Silencer box internal diagram

Mike · Post by **Mike** » Wed Oct 22, 2008 5:16 pm

I'm reliably informed by an expert in these matters (Barry) that floating somewhere in cyber-space
is a diagram of the internals of a silencer box for the conversion from single outlet to twin pipe sports exhaust. Anybody have the link?

thanks, Mike

Matt black70 · Post by **Matt black70** » Wed Oct 22, 2008 5:26 pm

Hi Mike, I've got it somewhere,I'll try and sort the link out for you.

Cheers
Matt

TheEasyLife · Post by **TheEasyLife** » Wed Oct 22, 2008 6:14 pm

Matt, let me know too please as my exhaust is on its last legs.

I think the exhaust and gearbox are the only bits I haven't spent money on my car. Shouldn't have said that should I?

Cheers

James

Lightweight_911 · Post by **Lightweight_911** » Wed Oct 22, 2008 6:42 pm

Is this any good Mike ?

Mike · Post by **Mike** » Wed Oct 22, 2008 6:51 pm

Thanks Andy, been trying to ring you on your mobile today, you around

early_911 · Post by **early_911** » Thu Oct 23, 2008 12:04 pm

That's what I used for mine.

Phil

Ferry Man · Post by **Ferry Man** » Thu Oct 23, 2008 12:20 pm

early_911 wrote:That's what I used for mine.

And that exhaust sounds nice.

Matt black70 · Post by **Matt black70** » Mon Oct 27, 2008 9:42 pm

Sorry I'm a little.I notice you have the pic but the links are :-

http://members.rennlist.com/tweedt/sptmuff.jpg

and

http://www.911t.org/wklyreprint/modified_muffler.htm

I also studied some pics of a sectioned exhaust somewhere before I built mine. I'll try and find them but don't hold your breath

Mike, why don't you build a 3 outlet so you can cap the middle ones for quieter running when req'd?.

Regards
Matt

Matt black70 · Post by **Matt black70** » Mon Oct 27, 2008 9:51 pm

These sections of a standard exhaust may come in usefull for anyone modifying a muffler.

http://www.pbase.com/9146gt/rally_muffl ... er_exposed

Cheers
Matt

Bob_Salmon · Post by **Bob_Salmon** » Wed Nov 05, 2008 2:40 pm

Andy/Phil. Just got my car back from having a re-jet and tune and had the sound level checked at the same time. Sound (Very nice) is +/- 103db @ 4,500 and tempting fate for Castle Combe or Goodwood.

The silencer is a brand new SS one so we discussed how we could reduce the sound level a little and the welder there said he would just slit it along its length and re-pack it! It sounds logical but far beyond my welding skills.....

If I am going to the expense of having them do it, I thought of having your twin pipe modification done at the same time. Do you have any idea what effect the mod has/had on the sound volume?

Many thanks.

Bob

Matt black70 · Post by **Matt black70** » Thu Nov 06, 2008 11:25 pm

Hi Bob. I made a 3 outlet system this year with caps for the centre 2 outlets. It does sound much louder when all 3 are open.From the inside it's a little boomy at around 2500 rpm but sounds lovely above 4k. From outside it's loud from tickover upwards but does IMHO sound great if a little attention grabbing. Most people tell me it sounds great.
Hope this helps.
Regards
Matt

912uk · Post by **912uk** » Fri Nov 07, 2008 8:27 am

I was thinking to do this on an orginal exhaust I have for the 12. I had a dansk on before that was a twin out let and when I was driving down that very nice straight Nr Phils house in Yorkshire I pulled into Phils place and every one was shocked it was me in my 12 as they all thought here comes another 911

The only way I can think that happened was the twin out let must have at high revs sounded much more 11 sounding. Interesting as also if I capped one out let it was a quite as a mouse, so booming as you say I think what must happen to the sound when the twin out let is the set up is the sound bouncing off each other ( not sure how the hell all that works I am not a sound engineer ) .

Bob_Salmon · Post by **Bob_Salmon** » Fri Nov 07, 2008 10:39 am

Thanks Matt/Mark,

I really need to reduce the measured sound level, the sound itself is fine

!

Somehow, I thought the twin pipe modification might be slightly quieter than the single outlet but from what you say, perhaps that's not the case. Ah well; they never said life was easy...................

Bob

Matt black70 · Post by **Matt black70** » Mon Nov 10, 2008 12:17 am

Hi Bob, I'll do some measurements with a decibel meter next time I use the car and post them up.

Matt

Bob_Salmon · Post by **Bob_Salmon** » Mon Nov 10, 2008 9:48 am

Thanks Matt

Bob