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Need advice on my muffler system - 1998 G320 i6

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Kerouac
Posts: 13

Need advice on my muffler system - 1998 G320 i6

Post#1 » Mon Mar 09, 2015 10:18 am

So here's the story...I recently replaced the muffler on my 1998 G320 i6 (Europa truck) due to some rusting of the brackets and the muffler.

I had this done at a professional shop w/ good recommendations. The original muffler system configuring had the cat converter on one side with pipe laid over the axle and the muffler on the opposite side with single exhaust exit point.

I opted to remove the piping over the axle and move the entire system on one-side of the truck — the side with the Cat Converter — I also had a Dynomax muffler installed to replace the faulty OEM muffler. Unfortunately this has caused a loud droning noise in the cabin. Which, reaches eardrum shattering proportions at speeds between 50-55 mph 2500 RPMS (perhaps a slight exaggeration but I do have to plug my ears).

Now the question to those more knowledgeable. Should I move the pipe back over the axle to allow for greater dissipation of sound, look for an OEM muffler to replace the Dynomax or both?

I really appreciate any advice anyone can offer. Thanks!

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nihil
Posts: 1269

Re: Need advice on my muffler system - 1998 G320 i6

Post#2 » Mon Mar 09, 2015 10:40 am

I didn't see any mention of a resonator? Presence of a resonator can make a huge difference in exhaust sound, particularly droning. It attenuates the sound waves that propagate through the exhaust system without impeding flow, with the remainder being quieted down by the muffler.

Performance mufflers are almost always going to be louder than stock/oem type mufflers, and yes, routing the exit farther from the cabin will reduce the noise heard in the cabin. If you want very quiet, Cadillac mufflers are some of the more quiet units on the market. They're often found behind large displacement V8's so the flow is generally adequate for smaller motors.

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AlanMcR
Posts: 1922

Re: Need advice on my muffler system - 1998 G320 i6

Post#3 » Mon Mar 09, 2015 11:12 am

If you can fit a resonator into the lineup it will likely help a lot. Unfortunately I don't know a way of easily figuring out the correct size/length without resorting to trial and error. I'm sure that there is CAD software that will calculate this. I'd love to get my hands on that SW, but I don't know any exhaust systems engineers.

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vadimivanovich
Posts: 4592

Re: Need advice on my muffler system - 1998 G320 i6

Post#4 » Mon Mar 09, 2015 12:25 pm

I had the same situation with a new original 126 muffler and all new 2.5" piping on a 617a. I added a small resonater early in the piping (down-pipe), and the problem was solved.

Alan has the right idea - muffler location and overall pipe length can be manipulated to eliminate the resonance, but it would be tough without good software or lots of guesswork. My resonator was an off-the shelf Toyota part :o The noise is gone though!

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nihil
Posts: 1269

Re: Need advice on my muffler system - 1998 G320 i6

Post#5 » Mon Mar 09, 2015 12:45 pm

Many custom exhaust shops will test fit pieces for you while it's on the lift so you can pick and choose what your final setup will sound like. Without some expensive CFD software and enough experience or previously logged data to be able to apply those numbers to real world situations, trial and error is the best way to tweak your exhaust for sound.

Alan: Having the software is one thing, but the real trick is the massive amounts of test data to use for a comparison with real world results. Companies spend huge amounts of money on sound booths and high end audio capture hardware to be able to predict within a reasonable margin what an exhaust will sound like. It's ridiculous.

Kerouac
Posts: 13

Re: Need advice on my muffler system - 1998 G320 i6

Post#6 » Mon Mar 09, 2015 1:59 pm

Thanks for all the feedback!

I'm going to try fitting a resonator and see if that solves the sound/vibration problems.

kiato4
Posts: 134

Re: Need advice on my muffler system - 1998 G320 i6

Post#7 » Tue Jul 25, 2017 5:57 am

In my 1995 G320, the resonator was over the rear axle. A previous owner had removed mine and it had a horrible sound, when I put it back in the truck sounded great again.

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