Sound ETR #2

[01badz28]

I failed the sound on my car last year and over the winter found these baffles at Summit racing http://www.summitracing.com/parts/DTC-72-32520/
Last my car was louder than yours (102+) and this weekend it maxed at 94.9 (SM10) the baffles helped eliminate the popping when I lifted from red line.

I think the grading of the hill may have helped, too.

One thing to keep in mind is that if you were at 95, there may be a point where you need to do something to pass sound. Anybody over 90 should probably have some sort of contingency plan.

I think putting the plates back on the Borla helped too.

Yeah, sound and course setup matters tremendously. At one event I went from not being a problem, to 95db, and back to no problem the rest of the season with no exhaust or engine changes, aside from my standard lumpy cam, long tube headers, and no cats.

[jcox07]

Cool, thanks for the tips guys, I will try different things till I get the right levels. Thanks again and it could have been that easy coming from Ted if he had done it in the same manner that every one else has done. Thanks

[roadwarrior1956]

I failed the sound on my car last year and over the winter found these baffles at Summit racing http://www.summitracing.com/parts/DTC-72-32520/
Last my car was louder than yours (102+) and this weekend it maxed at 94.9 (SM10) the baffles helped eliminate the popping when I lifted from red line.

I think the grading of the hill may have helped, too.

One thing to keep in mind is that if you were at 95, there may be a point where you need to do something to pass sound. Anybody over 90 should probably have some sort of contingency plan.

I hear what your saying and do have plans to reduce the sounds further on my car (put muffler packing behind the baffle) I also took my last and best run in second gear going down the hill and will be bet you it was my quietest too.

[TedV]

Try to play catch up here. For those who don't know me, If yall want some history, Ive been involved in the racing tire industry for almost 20 years. Sorta retired from it since 2005 tho. I’ve been partial to VW Scirocco's and autocross since 1991

The FF is 1100 lbs, 115hp, and should be under 103dB in road race trim. Obviously I had to do research, install mufflers that worked, fit my budget and kept it under 96 dB. I have had to make a muffler change at an event in Huntsville. Supertrap was light, and with the disks made for easy change in grid between runs.

The old SM VW motor was turbo, over 200Hp in an 1800lb front wheel drive Scirocco. Had to add weight to be legal in class. So nope, not a 600hp mustang, but I have driven some handfuls autocrossing. Tuning the MS EFI on the street I outran a 600cc sportbike. One of the most stupid things I’ve ever done, should have put it on a dyno to tune. When I finally pulled over after realizing bike guy was gonna kill himself trying to keep up, he stopped and had to ask “WTF is that thing??” On used Yokohama road race rubber it would spin the tires to at least 4th gear if not 5th if I just planted my foot and shifted. I had to work at modulating the throttle exiting a turn on Hoosier Autocross compound. Wheel spin does not effectively turn power to acceleration. It can help rotate a rear wheel drive car. Also had to work the exhaust on the Scirocco to be under 96dB cause the turbo was not an effective muffler. I feel your pain at trying to keep it quiet and put power to the ground. Do some research for what might work for the GT500. I know other V8, boosted, and even stock class 4 cylinder cars have been working to figure out what works at being quiet enough yet still makes or does not rob power.

The cones mentioned have been on my list to try on my next too loud exhaust. It looks like they may do the trick.

The best way to control sound with your right foot is no sudden movements. Being told to lift past the meter may have been an incorrect explanation. It’s more a hold the throttle steady and no sudden changes in throttle application. Yes, hard to do when power comes on like a ton of bricks. Ease on, ease off, be smooth. From what I’ve seen the sudden lift is where most cars are the loudest. Some cars have a resonance at certain RPM. Autocross is constant changes in throttle, and turning. Yup, makes it hard to be smooth yet agressive.

So many things go into what makes something loud its hard to make a complete list. So yes, if you are over 90, especially 93 you should be concerned about sound. The missing grass, bare dirt or anything can change how it is reflected.

STM7 90.5 to 92.2

Sometimes being brief on a forum things come across not as planned. Sorry bout that, Poo happens.

[onebadbugeye]

WOW 92.2! and the limit is 96? I did not think my lil 2.0L subie was nearly that loud

[Oberstwill]

When I wen tout and spoke with Mr. T, we thought that maybe the temporary burm which was created might cause a reverberation effect on the sound meter as well sicne one car from last year was comign in 4-5 db higher than before.

No one os trying to bitch, we are jsut trying to protect what we currently have for the good of everyone...........

I failed the sound on my car last year and over the winter found these baffles at Summit racing http://www.summitracing.com/parts/DTC-72-32520/
Last my car was louder than yours (102+) and this weekend it maxed at 94.9 (SM10) the baffles helped eliminate the popping when I lifted from red line.

I think the grading of the hill may have helped, too.

One thing to keep in mind is that if you were at 95, there may be a point where you need to do something to pass sound. Anybody over 90 should probably have some sort of contingency plan.

[integra55]

Walter, the integra o doom was 91.2 - 91.5

Be glad I was playing musical cars and either spun, or underspun JohnB's me-otter, not figuring it out fast enough.

integra o doom ???????


whatever....... bring it on I'll be there

[jcox07]

Got the super turbo dynamax axle backs ordered for the gt500 and hopefully this will get me in the ball park with the sound meter, thanks for the options on this. If this does not get me where I need to be would baffles in the exit tips help, I already have a resonator in the pipes in front of the mufflers. Thanks again Jeff

[TedV]

Yes. A while back Stuart Gibson had some problems with his Mustang making sound. scott made some perforated inserts that fit in the tips that quieted the exaust down. Scott had too much time on his hands drilling all those holes I wonder if an insert using the cones mentioned might be able to be fabricated..??

[scottgib]

I have since found items similar to what I made at auto parts stores. Don't remember which ones, but they are cheap. Stu's knocked 4-5 dBs off.

[jcox07]

Scott, are they cones that go into the tips of the exhaust. If that is the case then it would not hurt to have them on standby just in case the dynamax does not get me low enough. Thanks Jeff

[scottgib]

http://www.mufflermall.com/index.php?ma ... ge&pID=448

http://www.mufflermall.com/index.php?ma ... cts_id=448

This is similiar to what I made.

http://www.mufflermall.com/index.php?ma ... &cPath=100

[jcoatney]

I thought about making some sort of baffle for my truck by drilling holes and insulating the pipe like a glasspack but I looked around and Performance Products sells some nice ones for $29.95. I replaced my exhaust tips with these and it made the truck much better, especially on the Intersate. I still don't think it would pass sound though.