JCR-Porsche

We have a good amount of owners running our Titanium Silenced Tips now in the UK with great success. For a 10 minute job its a great thing to have as a 'just incase' as you can find yourself unlucky with weather / wind direction etc and fail on days that you would have otherwise never had an issue with.

JC

JarmoL

Ignore this..

JarmoL

This sounds interesting. But what is rad tubing? You say it won't melt. What material is it?

fxz

To stroke the gases isn t bad for the engine when at high rpm (high pressure) ?
Why Porsche spend mo ey on that convoluted center and side mufflers to reduce the dB if 2 simple design silencer are enough? i guess you can kill the dB but you need something more for a 4liters engine, afterall is not a motorcycle where pressure is way less, i guess Dundon has a black center muffler but not sure is quiter than stock center muffler

Manufacters should publish their dB inside and outside (idle and throughout rpm)
will take 1hour job

Bob Rouleau

Well thanks for the info guys. I am going to the track to test the valves wired shut option. Takes only 5 minutes to install. Not sure about damage to the engine since we run high speeds only 20 minutes out of the hour. On the road it won't matter since full throttle is almost never used. Next step will be the Soul performance turn-downs with built in resonator..

Our track measures at multiple locations so simply lifting in front of the measuring point is near impossibkle since the sound police move from spot to spot.

Best,

A/S

^^^Please, keep us posted of your experience with shutting the valves closed (which surely will pass any 92dB day).

I would plug a data logger (Solo DL2 is affordable) with the ODB2 connector, and get a reading from the multiple temperature sensors running with the valves in normal position for a track session, and then valves forced closed for another track session.

You'll be running the equivalent to a 50mm restrictor plate on the exhaust of a 3 cyl engine that revs 9,000rpm, so it should reduce power.

I'm planning a Dyno day this week to test my car with valves wired closed, then valves in normal position, as I want to see how much power my car loses on a quiet (sound regulated) event where anything under 94dB is required.

ajw45

FWIW, the Dundon quiet center shaved about 8db off the titanium RS center on my GT4. It works. Add turn downs and it's probably a >10db reduction from stock....

K_style

But $1800 seems little crazy price..

Bob Rouleau

OK, we tested today. My 2019 GT3RS which did break the 92 dB limit was 5dB under with the valves wired closed. An identical car without the modification was at 90 dB just under but too close for comfort. No heating issues were observed. Note since this was an unrestricted (no noise limits) we were all making maximum noise. The loudest car was a 2018 GT3 - go figiure. Surprisingly a Cayman GTS (4 cylinder turbo) was almost as loud as the Gt3. So for now two pieces of wire seems a simple and cheap way to stay legal.

A dyno run is posted onthe sharkworks web site, it showed 7 HP and 17 ft lbs of torque lost. With 520 to start with, I can take the small decrease.

The next test will be with the Soul Turn-downs with built in resonator. All tests were supervised by track management and a professional sound engineer.

Best,

TRAKCAR

^^ Thanks Bob!

mchrono

yes point it down or away from the mic and that might work!

Dougr743

Radiator tubing can withstand the heat, and is strong enough to keep its shape under pressure. its going to drop DB way better than pointing metal tubes. The rubber kills the sound wave and muffles the note. Its so simple and works better than turn downs. try it, take s2 c clamps and 4 bucks in tubing, plus you can take it off in seconds. no damage, no worries

Dougr743

Put it about an inch from the ground. the sound never gets off the surface of the tarmac. It cant hit the resonation and bounce back. the DB sensors will never pick it up, or at least minimally We use to do this to pass sound ordnance running late at night, testing bikes. also when you need to cut sound on our dirt bikes to go into national forest areas that require sound levels and spark arrestors. Its the way around this. try it!

Bob Rouleau

Just a follow up to my post about sound tests. We had only 4 cars on track a pair of 2019 GT3RS - one with valves wired shut (mine) and another without as a control. A 2018 GT3 stock and a Stock Cayman 718 GTS.
None of the cars exceeded 92 dB! All of us were trying to make as much noise as possible - full throttle passes at near max revs and on some passes upshifting right in front of the sound meter.

Does this sound odd? Yes, obviously since the same cars had exceeded 92 dB a few days earlier. We discovered a few things, for example, full throttle in the mid range gave higher readings that at high revs. Go figure. The other big factor was the ambient noise level. With only 4 cars on track, we didn't make a lot of noise, so the ambient level was low. With 30 cars on track the situation would be different. For those who know Le Cicuit Mont Tremblant testing at T5 (exit of the esses) showed an ambient level of 30 dBA. With cars on track at Bridge T12 the ambient level at T5 was 60 dBA! even though there were no cars at T5. While T5 is far from T12 track-wise, it is only a few hundred yards line of sight.

What this means is that a single car might easily pass sound but if the ambient level is raised by other cars even at some distance, the same car might exceed 92dBA. Based on some rather rough estimates, it looks as if ambient noise can add 2-3 dBA to the measurement of a car which passes sound when alone on track. Which explains why a car measured full bore at 90 dBA got black flagged for exceeding sound limits a few days earlier when there were dozens of cars on track.

krell

I don't doubt the observations but technically that doesn't make any sense. Regardless of the noise floor of an environment, something that is louder (dB) will always rise above it and not be influenced by it.