3" Exhaust Advice

[Lane_S]

I just put on a KermaTDI 3" turbo back exhaust - no CAT. My goal is to improve engine performance for MPG gain. I expected it to be louder but after a few days driving and tweaking I've decided I'd like it to be quieter. The droning is the issue. Running flat its OK but once you load the engine going up a hill it drones. Is there a good high flow muffler that I can add? Would putting the CAT on (I do have it but didn't install it) be sufficient? Would I need to go to a 2.5" system instead or back to stock? Wanted to see what others have tried. I take full responsibility for thinking I knew what I was doing but in reality had my head up my a**

 

[A5INKY]

Cat is going to help a lot. That exhaust is way overkill for all but the most radically modified 4 cyl TDI. You will be able to tame the drone with the cat and maybe a muffler too but didn't need to go that big in the first place.

 

[NonStop]

I take full responsibility for thinking I knew what I was doing but in reality had my head up my a**

HAHA.. guilty of this myself.

I'm actually thinking about doing the same thing, 3in turbo back.
The droning issue has come up in my research. Guy mentioned that he extend the tailpipe a little past the end of the car to calm it down.

Where's your tailpipe exit?

Any chance you can make a youtube clip of the droning noise?

 

[JFettig]

Way way overkill, No straight thru muffler will tone down the drone. Try a Flowmaster DBX muffler or a chambered muffler.

 

[Lane_S]

In your opinion should I drop down to 2.5" system? I know this will sting but I can sell the 3" here or on Ebay maybe....or should I try the baffled muffler, then if that doesn't get it to acceptable levels, put the CAT on?

 

[Lane_S]

I'll post a pic soon.

 

[FL/COtdi]

Check my sig for the fat cat mod. I did it on the same 3" exhaust as yours. No muffler needed. Then get a new tip of your choice and point it out the back bumper and you will lose that incredibly loud obnoxious drone. Put some bags in the rear springs, get an egt gauge, and you can tow just about anywhere!

 

[FL/COtdi]

I did try a muffler with the cat. I cant remember what kind. It was advertised as a high flow racing diesel muffler. Did not make a noticeable difference in sound volume and the egts went up. So it came out. Put in the cool tip out the back. Now the turbo whistle is readily apparent. I like it!

 

[Ganoid]

If you haven't already done it try angling the tip to the side. Out the back is ideal but in a pinch the angle thing helps a little.

 

[Lane_S]

I tried angling in about 45 Deg to the outside but it didn't help. Maybe to far in yet. I'll see if I can stretch it out to the bumper with the tip I have.

 

[Lane_S]

Thanks FL/COtdi. Will take a look. I haven't got "The Look" from the wife, concerning the 3", since I dropped a 302 V8 in a 1976 Mercury Bobcat Station Wagon back in 1980. I was only trying to improve the engine...REALLY!

 

[FL/COtdi]

I think I know what you mean. That unmodified 3" exhaust is incredibly loud. Honestly I wish I had spent my money elsewhere and I have ever since!

 

[aNUT]

I think they key with this exhaust is getting the exit beyond the rear valance a bit and kicking the turn of the tip off to the side a bit. That way the sound isn't coming up off the ground and right into the cabin. I set mine up like this.

 

[DieselRacer]

In your opinion should I drop down to 2.5" system? I know this will sting but I can sell the 3" here or on Ebay maybe....or should I try the baffled muffler, then if that doesn't get it to acceptable levels, put the CAT on?

Yes, Yes and Yes...2.5 flows plenty with better backpressure in my opinion, but what do I know, according to some...

 

[Ganoid]

I don't know that you would want any back pressure in a turbo vehicle. I wish I had opted for 2.5" as well but my goal was the pressure differential from the exhaust manifold to the over sized 3" exhaust would help spool up the hot side faster and in turn the cold side as well ultimately reducing any lag in the future with a larger turbo. It sounded like a good idea lol.

 

[Fix_Until_Broke]

You already bought and installed the 3" system and will be further ahead financially to add a muffler than to sell it at a loss and buy a 2.5" system that will still need a muffler.

As others have said, see if you can kick it out at a 45 degree angle to the left (drivers) side and get it as far back as you're willing to go with it. A 3" does not have to drone (my 4" does not drone), but you'll have to add a muffler. Handy thing about a 3" muffler, is that it can be relatively restrictive (for a 3" muffler) and not pose any significant restriction to your TDI, plus it will be quiet.

An aeroturbine fits well in the cat location but are a bit expensive, there are many options to put something in the OEM location. Many have had good luck with a cheap "Cherry Bomb" (or two in your case - one in the cat and one in the oem locations). Will quiet things down quite a bit.

You don't need/want any backpressure in your exhaust system and you won't gain any benefit in performance or MPG's over a stock system (unless the cat is plugged), even on a mildly modified car (injectors, tune, etc). If you change turbos, then consider changing exhaust. Unless you like the sound - nothing else to be gained really

 

[Lane_S]

I talked to Paul at Kerma and he said he's not heard of drone issues...

"I would try the CAT ... droning is not an issue I have encountered.
The muffler is something we never see much need for, But the CAT is a really good thing."

Also got this reply from a Muffler Manufacturer...

"Thank you for your inquiry for Dynomax Exhaust. We appreciate your interest in our products. I am sorry but the VT muffler is not designed for diesel applications. Unfortunately I do not offer anything that would rectify the issue with your vehicle."

I wasn't aware of design restrictions for Diesels.

Pic coming soon.

 

[tyson]

I have the same exhaust as you. I've loved it and to me drone would mean flat road driving with the sound you're complaining of. At load its gonna get loud whether you had the 2.5" or the 3" To me drone is not the sound you're complaining of. If its too loud under load then that's one thing

 

[VeeDubTDI]

Behave yourselves.

 

[Lane_S]

Had me worried for a minute. I was just looking for some help. Didn't mean to start backpressure wars.

As to some previous posts, I'm trying to describe a reverberation inside the car that when I'm on cruise and say running 60 mph on flat road, I get no irritating noise. Its acceptable. If I start up a hill and downshift, rev to 2200 & up, the noise? is tough. I can't really compare it to loudness from the tip as I'm well acquainted with loud from dual exhausts on V8 Gassers. Its more vibration related I guess.

With the car in neutral and brake on, I've revved it up and the noise from the back isn't all that bad. I've just started reading about "J- pipes" and pipes installed perpendicular to the exhaust, length determined by some calculation, to cancel out the wavelengths in the system. Trying to learn all I can and get back to a nice driving experience.

 

[Digital Corpus]

low frequency sound with a great enough amplitude is easy to be physically felt. However, with respect, given a person's age they can have an issue actually hearing such a frequency. 30-40 Hz or below is usually where the average person starts to not hear the sound.

 

[DieselRacer]

Do you have a resonator on it...

 

[Lane_S]

Here is a link to the exhaust.
http://www.kermatdi.com/servlet/the-740/exhaust/Detail

It has a resonator on the one pipe. If all else fails I do have the CAT that is offered with this exhaust.

 

[DieselRacer]

There is no resonator on the pipe in the pic...

 

[Lane_S]

its on the upper pipe. I'll try to get a pic of that as well. If its not a resonator I guess I don't know what one is. Its larger in diameter than the main tube and some odd looking interior, at least what I can remember before installing it.

 

[DieselRacer]

it looks like a 5 inch cylinder about a foot long, should be nice and shiney...

 

[darkhorse]

3" is over kill but not much louder than 2.5" I had the same problem with drone. I solved the problem with a tip like aNUT's & one of these instead of a cat.

 

[dirtride]

I recently installed the Kerma 3" exhaust in my Golf, and did urethane dogbone bushings at the same time. WOW! What a difference, like a new car ~ in a great way!
I was really surprised how much the motor rocked back and forth with the dogbone removed, doesn't seem normal.... BFI motor & trans mounts on the way.

With the Kerma 3" and Neuspeed dogbone, for the first time I actually look forward to starting the vehicle in the morning!!

 

[red16vdub]

3" is over kill but not much louder than 2.5" I had the same problem with drone. I solved the problem with a tip like aNUT's & one of these instead of a cat.

Question did you install aero muffler in the cat's location?

 

[darkhorse]

Yes. It fits nicely