion then!

What did you use on yours Ian, is it a full custom?

[ian332isport]

What did you use on yours Ian, is it a full custom?

Yes, full custom.

It was originally twin 2.5" all the way down, but the BTB front section is twin 2" up to the front of the middle silencer, and 2.5" from there onwards.

If you measure the O/D of a standard S50 system, it's 2.5", but it's apparently double skinned, and only 2" internally.

Cheers,

Ian.

[Reeeedish]

Thanks for all the replies!

I ended up making my own as I was in a desperate rush to get it road worthy (Castle Combe Action day last saturday).
That was a perfect opertunity for its first shake down and test it before a full track day in Oct.

Please remember - this is only a temp exhaust system (especially back box). But its a fully sealed system and has no leaks and sounds fantastic.
Also it was dead on 100db at Castle Combe and they pondered but let me out.

My new finished front section:


How I did it;

I did offer up a E36 3.0 rear box but it was a struggle to get the rear silencer into the E30 space. plus the pipe were completely too low as they have to go under a axle beam on the E30, where as they go to the side of a diff carrier on an E36.
So that idea was scrapped and the only option I had to go with (completely in a rush) was use a E30 325i back box (2 piece system job)


Which ended up leaving the rear box pipes here (just past the front edge of the fuel tank). Plus the X-pipe wasn't too far away:


So bought some sections of jetex 2" pipe and 2x Simons small silencers which I planned to use as centre box's.


So I cut the flanges off the rear end of the E30 325i centre section so it could mate to the flanges on the 325i rear box. Then sleeved it with some short 2" pipe and mocked up 1 of the silencers in place. Then started building from the X-pipe to the silencer which was quite easy on the right hand side bank as it just needed a 90 degree piece and a short piece of straight 2":


Tacked in place:


I couldnt have the silencers too close so had to space them apart slightly which meant lengthening the left hand bank as it came out of the X-pipe before it made its 90 degree bend. So made this shape:


Which got them installed without touching each other or the heatshield.
Both tacked in place:




Took the system down so I could fully weld the new sections:


What it looks like with the silencers in place:


Installed back on the car:



Temp exhaust system finished:



Thanks again for the suggestions, those Jetex piece are fantastic.

James

[Jhonno]

Fook if yours is 100dB with silencers and a standard 325i backbox I wonder what mine must be with a Supersprint race setup! (Small backbox, no silencers!)

I refuse to weld my btb crosspipe due to the value of it!!

[ric325i]

not a bad bodge that! im a big fan of jetex.

my first m30 exhaust was made from jetex 3inch pipe. was great but my back box was diddly.

now i am messign about with a e30 m3 exhaust. i dont see it being too small as its 2.5inch all the way through!
has 2 good size middle boxes and a MASSIVE back box. all scorpion stuff.

i had it fully sealed last night before i ripped it off to make the mani and down pipes fit better around my steering mech. head ache but it will be worth it.

so i think if you wanted a good system m3 is the way forward, i see no reason for it being to restrictive.

[Reeeedish]

Fook if yours is 100dB with silencers and a standard 325i backbox I wonder what mine must be with a Supersprint race setup! (Small backbox, no silencers!)

I refuse to weld my btb crosspipe due to the value of it!!

LOL, yeah i would say your will be over 100db then

I had the same though when it came to welding against the X-pipe. But under the time limit and the fact that if I didnt weld it, there was no way of clamping stubby 90 degree bends to it as they are also 2" not 2" flared. The only other way I could see would be to cut off the bends on the end of the X-pipe but then its just as bad as welding. So I went with the welding option and kept the X-pipe with the bends that BTB made them have.

Silly price for the X-pipe though wasn't it!

[e30_Turbo]

Looks like it worked really well then

Jetex bits are great, I've rejigged mine a few times, only welded a few bits as I have clearence issues, i.e. 3 inch pipe under the rear beam with -35mm suspension!

Next downpipe I'll do will be 3.5inch as they've added that to the range since I bought my last bunch of parts.

The main thing for me was I was able to build the whole exhaust, including teh clamps etc for less than £160, which when you consider the local stainless echaust place quoted me well over £500 for just under the car, they didn't want to touch the downpipe at all, can't have been that hard as I did it, ok Ant helped but I welded it! ( That's why it's wrapped my welding isn't all that."

Excellent job tho, glad it worked out for you.

Fozz.