Exhaust Modifications 560SL

Model 107 Specific Mods -
We seem to have a lot of posts around this particular model, I wonder why?!!???
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nucci
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Exhaust Modifications 560SL

Post by nucci » Sat 21 Apr, 2012 8:15 pm

Looking at replacing and modifying the exhaust system on the 560SL... I would like to improve air-flow, performance and a produce deeper sports sound.

Thinking about a custom system with dual 2.25" stainless pipes. After checking out the modifications made by others, I've tried to picked up similar components from ebay at reduced costs. To help increase low end/mid-range torque and also balance the pressure between the engine banks, thinking about fitting a Merge Pipe, (produced by Sureflo Exhaust NSW). From there, the exhaust moves on to twin High Flow Catalytic Converters, (produced by HJS GERMANY). The twin pipes will then lead on to a duel inlet/outlet oval body shaped Sports Exhaust Silencer with welded Steel Angle Cut Exhaust Tips, (produced by Team XRacing NZ).

Merge Pipe, (Sureflo Exhaust)

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High Flow Catalytic Converters, (HJS)

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Sports Exhaust Silencer, (Team XRacing)

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Anything I should be aware of?

Paul
1978 450SL
1986 560SL

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nucci
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Re: Exhaust Modifications 560SL

Post by nucci » Sat 21 Apr, 2012 8:20 pm

Realize the twin slash cut outlets will require the rear panel (under the bumper-bar) to be modified. So I've picked up a second hand panel so that I can modify it and still have a spare if I decide to go back to stock at a later date.

Paul
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1986 560SL

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Re: Exhaust Modifications 560SL

Post by Mercmad » Sun 22 Apr, 2012 9:13 am

i do not know where the maker of the merge section did their research but the maximum size for the connection between the two pipes is only 50mm. Any more and no power increase will be realized.
Your engine is the USA low compression version so every little bit helps. I would be more inclined to swap in a set of hi comp pistons and AMG stage 1 cams to get some real power out of it.

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Re: Exhaust Modifications 560SL

Post by CraigB » Sun 22 Apr, 2012 10:23 am

Just checking so i understand - merge pipe is good but must be max of 50mm? For a track car I imagine the cats wouldn't be needed. Would a 2 in 2 out which is what AMG used be the way to go, like this one is? Or just bundle it all into one big pipe after merge? The problem with exhausts is that you put your faith in an exhaust place, pay a fortune and then later if you find they have done something fundamentally wrong you are stuck with it!
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nucci
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Re: Exhaust Modifications 560SL

Post by nucci » Sun 22 Apr, 2012 5:46 pm

Thanks for your feedback, will continue with the research before going ahead... Some further information about merge pipes...
http://www.surefloexhaust.com.au/xpipe.htm

Cheers
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Re: Exhaust Modifications 560SL

Post by John Green » Mon 23 Apr, 2012 8:32 pm

JoeB has a rather full on system in his 560SL, he is bound to see this thread and comment...
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Re: Exhaust Modifications 560SL

Post by Greg in Oz » Mon 23 Apr, 2012 10:11 pm

Mercmad wrote:i do not know where the maker of the merge section did their research but the maximum size for the connection between the two pipes is only 50mm. Any more and no power increase will be realized.
I have heard similar info to Ron supported by measured results. There was an episode of "Gasolene" which discussed V8 exhaust systems for modified Holden Commodores which revealed greatest power outputs were achieved with an "X pipe" with only a small diameter opening between the two pipes. I forget the actual diameter of the opening but it was only something like 25mm.

For those unfamiliar with it, "Gasolene" is an enthusiast car show which features modified muscle cars and restoration of classic cars. In Sydney it was previously shown on TVS (digital ch. 44 and formerly ch. 31 analog). I noticed that it is not being shown on TVS now and a check of the "Gasolene" website revealed that it now screens on TV4me (digital ch. 74 on the 7 network and 64 in regional areas which get Prime instead of 7).

Just on the issue of V8 exhaust systems, my 500SLC doesn't have an "X" or merge pipe, but does have a balance pipe which runs across all four engine pipes before they merge into two. The balance pipe is only around 40mm diameter. I am unsure whether it is there to improve torque, power or just noise levels. My 350SLC originally had a similar balance pipe (across its two engine pipes) but when it rusted many years ago I had new engine pipes made without the balance pipe (on the strength of the 280SE 3.5 we had in the family at the time never having had a balance pipe from new). There was no noticeable change in performance although I notice that my 500SLC has a quieter exhaust than my 350SLC. The balance pipe under my 500SLC can be seen in the lower right in the attached photo.

I have considered a custom exhaust system for my 500SLC to allow the engine to breathe better in the upper rev range. It's low down torque is good (as would be expected with tri-Y engine pipes), but I believe that the 5 litre engine's power output is restricted by the exhaust system which, from the front muffler back, is shared with all 107 models including the 6 cylinder 2.8. My plan is to retain the tri-Y engine pipes but to make a copy of the existing system using larger diameter pipes from where the four engine pipes merge into two. I will make a copy of the rear muffler with larger bore pipes in an attempt to retain appearance and noise levels similar to the original (I don't mind if it has a little more of a note but I don't want to draw unwanted attention). I just don't know whether or not to retain a front muffler as I know that most of the noise reduction occurs at the rear muffler. It really comes down to what will give the best power output. If I retain a front muffler (which will also have larger bore pipes) it definitely won't have the small diameter restrictions midway through that the factory version has. I am tempted to try it initially without a front muffler although I have also read of research that suggests the engine pipes should reach a "termination" (that is open into a large volume) at a point well before the rear muffler. If the front muffler is not fitted there is also the question of whether or not an "X" pipe should be used is its place.
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107023 - 350SLC: 1973, 3sp auto, icon gold, parchment MBtex (sold July 2012 after 29 years ownership)
107026 - 500SLC: 1981, 4sp auto, thistle green, green velour
124090 - 300TE: 1990, 4sp auto, arctic white, cream-beige MBtex
124090 - 300TE: 1992, 4sp auto, malachite (spruce green), black MBtex
201024 - 190E-2.0: 1985, 5sp manual, black, black MBtex
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201034 - 190E-2.3-16 Cosworth: 1985, 5sp manual, blueblack, black leather
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Re: Exhaust Modifications 560SL

Post by AMG » Tue 24 Apr, 2012 3:23 pm

We need to go back to the very start of the discussion to understand the 'how' the merge collector works. it's designed to amplify scavenging. now on a v8 with 4-1 headers with big primaries the merge collector will work fantastically well. The reality is far from the desired effect however, in that the v8 already has crappy log style manifolds, into a 2" secondary which merges into a whopping big cat / front box on the 560SL, then travels rearward with twin 1 7/8 pipes to the rear muffler. The 500SLC has the benefit of the tri-y headers which does provide a small amount of scavenging assistance with the albeit short primaries - the main difference is the cylinders are correctly paired to produce the best possible effect without being overly complicated or expensive (remember, this is a production car, so there are compromises)

Back to the merge collector & it's usefulness.

It WILL quieten the sound. simply put, there are 2 sets of soundwaves (pressure) coming down two separate pipes and mingling in a confined space. instead of hearing both sounds clearly, they muddle and cancel each other out to a degree, and as a result, you can't quite hear the separate conversations they are having.
The advantage is that it should assist in low-end torque - as much as the correct size 'secondary' pipe will also do. However, you also need somewhere to put the cat converters, and in essence they provide the first change in cross-section (volume). placement of these won't be optimal due to the underfloor positioning requirements and the need to keep the exhaust from being continually bashed by speed humps etc.

The merge collector will improve the low burble, but will remove the messerschmitt staccato crackle and pop from the rear exit.

lastly the rear muffler. Doesn't matter what you have in front of this, whether it's a single or dual pipe arrangement. if you have a merge collector, then you'll have 2 pipes, if you have a y piece merge then you have a single pipe. (there are tables you can use to calculate the frictional losses from the pipes diameter which will correspond to a flow volume figure at a given velocity, which may aid your decision).

if you have a compartment style muffler, then the noise will be reduced further. If you have a baffle style it will be a little less and a perforated straight-through less again. Ultimately a supertrapp style disc arrangement which you can control the noise if you so prefer.

In combination, as you can see, there are many variables - which is why no 2 customized exhausts sound the same. Originally I had a quite seriously loud setup, which has mellowed over time, and I've probably lost about 9dB which is a good thing (because it was loud). Also I made a decision to not use a balance pipe and there is no merge collector. it runs 4-1 each side right to the back. I did this to preserve the messerschmitt sound and not for rumble, and also to feel the relationship between throttle position and rpm more acutely. The downside is that I lost a bit of low end throttle response and torque, which I can live with. I got a healthy midrange increase and a wailing top end which strikes fear into the heart of that c*ck in the audi or R36. It also means I won't break diffs and driveshafts getting off the line, helps a little with traction in 1st gear (but the redline shift into 2nd still leaves elevensies for a good distance) and ultimately you do need an amount of civility and a small rpm band where the engine is docile so you can potter around in the wet in a peak hour traffic jam.

But most of the previous posts cover the bits I have chosen to not repeat anyway. At the end of the day it's your car and the note is just as important as the look and the drivability.
I have plans for a similar 4-1 x2 style system, to which I will be using custom headers, but at this stage, it is a street car, and there is no need to go to all these lengths to get a healthy sound and increase the power at the same time.
Current:
1987 560SL 4sp. auto Signalrot "Stella"
1987 190E 2.3-16 5sp. man. Blauschwarz "Hermann"
1992 300CE-24 6sp. man. Perlblau / Iceblau "Gretel"
1992 Range Rover Classic 4sp auto Ardennes Green "Oswald"
2012 E63 AMG Speedshift MCT Diamantweiß "Klaus"
Previous:
1986 560SEL Anthracitgrau "Schultz" - In Mercedes Heaven
1987 190E 2.6 4sp. auto Signalrot "Sabine" - which now resides/owns Andrew M's Garage
1972 350SLC Astralsilber "Lurch" - now in the loving care of Craig B
1989 2.5-16 Blauschwarz 4sp. auto (parted) formerly owned by Derek/Hasan.
2012 Renault Sport Megane RS265 Trophy 8:08 6 sp. man. Liquid Yellow "Jean Rédélé"

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nucci
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Re: Exhaust Modifications 560SL

Post by nucci » Wed 25 Apr, 2012 9:08 am

Thanks Joe, (and others) for the information... You mention the space required to fit the twin Catalytic Converters so that I don't have problems with speed humps etc... Can they fit side by side roughly where the stock Cat is located (straight after the merge pipe)? Where did you place yours Joe? You would happen to have a picture of it...

Thanks again for all the information.
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Re: Exhaust Modifications 560SL

Post by nucci » Tue 03 Jul, 2012 7:18 pm

Had to alter my original plans. The High Flow HJS Cats I had in mind were a little to large in terms of diameter. I exchanged HJS Cats for a pair of Racing Cats (which are narrower). Then spent time trying to find the appropriate location to place them:

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I'm happy with the tail pipes at the rear, it was a tight fit, even though I had enlarged the rear bumper panel opening:

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If it's too loud, I'll fit a second silencer just after the merge pipe...

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Last edited by nucci on Sun 08 Jul, 2012 10:43 pm, edited 1 time in total.
1978 450SL
1986 560SL

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nucci
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Re: Exhaust Modifications 560SL

Post by nucci » Wed 04 Jul, 2012 1:16 pm

Video of the exhaust can be found at:

http://youtu.be/WFzVISu7m0o

Later on I might have to tone it down a level, by fitting a second silencer (just after the merge pipe). In the meantime (until the police pull me over) I'll enjoy the sound of 'German muscle'...
Last edited by nucci on Sun 08 Jul, 2012 10:44 pm, edited 1 time in total.
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Re: Exhaust Modifications 560SL

Post by Starman » Wed 04 Jul, 2012 4:46 pm

Sounds good to me. Good job.
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