Exhaust too loud - please help

[sgernon]

Recently a cop with nothing better to do got me for a noise violation on my car. I downloaded an app on my phone and it shows the car is ~100db standing directly behind it at idle. More important than the ticket is that I am headed to Thunderhill in 2 weeks and need to be sure when I'm at speed I stay under the 103db limit and don't get black flagged.



The car currently has a pumped up 377sbc with dynatech 1 3/4 step headers, 3" pipes all the way out with an x pipe and summit race mufflers on it. I've been looking at the exhaust inserts to put in the exaust tips or collectors but I can't find anyone that has porof they really work to reduce noise more than a 1-2db reduction. Has anyone actually measusre the sound reduction for any inserts?

I like the way the car sounds and would rather not change out the mufflers but may if I have to. Can anyone give me confidence in a quiet mufflet that sounds good?

I also thought about adding a cheap (thinking $20 summit muffler) 3" glasspack to the exhaust to potentially bring the tone down. Anyone think this will work?

Thanks in advance

Steve

[Kenova]

Do you have tailpipes? If you have 3" tailpipes you could change them to 2 1/2" pipes without any power loss and still get a noise reduction.

Ken

[sgernon]

Do you think the tailpipes alone will be enough to drop it ~7db?

Where is the best place to find a set of mandrel bent tailpipes? Does it even matter if they are mandrel bent after the muffler since the exhaust heat is gone anyways?

[sam 74]

you can buy a tail pipe kit from summit, as for mufflers i use Borla XR1 race mufflers and they are actually pretty quiet especially since the exhaust is currently dumped at the axle, i switched from flowmaster 3 chambers and these Borlas are way quieter. you could try to add a short glass pack type muffler before your current muffler that'll quiet it down but i may change the sound a little.

[Randy67]

I had these in the tailpipes of my El Camino (3" exhaust) in combo with Magnaflow 18" long mufflers,
http://www.speedwaymotors.com/Speedw...fler,1736.html
It hit a highest reading of 86 dbs at 50 ft on autocross course. That was with a 377 sbc similar to yours. I have them in my Camaro as well, but I haven't run it yet to see how it is.

[sgernon]

Did you notice any power loss with the auger inserts? I was also thinking to try those but my tips only have ~7" to use so I either cut the insert down or add them at the collector. Any thoughts on how that would effect power?

Did you tack weld them in? Do they rattle at all?

[Flash68]

Recently a cop with nothing better to do got me for a noise violation on my car. I downloaded an app on my phone and it shows the car is ~100db standing directly behind it at idle. More important than the ticket is that I am headed to Thunderhill in 2 weeks and need to be sure when I'm at speed I stay under the 103db limit and don't get black flagged.

I plan in doing Thunderhill in a few months as well... I believe the sound tester is on the passenger side from what I remember reading.. is that correct?

[sgernon]

I have no idea where it is. I have been planning to attend but always had something come up. Things have finally worked out and I'll be there April 7. I'll let you know when I get back if someone else does not jump in with an answer first.

[esenior]

I bought a pair of CC Inserts, but haven't installed them yet. Car Chemistry claims a 5-7 db reduction using a 3 disk insert and you can reduce further by adding the restrictor and/or pack stainless steel wool around the insert.

http://www.carchemistry.com/techinfo/car/inserts/

[Flash68]

I have no idea where it is. I have been planning to attend but always had something come up. Things have finally worked out and I'll be there April 7. I'll let you know when I get back if someone else does not jump in with an answer first.

I did a quick search and found that the tester is indeed on the right (passenger side) of the track. FYI. It's good for me since my Boom Tube exits only on the driver side.

Best of luck at T-Hill!

[Randy67]

Did you notice any power loss with the auger inserts? I was also thinking to try those but my tips only have ~7" to use so I either cut the insert down or add them at the collector. Any thoughts on how that would effect power?

Did you tack weld them in? Do they rattle at all?

I didn't test it without them, so I can't tell for sure. Putting them in the tailpipes shouldn't be much restriction as exhaust volume drops that far out. They are the same baffles as the ones in the Moroso Spiral flow mufflers, which supposedly don't restrict exhaust, but drop sound by 6-7 dbs (claimed). My thinking in quieting the car down was since I had straight through mufflers, I wanted a second muffler with baffles, trying to cancel out as much noise as possible. The El Camino definitely didn't have any glasspack popping sounds so the baffles did help.

[rustomatic]

The glasspack idea sounds good, but may be slightly restrictive at first; then, you'll burn through the insulation, and have dead weight. You might find some used Flowmaster single chambers on Craigslist or something. Depending on how handy you are, you could buy some sheet metal and make an equivalent of the small Flow*******s yourself...

It's just hard if you're committed to three-inch pipe without the quieting benefits of a turbo.

[sgernon]

I think I'll try adding the auger inserts before the mufflers. I put 3" on because the plan is to add a centrifugal at some point.

I tried making 4" plugs for the end of the tails by reducing 3" pipe, capping one end with expanded metal and the other with sheet metal and drilled a 2" hole in it. I then filled it with steel wool. It made no difference in the decibel reading so now I'm even more nervous.

My other thought after reading about mufflers so much is to swap to a hooker max flow and make 2.5" tail pipes. They seem quiet at idle and part throttle but I'm not sure if I'd be going backwards at full throttle but I like how much more they flow than the chambered style I have..... I think I'm over thinking this...

[Flash68]

or just make some pipes that exit or turn toward driver side?

[sgernon]

That helps for the track but I still have to fight the ticket. There no way I'm paying tge fine.

I'm going to try to get some 2.5" mandrel bends tonight and build new tips with quarter exits to see if it reduces the level substantially. The 3" is rubbing the tires a little and rattles so it will help the car anyways.

[Flash68]

That helps for the track but I still have to fight the ticket. There no way I'm paying tge fine.

I'm going to try to get some 2.5" mandrel bends tonight and build new tips with quarter exits to see if it reduces the level substantially. The 3" is rubbing the tires a little and rattles so it will help the car anyways.

Oh yeah I forgot already what instigated the post! My bad!

When I was considering making mine quieter to make it to Laguna I kept being told to go with 2.5" tails also with some Walker Super Turbo muffers.

[Protour_Pinto]

What car do you have?

[sgernon]

72 Camaro

[sgernon]

I couldn't find any aluminized madrel bends locally the other night so my ADD took over again and I decided to pick up some new Magnaflows from Summit to see if they help. They will be delivered today and I'm going to try to mock them up this weekend. I'll measure the sound level for both mufflers to see if they help. If I'm still too high I'll also swap to 2.5" tailpipes and measure the difference with them so finally definative proof of how much sounds reduction is possible.

[Protour_Pinto]

I know a lot of guys running the Hushpowers with really good results.