Inside a Dansk OE exhaust

[Simon Davidson]

Hello folks

We have been working on some exhaust development and had the chance to open up a customers brand new Dansk OE spec rear box (bannana box) and I though you might like to see whats inside, very big pic but shows detail better.

As you can see there is no wadding, the box uses expansion chambers and perforated pipework to create the correct level of turbulence to create the back pressure and baffling required.

We are converting this box for a customer and I hope to get pictures of the finished pipework before its all welded up.

This box is sold as the OE version for both 3.0 and 3.2 911.
Best Regards, Simon

 

[Anil]

Simon

Nice picture. I assume this the standard stainless steel rear box listed below :

930.111.043.00 3.2 REAR BOX SS OE

Interesting to see no wadding of any sort.

What are your views on the general workmanship (i.e quality of welds,etc) of the Dansk box?

Secondly, what exactly are you converting it to?

Cheers

Anil

 

[Guest]

wow, really interesting, always wondered what they looked like. Like you say, no wonder they produce such a good sound, not much to muffle it.

 

[Guest]

Simon.
I' m thinking of getting a Dansk 1in/1 or 2 out 84mm tipped silencer at some point. I really love the sound of them!
Do you know if the internals of the 1 out 84mm silencer is the same as my standard one? i.e could I remove the current tip, make the hole bigger and fit a new tip to achieve the same V8ish sound?

Cheers

Chris

 

[Simon Davidson]

The box pictured is the standard OE spec mild steel system, (i dont hav the part number as the customer supplied it) its not the sports version.
The outer case is deffinitely mild steel, its made of two layers of 1mm thick skin. The inetrnals look like stainless , we will know more tomorrow when i am back in the workshop with it tomorrow. Quality of finish is fine, I would even say good for the price.

The box is being converted for race use. the carcass and tailpipe have to be standard sizes. The owner wants to reduce baffling, giving a faster flow, hopefully I will be able to get pics of the finished version so you can see what we have done, but basicly we are connecting the open ended pipes together and reducing the baffle effect of the perforated sections by either wrapping with very tight stainless wadding or replacing with straight pipes.
The box has to look standard in order to pass scrutineers on the race track but we are allowed to do what we like inside as long as it passes the noise level tests afterwards.

With regards to altering the tailpipe this can be done as I have seen finished items, I have not tried it myself and would consider the main problem to be that if you cut a bigger hole in the skin you will take away the joint for the inner pipe.
You could of course buy a junction pipe, cut the tailpipe and fit a larger one via the junction, you would need to know your current external tailpipe diameter and then see what is available.

You would need teh assistance of a good welder and probably a tube engineer to bend the pipe for you, also need to know your current box is reasonable condition as old mild steel wont like being welded and often fails within a year or so if its past its best.

Hope this helps, Regards, Simon

 

[Guest]

Thanks Simon. I guess my idea is a bit of work. Thats probably why the 84mm out silencer is £300+. I' ll look forward to seing the end result.

 

[Simon Davidson]

Here are the latest pictures of the converted exhaust.

The first shows the welding work and additional pipes. note that we have replaced one of the perforated sections with a straight thru pipe and then connected the rest of the system to give a straight through flow rather than leaving expansion chambers to create additional baffling.

 

[Simon Davidson]

pics of welded connection

 

[Simon Davidson]

pics of baffled centre section,

 

[bert gear]

Looks very good and should sound great
infact this is NOT an OE box but a Dansk aftermarket box, the Dansk OE box is Stainless steel, and with the SC box being different to the 3.2

 

[Guest]

Beautiful work Simon.

Bert, do you know what the internal differences are between the one shown and my standard SC box?

 

[bert gear]

Cant say without knowing what you have fitted, the SC and 3.2 are basicly the same with just some external differences

 

[Guest]

Thanks Bert. I' m basically trying to find out if its possible to get the sound and look of the Dansk 1in / 2out with 84mm tips, but without paying over £300 for one .....yes I' m a cheap skate!

 

[Simon Davidson]

Hi folks, Bert is correct but thats what I meant to get across however Bert has stated it correctly, I hope you all get what i meant.

I havent seen the insides of a Dansk twin 84mm outlet box but I have one on my car, when we get round to designing our own version for my car we will open up the box to get an idea of what they have done. I fancy a twin outlet design possibly with 2 tailpipes each side, but we will have to wait and see, it needs to keep a hint of the eighties about it if you know what i mean. I hope to start this in April and will probably post notes/pics on the forum.

CHRIS If you are interested in converting your existing box email me your phone number - ITS BEST TO SWAP NUMBERS " OFF-FORUM" and I will give you a call.

Best Regards, Simon

 

[Guest]

Hi Simon,

This looks like a fun project and I for one will be following the results closely. I would like to think that someone might produce a muffler for 3.2s that was a little smaller than OE and hence a lot lighter removing weight from the very rear of the car. A single outlet would be (I think) of the greatest interest to the greatest number of people as the rear valence modification is an extra expense and something that many will be reluctant to do. If you can produce free flo, good looks and light weight without any annoying resonance then you are on to a winner.

Pretty much the best option I have seen the market currently is the Fabspeed muffler. Check out the fabspeed site - www.fabspeed.com. It looks like a beauty as it is smaller and has the single/twin outlet option - but it is pricey. They are also not yet available in the uk.

 

[Guest]

Hmmm, I can' t get a picture of the actual muffler to upload so you will have to have a look at the site. If you could make the equivalent at a reasonable price, I will buy.

The best sounding muffler I have ever heard (and the best sounding 911 I have ever heard) was a 3.2 Clubsport at Le Mans last year with a custom exhaust apparently built at enormous cost by engineers at Lotus. In layout it was similar to the standard system and used a one-in one-out muffler similar to the Fabspeed in style but smaller (and just one outlet). Boy, did that car sing. If anyone knows the owner perhaps he can post info/pictures. The car had a cage, race seats, light door panels, other engine mods and had the heater stuck on in the French summer sun. Those clues should help track it down.

Whatever you do, Simon, maybe you should allow for different tip options to suit all tastes.

Best of luck.

Richard

 

[Guest]

Simon,
At the moment I cant afford to modify my silencer as I' ve just biught new shocks and wheels which should be arriving soon. I would be interested in the future though. I think I' d buy a 2nd hand one so my car isnt off the road. Do you get a lot of work like this?

On the matter of sound, one of the best I' ve heard is an American make called flowmaster. Some of the guys at pelican parts forum have them and love them. They only cost about $200

 

[Guest]

Go here to download a 266k mp3 of a Flowmaster fitted to an SC.

 

[Guest]

Just wondering if anyone knows whether the internals of the OE Dansk pictured above are the same as the mufflers that our cars were originally fitted with. One would assume so, but is this correct?

Does anyone know what the internals of the " sport" mufflers sold by Type 911, Porscheshop etc are like. Perhaps like what Simon is building? Maybe just like OE but with bigger exit pipes?

Many thanks,
Richard

 

[ClubSport 911]

FYI - one of the Region 10 contacts had just had his SC exhaust replaced with SSI' s over at Francis Tuthills...more power etc, but what is interesting is that he works for touring car preparation company 888 racing. He has his (old) back box " fettled" by his race engineers and they found some interesting tricks to make it sound better and produce more power.

I think this is where Simon is heading perhaps ?


Nice

If you want to get more details, let me know and I' ll ask him to drop a post

Steve