108 exhaust question - PeachParts Mercedes-Benz Forum

68greezr · #1 11-11-2003, 08:53 AM

ok,gentlemen i'm doing the research on changing the exhaust on my car.i really don't like the stock set-up,i was thinking of a couple of flowmasters or something like them,also trying to keep it as quiet as possible.thanks in advance for your comments.

Tomguy · #2 11-11-2003, 01:42 PM

I really don't see any more than 5-10HP from a new exhaust system consisting of dual flowmasters - I know the MB stock exhaust looks "tiny" but remember how efficient the 3.5 and 4.5 engines are for their era - the same is probably true from their exhaust. I would think a front muffler from a 4.5 would fit perfectly (same size, same pipes) and although might be louder (probably not too much though), it would give less backpressure. (I think the rear mufflers for the 6 and 8 were the same - it's really a "resonator" and not a muffler - it adds that nice tone to the exhaust). Looking at my book, the mufflers' attached pipes from the 6 and 8 look identical in shape and size and length, just popping the 4.5's front muffler on would probably work well. I really don't see how you could actually route a dual setup or even a non-stock setup that isn't professionally customized (proper bends, etc). I know there are indeed plaes that can customize a system that goes from the engine (header) pipes back to the tail of the vehicle, but will it be as efficient, quiet, and durable (IE: last over 30 years) like the stock did?

68greezr · #3 11-11-2003, 01:58 PM

well i don't know if it will be better than the old.but what want to do is single muffler again but just a better flow muffler,not pipes on each side.thought if i built some "y"'s to fit the two pipes and fab it up to a single flow muffler that it would breath better.i'm not sure about all this so i posted it here so i could get everyones thoughts.i thought the better the air flow the better it runs.

jas2wa · #4 11-11-2003, 02:09 PM

I am in the market for exhaust for my 73 280SEL 4.5, and have all but decided to go with a Timevalve stainless system from front to back. Just need to save up a bit of cash, but truthfully, the whole system is less than OE regular steel replacements. Used a similar Timevalve stainless system on a 70 280SE 6-cyl., and loved it.

-JAS

Litton · #5 11-11-2003, 03:20 PM

The local muffer shop showed me a neat trick he uses for checking if a cat is bad. Drills a tiny hole just forward of the cat and attaches a pressure gage. Runs the engine up through the rpm range and sorta profiles the back pressure. Mine was running at 6 psi and he said that was just fine. Point is.....one could use this trick and avoid the guessing games everyone does on "backpressure" and the relief threreof.

Tomguy · #6 11-11-2003, 03:30 PM

Litton: My problem with that is you have to seal the hole 100% or it'll cause it to grow, and grow, and grow... etc.

geezer: You'd have to raise the diameter quite a bit. The dual 45mm pipes have a total flow area of 3181mm^2. To achieve that same flow with 1 pipe, you would need a pipe with a diameter of 64mm (2.5"). The dual 45mm pipes are 1.77" in diameter. However, not only would it have to be 2.5" in diameter for a single pipe, you would need a muffler with equal or less backpressure to achieve the same flow and power. If you want to go to a 3" single pipe and flowmaster, yeah, it would achieve more volume - but the engine really doesn't NEED that much volume. I don't see that much of a performance gain, but I do see a noise gain.

The point is that yeah, those dual pipes look tiny, but it's like having 1 big 2.5" pipe. I think that's bigger than the pipe diameter on my Jeep!

68greezr · #7 11-11-2003, 04:10 PM

ok,well thats just about what i had in mind.i went out looking at the local muffler shops,the minute you say,i have a mercedes those guys see dollar signs.i built the system on my jeep so weldings no problem,and i can buy the parts for about 75.00 so we'll see how it turns out.

thanks again everyone

tosbt · #8 11-11-2003, 05:41 PM

Check this thread under search for exzause . I will tell you I had BIG BIG problems. Say what they might TIMEVALVE never squared with me about their system. Its all in the thread. Best of luck.

jas2wa · #9 11-26-2003, 02:15 PM

So, any further conclusions about exhaust for the 108 4.5?

I've researched OE steel parts, Borla stainless, and Timevalve stainless, and the cost of each goes highest to least, in that order.

Seems odd to spend about a grand on OE steel when a complete stainless system goes for less, in the aftermarket.

I am still torn about which system to go with, and I know about tosbt's problems with his 300sel.

Any further thoughts?

JAS

Tomguy · #10 11-26-2003, 02:52 PM

This is another thing I don't understand (like the timing chain guide rail thing - check my other thread

)...
Why would you replace your original stainless system? Did something actually happen to it, or is it because it's "32 years old" and you want to ensure that it won't blow out?

I am going to wait until my stainless system either falls off or blows out to replace it. I find no need to downgrade my system to steel!

jas2wa · #11 11-26-2003, 03:15 PM

But the original system isn't/wasn't stainless-

Surely what's on my car now is not stainless, either- I have several exhaust leaks with what is on the car now, and when it comes to exhaust work, there's nothing worse than trying to piece new parts to old. Would much rather just go all new from front to back.

So, in order to replace what is on there (old, battered, rusted regular steel), it seems logical to me to go with the aftermarket stainless system, which just so happens to be cheaper than OE regular steel (even if they are good parts).

I'll have to go back to find your timing chain rail thread, btw...

JAS

Tomguy · #12 11-26-2003, 03:55 PM

If my system isn't original and isn't stainless, it's a miracle that it's still on there. It's been on as long as my parents and I have had the car - since 1989. It has not 1 spot of rust on it, nor does it have any holes. And this is a miracle considering what the body looks like, if it isn't stainless. The exhaust system on the 11 year old Jeep is in much worse condition (and covered in bubbly, crumbly, cracking rust) and on probably its 7th muffler or so. My Benz, however, is still on all original pipes and mufflers except the right header/manifold pipe, which blew out on me after I started it for the first time in 5 years (and it didn't have a spot of rust on it either - the metal was just "Fatigued" to the point I could crumble it in my fingers).

jas2wa · #13 11-27-2003, 08:30 AM

Huh. Most likely it has been replaced some time between the early 70's and 1989 then? From the factory it would have had a steel system, maybe it has since been replaced with stainless, before you and your parents got it?

Mine isn't orginal, nor is it a stainless replacement, and it isn't in the greatest shape...

I am thinking stainless b/c it is not driven every single day, and thus might be more prone to rust than my TD which gets excersize daily.

Be happy yours is in good shape, the stuff isn't cheap!

Cheers,

JAS