How can I make my Viper quiet?

[Radu]

Guys, I know this is heresy but I need to pass a noise and smog inspection in Switzerland and even stock, a Gen3 is too loud for the granny-regulations they have over here.

I have a Paxton + Corsa cat-back on the car and I still have the stock exhaust lying around, so I'm looking for a way to modify the stock mufflers to make them as quiet as possible so I can swap them on the car just to pass the inspection -- then they'll come right off again

Any ideas?

PS I already tried stuffing some stainless Brillo pads in there but they just came shooting out as soon as I revved the engine

 

[BillionDollarDan]

Let's make a trade. I'll give you my 3.8L v6 from the Wrangler and you give me the v10. I guarantee it'll be quieter

edit: on a serious note there is a post on here somewhere of decibel levels of different exhausts. Even stock exhaust might be too loud for your inspections. If I find the post later I'll link to it for you. They even have a Ford GT at the end... really cool

 

[BillionDollarDan]

http://forums.viperclub.org/srt10-s...video-viper-dyno-day-exhaust-sound-tests.html

easier to find than I thought. Check it out. It will show you stock and some modified information. It won't tell you how to make it quieter but it may give you a starting point so that you know how much you should reduce the decibel level.

 

[99 R/T 10]

Give the inspector a set of ear plugs prior to, or just pay him off.

 

[Radu]

99RT10, clearly you've never had the pleasure of dealing with a Swiss automobile inspector.. can you spell a-n-a-l?

 

[Bolt]

I don't have the answer but I just bought a new volt/ohm meter from harbor freight which has a db sound level tester. I only paid $35 for this meter and the db tester works great. It would be a good idea for you to check your own level of sound.

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[Shandon]

Try some "vortec cones" in the Stock Exhaust. I hear a lot of people have real good luck with them. Fairly cheap too.

 

[eucharistos]

can you describe the testing procedure?

how high do they rev your engine, slowly or gun it, just at idle, etc.

i guess too loud could trigger an avalanche

edit: also is the sound and emissions test at the same time?

 

[mjorgensen Woodhouse]

Tack weld Vortex cone into the cat pipe outlet with some "packing" behind it, slip on stock exhaust system and pass. Then remove above

 

[Radu]

The car has to pass a complicated test where they measure drive-by noise at full throttle from a specific distance, around 40 MPH in a specific gear (not sure which but the revs are pretty low). The wide tires on the Viper actually generate quite a bit of noise and leave that much less headroom for extra sound coming from the exhaust.. and if the test track is wet that day, forget it, most high-performance cars don't pass!

Mark, any reason I couldn't weld the cones into the stock muffler instead of the cat pipe, thereby allowing me to swap in the whisper-queen setup anytime I need to? Also I guess I'd have to be careful not to put too much packing in there, since the excessive back-pressure might damage something..?

 

[ViperGTS]

Holero-di-del-di-öh-!



Must be fun with the "inspector" in der Schweiz.



Da bleibt wohl nur der Einbau des Dämpfers, um die Schlange leiser zu machen!

 

[mjorgensen Woodhouse]

You can I just figured since the exhaust slips over the cat pipe it would be easier. As long as the packing can take the heat for the time you need it should be fine, I would use a coarse steel mesh of some sort so there is a negligible amount of back pressure increase, you just want to break up the sound.

The car has to pass a complicated test where they measure drive-by noise at full throttle from a specific distance, around 40 MPH in a specific gear (not sure which but the revs are pretty low). The wide tires on the Viper actually generate quite a bit of noise and leave that much less headroom for extra sound coming from the exhaust.. and if the test track is wet that day, forget it, most high-performance cars don't pass!

Mark, any reason I couldn't weld the cones into the stock muffler instead of the cat pipe, thereby allowing me to swap in the whisper-queen setup anytime I need to? Also I guess I'd have to be careful not to put too much packing in there, since the excessive back-pressure might damage something..?

 

[Asp Man]

The car has to pass a complicated test where they measure drive-by noise at full throttle from a specific distance, around 40 MPH in a specific gear (not sure which but the revs are pretty low). The wide tires on the Viper actually generate quite a bit of noise and leave that much less headroom for extra sound coming from the exhaust.. and if the test track is wet that day, forget it, most high-performance cars don't pass!

Mark, any reason I couldn't weld the cones into the stock muffler instead of the cat pipe, thereby allowing me to swap in the whisper-queen setup anytime I need to? Also I guess I'd have to be careful not to put too much packing in there, since the excessive back-pressure might damage something..?

Who's driving?
Why not mechanically limit the wide open position of the throttle?

 

[eucharistos]

The car has to pass a complicated test where they measure drive-by noise at full throttle from a specific distance, .....

full throttle on a paxton, hope you are driving and not the tester

 

[vancouver-gts]

If you have a friend with fabricating skills , I'd ask to make a slip in muffler we use in boats. I have this s/s slip in muffler for my boat taking it with me to the lakes where cops now checking boaters for dB level.When I boat in the ocean the mufflers come out in secondsThis gizmo drops the dB level by 10 !

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[Phun70]

Easy, Don't start it!!

 

[10 BANGER]

50 chamber exhaust!

 

[Sweet Ride]

Strap the car down to an open trailer, start it up and let it idle, and tow it through the test.

 

[ViperGeorge]

If you have a friend with fabricating skills , I'd ask to make a slip in muffler we use in boats. I have this s/s slip in muffler for my boat taking it with me to the lakes where cops now checking boaters for dB level.When I boat in the ocean the mufflers come out in secondsThis gizmo drops the dB level by 10 !

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Do you have any plans for this slip in muffler? I could use something like that myself to quiet the car down at certain tracks with sound limits.

 

[plumcrazy]

just make sure to take them right out when inspected. they are gonna create a lot more heat that will go right back up into that engine. IMO and experience that can be bad.

and the cats could melt frm this heat and cause the same issues

 

[Coloviper]

A real pickle you are in! Easiest to just move!

My only other suggestion is to to try factory Cats and a set of Gibson Mufflers. Though they probably don't make a Viper application, it is a long round muffler similar in size and shape to a Viper and they are very quiet. Installed the system on my Supercharger Lincoln Navigator a few years ago and it was very, very quiet. Might be worth a shot, if you can fit it in the side panel. Seems to me it "looked" the same size. The Lincoln Navigator one was a nice muffler and sound was quiet but low pitched tough. As the sound comes from air moving through the motor and mufflers, what about a restrictor plate on the front air filter area? Less air in would mean less air to flow through for that brief period. Quieter...no?

Beyond that, as I said..........moving truck! How far off the mark are you?

 

[vancouver-gts]

Do you have any plans for this slip in muffler? I could use something like that myself to quiet the car down at certain tracks with sound limits.

It's easy to make one .The one I have in my exhausts are for 4" pipes , but can be made in any size. The back pressure dropped my WOT rpm by only 150 .To get rid of more back pressure , in the center of the baffle wall , a 1/2" hole can be drilled without gaining extra noise.

Here's a link to show what they look like > Rex Marine Insert & Inline Mufflers and Silencers for Boats: Automotive Performance Products, Boat & Marine Parts & Hardware

 

[slysnake]

Well, as said, check the sound level out yourself if you can. I have not driven a coupe so can't say for sure, but when I'm driving my vert the sound of the car seems louder to me with the top up than with the top down. What I'm saying is that maybe the car isn't as loud as you think on the outside, just inside the closed cockpit it seems really loud. To me, at cruseing speed with the top down the car seems fairly quiet.

 

[Phoenix SRT]

A mechanic buddy of mine had an obnoxiously loud ATV. He tack welded large washers whose outside diameter fit tightly into the inside diameter of the exhaust pipe. It cut the exhaust noise in about half and was really cheap and easy to do. Sure, it restricts exhaust flow and that no doubt will cause loss of power and heat build up. But if you only put the mufflers with the washers on to pass the sound test then swap real mufflers back on, it makes no difference.

It sounds like this is just another way to restrict exhasust flow like some of the suggestions so far in this thread, but tack welding washers is really cheap and easy.

 

[bluesrt]

ya the ol homade supertrapp