Exhaust options

[chinny4290]

Hey all. As typical, my exhaust needs replacement because it is old, fragile and rusted. The center muffler is sitting low and theres nothing i can do to fix it. And there's a hole in it.

What are my options aside from getting an OEM replacement?

I have a friend who knows how to machine metal really well and I'm thinking about asking him to make me a new system, with no mufflers, mainly since the cat sits right next to the engine. I like the sound it makes now with the hole in the center muffler 

Ups and downs to this?

And what if I were to delete the cat? The car is registered as a Historic vehicle which puts no inspection requirements on it, meaning no emissions whooooo!

Ups and downs? Performance gains?

[WGB]

Ditch the cats and get a dual stainless steel system.

Will need some muffling or else a headache from the noise or the constabulary will occur at some stage.

Bill

[chinny4290]

Any sources you suggest if you my friend doesn't come through?

[WGB]

There were a number of non-oem stainless systems available years ago.

See what some other USA members say.

I have a custom "Powerflow" exhaust on my 6.9 and it is not particularly quiet - I usually ease off the throttle if I see a Blue Meanie.

Bill

[13B]

You need some degree of back pressure to help the engine breathe efficiently.  If you have no back pressure you'll find the engine has poor performance on cruise mode and part-throttle acceleration.  Mufflers help create the necessary back-pressure.  Also with no mufflers the car will be deafening at WOT, so there won't be any rev range you can comfortably drive the car.

If you are after a sporty note consider a custom twin system with a dog in each pipe and a smaller-than-stock dual-in-dual-out sports muffler and horizontal (as opposed to pointing down) tailpipes.

I.

[craigb]

If it is the 280s with carbs, back pressure is not an issue and I believe from factory it has 2 straight through resonators, 2in 2 out.  I believe the djet (and maybe k too) needs some back pressure to work as Ian points out. My 280 has just the center box removed and just a straight through on the rear and it is not loud by any means at all and even on the track you can't hear it on the video! (a bit of a shame really).  I believe stainless is noisier than steel and was told by an exhaust place that is why some cars were fitted with mufflers in place of the resonators (thinner material?).  What I can tell you is that when I had the center one removed there was a massive increase in power and ability to rev - different car. I then had the rear one replaced and while not as bigger jump, still a clear improvement in performance and also a substantial reduction in fuel use (I reported it on here somewhere but something like15 to 20 mpg?) 

Anyway, my recommendation if you still want it pretty quiet but with a slightly throatier sound, just replace the rear with a standard straight through benz item and replace cat etc with straight through pipes.

[pez]

All motors need some amount of back pressure to scavenge the cylinder of exhaust gasses....without this, the motor will not run correctly.  It is highly unlikely that the flow rate/backpressure in the resonator or the muffler would contribute much to this process, which happens in the first few cm's out of the exhaust valve....however, the exhaust manifold plays a huge role here.

It would be a great idea to pursue the removal of the cats, which are [as I understand it] integral with the exhaust manifold. But I also understand that there may be many other systems that are affected...air injection, air pumps, tensioner, computer, etc.  I would do some research before you start pulling parts off.

I have a euro and it does pass emissions cleanly here in CO [front range emissions are as tough as CA on old cars]....however, I have been considering installing an aftermarket cat where the resonator is - it would not be as effective as the one further upstream, but would still would be a huge help on emissions [the exhaust stinks!], and I don't think a high volume/capacity cat installed in the resonator location would cause any performance drop of a straight exhaust setup.

AutoHaus AZ has the ansa muffler, but no longer stocks the ansa resonator.

[chinny4290]

Yes. My car is a 280S. So at this point, I should probably keep the center and rear muffler but remove the cat.

Anyone know where I can get a catless exhaust manifold by factory or would it be cheaper to have my friend make one?

Also...how specifically are the air injection, air pumps, and tensioner affected if I remove the cat? What specifically? And computer? The closest thing to a computer on my 280S that I found is the ICU 

And pez, i do not need to worry about emissions requirements since it's registered as a historic vehicle.

[s class]

Have a look at this :

Link

I paid the equivalent of about US$450 for this exhaust.  Custom stainless, true dual, all the way from the manifolds back.  The price included the silencers hand-made to my specification. 

The silencers were made as per the drawings in that thread.  I have since however discovered that the original 6.9 rear silencer is actually stepped inside, not straight through.  Nonetheless, even if I had known that, I would not have changed my design. 

Its a beautifully made system, with no boominess or resonances, just a business-like sound at low revs.

If you can be patient, I'm planning to design a similar system for my 280SE euro.  I just need to get time to do the calculations for pipe diameter etc.  Perhaps this weekend. 

[Zagato]

I don't know how the 280 sounds, but if anyone has a V8 I highly recommend having at least one muffler.

I got my center muffler removed as it had shot baffles causing a terrible clatter, and replaced it with straight pipes. However, it turned out the rear muffler was not long for this world either. After two days my exhaust became about 80% straight pipe. Sure, when idling it now chugs and putters like a drag racing car, and has a muscle car acceleration note, but the noise is unbearable when cruising. 2 hours in traffic, the dragster growling will annoy you.

[WGB]

Anyone know where I can get a catless exhaust manifold by factory or would it be cheaper to have my friend make one?

Also...how specifically are the air injection, air pumps, and tensioner affected if I remove the cat? What specifically? And computer? The closest thing to a computer on my 280S that I found is the ICU 

I would assume either the "Element" in the Catalytic converter can be removed , the pipe can be removed and a new length put in or a custom header or non-cat exhaust manifold used.

The air pump will absorb some horsepower so removal of the pump and belt must improve performance - at this pont you no longer need all the attached tubing so it can be removed and either the manifold connection plugged or the manifold changed.

Bill

[chinny4290]

I don't know how the 280 sounds, but if anyone has a V8 I highly recommend having at least one muffler.

I got my center muffler removed as it had shot baffles causing a terrible clatter, and replaced it with straight pipes. However, it turned out the rear muffler was not long for this world either. After two days my exhaust became about 80% straight pipe. Sure, when idling it now chugs and putters like a drag racing car, and has a muscle car acceleration note, but the noise is unbearable when cruising. 2 hours in traffic, the dragster growling will annoy you.

http://www.youtube.com/watch?v=EFSgIMrPfG0

[craigb]

Reading the new posts I see again the dangers of the international forum. I should have said my 280 has a euro motor, no emmission gear at all and no tests are done in Oz. My understanding from a number of sources including a benz dealer here is that my car would have had 2 straight through resonators as a new car. But with the one I have now, how loud was it today Bandolero as I rung its neck pushing 7k revs at times around Mallala (pissed off that the little Alfa in front could get the leap out of corners on my 1700kgs... and both of us getting nervous as I gathered him up under brakes!)

[oscar]

(pissed off that the little Alfa in front could get the leap out of corners on my 1700kgs... and both of us getting nervous as I gathered him up under brakes!)

You would think he would've moved out of the way.  Imagine being in the Alfa, hard braking and the width of your rear view mirror quickly taken up by w116 grill.   

Here's the pics I promised chinny what I assume to be standard system on a non emission controlled 280S.   

From the two header halves it goes into a "y" piece, travels single to till a couple of feet under the floorpan then opens up into another "y" creating two pipes.  These two carry on to the centre muffler, 2 in 2 out to the rear round muffler.  Again 2 in 2 out.


It's a poor photo above but here's a closeup of a new "y"


Under the floorpan where the on pipe splits into two.



Lastly, this shot is of the racer.  Rather than have that "y" piece, a previous owner put two pipes from the header halves right through to the centre muffler.

[s class]

Oscar, I think the y-piece arrangement was only on the RHD cars.  The LHD cars don't have all thw misery of cracked y-pieces.  They have a pair of pipes right through with a balanace arrangement under the firewall area.