Bob, excellent thread it has been a pleasure to read and I greatly appreciate all your efforts for the fellows running at Tremblant. I'm working on a solution for the 987.1 to 718 Cayman/Boxster platform as we speak. I very much look forward to hearing your thoughts once you guys start putting our resonated turndowns to good use up there.

Per your latest post and krell's feedback, I reached out to Mike (mdrums) as he is a bit of a sound extraordinaire and it was interesting to hear his thoughts.

"Noise floor does not add to peak db level... a 100db sound is only that no matter the noise floor around the db meter. I wonder what meter they are using? Is it A, C, Z weighted to measure sound. A weighting measures sound more like the human ear heads in the more sensitive human hearing range of 500hz-6k..... If they are weighting the mic in C or Z weights it will pick up more frequencies and produce a higher db. They should use A. Also the difference in db from day to day with the same car has to do with weather..humidity and temp plus there is no way to say the car passing the db meter was in the same exact spot and angle to the mic...plus as engines and exhaust heat up and cool they expand and contract and can produce different loudness levels...it's really hard for human hearing to tell the difference of 1-3db but a microphone db meter surely can." -mdrums

Regards,
John Gaydos

 

Thanks John, to reply to MDrums (I met him at Barber The day we tested years ago and again a Tremblant fewer years ago) the meters read dBA. W were trying to understand why cars that eceeded 92 dBA one day did not on another day when weather conditions were essentially the same. Hard to believe tthat humidity etc could add 3 dB to a measurement taken 50 feet away.

Sadly the Soul turn-downs seem to be stuck in Customs according to Fedex. Hope they are released in time!

Best,

Bob

 

Appreciate all your testing at LCMT! I'm heading up there in August and trying to figure out what exhaust to run. On my GT4 with race headers and Dundon quiet GT3 center I can just squeak by (got flagged for .5 db over last summer). Hoping to see if I can run the race headers with the 991.1 GT3rs center exhaust with soul resonated turn downs this year so I look forward to hearing your results!

 

Dougr743,

I'm intrigued by your potentially easy solution. I've googled S2 C clamps. I can see C clamps but its not showing an S2. Do you have photos of your setup? I'm having a hard time visualizing how the radiator tubes connect to the tailpipes. Do the slide over tubes over the tailpipes or inside and how do you attach them?

Thanks

 

Guys, we just came off our two day event at LCMT. The good news - GT3, GT3RS, GT4, 718 GTS with vales wired shut did not get black flags. Those with valves open were busted. There was one exception - a 2019 RS Weissach edition vales open did not get busted. Go figure. He was busted at the May event. Another GT3RS with valves wired shut but the center muffler removed was black flagged. On day 2 he installed the missing muffler and was fine.

Another oddity a 2016 RS with the Soul Turn-downs (with resonator) was busted with his exhaust valves open. As you can see there are some inconsistencies I cannot explain. In case you are wondering the 2019 RS Wessach I mentioned above was not *****-footing. I was following him in the red group and he was making no effort to reduce sound.

So things we learned - valves wired shut with a modified exhaust system you are probably at risk. Stock cars that usually get nailed are fine with the valves shut.

Best,

 

Thanks for the update Bob. Crazy results. I have a GT4 and stock I was fine (in 2016), with race headers and stock exhaust I was flagged 94db and had to take it easy (2017), with race headers and the Dundon Motorsports quiet GT3 exhaust I got dinged for 92.5db (2018) but it seemed to be a fluke and was able to keep driving the rest of the days with no issues. PSE off but no valve overrides.

Do you think there have been changes to the sound meter hardware over time or greater/different use of the roaming sound guy? Any worries about running hard with valves forced shut? Were any of the GT3s running race headers and side deletes? This year I was thinking of going with race headers, GT3rs stock titanium center, and Soul resonated turn downs but it sounds like that might not be even close to passing....

 

Whoa, Tremblant has gotten strict. Sound limit is 92, I got pulled for hitting 92 - strike one. Hit 93db next session so they kindly let me take the afternoon off at the hardware store....

Drove the dryer vent mod all day and passed without issue!


GT4, PSE off, sport on, valves still working, race headers, DMS quiet center, and 4" dryer exhaust turn downs pass np.

There's an M3 running turn aways pointed right (infield). I think that's the answer, lift for the sound meter on the straight and then hammer around the rest of the track since the floating sound check guy seems to be mostly in the outfield (left side) of the track. I'm tempted to run the oem RS center exhaust next year with soul resonated turn aways pointed infield...

 

Ajw45 Turning the down pipes to one side or the other doesn't work, they measure at different locations on opposite sides of the track. Having been part of an experiment a month ago, our cars made more noise existing the esses and at turn 7 than on the front straight. ALL the GT3, GT3RS and STOCK GT4s run with the valves wired shut and pass sound. Else we get invited to leave. In case you didn't know Le Circuit is my home track and they have really tightened up on sound. Oh and the 718 GTS also need to close the valves.

best,

Bob

 

We have new tips for the quiet muffler and getting good results

The tips are modeled off of the ones Porsche used at the Nurburgring record run!

 

I passed sound at LCMT with NNJR/NER early July, with Soul turn downs pointed slightly towards right, valves left alone. Stock 991.2 GT3 PDK, Mustang 350R in our group got black flagged.

I'm sure of measurement at front straight, leftside - I also saw measurement guy after the bridge on the right. Could be more that I haven't seen.

I visited the tower multiple times during that event, and guys were getting black flagged left and right. Definitely a new era at Le Circuit.

I have a suspicion that PDK cars a bit more likely to get black flagged because they're so effortlessly running higher revs, and the shifts seem quicker with some pops and bangs.

 

Argh, you're right. The sound guy moved from turn 6 to the exit of turn 7 and what worked yesterday blew 94db today . Lots of cars got flagged for the first time this weekend since he moved to 7.

Fortunately the dryer vents articulate so turning them to the right made all the difference. The DMS setup looks good but I think something that rotates so we can point away from the sound ninja would be good too.

 

Nice, any idea how many db you are shaving off the stock tips?

 

So far took a customer from failing to passing at the NRing,

can get you a discounted set to try. The science is the sound wave is reflected back on itself and the mass flow (gasses) come out the bottom.

 

As earlier reported wiring the valves shut allows cars to pass sound at Tremblant. Have just installed the Soul Performance valve controller. Push a button on the remote and the valves stay shut. Push another button and they stay open.. Works like a charm. Nice job Soul!

 

This is the same concept but with radiator hose, the rubber slows the wave, and also flexes in case you hit it or if it falls off, it does not cause damage to anything or anyone. simple C clamp and go