W126 exaust question - PeachParts Mercedes-Benz Forum

ned2683 · #1 07-29-2003, 12:59 AM

i have a 1984 300SD, i was wondering what side exaust pipe i need to use, is it a 2.5" or 2.25" or do they use a different system? i need a perfect fit because i don't have a welder and i am too cheap to take it to a muffler shop (they take out a whole nother cash register with a benz). also is it legal to do side pipes (long story why i am losing my exaust system) thanks

ned

P.E.Haiges · #2 07-29-2003, 12:57 PM

Ned,

Which pipe are you talking about. A muffler shop with a pipe bending machine will be able to flare the ends of the pipe to fit.

I replaced the whole exhaust system on my '79 300SD except mufflers for $30 by getting pipes custom made, but I welded them together.

P E H

Snibble · #3 07-29-2003, 02:46 PM

PEH... I have asked this question before, but never got a responce from anyone. Perhaps you might be able to answer this. Would I have have some sort of gain if I get a "remus or remus style" muffler and put a straight pipe in place? How much would something like this run(minus the remus muffler)? I understand my car is not a diesel.. but it is a w126 exhaust

ned2683 · #4 07-29-2003, 03:04 PM

Quote:

Originally posted by P.E.Haiges
Ned,

Which pipe are you talking about. A muffler shop with a pipe bending machine will be able to flare the ends of the pipe to fit.

I replaced the whole exhaust system on my '79 300SD except mufflers for $30 by getting pipes custom made, but I welded them together.

P E H

what i was meaning is what size pipe would i use to couple into the pipe BEFORE the middle muffler. long story, but i have a straight pipe in the middle of my car. (everything from the middle muffler back is gone) i want to put on a muffler in the middle of the car, and have it dump out in front of one of the rear wheels (for legal purpose) other wise i wouldn't mind a straight pipe at all. so i was wondering if i need to buy a 2.5" or a 2.25" muffler.

P.E.Haiges · #5 07-30-2003, 12:36 AM

Ned,

Sorry, I don't know. Can't you measure the one you have?

P E H

william rogers · #6 07-30-2003, 03:10 AM

You'l have to get metric pipe if you plan a slip over no weld connection, Or as I did on my SE get an exhaust pipe expander and then sort through store with a set of calipers untill you find american size that will strecth enough for your fit , probably best to go to a muffler shop as they will weld it and usally don't charge that much.........
William Rogers......

P.E.Haiges · #7 07-30-2003, 03:45 AM

Snibble,

What's a remus muffler? I never heard of them.

Cost, you should be able to do it for $30 like I did.

P E H

nismodrifter · #8 07-30-2003, 03:50 AM

Quote:

Originally posted by P.E.Haiges
Snibble,

What's a remus muffler? I never heard of them.

P E H

remus = GOOD exhaust manufacturer

quite a popular brand for aftermarket exhausts on German cars (bmw benz etc..)

check their website at http://www.remus.at/

ned2683 · #9 07-30-2003, 01:59 PM

william & PEH: that's what i was thinking. i tried measuring it before but i didn't find any that would be a directly slip on. so i suppose it is a metric size. i suppose i'll go to a muffler shop to do it, i wanted to avoid this because well 1. i am cheap, and 2 i am kinda busy around now. perhaps i can get them to expand the ends to fit my car.

i heard a bench on remus and "remus style" mufflers. the real ones are really expensive aren't they? i am kinda liking straight piping right now, wish i could keep it.

in missouri diesel vehicles do not need to pass emission testing, and i thought a muffler was a part of the emission system. but i don't want to push my luck.

rdetoy · #10 08-18-2003, 11:48 PM

The diameter of the stock exhaust piping is 2.5 inches. Greater flow can be achieved by going to 3 inch pipe, but you will run into ground clearance problems since the pipe runs under the rear suspension and in some spots is the lowest part of the car. Remus mufflers are extremely high quality but their prices are science fiction and their design of questionable benefit to a diesel. On a 126, the greatest source of exhaust restriction is the resonator, sometimes referred to as the kidney mufflers or butterfly mufflers. The resonator is specifically designed to dampen a resonance that occurs at 2000 rpm. If yo remove the resonator you will have a momentary buzz as your engine moves through that range, but what you gain in throttle response, improved engine breathing at higher revs and cooler engine operating temperatures more than make up for the buzz, as far as I'm concerned. The factory rear muffler is 2i inches long and 7 inches in diameter, with a 2.5 inch inlet. It is of rather straight-through design and not a major hindrance to flow. Changing that muffler might 'shape' the sound but will not likely improve performance meaningfully, especially if replaced with a chambered muffler. If you plan to use an aftermarket muffler, chosing one with a straight-through (as opposed to louvers or chambers, a la Flowmaster) design will provide you with the greatest opportunity to maintain performance while developing your SD's sonic signature. Take a look at the Magnaflow product line for hgih value in either aluminized or stainless models. For best bang for the buck, though, it's hard to beat losing the resonator.

ned2683 · #11 08-19-2003, 12:26 AM

currently i am running a straight pipe. i do know what you are talking about when u say the "buzz" at 2,000 rpm. i do notice the throttle response gain, but it is slight. what i plan to do is maybe a flowmaster ($40 on ebay) and have it dump out before the rear wheel. i am not in any hurry to do this tho (but it would suck if i do get pulled over and fined wouldn't it?). but thanks a bunh for the info it makes my job in buying couplings and stuff easier, and i can always widen them a lil bit if there is any difference in size.

rdetoy · #12 08-19-2003, 12:45 AM

You might want to think twice about using a Flowmaster. Flowmasters are essentially race mufflers that have been marketed to guys who run healthy V8s, like in Mustangs and Camaros. Flowmasters are designed to use the strong V8 exhaust pulses, or actually the vacuum behind each pulse, to scavenge the next pulse right behind it and create the effect of pulling exhaust away from the engine. One reason why this type of design is not as effective for your car is that the exhaust turbine in the turbo 'chops' the exhaust pulses into many little pulses, effectively negating the scavenging opportunity. Also, most original Flowmaster designs have wicked resonances that can make street driving unbearable, though their DeltaFlow product is not bad in this area. Finally, early Flowmaster product was not so well made and rusted quickly, though that situation has improved over the past couple of years. Have you scoped out how much room you have for a side exit exhaust? I don't know where you would put a Flowmaster without knocking it off on speed bumps, crowned driveways and the like. Three inch pipe such as I put on my SEL touches the ground with alarming frequency. If you add a non-chambered, straight through muffler in the stock location it will give you room to tuck it up so it doesn't drag and will keep the sound at the rear of the car as opposed to underneath you.

rwthomas1 · #13 08-19-2003, 09:54 PM

Not to pee in your cornflakes Rich but Flowmasters have nothing to do with scavenging. The design uses the exhaust flow pulses to cancel out noise and this is why at certain rpm's resonant frequencies can occur that are "harsh", they do however flow really well. Every test has proven so. Since the exhaust pulses are neatly chopped up by our turbos and every straight-piped turbodiesel I have heard is tolerable to quite quiet the muffler becomes a legal issue. Flowmasters come in all shapes and sizes so fitting one shouldn't be a problem. Any custom shop could bend up a system for a third of the cost of a Factory setup. My 95 Chevy truck had a custom system with 3" pipe and a 3 chamber Flowmaster on it, installed in 95. The same system is still on the truck, and it has been in NH now for 4yrs so I guess the corrosion problem has been solved. RT

rdetoy · #14 08-20-2003, 12:06 AM

I'm glad you like your Flowmaster exhaust RWT. The Flowmaster Delta series muffler on my son's Cherokee is the ideal muffler for the vehicle, based on our subjective appraisal of the sound. I like Flowmasters for certain applications and understand their history and design very well. What I said was true: their product line started as a race muffler (two chamber) designed around scavenging principles. They only had to meet the liberal noise standards of quarter mile race tracks and were successful enough that their products quickly found their way to the street. It was because they were so noisy on the street, both inside and outside the car, that the company developed its three chamber and then its Delta Flow line of mufflers, which does use acoustic cancellation theories (effectively) in its design. Delta Flow mufflers were priced a good deal higher than the race-derived mufflers due to their more complicated construction and so I figured that it was unlikely a Delta series muffler would be selling for $40, as reported, though I could be wrong. You need go no further than the Flowmaster web site to see their claim that their product's PRIMARY advantage is its scavenging ability. I didn't make this stuff up.

The fact remains that there is little room for a muffler under the mid-section of a 126. The stock resonators are rather shallow and the only recess appropriate to both hanging a muffler and achieving a side exit for the exhaust would be the location of the resonator. The combination of a right angle turn in the primary pipe and the small physical dimensions necessary to fit a muffler into the resonator recess conspires against high exhaust flow. I agree that a muffler shop can effectively and inexpensively whip together some crush-bent pipe that will work well--that's how I did the 3 inch exhaust on my 500SEL--but it will be just as easy (since the system runs under the rear suspension) to terminate it at the rear where there is room for an adequate muffler, regardless of brand.

rwthomas1 · #15 08-20-2003, 05:49 PM

Hey Rich,
I didn't say you were making it up.... Flowmaster is!! Marketing hype is all it is. Scavenging effects will occur in a properly designed header system where the exhaust pulses of each cylinder actually pull the gases of the adjacent cylinders along providing a boost in velocity at that point. Since the gases are completely mixed and flowing along at the same rate in our turbodiesels or for that matter any other car once downstream of the header collector, the only thing Flowmaster can provide is sound attenuation through the redirecting of sound pulses and the lowest possible impediment to flow. Since good headers are tuned to provide the correct scavenging effect based on engine size, design, etc. I would have a hard time believing that a muffler that is effectively universal has any scavenging effect. Either way I wouldn't put one in the resonator area either. A good shop will mandrel-bend a system and put the muffler in the OEM spot where it belongs. RT