DDK - Die Deutschen Klassiker

Hi all,

I keep seeing 911's with 2 small rocket launchers coming out of the muffler box under the rear numberplate. They seem to be blocked off with a lockable cap. What are they and what do they do?

What are the options for exhaust systems for early 911s and there relative merits? Sorry to be technical

regards

Mike

This one came from Autofarm, but I know Barry and others have made their own. Uncap the centres and the sound is glorious, but too much for towns and villages.

Transend sells a twin pipe without a side exit, haven't fitted it yet so can't vouch for it, supposedly good sound, deep noise, galvanised steel,
Pelican sells Bursch exhausts, they have side exit but smaller actual muffler box, appare ntly they sound fantastic

Hi Nick,

Thats the suckers They look wonderful, is it a case of only unpluggin them on track days etc? what kind of DB's do they give out since i'd be concerned at tracks like Castle Coombe (100BD static limit )

Is it a completely new exhaust system? how does it work? hmmmm, whats that sound......kerrrching!! oh no, more cash gone

regards

Mike

Mick Cliffs twin outlet regestered approx 107+Db @ elvington

The one that I modified was a bit loud for road use: the whole car used to resonate at around 3000 revs, just as you were going through towns. In the end I made a couple of simple baffles for the twin pipes.

They were just a couple of lengths of pipe that were a good fit in the tailpipes. At the silencer end I ran four (90 degree spaced) cuts about one ince long up the length of the pipe. I then folded these 'flaps' in slightly to disrupt the gas flow. It was then possible to keep tweaking the amount of 'fold' until the sound was a nice balance between tuneful and socially acceptable.

I had chrome exhaust trims on mine which hid the fact there were inserts there. Obviously the gas-flow was compromised slightly, but frankly you are more likely to be putting the triple outlet type box on for looks and noise, rather than outrght performance. I would suspect that a good quality standard box would flow just as well.

Forgot to say, I just modified a standard box, which I believe is all Autofarm do (?), therefore the 'new' backbox can go directly onto the existing heat exchangers.

I'm sure there are a number of other options, but I supose a lot is going to come down to what you are looking for: sound, looks, performance, standard appearance etc etc.

It'd make a good sticky article if someone had a good handle of all of the 911 exhaust options right through from a budget, mild steel system, right up to a stonking, top of the range, ultra performance stainless solution .

Some more options:

This is the twin outlet sports exhaust on my 2.8 twin-plug car:



Here's the set-up on my 911R-inspired car (short stainless steel megaphones attached directly to the heat exchangers):



& here's the 911R system that will be on the above car once the 2.8 twin-plug engine is swapped into it:

Hi Andy, whats the 911R system made of, and how will you refinish it?

Mick Cliffs twin outlet regestered approx 107+Db @ elvington

106.7dB at 4500 revs and Gawd knows what at 7300 revs

Quite intoxicating for a while, but tiring after a couple of hours. I carry ear defenders to wear for the last hour on the way home to regain some sanity!!

Mike - it's mild steel.

I'll probably get it ceramic coated.

I have no idea of the dB level, but as Barry says its too loud with the caps off except for open roads, so probably to much for a trackday. With the caps on the noise level was normal I would say. The rest of the system was SSI which is a little louder tahn standard anyway. Steve Wright may know the dB level as he has an Autofarm triple on his 2.2S before he modded it, and I thing he used it on track days.

hi mike


i have a twin pipe from here:

http://www.mkexhaust.com/home/home.html


you can buy direct or from pelican and they sound fantastic although not too sure of db's


paul

Andy, what are you going to do about heat, demisting etc - are you fitting a heated screen?

Andy, what are you going to do about heat, demisting etc - are you fitting a heated screen?

- wear a thick coat & carry a demisting cloth !