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Any suggestions for an exhaust system for a 6 cup with a street gt3 motor? I need to get it close to 103dB for the local tracks.
Any advice appreciated.
Some UK Cup cars used curved downward facing exhaust tips to meet noise levels, sorry I can't find a photo just now. I think Karl Lenord posted a photo here years ago.
Forgot to mention that we tried this method. Did not work. Still had to pack it up and go home. I have been told that a center street GT3 muffler may be the fix.
I've used the street GT3 exhaust minus the cats with good results at Lime Rock
which requires 87 db. We don't get to 87 but close enough they let you run
There are a number of European vendors that sell exhausts that fit the 6 GT3 that will meet you noise requirements.
Look at "https://rennlist.com/forums/porsche-cup-cars/805124-can-someone-identify-who-made-these-mufflers.html" for examples. My car runs at Calabogie and LCMT just fine. I have the 110db cup car center muffler
In case you did not know...
There are quiet and loud versions of 6cup and early 7cup exhausts.
I have a quiet version on my 6GT3. .. I manage to get around LCMT which has noise restrictions with a little caution/lift where the soundman hides.
Thanks for the help everyone. There is a shop a couple hours away that has a street gt3 center exhaust that they have used successfully to get below 103 at the local tracks. I am going to try that route. Will post back after we go back out. It was very difficult for me to concentrate on my driving while worrying about the sound meter and getting meatballed. Not a multitasker I guess!
In case you did not know...
There are quiet and loud versions of 6cup and early 7cup exhausts.
I have a quiet version on my 6GT3. .. I manage to get around LCMT which has noise restrictions with a little caution/lift where the soundman hides.
I did not know this. What are the differences between the quiet and loud exhausts on the 6 Cup? Can you tell by looking?
We have worked on the exhausts and tested many of them including open exhausts. We make one, but I would not say that it is going to do any better to meet your 103db requirement than what you have.
Burns Stainless does make a high quality muffler, but it does about the same for sound as many of their competition (including the one you already have). They can make one that has more sound deadening, but at the price of back pressure and therefore horsepower.
A system like the factory 103db or something more exotic like a full M&M system (which is going to run $10k or more) is what you need to get you there without significantly reducing Hp. (you would actually have a Hp gain. Even our exhausts have shown a Hp gain over straight pipes)
Even in some atmospheric conditions, however, the factory 103db system is going to blow over the 103. You need a factor of safety to meet the number.
Also, advertised numbers are not necessary all measured the same. This is why when we were looking at ours, the factory muffler, and others, we did the testing on a dyno, indoors, and a controlled environment back to back to get true, however, relative not absolute, sound readings.
Thanks Ed, always appreciate your help and input. Thanks also to rbahr-I found your previous posts and am appreciative of them as well. I think we are going to try a street GT3 center muffler section, as I don't think an original 996 cup center muffler is going to be easy to find. Too bad, as it sounds as if it is working perfectly for Bob (fstop carrera). It sounds like the european folks probably have an easier time of this than we do, as MandM is local to them.
Spiller, the part number is stamped on the exhaust and as you can see by rbahr's parts diagram, the quieter exhaust ends in .93, with the 102 ending in .92. I read someone's post, though that the part number gets pretty rusted over time, and you may have to do some searching to find it.