Muffler or no muffler

[farkman]

Hey guys

I'm in the process of making a stainless exhaust for my car a 1994 Golf 1.9TD. I was planning on making a muffler but am now wondering how loud my car would be without one. If anyone can tell me how much louder my car will be without a muffler I'd appreciate it.

Peter

[1985JettaTD]

i too would like to know. sometime in the next 3 weeks my 1985 Jetta 1.6TD will be going in to the shop for 2.5 '' right from the turbo. i am thinking about not putting a muffler put dont want to do it if is going to be really really loud. anyone have any db readings or sound clips?
thanks for the help!

[Dr. Diesel]

my A2 is sporting a techtonics 2.5" with the two front resonators (glasspack style) and no mufflers. Almost silent at highway speeds. (that is to say, can't hear the exhaust over the engine noise)  Driving under a bridge though, sounds pretty loud on the outside.
A stock A2 exhaust with the rear muffler cut off actually sounds better. The turbo sound is very prominent, and it's small enough to not amplify the engine noise.

[VWRacer]

One of the most common mods to late-model TDI's is the "mufflerectomy"...

These cars have a mandrel bent 2" OD exhaust. Removing the muffler has no effect on power, but changes the exhaust note to a nice deep rumble with a pleasing turbo whistle. Even guys who go to the 2.5 pipe report no problems with the authorities...unless your area requires a muffler during smog checks.

[fspGTD]

Yeah, what they said.  

For street application I'd recommend a muffler, but just a "straight-through" design (you can call it a "glasspack" / "resonator" / etc... you get the picture) so it has minimal backpressure.  Even with only a single straight-through muffler, it will be quite reasonable in volume levels and likely will not be too loud for a daily driver.

Running with no muffler at all (including no resonators) you could always try by just removing you muffler and taking the car for a drive.  I think it would be too loud for a daily driver.

I've been using aluminum materials lately and am finding some interesting observations... it could be that the sound levels are quieted just by using aluminum!  It's hard for me to believe but I'm amazed how quiet my car is consider there are no mufflers at all (including no resonators.)

Also, for best mid-range torque, you'll want a full-length exhaust system.  Don't terminate it early.

[BlackTieTD]

if you're going to go with no muffler, at least have a resonator or two on there. i have a downpipe on the 1.6TD that ends right about at the drivers feet and it is very loud. ie: when i pull up somewhere and i want to talk to someone, they ask why i don't turn my car off so they can hear what i'm saying (i leave it running to give the turbo a chance to cool).

i'm going to put on a resonator and see how much quieter it is...

ditto about what jake said about mid-range torque, you'll want a full length system.

[Rat407]

Yeah, what they said.  

 Also, for best mid-range torque, you'll want a full-length exhaust system.  Don't terminate it early.

I thought that there was no valve overlap on these engines???  If so then it would not matter how long the exhaust is would it??

[deepmud]

I have a mandrel bent two inch exhaust that runs straight out the back. The length should be similar to your normal application, as my rig is about the same length. I find it no worse than the ricers exhaust untill I get the turbo in full bypass - then with a significant portion of the gases getting around the turbo it gets quite a bit louder, tho' I still find it acceptable. I did run a glass pack on the end of the pipe for awhile, and I thought it was about the same volume, but it cut some of the turbo whistle, which I like.

[BlackTieTD]

i think mine is so loud because the exhaust is about 2 feet in length and i have an open K&N filter on there instead of a proper airbox....

[Cheesetoast]

i removed hte resonator and the muffler on my 93 td with 2" piping stock.  didn't notice it being any louder at all.

[farkman]

Thanks for your responses guys. I've decided to first make the exhaust without a muffler and see how loud it is. If it is too loud I can just cut out the rear section and stick in a muffler.

Lanny, I slightly underestimated and had to use part of the fifth elbow, but I'm going to a store to pick up some things that I ordered and the stainless place is right across the street. I'll pick up 3 more in case you need that many. If not I can always sell them.

[Wingaman]

I have no muffler right now on my 1.9TD 94 in a A2 90. The exaust line is finishing 1 feet before the rear axelbeam. I didn't got the time to finish the exaust line when i drop the 1.9TD in my car.

On idle you cannot tell me if i got a muffler or not, but at WOT and on highway it's a little loud. I'm thinking to install a Dynomax or another high performance exaust on it. It's cost less than a Bosal ou a VW muffler and is lifetime waranty (the dynomax one). Police in Québec is a "pain in the ass"  :roll:

[DVST8R]

Well I ran a custom mandrel bent DP into a 3" pipe that ended just b4 the gas tank no mufflers or resonators for about 6months, but it wasnt the volume that got to me it was the frequency the resonnace off the car body, so I finished it with a 3" mandrel bent back and a dynomax bullet race muffler about were the stock muffler goes and the stright 3" about 1" past the bumper and that made a world of difference still can hear the turbo loud and clear, has a good rumbley sound, but is fine for a daily driver

[fspGTD]

Yeah, what they said.  

 Also, for best mid-range torque, you'll want a full-length exhaust system.  Don't terminate it early.

I thought that there was no valve overlap on these engines???  If so then it would not matter how long the exhaust is would it??

You are right that there is no (or at least very little) intake-valve overlap.

But, the observations I made from tests are that a full-length exhaust system makes improved torque vs a short exhaust system, terminating before the exhaust tank.  The turbo spools up quicker and mid range torque is noticeably improved with the full length system.

So... I think it must be the wrong conclusion to make that intake-exhaust valve overlap is not necessary for exhaust pulse tuning to make a difference.  It makes sense to me anyway, that if a negative pressure pulse arrives at the exhaust valve before it shuts, it would help things, even if the intake valve weren't open.

[moTthediesel]

When I installed the turbo diesel in my LandCruiser I made up a 2-1/4" straight thru stainless exhaust system with no muffler. It was not too loud under normal conditions and garnered no attention from the cops. It did get a little loud under load when the waste gate opened, however.
We decided to put a SuperTrapp tunable muffler on the end, and that made it nice and quiet, but I do miss the turbo whine it used to make.