Skibum1963

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.

major dad

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.

major dad

Skibum1963

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.

Dan Jacobs

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

rbahr

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

Ray

DHI

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.

Skibum1963

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!

Skibum1963

Here is a picture of current setup.

spiller

I did not know this. What are the differences between the quiet and loud exhausts on the 6 Cup? Can you tell by looking?

rbahr

Hi All,

I spent 2 winters ago trying to figure this out.

There are indeed 2 cup car exhausts:



BUT 103 AND 110 DB are both loud enough to upset folks.

The Europeans have been worried about noise a bit longer than us. There are at least 2 companies that have made systems for the 996/7 cup car that Porsche has used:
http://www.ferrita.com/en/ and http://www.m-m-germany.de/unternehme...treet-exhaust/

You can fab something using Burns Stainless components: http://www.burnsstainless.com/ - which are expensive but pretty good quality.

I was lucky to fine a used European system that uses the 110db cup car center section that still works at LCMT and Calabogie to name 2 tracks.

I have also tried both up facing and down facing outlets - neither worked well enough.

DHI: There are 2 sound testers at LCMT - one is fixed across from the Start/Finish and there is one that roams around...

Ray

911racer

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

Skibum1963

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.

Skibum1963

correction, the 110db ends in .92

Dan Jacobs

If you are talking about a 997 GT3 center muffler I doubt very much that will get you to 103